Optical code division multiple access using carbon nanotubes system

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INTERNATIONAL JOURNAL OFELECTRONICS AND International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME COMMUNICATION ENGINEERING TECHNOLOGY (IJECET) ISSN 0976 – 6464(Print) ISSN 0976 – 6472(Online) Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME: http://www.iaeme.com/IJECET.asp Journal Impact Factor (2014): 7.2836 (Calculated by GISI) www.jifactor.com IJECET © I A E M E OPTICAL CODE DIVISION MULTIPLE ACCESS USING CARBON NANOTUBES SYSTEM Jafaar Fahad A. Rida, A. K. Bhardwaj, A. K. Jaiswal 1Dept. of Electronics and Communication Engineering, SHIATS -DU, Allahabad, India. 2Dept. of Electrical and Electronics Engineering, SHIATS - DU, Allahabad, India, 3Dept. of Electronics and Communication Engineering, SHIATS - DU, Allahabad, India 1 ABSTRACT In recent years, significant progress in understanding of the physics of carbon nanotube electronics devices and identifying potential application has occurred. In a nanotube low bias (160m V – 200m V) can be nearly ballistic across distances of several hundred nanometers. The study and analysis of the optical proprieties through Katuara plot explains the behavior as semiconducting or as metal, Carbon nanotubes are supporting in optical system applications. The electronic proprieties are governed by a single parameter named the chiral vector, and there are three parameters affecting the performance of carbon nanotubes diameter, chirality, and number of walls. The carbon nanotube supports optical proprieties by three main parameters very important to develop work with optical system application such as Electronic structure of carbon nanotubes, Saturable absorption, and third order Nonlinearity. Depending on the chiral vector carbon nanotubes behave as semiconductor or metal. But here focus on semiconducting carbon nanotubes to improve optical integrated circuit. The analyze Optical Code Division Multiple Access (OCDMA) with Carbon Nanotubes (CNTs) to improve three parameters very important in any communication system as data rate (R), bit error rate (BER), and signal to noise ratio (SNR). It can be divided into broad categories based on the way in which a particular user’s code is applied to the optical signal. The presents optimized design performance of incoherent OCDMA as well as coherent OCDMA using carbon nanotubes (CNTs) based devices with reference to increased Data Rate (R) and reduced Bit Error Rate (BER) which is far enhanced in comparison to Silicon based Optical Devices. The carbon nanotubes with OCDMA system supports ultrahigh speed network with data rate upto Tb/s and exceptional BER performance in the system. As observed and presented in this paper, the carbon nanotubes brought in the improved performance OCDMA system network with highest data rate and lowest bit error rate. Keywords: OCDMA, CNTs, Optical Systems, Coherent OCDMA, Incoherent OCDMA and PPM and OOK Formats.

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME 2 INTRODUCTION Carbon Nanotubes (CNTs) were discovered by Sumio Iijima in NEC in Japan in the early 90s [1].Carbon is the most important element of the periodic classification for human being. The six electrons with two of them fill the first orbit as shown figure 1. The remaining four electrons fill the second orbit as Diamond ( ) and Graphite ( ) as well as Sp hybrid orbital, responsible for bonding structure of diamond, graphite, nanotubes, and fullerenes [3]. It has since become a prominent material for an amazing breath of scientific and technological displines of ranging from structural and material science to chemistry, biology, and electronics [2]. Carbon nanotubes are one of most commonly mentioned building blocks of nanotechnology, with one hundred times the tensile strength of steel, thermal conductivity better than all but the purest diamond and electrical conductivity similar to copper but with the ability to carry much higher currents, they seem to be a wonder material, thin cylinders of graphite. Graphite ( ) is made up layers of carbon atoms arranged in a hexagonal lattice like chicken wire. Though the chicken wire structure itself is very strong [4]. But let’s look at some of the different types of nanotubes and nanotube pretenders such as One of major classification of carbon nanotubes is into Single – walled varieties (SWNTs), which have a single cylindrical wall, and Multi-walled varieties (MWNTs), which have cylinders within cylinders as shown in figure1 which illustrates all stages fabricated for carbon nanotubes (CNTs). There are three parameters very important in carbon nanotubes (CNTs) as diameter, chirality angle, and number of walls, and also has unique physical and chemical properties. There are two types for fabrication first, chemical (chemical vapor deposition (CVD)) and second, other physical methods (Arc discharge, Laser ablation).The graphite layer appears somewhat like a rolled up chicken wire with a continuous unbroken hexagonal mesh and carbon molecules at the apexes of the hexagons [5]. They have two conduction bands and and two valence bands and, these are called Van Hove Singularities observed in their electronic density of state (DOS) of these carbon nanotubes (CNTs). The direct electronic band gap proportional to diameter for semiconducting carbon nanotubes, while the direct band gap equal zero for metal carbon nanotubes so, they use in high electrical current. It has typically have diameters range (1-2) nm for single walled nanotubes and (2- 25) nm for multi-walled nanotubes as well as the length of nanotubes may be (0.2 - 5) μm or some centimeters, and the spacing distance between walls is 0.36nm. Here, a single wall nanotube is prepared for optical proprieties applicable with optical system [6]. The potential applications of carbon nanotubes have been attracting increasing attention from the photonics research community [7]. It exhibits an exceptionally high third order optical nonlinearity and nonlinear saturable absorption with ultrafast recovery time and broad bandwidth operation. Thus, carbon nanotubes are becoming a key component towards the development of fiber lasers and nonlinear photonic devices.They are making a more significant contribution towards the development of next generation devises both from an academic and a commercial point of view. General rules have desired the topology of the termination as a function of the Hamada indices (n, m). Carbon nanotubes can also be opened ended, according to the integer n and m so, they may behave either semiconducting or metallic.These calculations electronic structure for carbon nanotube shows about 1/3 of carbon nanotube is metallic and 2/3 is semiconducting, depending on the nanotube diameter ( ) and chiral angle ( ). Another classification for carbon nanotubes depending on chiral vectors (

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), they are Zigzag nanotube, armchair nanotube, and chiral nanotube. There are three parameters to develop carbon nanotubes optical proprieties to work in optical system, Electronic structure of carbon nanotubes, Saturable Absorption of carbon nanotubes, and Third order nonlinear for carbon nanotubes. The high pressure carbon mono-oxide (HiPCO) has been one of the fabrication methods for the mass production of carbon nanotubes. The typical network architecture for OCDMA with broadcast star is shown in Figure2. It can be seen that one of the key issues to implement OCDMA networking and communication is how to

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME encode and decode the user’s data such that the optical channel can be shared, that is, we need to develop the practical encoding and decoding techniques that can be exploited to generate and recognize appropriate code sequences reliably [8]. Therefore, The OCDMA encoders and decoders are the key components to implement OCDMA systems. In order to actualize the data communications among multiple users based on OCDMA communication technology, one unique codeword-waveform is assigned to each subscriber in an OCDMA network, which is chosen from specific OCDMA address codes, and therefore, different users employ different address codeword-waveforms. Figure 1: illustrates all stages fabricated for carbon nanotubes (CNTs) from carbon atoms, graphite sheet, and rolled as form tube Optical code division multiple access (OCDMA) technique is an attractive candidate for next generation broadband access networks [9-10]. Basic architecture and working principle of an OCDMA passive optical network (PON) network, in the OCDMA-PON network, the data are encoded into pseudorandom optical code (OC) by the OCDMA encoder at the transmitter and multiple users share the same transmission media by assigning different OCs to different users. At the receiver, the OCDMA decoder recognizes the OCs by performing matched filtering, where the auto-correlation for target OC produces high level output, while the cross-correlation for undesired OC produces low level output. Finally, the original data can be recovered after electrical thresholding. Due to the all optical processing for encoding/decoding, OCDMA has the unique features of allowing fully asynchronous transmission with low latency access, soft capacity on demand, protocol transparency, simplified network management as well as increased flexibility of QoS control. In addition, since the data are encoded into pseudo-random OCs during transmission, it also has the potential to enhance the confidentiality in the network [11- 15]. In an OCDMA network using on-off keying pattern, the user’s data is transmitted by each information bit “1” which is encoded into desired address codeword. However, the transmitter does not produce any optical pulses when the information bit “0” is sent. In terms of the difference of signal modulation and detection pattern, OCDMA encoders/decoders are roughly classified into coherent optical encoders/decoders and incoherent optical encoders/decoders. The incoherent optical encoders/decoders employ simple intensity-modulation/direct-detection technology and the coherent optical en/decoders are based on the modulation and detection of optical signal phase. As global network infrastructures expand to support various type of traffic, photonic networks are expected to take an important role. The increasing demand for bandwidth forces network infrastructures to be large capacity and reconfigurable [16]. The efficient utilization of bandwidth is a major design issues for ultra-high speed photonic networks, also it increases data rate (R), and decreases bit error rate (BER) so as to perform with improved signal to noise (SNR).The roots of OCDMA are found in 3

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME spread spectrum communication techniques. Spread spectrum was developed in the middle -1950s mainly as a novel form of transmission overcoming the grid restrictions in radio bandwidth allocations [17-21]. It is based on the idea of spreading the spectrum of the narrow band message over a much wider frequency spectrum by means of digital codes [22-23].Within the category of coherent systems, it is useful to further classify OCDMA systems based on the way in which phase coding is applied to the optical signal field. Since optical phase can be manipulated in either the frequency domain or the time domain, two types of coherent OCDMA systems are possible, as Spectral Phase Coded Optical CDMA (SPC-OCDMA) and Temporal Phase Coded Optical CDMA (TPC-OCDMA) [24-29]. Incoherent schemes use the simpler, more standard techniques of intensity modulation with direct detection while Figure 2: Schematic diagram of an OCDMA system coherent schemes are based on the modulation and detection of optical phase The most common approaches to incoherent OCDMA are based on spectral-amplitude coding, spatial coding, temporal (time) spreading, and two-dimensional (2D) wavelength-hopping time-spreading (WHTS) [30- 37].The performance of any communication system is fundamentally limited by the available bandwidth, the signal to noise ratio of received signal, and the codes used to relate the original information to the transmitted signal. These limits inevitably lead to increased errors and corresponding loss of information [16]. An OCDMA network is expected to be able to accommodate many subscribers and simultaneous access users, and to have high date rate for each user and low bit error rate [8]. However, since they are strongly associated with each other, optimized performance analysis of network becomes an issue of multiple target function description, which is very complex. Next generation of optical communication system may preferably incorporate carbon nanotubes based devices so as to achieve much higher data rate up to Tb/s in comparison to present systems using silicon optical devices giving data rate upto Gb/s. Besides, such systems with advanced energy source power realize in much longer life Nevertheless, future requirements of ultrahigh speed internet, video, multimedia, and advanced digital services, would suitably be met with incorporation of carbon nanotubes based devices providing optimal performance. Two novel types of carbon nanotubes (CNTs) based multiplexers. The new device is a solid – state transmission gate (t-gate) multiplexer that uses carbon nanotube as channel in the Field Effect Transistor (FET) of both n- FET and p- FET type. Because it has been shown that carbon nanotubes – based FET switches are reliable and ultrafast responsivity using much less power than a silicon optical – based devices, and thus support ultrahigh data rates to Tb/s for ultrahigh speed application networks. The new device will consume less power than traditional t – gate multiplexer [38]. Nanotechnology is new field of Research that cuts across many fields of electronics, chemistry, physics, and biology, that analyzes and synthesize objects and structures in the nano-scale ( ) such as nano particles, nanowires, and carbon nanotubes (CNTs). Carbon nanotube is one of several cutting- edge emerging technologies and very wide range of applications in many different streams of science and technology [39-46]. Here, we determine some of important parameter in this system as data rate (R) with Pulse Position 4

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME Modulation (PPM) formats, and bit error rate (BER) and also for On- OFF Keying (OOK) formats on Incoherent OCDMA 2-D wavelength – hopping / time spread technique and coherent OCDMA spectral phase encoding and temporal phase encoding for analysis and computing BER for silicon optical devices and carbon nanotubes. Multiplexing technique is to increase the capacity of an optical link beyond the limit available for serial transmission, a service provide can either install an additional fiber or to use some form of multiplexing. Multiplexing allows multiple channels to be transmitted simultaneously over a single optical fiber giving networkprovides access to the large bandwidth capabilities of single fiber which can lead to increased throughput in the network without laying additional fiber. Optical multiplexing can be achieved through multiplexing either in the time domain, wavelength, or hybrid of both. Due to the large bandwidth (5GHz) and associated high bit rates, the multiplexing process is beyond the capabilities of pure electronic methods and has to be implemented optically as well. Code division multiple access (CDMA) is strong candidate for creating effective multiple methods for the optical subscriber access network because of its asynchronous access and code multiplexing [47]. ASSUMPTION SYSTEM AND SIMULATIONS A single wall carbon nanotube (SWTN) can be described as a single layer of graphite crystal that is rolled up into a seamless cylinder, one atom thick usually with a small number (perhaps 20 - 40) of atoms along the circumference and along length (micron) along the cylinder axis [49]. This nanotube is specified by the chiral vector (

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(1) Where nand m are two integers indices called Hamada integers, which often described by the pair of indices (n, m) that denote the number of unit vectors n* and m* in the hexagonal honeycomb lattice contained in this vector and where = = = * =0.246nm,where = 0.142nm the c-c bond length and are graphite lattice vector ,which two vectors real space vectors[2], [3],[48][49]. The chiral vector makes an angle ( ) called the chiral angle with the zigzag or direction.as figure 3. The vector connects two crystallographically equivalent sites O and A on a two – dimensional (2D) graphene sheet where a carbon atom is located at each vertex of the honeycomb structure [48]. The axis of the zigzag nanotube corresponds to = 0, while the armchair nanotube axis corresponds to = 30, and the chiral nanotube axis corresponds to 0 30. The seamless cylinder joint of the nanotube is made by joining the line AB to the parallel line OB in figure 3, in terms of the integer (n, m), the nanotube diameter ( ) is given by equation (2). 5 !! # (2) The nearest – neighbor C-C distance 1.421 or 0.142 in graphite,

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is the lengthof the chiral vector and the chiral angle ( ) is given by equation (3) $ %'() *!)+ (3) Thus, a nanotube can be specified by either its (n, m) indices or equivalent by and .

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME Next, defined the unit cell OBBA of the 1D nanotube in terms of the unit cell of the 2D honeycomb lattice defined by vectors and as shown figure 4 a) the unit cell and b) the brillouin zone of two – dimensional graphite as adopted rhombus and shaded hexagon, respectively, where and are basis vector in real space, , and ,are reciprocal lattice basis vectors. In the (x, y) coordinates in figure 4, the real space basis vector and are expressed as equations (4) and (5). Figure 3: explaination of synthesis of carbon nanotubes from graphite sheet 6 -/ - - .( -/1- 0 / - '( + (4) And 2 . 3 (- / 3 - 0 / 2 ' 3 (-/ 3 - + (5) Figure 4: characteristics of structure the unit cell real and reciprocal where a= = = 0.246nm A is the lattice constant of two – dimensional graphite, correspondingly the basis vectors , and , of the reciprocal lattice. Corresponding to a lattice constant of 45 6 in reciprocal space, the direction of the basis vectors , and , of the reciprocal (b=2.949nm A) hexagonal lattice are rotated by 30 from the basis vectors and of the hexagonal lattice in real space, by selecting the first brilluoin zone as the shaded figure 3, the highest symmetry points, , K, and M as the center, the corner, and the center of the edge respectively. The energy dispersion relations are calculated for the triangle MK shown by the dotted lines in figure 3. To define the unit cell for the 1D nanotube, defined OB as figure 3 as the shortest repeat distance along the nanotube axis, there by defining the translation vector (T) 7 8 - 8 - (6) Where the coefficient 9 and 9 are related to (n, m) by equation (7)

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME 7 8 ' *!)+ :; -*:8 ' *!)+ :; (7) Where dR is the greatest common divisor of (2n+m, 2m+n) and given by equation (8) :; :/ = 1 =?@9AB9=BC@: (:/ = 1 =?AB9=BC@: D (8) In which d is the greatest common divisor of (n, m). The magnitude of the translation vector E E 7 (F :; (9) Where L is length of the chiral vector

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and isthe nanotube diameter. The unit cell of the nanotube is defined as the area delineated by the vector T and

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. The numberof hexagons, N contained within the 1D unit cell of a nanotube is determine by the integers (n,m) and given by (10) G '* !*)!) + :; (10) The addition of single hexagon to the honeycomb structure figure 1 corresponds to the addition of two carbon atoms. Assuming a value H IJ on a carbon nanotube, we selected here (17,0), (12,5),(10,10),(16,2),(15,0), and (11,11) nanotubes. Since the real space unit cell is much larger than that for 2D grapheme sheet, the 1D Brilluoin zone (BZ) for the nanotube is much smaller than the BZ for single two grapheme 2D unit cell. Because the local crystal structure of the nanotube is so close to that of a grapheme sheet and because the Brillouin Zone is small, Brillouin Zone – folding techniques have been commonly used to obtain approximate electron and phonon dispersion relations for carbon nanotubes (n, m) with specific symmetry – whereas the lattice vector T, given by equation (6), and the chiral vector

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, given byequation (1), both the unit cell of the carbon nanotube in real space, the corresponding vectors in reciprocal space are the reciprocal lattice vectors (k2) along the nanotube axis and (k1) in the circumferential direction, which gives discrete k values in the direction of the chiral vector

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. The vectorsK and K are obtained from the relation ;L MN 3 OLN, where PQRS are the lattice vectors in real and reciprocal space respectively. Form KK can be written as T G '18 2 8 2 +-*:T G')2 1 * 2 + (11) Where , and , are the reciprocal lattice vectors of a two – dimensional graphene sheet given by equation (5). The N wave vectors UK'U /V/W 1 + give rise to N discrete k vectors in the circumferential direction. For each of U discrete values of the circumferences wave vectors a one – dimensional electronic energy band appears, whereas each U gives rise to 6 branches in the phonon dispersion relations [48]. A nanotube (n,m) is formed by rolling a graphite sheet along the chiral vector

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on the graphitesheet rolled. The nanotube can also be characteristized by the diameter ( ) and the chiral angle is with respect to zigzag axis . A Single Wall Nanotube (SWNT) can be visualized as a hollow cylinder, formed by rolling over a graphite sheet. It can be uniquely characterized by a vector

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in terms ofa set of two integers (n, m) corresponding to graphite vectors and. By rolling a graphite sheet in different directions, two typical nanotubes

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME can be obtained: zigzag (n, 0), armchair (n, m), n= m, and chiral (n, m), where nm0, they are (17, 0), (15, 0), (12, 5), (16, 2), (10, 10), and (11, 11). The lattice constant and intertube spacing are required to generate a SWNT bundle, and MWNT, the most experimental measurements and theatrical calculations, agree that on average the C-C bond length and intertube ' HI+ [49]. Thus, equations (1) and (2) can be used to model various tube structures and interpret experimental observation. They now consider the energetics or stability of nanotubes; strain energy caused forming a SWNT from a graphite sheet is proportional to + ghi .T`- 0 fjdk 'T`- + (12) 8 XY per tube or XY Z per atom [3]. Typical experimentally observed SWNT diameter is between (0.6 nm – 2.0 nm) while smaller (0.4nm) or larger (3.0nm). In simplest model [3], the electronic properties of a nanotube derived from the dispersion relation of a graphite sheet with the wave vectors (K[/ K), [3], [7]. ]^T_/ T`a bcde f ghi'(T_- Where lmis the nearest neighbor – hopping parameter and a lattice constant (ln = 2.5eV- 3.0eV) from different sources and a=0.246nm. When the graphite is rolled over to form a nanotube, a periodic boundary condition is imposed along the tube circumference or the C directions. This condition quantizes the two – dimensional wave vector k = (K[/ K) along this direction. The k satisfies k.c=2op are allowed where q is an integer. This leads to the following condition at which metallic conductance occurs as equation (13) (n - m) = q metallic or (2n + m) = 3q (13) Semiconducting The top half of the energy curve corresponds to the conduction o energy band while the bottom half corresponds to the valence o energy band. The conduction and valence band come into contact at the six corners (high symmetry points k) in the Brillouin zone, implying that 2D graphite is a zero – gap semiconductor, when s=0, the valence and conduction band become symmetric a ball E=qrs this is given by equation (12) and lm = 2.9 eV. The positive sign is for the conduction band and the negative one for the valence band. In contrast to Si, which is an indirect band gap semiconductor and asymmetric band structures for electron and holes, grapheme has symmetric conduction and valence bands. The energy valleys are located at the corners of the Brillouin zones, which are usually referred as the Fermi points. The basis vectors in the reciprocal lattices,S. The periodic boundary condition imposed along the circumference direction restricted the wave vectors to k.c = 2oq (14) where k is an allowed wave vector and q is integer which is the quantum number [50] – [58]. The conductance for SWNT, a SWNT rope, or MWNT given by equation (15) t tu v .wZ

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0 v(15) Where tu .wZ

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0 ' JHxK@y+is quantized conductance, M is a apparent number of conducting channels including electron - electron coupling and intertube coupling effects in addition to intrinsic channel, M=2 for a perfect SWNT G= 'zH{K@y+ that means resistance for nanotube

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME R= 6.5* ohm [24]. The knowledge of this limit (which only depends on the communication channel) allows evaluating the performance of the system, and finding the guidance to its improvement. In particular, for a linear communication channel with additive noise, and a total signal power constraint at the input, the fundamental limit to the information capacity is given by the celebrated Shannon formula [16],[ 37]. 9 |B@}~ € ] (16) Where W is the channel bandwidth, ‚u is the average signal power, and ‚ƒ is the average noise power. In comparison, the standard On- Off Keying (OOK) procedure where the information in encoded via a “ train” of nonoverlapping pulses – with the presence of the pulse in a given time corresponding to “1” and it’s absence to “0”, leads to the transmission bit rate (data bit rate R) of one bit per time slot. To avoid the interference of pulses from the adjacent slots, the size of the time slot is generally chosen to be no less than the pulse width („), leading to the transmission rate up to … bit/sec. Since the corresponding bandwidth is on order of … , OOK algorithm performance is by a factor of †‡ˆ'‰Š‹+ less than the fundamental limit. However, the representation of the fundamental limit to the information capacity in the standard form of equation (16) is unsuitable for applications to fiber – optical systems, as it was obtained based on the assumption of linearity of the communication channel, while modern fiber optics systems operate in a substantially nonlinear regime to improve the performance. Since the optical transmission lines or devices must satisfy very strict requirements for bit error rate (BER) ( E@ Œ+/ to use optical fiber for longest distance and also use integrated circuit from silicon but when the using integrated circuit from silicon does not support its work enough to transmission rate between these devices and optical fiber has largest bandwidth to transport most information but it needs the optical devices to support that use here the new device called carbon nanotubes (CNTs) preferably of the type Single Walled Carbon nanotubes (SWNTs) to get better improved performance of the system such devices are called biological device and can be used with human bodies that means it uses in small length maximum 1 centimeter so they cannot be used like fiber or optical fiber cable but they can also be used in manufacturing integrated optical circuits like encoder and decoder for optical signal, also mode locked lasers which have highest efficiency for energy and transferring optical signal with optical code division multiple access (OCDMA) to develop communication system from increasing data bit rate and to improve the SNR in the system. For OOK modulation format, the slot length is equal to the length of a frame. Assuming that both the chip time E {H Ž?C and throughput are held fixed, the code length is given by equation (17) [27] [37]. ‘ @’““R ”m•Z– –‘ @’‚‚v D (17) Where M indicates the number of possible slots within a PPM time frame and Pu H denotes the throughput in bits/chip time. At the receiving end, the data are restored by the OOK/PPM chip – level optical receiver. Since the chip – level receiver are dependent on the number of photons (optical energy) per chip in the received frame when it uses silicon optical devices the optical source power is {Hxx —99, whereas when it uses carbon nanotubes the optical source power is J IH —99. That means when we use the carbon nanotubes devices the consumed power is very low. Here, the time duration of time slot E˜ H n sec or nanosecond in silicon optical devices, but the time duration E˜ JH{ ?C or femtosecond in carbon

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME nanotubes, therefore, the carbon nanotubes ultrafast switching based system, are formulated to attain optimized performance of OCDMA technology. Parameters as indicated in table 1 are assumed for achieving enhanced performance of carbon nanotubes based OCDMA in comparison to silicon optical devices based devices which would in turn consume lesser power, miniaturized in dimension and withstand higher temperature. Table 1: parameters assumed in simulated OCDMA system Parameters Silicon optical devices Carbon nanotubes Time duration (E˜) H nsec JH{ sec Data rate (P˜) H ,=9?™?C šHš{ x ,=9?™?C Code weight (w) W=3,5,7 W=3,5,7 Load resistance (RL) { JHx Temperature for material 300K 973 K Refractive index () J n™—99 H{{ ›™—99 Source power laser (‚mmœ) {Hxx —99 J IH —99 Recharge electron (e) Hz Hz Light of speed › › Threshold value (Th) —99 —99 Boltzmann’s constant 'R˜+ H ™R H ™R Area of devices JH{ Œ JH{ Œ Length of code for OOK n=1000 n=1000 formats 10 Length of code for PPM formats n=375 n=375 Throughput in bits/chip timePm H H Noise for MAI zH{ Œ—99 zH{ Œ—99 Band gap energy 'q + H JCž JHxCž Time chip (E) {H Ž?C {H Ž?C Wavelength center (Ÿ) {{ {{ RESULT AND DISCUSSION 3.1 Electronic Structure of Carbon Nanotubes (CNTs) The electronic properties of a CNT are determined by its chiral vector

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from (1). This vector describes how the graphene sheet is rolled when forming the nanotube. Here, we take many carbon nanotubes as (17, 0), (12, 5), (10, 10), (16, 2), (15, 0), and (11, 11). They consist of (17, 0), (15, 0) which is called zigzag nanotube that means the integer (n, m) as n= 17, and m=0, the chiral angle ( ) this nanotube is used either as metal or semiconductor depending to prepare carbon nanotube open fabricated process. Here, we focus on semiconductor chiral nanotubes (12, 5), (16, 2) wherein of n= 12 and m=5 and the chiral angle (0 ), further armchair nanotubes (10, 10), (11, 11) wherein of n=m=10, the chiral angle' +, behaving as metal as expressed by equation (3). In the simulation we have got the diameters of nanotubes as (1.33nm, 1.185nm, 1.35627nm, 1.338nm, 1.175nm, and 1.356nm) respectively. We get the result between the electronic density of states (DOS) (unit measurement - arbitrary, unit), to Fermi energy in unit cell of the atoms of carbon nanotubes and energy band gap in semiconductor nanotube focused on semiconducting nanotubes, wherein band gap is given by equation (18)

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME 11 ] -j¡jcd :8 ¢H£¤¥ :8 (18) where q• the energy band gap for semiconductor which has two conduction bands and two valence bands as shown in figure 5 which illustrates how to work with two van hove singularities , with Fermi energy lm JHxCž. If (2n+m) = 3q ¦ , the carbon nanotubes would be 2/3 semiconductor from equation (13). The Kinetic energy (qœ) form the lowest subband is determine by the minimum value given by equation (20) Figure 5: illustrates two van hove singularities in semiconductor carbon nanotubes MjH§ (:8 (19) Where is the diameter of the carbon nanotube the energy output for CNTs are given by equations (20) ]'M8+ b(-j¡jcd eT8 ' ¨ + (20) (:8 And ]d b(-j¡jcd (21) Where qm is energy gap with normal temperature for graphite. Subsequently from equations (20) and (21) we get equation (20) for ]d©8 , the output energy band gap. ]d©8 ]'T8+ ]d (22) The output energy band gap for carbon nanotubes depends on doping the electron density of states in during fabrication and expressed by equation (23). ª']T+ £ (3-j¡jcd ]'T8+ e]'T8+' ] ¨ + (23) From the equations 20, 21, 22, 23 has got results as shown in figure 6 a and b has been obtained which calculated is nanotubes the energy band gap has positive as well as negative values, that is the carbon nanotubes show very high symmetry in (a) and (b) of figure 6 which illustrate (17, 0), (12, 5), (15, 0), and (16, 2) for energy gap has two van hove two conduction bands (/ ) and two valence bands () symmetries in both side positive and negative in energy gap

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME depend upon doping in electronic density of states (DOS) as in case of semiconductor carbon nanotubes, while (10,10), and (11,11) these have one conduction band and valence band these behave metallic carbon nanotubes because band gap is zero as shown figure 6 a and b..In metal carbon nanotubes the band gap between one conduction band and one valence band is zero while in semiconductor carbon nanotubes have band gap between two conduction bands and two valence bands. The incident light (photon) is observed by valence band () to excite electron to conduction band () leave a hole in and move electron from valence band () to and then leave hole in and move electron from to conduction band () to move to causing the flow of electric current is called van hove singularities as in figure 5 where energy gap is very symmetrical and low consumption optical power along life time as shown in figure 6 a and b. Figure 6 (a): the results for some carbon nanotubes (17, 0), (12, 5), and (10, 10) to get energy gap with relation DOS in this system Figure 6 (b): the results for some carbon nanotubes (16, 2), (15, 0), and (11, 11) to get energy gap with relation DOS in this system The energy corresponding to the symmetric transition p=q for Semiconducting (S) and Metallic tubes (M) follows the relations with one p – orbit approximation equation (24) and (25). [3] - [8], [48-63]. 12

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME 13 ]«« ¬ «-j¡jcd :8 (24) For semiconductance carbon nanotube, ]«« ®«-j¡jcd :8 (25) for metallic carbon nanotube, as shown figure 6 part (c). Wherein the number p (p=1, 2….,) is used to denote the order of the valence and conduction bands symmetrically located with respect to the Fermi energy as shown figure 6 c . The good diameter distribution has been chosen from 1nm to 1.5nm, and we select 1.33nm diameter for (17, 0), and 1.185nm diameter for (12, 5) carbon nanotubes respectively. This relation is between diameters (nm) for carbon nanotubes from (1nm – 2nm) for single walled carbon nanotubes (SWNTs) and energy gap. The metallic carbon nanotube has high energy because band gap is zero but for the semiconducting carbon nanotube the energy here the band gap exists and depends on p where p=1 or p=2 and this results from the equations (24) and (25). [3], [50], [63]. Figure 6 (c): the results for Kataura plot for some carbon nanotubes behavior either as semiconducting or as metallic energy gap is relation to carbon nanotube diameters in the system metallic energy gap with relation carbon nanotube diameters in this system 3.2 Saturable Absorption of Carbon Nanotubes (CNTs) The optical absorption of CNTs is of saturable, intensity-dependent nature, it is a suitable material to employ for passively mode-locked laser operation. Passive mode locking is achieved by incorporating an intensity-dependent component into the optical system. The typical absorption of a suspension of CNT fabricated by the high pressure carbon monoxide method (HiPCO) and measured by a spectrometer. This is generally a saturable absorber which absorbs the light which is incoming linearly up to a given threshold intensity, after which is saturates and becomes transparent optical power intensity for output with losses 5% from input incident optical power intensity. Such saturable absorbers discriminate in favor of pulse formation over continuous wave lasing. This is one of the key advantages of carbon nanotube – based devices as has been achieved passive in mode – locked operation not only in the C (1530nm – 1565nm) and L (1565nm – 1625nm) bands but covering also the wavelength (Ÿ) range from (1Um - 2Um) using single wall carbon nanotube saturble absorber [7], [64], [65]. The three parameters the non-linear saturable losses (¯°r HII{), the modulation depth or the linear saturable losses (¯m H{), and saturable intensity'±r6 šHxv|™), together

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME response time (²= 1.85 ps) give us the location of the applicability of carbon nanotubes for passive mode locking applications. ¯'±+ ³€ 14 ´! µ µ¶·Y ¯°r (26) The equation (26) gives the relates between the various parameters where ¯'±+ is optical intensity for carbon nanotubes and comprises of information. We selected for simulation only two carbon nanotube diameters 1.33nm and 1.185nm carbon nanotubes to get optical intensity relationship with wavelength (Ÿ) from (500nm – 3000nm). We see increasing optical intensity with increasing wavelength because the absorption is decreasing also as shown in figure 7 (a). Another relationship between the energy gap with the wavelength is as per equation (27). ] ¸j ¹ (27) Where h is Planck’s constant is equal (6.626* 4J-s) and c is speed of light (3 * ›m/s), resistance also equals (R= 6.5 * ) ohm, the half width short pulse for this simulation („ H{ s) or is femtosecond (1 * Œs). Figure 7 (a): illustrates the results for optical intensity (a, u) in satuarble absorption for carbon nanotubes (1.33nm, 1.185nm) The saturable absorption in carbon nanotube is achieved from the relationship of wavelength and absorption that means when the wavelength increases in this system the absorption decreases. Specifically of the wavelength center (1550nm), the third window in optical frequency, the absorption is approximately (0.02 d B/km) from equation (28) as also as shown in figure 7 (b). [7], [66], [67]. º »h¼¢' 7+ (28) Where T is transmittance optical intensity and can be derived from equation (29)

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME Figure 7 (b): illustrates the results for optical absorption (a, u) in satuarble absorption for carbon nanotubes (1.33nm, 1.185nm) 15 7 1 ½¾ ! ¿ ¿k-8 ½*k (29) The transmittance results in figure 7 (c) which illustrates reverse proportion with absorption it means the absorption is decreasing when the wavelength is increasing but the transmittance is observed to be increasing as shown in figure 7 (c). This also supports optical system application and can be used with Erbium Doped Fiber Amplifier (EDFA) for pumping optical power intensity of the transmitting signal so that it can be used with Wavelength Division Multiplexing (WDM) and Optical Code Division Multiple Access (OCDMA) to bring in improvement performance of optical system applications with increasing data rates. Figure 7 (c): illustrates the results for optical transmittance (eV) in satuarble absorption for carbon nanotubes (1.33nm, 1.185nm)

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME Figure 8: the results for optical power output (d B m) in saturable absorption for carbon nanotubes (CNTs) This also supports optical system application and can be used with Erbium Doped Fiber Amplifier (EDFA) for pumping optical power intensity of the transmitting signal so that it can be used with Wavelength Division Multiplexing (WDM) and Optical Code Division Multiple Access (OCDMA) to bring in improvement performance of optical system applications with increasing data rates. Figure 9: the results for optical intensity in saturable absorption for carbon nanotubes (CNTs) 3.3 Third Order Nonlinearity of Carbon Nanotubes The third order nonlinear material can be considered for optical switching, routing and wavelength conversion. Optical nonlinearity is due to optical intensity dependent nonlinear response of dielectric material. When the optical intensity of the propagating light is dielectric material is low, stimulated polarization is linearly proportional to optical intensity. However, at high optical intensity, the simulated polarization (P) exhibits a nonlinear response to the optical electric field (E), as described by equation (30). ‚ Àu'Á'+H q Á'+H q Á'+H q (30) 16

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME Where Á'+/ Á'+/ Á'+ correspond to the linear, the second order nonlinear, and third order nonlinearity susceptibility respectively. It has been reported that some types of carbon nanotubes present a highÁ'+, however, there is not much active research on exploiting this property. On the other hand, the high values of Á'+ calculated theatrically and experimentally are of great interest. There refractive index in carbon nanotubes can be described by equation (31). [49] - [66]. 17 * ( £* ;¤Â___ '(+ (31) Where Re stands for the real part the optical field is assumed to polarized so that only is components Á[[[ '+ , (n=m ) is refractive index in free space (air). We have another equation to get refractive index to get from simple equation (32) * j Ã (32) Where v is the optical frequency if we take wavelength (1550 nm) that means' H{ › | ¨ ) is high. The third order susceptibility of carbon single walled nanotube from Z-Scan spectroscopy was estimated for the same. Á[[[ '+ can be expressed by equation (33) Â___ '(+ ';¤Â(+ '¿)Â(+ (33) Where ;¤Â( f (3 *d j Äd ½*k is real part of Á'+ ; (Åm H{ +, and ¿)Â'(+ (3 *d j Äd ½*k ¹is the imaginary part ofÁ'+. The values of real and imaginary part of Á'+ are being of the carbon single wall nanotubes, the vacuum permittivity (Åm). The nonlinear relationship between the average electrical fields inside materials (D) and the incoming optical (E) field, nonlinear effects is defined the tensor of optical susceptibility x, which is the transformation matrix of the incoming E vector to get the result polarization (P) vector inside materials given by equation (34) Æ Ä¾~Â'+ ] ghi'Ç²+ Â' + ] jdk 'Ç²+ Â'(+ ]( jdk('Ç²+È (34) We get another expression given by equation (35). Æ ~ Ä¾ Â' + ] .Ä¾ Â'+ ] ( f Ä¾ Â'(+ ](0 jdkÇ² Äd ] jdkÇ² Äd Â( ]( jdkÇ²È (35) According equation (34) and (35) we can get new equation (36) Æ_ ½ ] ½*k ] + * ]( (36) We can get results for optical polarization intensity in third order nonlinearity for carbon nanotubes the maximum optical intensity between wavelengths (1540nm – 1550nm) for single wall nanotube by equation (36) as shown in figure 10 (a).

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME Figure 10 (a): explains optical polarization intensity in third order nonlinearity for carbon nanotubes (CNTs) also single wall nanotubes (SWNTs) The optical intensity in third order nonlinearity we get maximum in wavelength center at (1550 nm), the third window in optical systems and covers large bandwidth to support optical integrated electronic circuit to work in optical frequencies to improve performance for optical system application as shown figure 10 part (b). The relationship between the potential V (E) and the electrical field (E) will be symmetrical given by equation (37) 18 ¥']+ 1~. 0 ½ ] . (0 * ]( . f0 * ]fÈ (37) The symmetrical potential of the material under the influence of an incoming signal optical E field implies that the material is contrast electrical that electron polarization in positive and negative direction as shown figure 10 part (c). The optical potential in third order nonlinearity the ultrafast optical switches to get approximately (1.85 ps) or few femtosecond (ˇˇ 10 15), fast relaxation process in the order of 100s of femtoseconds combined with an extremely high nonlinear coefficient can be observed in real carbon nanotubes devices in fabricated optical integrated circuit in ultra large scale integrated circuits (ULSI). It is also very high third nonlinear and ultrafast respond times [7], [68], [69]. Figure 10 (b): explains optical power intensity in third order nonlinearity for carbon nanotubes (CNTs) also single wall nanotubes (SWNTs)

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME Figure 10 (c): explains optical potential in third order nonlinearity for carbon nanotubes (CNTs) also single wall nanotubes (SWNTs). 3.4 The Coherent OCDMA with the Nonlinearity In the coherent approach to optical CDMA, the information is first encoded in pulse train using standard OOK. The OCDMA expresses encoder and decoder; here focus SPC-OCDMA encoder and decoder for both optical fiber silicon and carbon nanotubes. Here, we get improved results with parameter signal to noise ratio (SNR) using carbon nanotubes than silicon optical fiber. When the number of users (M) are increasing, the signal to noise ratio is decreasing because the carbon nanotubes has high energy band gap and high refractive index third nonlinearity, that means the enhancement the nonlinearity properties in optical code division multiple access (OCDMA) we got these result by equation (38) as shown figure 11. 19 ¬G; Æ«¤-T ÆG!Æ«¤-T'+ ² 7 !c : G Æ«¤-T '+ . ² 70 (38) Where ‚sw6œthe optical power input for coherent OCDMA system, M is number of users of the system, d is distance silicon or carbon for area integrated and others parameters mention in previous section in assumption [16]. Figure 11: represented the SNR in the coherent OCDMA for silicon optical devices and carbon nanotubes First, we substitute the optical fiber parameters in equation (38) and get the result as in figure 8 curve 1, decreasing SNR when the increasing number of users in the system, subsequently, we substitute the carbon nanotubes parameters in same equation to get result as shown figure 11 curve 2. For improved system, we need to improve SNR values and it is observed that the SNR values with

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME carbon nanotubes are better than silicon optical devices. The figure 12 illustrates about data bit rate which is observed to be decreasing when the number of users (M) increase, that means that signal to noise ratio SNR decreases while substituting parameters for silicon optical devices and carbon nanotubes [16], as governed by equation (39) 20 P É~ 1 B@} Ê Ë Ë Ì CÍ Î ÏÐ€ ÑÒÓZÔZZÕÖ×·Ø Z'Ù¡Ñ+Z. Ú ZÜ ZÛ0 Ý Þ Þ ß È (39) But the data bit rate (R) in coherent OCDMA with carbon nanotubes are better than silicon optical devices, this is clearly observed from curve 2 for carbon nanotubes and curve 1 for silicon optical devices as shown in figure 12. Figure 12: represented the data bit rate (R) in the coherent OCDMA for silicon optical devices and carbon nanotubes The figure 13 illustrates bit error rate (BER) in the same system for carbon nanotubes increasing from 9@ while the silicon optical devices BER from 9@ n, to make the improvement in system performance governed by equation 40. This indicates the effect of SNR to improved coherent system. The encoder works when using silicon optical devices the light spreads by lens but while using carbon nanotubes ( single walled carbon nanotubes ) (SWNTs) making narrow band, the light focuses on one point on the filter nanotubes that is observed to be the most active in applications of passive optical CDMA network [16]. à]; ' ¬G;d Òc : G Æ«¤-T á* ¤_« '¡+ . ² + 70 (40) Figure 13: represented the bit error rate (BER) in the coherent OCDMA for silicon optical devices and carbon nanotubes

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME 3.5 The Incoherent OCDMA with the Nonlinearity In the incoherent approach to the CDMA, the original OOK- modulated signal is divided into several parts and each part is delayed by the amount determined by the code used. The way the OOK signal is divided depends on the particular realization of the incoherent OCDMA, and poor signal to noise power SNR in this system as shown figure 14 illustration decreasing the SNR values to take negative value when the number of users increasing. This performs to effect efficiency performance OCDMA system with carbon nanotubes curve 2 and silicon optical devices curve 1, given results by equation (41) [16]. ¬G; G¹Æ«¤-T 21 ² 7G¹â¹ã ä .åæ¾ Òåæ 0 çÆ «¤-TÒèåæ Òåæ¾ åæåæ¾ ÆG (41) Where Wéis the carrier – hopping incoherent OCDMA system with wavelength that is the original OOK signal is passed through a filter (e.g, prism or grating – based) that separates Wé components differently by their central wavelength,å| the single channel spectral width |uis its central frequency,ê is the frequency spacing between different carriers.té is the gain to the crosstalk between channels equal 'té {ë) [70] . Figure 14: represented the SNR in the incoherent OCDMA for silicon optical devices and carbon nanotubes The figure 15 illustrates the data bit rate (R) is also decreasing when the SNR is decreasing with increased number of users; this is given by equation (42). The data rate in the system with carbon nanotubes is better than with silicon optical fiber as shown in figure 15. Here, the curve 2 is for carbon nanotubes results, while the curve 1 for silicon optical devices [16]. ; 7 ~ 1 ád Ê Ë Ë Ë Ì ¡ 7 ²â¹ ¤_« ì í ä åæ¾ î Òc : G Æ«¤-T ' (( ÒG¹'¡+ï ¹²7 ð Ý Þ Þ Þ ß È (42) The figure 16 illustrates that the bit error rate (BER) is increasing when the number of users are increasing, but the SNR is decreasing on proportional relationship between numbers of users (M) and BER but reverse relationship between BER and SNR. This is given by equation (43) and as shown in figure 16, the incoherent OCDMA with carbon nanotubes is observed to be better than silicon optical devices as shown by the curve 2, for carbon nanotubes and the curve1 for silicon optical devices [8], [16].

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME Figure 15: represented the data bit rate (R) in the incoherent OCDMA for silicon optical devices and carbon nanotubes Figure 16: represented the bit error rate (BER) in the incoherent OCDMA for silicon optical devices and carbon nanotubes 22 à]; á* ¤_«'1 7 ²â¹ì í ä åæ¾ î Òc : G Æ«¤-T ' (( ÒG¹'¡+ï¹²7 + (43) ð In this paper, we have investigated the transmission analysis of OCDMA communication systems using silicon optical devices and carbon nanotubes under the set of the wide range of operating parameters as shown in table 1. It is aimed to improve the performance of the incoherent OCDMA systems by OOK formats and PPM formats using carbon nanotubes (CNTs), and silicon optical devices. Figure17 illustrates that the data rate is decreased when the number of users are increased in the PPM format for OCDMA system given by equation (44) [16]. ; Mád *72 (44) Where K is the number of simultaneous users, E˜ is the signaling period “symbol interval “, n is the code of length, where each user is assigned a set of M codes, each corresponding to a particular “ digit”. In the M-ary system with M=8 [16].The data rate with carbon nanotubes as obtained result represented by curve 2 is better than silicon optical devices as represented curve 1as shown figure 17. It is indicated that in the simulated system with the existing coding technique for PPM/OCDMA

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME system, the bit error rate increases much more with silicon optical devices but the bit error rate is very low with carbon nanotubes used „ = E˜ JH{ ?C, source power of laser ‚uuñ J IH —99, and refractive index H{{ ›™—99 from table 1 [16],[18],[71][72] Figure 17: represented the data rate (R) in the incoherent OCDMA by PPM format with silicon optical devices and carbon nanotubes Bit error rate in PPM/ OCDMA format is given by equation (45) *) )÷G¹ ø 23 à]; òó *ô )ô'*)+ô õ]8G¹² 7j ) õ 1]8G¹² ö 7j ö ]8 (45) Let M is the number of simultaneous users and „ is the single pulse width used in silicon optical devices and carbon nanotubes, Wé is code with Wé =8 different wavelength channel and different values of q in silicon optical devices is q =1.12 e V, and carbon nanotubes is q =2.9 e V. Then, as a function of number of users, the bit error rate (BER) performance codes C is affected by the multiple access interference (MAI). In the limiting case where the noise due to spontaneous emission in optical amplifier, detector dark current, etc., can be neglected as compared to the effect of Multiple Access Interference (MAI). The multiple access interference affects the incoherent OCDAM system. The bit error rate (BER) increases marginally with carbon nanotube as represented by curv2 compared with silicon optical devices represented curv1 as shown figure 18. Figure 18: represented the bit error rate (BER) in the incoherent for silicon optical devices and carbon nanotubes

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME Therefore, we can say that the Data Rate (R) incoherent OCDMA with OOK/OCDMA format gives better results than PPM/OCDMA with carbon nanotubes (CNTs). In the OCDMA system increasing the number of users decreases the data rate, while increasing the bit error rate enhances the system performance. For the best performance of optical communication with highest data rate and lowest bit error rate, we investigated the optimized OCDMA performance with carbon nanotubes in comparison with silicon optical devices. 3.6 The OOK/ OCDMA Chip – Level Receiver and Its Performance Analysis In the OOK/ OCDMA system uses the (n, w, 1), the signature with optical pulse is sent for data bit “1” while nothing is sent for data bit “0”. Hence, we focus the Bit Error Rate (BER) for OOK/OCDMA chip level receiver with carbon nanotubes less than BER with silicon optical devices and we got result when the number of code length n=1000 is given by equation 17, resulting in BER with carbon nanotubes as represented by curv2 very less than silicon optical devices represented by curv1 as shown figure 19.Tthe BER can be given by equation (47) and equation (46). Æ7 Ç 24 * ÆddT (46) Where ‚É the transmitted power is for OCDMA system, w is weight of the code, and n is the length of the code. Æ2 ó '1+L^ÇL a . 1 L Ç *0 Ç L÷ ù (47) Figure 19: represented the bit error rate (BER) by OOK/OCDMA formats for silicon optical devices and carbon nanotubes 3.7 The PPM/ OCDMA Chip – Level Receiver and Its Performance Analysis In M-ary PPm signaling format the ú

38.
symbol, jû v={0,1,…,M-1}is represented a signature sequence at the ú

39.
slot and otherwise,there is not any pulse within all other slots the result bit error rate can be given by equation (49) and equation (48) '*+ Ç'Ç+ (48) Æ: ™ '1 +ó '1+L^ÇL a ò 1 'L Ç+ Ç *ø G a ò'G+Ç¤ 1^ * ø Ç Ç L÷¢ ù (49)

40.
International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME OCDMA system with PPM receiver can enhance the security of information transmission. However, in the hardware implementation OCDMA system with PPM chip – level receiver is more complex than OOK chip level receiver system. Figure 20 illustrates the result for PPM/OCDMA format with carbon nanotubes as represented by curv2 which is observed to be better than silicon optical devices represented curv1. The result can be given by equation (49) and equation (48). Figure 20: variations of the Bit Error Rate (BER) PPM format for silicon optical devices and carbon nanotubes (CNTs) Optical overlapping pulse position modulation (OPPM) chip level receiver [16],[8], [73], whose difference from PPM chip level OCDMA is that it allows partial superposition of two adjacent modulated signals or two adjacent slot with width „ and the overlapping depth index l, it’s hardware is more complex than that of PPM – chip level OCDMA system. 3.8 Performance Analysis of Two – Dimensional Wavelength Hopping/ Time Spread Ç')+ Ç')+L L÷Ç (50) 25 Incoherent OCDMA System Comparative analysis is made for BER performance of 2-D incoherent OCDMA system with carbon nanotubes and silicon optical devices. Figure 21 illustrates that the BER performance OCDMA system with carbon nanotubes represented by curv2 is better than silicon optical devices which represented curv1. Because, carbon nanotubes have high optical power‚mmœ J IH —99, band gap energy q =2.9 e V, high refractive index H{{ ›™—99, and duration time E˜ JH{ sec ,resulting in ultrafast switches performance better than in case of silicon optical devices which has low power optical source ‚mmœ {Hxx —99, band gap energy q =1.12 e V, low refractive index J n/watt , and duration time E˜ H n?C. The result is given by equation (50) and equation (48) [74], [75], [76], [77]. Æ2 L a . Ç ó ^Ç')+ T0 L . 1 Ç T0 3.9 Performance Analysis of Spectral Encoding Coherent OCDMA System For the On – Off Keying format; when the data is “1”, the ultrashort pulse is fed into the spectral phase encoder. The spectral phase encoder imposes a specific phase shift on each spectral component of the ultrashort pulse. Otherwise, when the data is “0”, the output of the spectral encoder. This encoding process is implemented through a spectral phase code generator multiplying each spectral component of the ultrashort pulse. Since the phase code generated by the spectral phase code generator of each subscriber is unique, the solely spectral phase encoding (C) of data from each user is implemented.

41.
International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME Figure 21: represented the BER performance by 2-D WH/TS incoherent OCDMA for silicon optical devices and carbon nanotubes (CNTS) The spectral phase code can employ the binary codes with good properties which are widely applied to the electrical wireless CDMA, such as m- sequences, Gold codes, etc. The optical signal with spectral phase encoded in time domain. The optical signal with spectral phase encoded in time domain looks like a low intensity pseudo – noise burst (D), which is fed into the optical communication network. Figure 22 illustrates the BER performance in spectral phase coherent OCDMA with carbon nanotubes more better than silicon optical devices, we can say the spectral phase encoding in OCDMA system is best among other types in OCDMA system, BER is given by equation (51) and equation (48) 26 ‚˜ ¿ a . ó ^ M0 ¿ . 1 M0 ¿ ' 1 c'¿+à'c'¿+ 1 Æ'¿++ ¿÷ ù (51) Where R Éü Éý , and is the number of simultaneous subscribers in the network, B is solid lines, I is number of interfering subscribers, P(I) is a random variable and satisfies a binomial distribution, and l'±+ represented the probabilities of false alarm and missed detection. The result obtained BER performance with carbon nanotubes much better than silicon optical devices [8], [78]. Figure 22: BER performance by spectral phase encoding in coherent OCDMA with silicon optical devices and carbon nanotubes (CNTS)

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME 3.10 Performance Analysis of Temporal Encoding Coherent OCDMA System The temporal phase encoding coherent OCDMA system is a type of Time – Spreading OCDMA, whose model is shown in figure 23. Four kinds of noises are presented in this model, which are the MAI noise from the OCDMA network, the multiplied beat noise and additive shot noise from photodetector, and the thermal noise of receiver. In the temporal phase encoding coherent OCDMA, the coherence of the optical signal has to be maintained within the chip duration and thus the coherent beat noise becomes critical. It has been shown from investigation that the BER performance of the incoherent OCDMA system mainly confined by the MAIs from the network and otherwise, the BER performance of the coherent OCDMA system is limited by the beat noise [16], [8]. Figure 23: model of temporal phase encoding OCDMA system with various noises The BER performance in temporal phase encoding OCDMA system with carbon nanotubes represented by curv2 gives better result than silicon optical devices represented by curv1 and analyzed by equation (52) and equation (48) [8], [79] Æ2 ó Æ'¿+Æ2 '¿+ 27 ¿÷¢ (52) Where P(I) indicates the probabilities that subscribers among M-1 interfering subscribers, and ‚X'±+ is the bit error rate with I. Æ'¿+ ^ ¿ a '+ (53) And Æ2 õò 1 7j 72 øÆ¤'¿+ 7j 72 Æ¤'¿+ö (54) Where ‚w'±+ indicates the probabilities of chips 0 and 1 respectively. Æ¤'¿+ ¤þj .Æ:'7¸¿+ * 0 (55) Where * 8¸ k¸ º¿ and 8¸ fTà7 ;F à Where K is the boltzmann’s constant ( H ™R) from table 1, T is the ambient temperature ( É É‘ ) Em=300K, B is transmission bit rate for silicon optical devices B= H ,=9?™?C and for B= šHš{ x ,=9?™?C, and load resistance for silicon optical devices is { ,while load resistance for carbon nanotubes JHx ..

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME 28 We can get shot noise by equation (56) k¸ ¤ à ¿« (56) Where e is charge of electron, B is data rate, ±s the current of photodetector for carbon nanotubes and silicon optical devices. The BER performance in temporal phase encoding OCDMA system with carbon nanotubes is much better than silicon optical devices as shown figure 24. All types of coherent OCDMA and all types of incoherent OCDMA with carbon nanotubes provides comparatively improved performing system by way of getting highest data rate (Tb/s) and lowest bit error rate (BER) than silicon optical devices. Figure 24: represented the BER performance by temporal phase encoding coherent OCDMA for silicon optical devices and carbon nanotubes (CNTS) CONCLUSION The carbon nanotube used in this work is single walled nanotubes whose electronic structure is semiconducting. Optical integrated circuit has many advantages elastic in direction optical incident and the move almost of optical power intensity and low consumption power, it needs low voltage like (160mV – 200mV) and input power in microwatt or milliwatt . This performs in bio-electronic application. It has saturable absorption to efficient saturable absorbers optical power incident to get output with losses 5% this is very best for work in passive optical network applications. This is one of the key advantages of carbon nanotube – based devices in passive mode locking operation. It continues to work even in high temperature environments without affecting in its performance in the system. The Absorption in carbon nanotube is very low 0.02 dB/km that means very accurate in transfer the optical signal, their devices offer a very high nonlinear coefficient and fast response time to reach 100s of femtosecond, ultrafast work optical switches used in many in communication system applications, information technology, and sensors system.Three important parameters are very important for any communication system, named signal to noise ratio SNR, Data rate R, and Bit error rate BER. In optical code division multiple access (OCDMA) utilizing the nonlinear properties of materials used in silicon optical devices and carbon nanotubes, bring in improvement in the system performance. In Coherent as well as Incoherent optical CDMA, encoder is in transmitter and decoder in receiver. But the coherent OCDMA has been observed to be better than incoherent OCDMA, because of the poor signal to noise ratio in incoherent OCDMA and is demonstrated to be more robust to the effect of nonlinearity in terms of bit error rate performance and SNR. Considering the third order nonlinearity, carbon nanotubes are observed to be highly efficient providing very fast response and are more suited to next generation components required in communication system consuming much less power with time, extending the life of batteries used. Optimized design

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME performance of OCDMA with carbon nanotubes (CNTs) based devices have been observed providing highest data rate (R) and lowest bit error rate (BER) incorporating techniques like OOK/OCDMA and PPM/OCDMA in Coherent as well as Incoherent OCDMA system. Firstly, the incorporation of carbon nanotube, based devices result in improved system performance in comparison to silicon optical devices, with increased data rate upto Tb/s and much reduced bit error rate between 9@ n bits/sec. Next generation of optical communication system may preferably incorporate carbon nanotubes based devices so as to achieve much higher data rate up to Tb/s in comparison to present systems using silicon optical devices giving data rate upto Gb/s. Besides, such systems with reduced energy source power realize in much longer life Nevertheless, future requirements of ultrahigh speed internet, video, multimedia, and advanced digital services, would suitably be met with incorporation of carbon nanotubes based devices providing optimal performance.The Optical Wireless Communications (OWC) is a type of communications system that uses the atmosphere as a communications channel. The OWC systems are attractive to provide broadband services due to their inherent wide bandwidth, easy deployment and no license requirement. The idea to employ the atmosphere as transmission media arises from the invention of the laser. The visible light communication (VLC) based on Li-Fi (Light Fidelity)-The future technology in optical wireless communication refers to the communication technology which utilizes the visible light source as a signal transmitter, the air as a transmission medium, and the appropriate photodiode as a signal receiving component.The system develops with carbon nanotubes (CNTs) to improve for space communications but applied for indoor networks. Indoor optical wireless systems face stiff competition from future WiFi. 29 REFERENCES [1] S. Ijima “Helical microtubes of graphitic carbon “, Nature, 359.Pp..56-58 (1992). [2] M. S. Dresselhuas, G. Dresselhaus, and P. Avouris Eds,” Carbon Nanotubes: - Synthesis, structure, properties, and applications”, Newyork: springer- verlag, Berlin, Pp 305-323 (2001). [3] M. Meyyappan, “Carbon nanotubes sciences and applications”, NASA, Ame Research center, Moffett field, A,PP1-22 (2005). [4] Paul Holister “Nano Tubes white paper”, CMP, Cienifica, Pp5-12, Jan. (2003). [5] Wildoer, J.W.G.L.C.Venema, A.G.Rinzler,R.E smalley and C.Dekker,” Eledtronic structure of automatically resolved carbon nanotubes”.Nature 391(6662): Pp59-62(1998). [6] H.Kataura, Y. Kumazawa, I-Umeza, S.Suzuuki, Y.Othsuka, and Y.Achiba “Optical properties of single – walled carbon nanotubes “. Synth.Met 103, Pp2555-2558 (1999). [7] Jose Mauricio Merulanda “Carbon nanotubes applications on electronic devices” Goatia, Pp3-384 (2011). [8] Hongxi Yin and David J. Richardson (2007) “Optical Code Division Multiple Access Communication Network, Theory and Application”. Tsinghua University press, Springer, LLC, Pp168-300. [9] A. Stock, and E.H. Sartgent (2002) “The Role of Optical CDMA in Access Networks”, IEEE Communication Magazine, Vol. 40, Pp 83-87. [10] K.Kitayama, X. Wang, and H Sotabayashi (2004) “State of the Art and Applications of Optical Code Division Multiple Access (Invited)” in European Conference of Optical Communication (ECOCO4), Stockholm, Sweden, Tu4.6.1. [11] X. Wang, and K.Kitayama (2004) “Analysis of Beat Noise in Coherent and Incoherent Time – Spreading OCDMA “ J. Lightwave Technol. 22,2226-2235. [12] X. Wang, N. Wada, T. Hamanaka, T.Miyzaki, Gabriella Cincotti, and Kenicki Kitayama (2007) “OCDMA over WDM Transimission “IEEE. (ICTON)TuB1,Pp 110-113.

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME [13] T.k Shake (2005) “Confidentiality Performance of Spectral – Phase – Encoded Optical CDMA” J. Lightwave Technol., Vol23, Pp 1652-1663. [14] D.E Leaird, Z. Jiang, and A. M. Weiner (2005) “Experimental Investigation of Security Issues in OCDMA : a code – switching scheme” Electron Lett. Vol. 41, Pp 817-819. [15] X. Wang, N. Wada, Miyazaki, and K. Kitayama (2006) “Coherent OCDMA System using DPSK Data Format with Balanced Detection” IEEE Photonic Technol. Lett. Vol. 18, Pp 826-828. [16] Paul R.Prucnal (2006) “Optical Code Division Multiple Accesses: Fundamentals and Applications “Taylor and Francis Group, LLC, Pp55-268. [17] Q.Lin, Oskar J. Painter, and Govind P. Agrawal (2007) “ Nonlinear Optical Phenomena in Silicon Waveguides: Modeling and applications” OPTICS EXPRESS, Vol.15, No. 25, pp16610. [18] Jafaar Fahad A.Rida, A.K. Bhardwaj, A.K. Jaswal (2013) “Preparing Carbon Nanotubes (CNTs) for Optical System Applications” International Journal of Nanotubes and Application (IJNA), Vol. 3, Issue 2, Pp21-38. [19] Dixon, R.C. (1994) “Spread Spectrum System with Commercial Application”. New York, 30 Wiley – Interscience. [20] Dixon, R. (1975) “Why Spread Spectrum”. IEEE Communication Society. Magazine 13(4): 21-25. [21] Scholtz, R. (1977) “The Spread Spectrum Concepts”. IEEE Transaction Communication, 25(8): 748-755. [22] Pickheltz, R., Schilling, D.,Milstein, L. (1982) “ Theory of Spread Spectrum Communications a Tutorial”. IEEE Transaction Communication 30(5)855-884. [23] Utlant, W. (1978) “Spread Spectrum: Principles and Possible Applications to Spectrum Utilization and Allocation”. IEEE Communication Society Magazine 16(5)21-31. [24] Weiner, A. M., Heritage, J. P., Salehi, J. A. (1988) “Encoding and Decoding of Femtosecond Pulses “. Opt. Lett. 13:300–302. [25] Division Multiple Access Communication Systems “. J. Lightwave Technol. 8:478–491. [26] Etemad, S., Banwell, T., Galli, S., Jackel, J., Menendez, R., Toliver, P., Young, J., Delfyett, P., Price, C., Turpin, T. (2004) “Optical-CDMA Incorporating Phase Coding of Coherent Frequency Bins: Concept, Simulation, Experiment”. Proc. Optical FiberCommunications Conf. FG5. [27] Kitayama, K., Sotobayashi, H., Wada, N. (1999) “Optical Code Division Multiplexing (OCDM) and its Applications to Photonic Networks”. IEICE Trans. Fundamentals E82:2616–2626. [28] Sotobayashi, H., Chujo, W., Kitayama, K. (2004) “Highly Spectral Efficient Optical Code Division Multiplexing Transmission System (invited)”. IEEE J. Sel. Top. Quant.Electron. 10(2):250–258. [29] Lam, C. F. (2000) “To spread or not to Spread—The Myths of Optical CDMA”. IEEE LEOS Annual Mtg. 2:13–16. [30] Agrawal, G. P., Olsson, N. A. (1989) “Self-Phase Modulation and Spectral Broadening of Optical Pulses in Semiconductor Laser Amplifiers “. IEEE Journal of Quantum Electronics 25(11):2297–2306. [31] Baby, V., Glesk, I., Huang, Y.-K., Xu, L., Prucnal, P. R. (2005) “Demonstration of an All- Optical Interface between Wavelength-Hopping Time-Spreading Optical CDMA and WDM Networks “. Proceedings of IEEE LEOS Summer Topicals, TuC4.2. [32] Fathallah, H., Rusch, L. A., LaRochelle, S. (1999) “Passive Optical Fast Frequency-Hop CDMA Communications System “. IEEE J. Lightwave Technol. 17(3):397–405.

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME [33] Kwong, W. C., Yang, G.-C. (2004) “Multiple-Length Multiple-Wavelength Optical Orthogonal Codes for Optical CDMA Systems Supporting Multirate Multimedia Services “. IEEE J.Sel. Areas in Commun. 22(9):1640–1647. [34] Tanceski, L., Andonovic, I. (1994) “Wavelength Hopping/Time Spreading Code Division Multiple Access Systems “. Electron. Lett. 30(9):721–723. [35] Yang, G., Shen, Y. R. (1984) “Spectral Broadening of Ultrashort Pulses in a Non linear 31 Medium”. Optics Lett. 9(11):510–512. [36] Yegnanarayanan, S., Bushan, A. S., Jalali, B. (2000). “Fast wavelength-hopping time-spreading encoding/decoding for optical CDMA”. IEEE Photon. Technol. Lett. 12(5): 573–575. [37] C. E. Shannon (1948) “A Mathematical Theory of Communication”. The Bell System Technical Journal 27:379–423, 623–656. [38] Anas N. Al- Rabadi (2007) “ Carbon Nanotubes (CNTs) Multiplexers for Multiple Valued Computing “ FACTA Universities (NIS), SER, ELEC, ENERG, Vol. 20, No. 2, Pp175-186. [39] G. Amaratunga (2003) “Watching the Naotube “IEEE Spectrum, Pp28-32. [40] P. G. Collins and P. Avouris (2006) “ Nanotubes for Electronics “, Scientinfic American, Pp 62-69. [41] P. Collins, M. S. Arnild, and P. Avouris (2001) “Engineering Carbon Nanotube Circuits Using Electrical Breakdown” Science, Vol. 292. [42] V. Dreyclc, R.Martel, J.Appenzeller, and P. Avouris (2001) “Carbon Nanotube inter- and – intramolecular logic gates “ Nano Letter , Vol. 0, No., A-D. [43] J. R. Health and M. A. Ratner (2003) “Molecular Electronics “Physics. Today, Pp 43-49. [44] J. Jiao, E. Einarsson, D.W. Tuggle, L. Low, J. Prado, and G.M. Coia (2003) “ High – Yield Synthesis of Carbon Coils on Tungsten Substrates and Their behavior in The Presence of an Electric Field” Journal of Material Research, Vol. 18. No.11,Pp2580-2587. [45] K. Likhare (2007) “Hybrid Semiconductor – Molecular Nanoelectronics “The Industrial Physicst, Pp20-23. [46] A. N. Al-Rabadi (2004) “Carbon Nanotube (CNT) Circuits “in Proc. Of the Post – Binary Ultra large Scale Integration (ULSI). Workshop, Torento, Canada, Pp. 44-49. [47] L. Tanscevski, and I. Andonovic (1996)” Hybrid Wavelength Hopping / Time Spreading Schemes for Use in Passive Optical Networks with Increased Security” Journal of Lightwave Technology, Vol.14, No.12, Pp2636- 2677. [48] M.S.Desselthaus and P.C Eklund “Phonon in carbon nanotubes”, Advances in Physics, Vol.49, NO.6, Pp 705-814, (2000). [49] Dresselhaus,M.S.Dresselhuas, G.,and EKlund P.G. “Science of fullerenes and carbon nanotubes”. Network Academic Press (1996). [50] P.L. McEuen,M.S.Fuhrer, and H.K. Park,” Single- walled carbon nanotube electronics”. IEEETransavtions on NanoTechnology, Vol.91, Pp 1772- 1784 (2003). [51] J. Appenzeller, J.Kaech, V. Derycke, R.Martel, S.Wind and P.Avouris” Field modulated carrier transport in carbon nanotube transistors “, Physical Review Letters, Vol.89, Pp126801.1-126801.4, (2002). [52] S. Heinze, J.Tersoff, R.Martel,V.Derycke, J.Appenzeller, and P.Avouris, “Carbon nanotubes as schottly barrier transistors”. Physical Review Letters Vol.89, Pp 106801.106801.4, (2002). [53] J. Guo, S.Datta and M.Lundstrom “A numerical study of scaling issues for schottky – Barrier carbon nanotube transistos”, IEEE Transcations on Electron Devices,Vol.51, Pp172-177(2004). [54] M.Radosavljevic,S. Heinze,J.Tersoff and P. Avouris “Drain voltage scaling in carbon nanotube transistors” Applied Physicals Letters, Vol.83, Pp 2435-2437 (2003).

47.
International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME [55] A. Javey, H.Kim, M.Brink, Qwang,A. Ural , J.Guo, P. McZntyre, P.McEuen, M.Lundstrom and H.J.Dai “ High kappa dielectrics for advanced carbon nanotubetransistors and logic gate” Nature Material , Vol.1, Pp241-246 (2002). [56] S.J. Wind, J. Appenzeller, R.Mortal, V. Derycke and P. Avouris “Fabrication and electrical characterization of top gate single wall carbon nanotube field – effect transistors” Jorurnal of vacuum science and technology B.Vol.20, Pp 2798-2801 (2002). [57] A. Javey, J. Guo, Qwang, M.Lundstrom, and H.J. Dai “ Ballistic carbon nanotube field – effect transistors” . Nature Vol.424, Pp 654- 657 (2003). [58] A. Javey, J.GUO, D.B Farmer, Qwang, E. Yenilmez, R.G. Gorden, M. Lundstrom, and H.Dia” Self – aligned ballistic molecular transisors and parallel nanotube arrays “ Nano Lett. In Press, (2004). [59] B.T. Kelly,” Physical of graphite” Applied science, London (1981). [60] S.Saito and A.Zettl “Carbon Nanotubes: Quantum cylinders of graphite”, Elesevier, first 32 edition (2008). [61] Hamada, N., Sawada, S. and Oshigama,A. “Now one dimensiona, conductors: graphitic microtubules”. Phys.Rev.Let.68, 1579 (1992). [62] R.Saito , G.Dresselhaus, and M.S. Dresselhaus, “Physical properties of carbon nanotubes”. London” Imperial collage Press, (1998). [63] J.W.Mintmire and C.T.White “Universal density of states for carbon nanotubes” Physical Review Letters, Vol.81. Pp 2506-2509, (1998). [64] Samulik Kivisto, Tommi Hakulinon, Antti Kaskela, Brad Aitchison and Oleg G.Okhotnikov “Carbon nanotube films for ultrafast broadband technology” Opt Express, 17, Pp.2358-2363 (2009). [65] Samuil Kivisto “Short pulse lasers using advanced fiber technology and saturable absorbers” Tampere University of Technology Pp. 6 -75 (2010). [66] Jin- Chen Chiu, Yi-Fen, Chia- Ming Chang.Xi-Zong Chon,Chao Yong Yoh Cheo- Kuilee, Gong Rulin,Jiang – Jen Linond, wood-HI chang “ Concentration effect of carbon nanotube based saturable absorber on stabilizing and shorting mode locked pulse”, Vol.18. No.41, Optics expresses Pp. 3592-3600 (2010). [67] Zhiwei Zhong, Chujun Zhao, Shunbin LU, Ya chen, Ying Li, Han Zhang, and Shuanychun Won “Microwave and optical saturable absorption in grapheme”, Ultrafast optics (350- 4010)- Ultrafast lasers (320-7110), Vol.20, No.21/Optics express Pp. 23201-23214 (2012). [68] Jao Tao See, Seeng Min, Qiguang Yang, Lin wood CreakMORE, Russell Battle, Makene, Tabibi, Herbert Brown, Ashloy Ja ckson” Third – order optical nonlinearities of single wall carbon nanotubes for nonlinear transmission limiting application”. Department of physics,Hampton University, VA,23668, USA, Pp. 37-40 (2006). [69] Chiyat Ben Yan” Nonlinear optical effects and carbon nanotubes” Department of Physics, Universoty of Cininnati, Oh 453221, USA, Pp. 1-7 Deci.(2001). [70] P. R. Prucnal, M. Santoro, and F. Tan (1986) “Spread Spectrum Fiber-Optic Local Area Network using Optical Processing” Journal of Lightwave Technology 4:547-554. [71] Jafaar Fahad A.Rida, A.K. Bhardwaj, A.K. Jaswal (2013) “ Improved Designing of Optical fiber Communications System with Carbon Nanotubes (CNTs) based Optical Code Division Multiple Access “ International Engineering Research and Development (IJECIERD), Vol. 3, Issue 4, Pp 89-104. [72] Jafaar Fahad A.Rida, A.K. Bhardwaj, A.K. Jaswal (2014) “Design Optimization of Optical Communication Systems Using Carbon Nanotubes (CNTs) Based on Optical Code Division Multiple Access (OCDMA)” International Journal of Electronics and Communication Engineering (IJECE). Vol. 3, Issue 1. Pp77- 96.

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International Journal ofElectronics and Communication Engineering Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 01-33 © IAEME [73] Hemali PASQUAL, and Hiroyuki YASHIMA, (1999) “Analysis of Optical PPM/OCDMA System with M-Ary Convolutional Coding” IEICE. TRANS. Commun., Vol.E82-B, No. 10, Pp 1618-1624. [74] K. C. Kaa and G. A, Hokham (1966) “Dielectric Fiber Surface Waveguides for Optical Frequencies” Proceeding IEEE,Vol. 133, Pp 1151-1158. [75] G. P. Agrawal (2002) “Fiber –Optic Communication Systems” 3rd John Wiley and Sons Inc. [76] Tung – Wah Freqerick Change and Edward H. Sargent (2001) “Optical CDMA Using 2-D Codes : The Optimal Single – User Detector”, IEEE Communications Letters, Vol.5, No.4, Pp 160 -171. [77] K. Cui, M.S. Leeson and E. L. Hines (2007) “ Performance Analysis of Optical CDMA Systems with PPM Signaling “ University of Warwick, Conventry, CV47AL, ISBN 1-9025-6016-7. [78] Jawwad A. Salhi, Andrew M. Weiner, and Jonathan P. Heritage (1990) “Coherent Ultrashort Light Pulse Code- Division Multiple Access Communication System”, IEEE/OSA, Journal of Lightwave Technology Vol.8, No.3, Pp 478-491. [79] Hossam M. H. Shalaby (1998) “Chip Level Detection in Optical Code Division Multiple Access” IEEE/SOA Journal of Lightwave Technology, Vol. 16, No. 6 Pp1077-1087. [80] Pankaj Sharma, Sandeep Kaushal and Anurag Sharma, “To Analyze the Performance of Various Digital Filters in OCDMA Multi-User Environnent with 3D Codes”, International Journal of Electronics and Communication Engineering Technology (IJECET), Volume 4, Issue 5, 2013, pp. 80 - 89, ISSN Print: 0976- 6464, ISSN Online: 0976 –6472. 33 AUTHOR’S BIBLIOGRAPHY Jafaar Fahad A.Rida Received his bachelor of Electronic and Communication Engineering Technical Najaf Collage Iraq in 2003. He obtained M.Tech. Communication System Engineering from SHIATS Allahabad India in 2012. He is Pursing Ph.D in Communication System Engineering in Depart ment of Electronics and Communication Engineering in SHIATS, Allahabad. He has experience for five years with CDMA technical company and MW System. He has published several research papers in the field of Optical Systems Communication and Carbon Nanotubes Engineering. Dr. A.K. Bhardwaj Allahabad, 16.01.1965, Received his Bachelor of Engineering degree from JMI New Delhi in 1998; He obtained his M.Tech. degree in Energy and Env. Mgt. from IITNew Delhi in 2005. He completed his Ph.D in Electrical Engg. From SHIATS (Formerly Allahabad Agriculture Institute, Allahabad- India) in 2010. He has published several research paper in the field of Electrical Engineering. Presently heis working as Associate Professor and HOD in Electrical Engg. Department, SSET, SHIATS Allahabad- India. Prof. A. K. Jaiswal, Is working as Professor and HOD of the department of Electronic and Communication in Shepherd school Engineering and Technology of SHIATS, Allahabad, India. His area of working is optical fiber communication system and visited Germany, Finland for exploration of the system designing. He has more than 35 years experience in related fields. He was recipient of national award also developing electronics instruments.

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