A novel C+ L band erbium doped fiber broadband light so urce w ith hig h power was introduced. In the ex periment, a fiber loop mirr or made fr om 3 dB coupler was employed, mean while, power controlling circuit made fiber output steady. Single stage fiber and two pump LDs of 980 nm was used, and C band amplified spontaneous emission of backw ard again enhanced the efficiency of LD and stability o f output of fiber. Mean while, selecting appropriate Erbium doped fiber length simultaneously g ot output of C+ L band with power higher than 26.67 mW ( 14.26 dBm) , whose average wavelength was 1 550.887 nm.
A novel C+ L band erbium doped fiber broadband light so urce w ith hig h power was introduced. In the ex periment, a fiber loop mirr or made fr om 3 dB coupler was employed, mean while, power controlling circuit made fiber output steady. Single stage fiber and two pump LDs of 980 nm was used, and C band amplified spontaneous emission of backw ard again enhanced the efficiency of LD and stability o f output of fiber. Mean while, selecting appropriate Erbium doped fiber length simultaneously g ot output of C+ L band with power higher than 26.67 mW ( 14.26 dBm) , whose average wavelength was 1 550.887 nm.
Unit II- TRANSMISSION CHARACTERISTIC OF OPTICAL FIBER tamil arasan
Attenuation - Absorption losses, Scattering losses, Bending Losses, Core and Cladding losses, Signal Distortion in Optical Wave guides-Information Capacity determination -Group Delay-Material Dispersion, Wave guide Dispersion, Signal distortion in SM fibers-Polarization Mode dispersion, Intermodal dispersion, -Design Optimization of SM fibers-RI profile and cut-off wavelength.
STUDIED ON A MULTICLADDED ERBIUM DOPED DISPERSION COMPENSATING FIBER AMPLIFIERcscpconf
Erbium doped fiber amplifiers (EDFAs) are the essential components of a highly efficient, long distance optical data link.Their design has been refined to give better performance parameters.A novel design approach for erbium-doped fiber amplifiers is proposed based on Matlab and Fortran 77 Programming.In this paper, a combination of fiber intensity distribution, pump and signal power, optimum length and maximum gain are taken into account as objective function
and the results are presented for different core radius, fiber length, pump power and signal power. Dispersion compensating fibers (DCFs) which possess negative dispersion coefficient
equal to or greater than this 17ps/km-nm can be used to overcome this drawback. In order to upgrade the present long haul fiber optic communication system, comprising of CSFs, a
combination of EDFAs and DCFs would be the most feasible choice to compensate the dispersion as well as the loss.
Performance Analysis of Dispersion Compensation in Long Haul Optical Fiber wi...IOSR Journals
Abstract : In this paper, We investigate post, pre and symmetrical/mix dispersion compensation methods for 40
Gb/s non-return to zero link using standard and dispersion compensated fiber through FBG compensator to
optimize high data rate optical transmission. The influence of dispersion of FBG compensator and increases in
the power of CW laser has been studied to evaluate the performance of optical communication systems. The
simulation model of the WDM based on the Optisystem 11.0 is presented according to the above principle. The
simulation results are validated by analysing the Q-factor and Bit error rate (BER) in the numerical simulator.
It is found that post compensation performance is best and the input fiber power is taken as 5-10dB, the
corresponding BER performance is better.
Keywords - BER, Dispersion compensation, Q-factor, WDM.
A novel C+ L band erbium doped fiber broadband light so urce w ith hig h power was introduced. In the ex periment, a fiber loop mirr or made fr om 3 dB coupler was employed, mean while, power controlling circuit made fiber output steady. Single stage fiber and two pump LDs of 980 nm was used, and C band amplified spontaneous emission of backw ard again enhanced the efficiency of LD and stability o f output of fiber. Mean while, selecting appropriate Erbium doped fiber length simultaneously g ot output of C+ L band with power higher than 26.67 mW ( 14.26 dBm) , whose average wavelength was 1 550.887 nm.
Unit II- TRANSMISSION CHARACTERISTIC OF OPTICAL FIBER tamil arasan
Attenuation - Absorption losses, Scattering losses, Bending Losses, Core and Cladding losses, Signal Distortion in Optical Wave guides-Information Capacity determination -Group Delay-Material Dispersion, Wave guide Dispersion, Signal distortion in SM fibers-Polarization Mode dispersion, Intermodal dispersion, -Design Optimization of SM fibers-RI profile and cut-off wavelength.
STUDIED ON A MULTICLADDED ERBIUM DOPED DISPERSION COMPENSATING FIBER AMPLIFIERcscpconf
Erbium doped fiber amplifiers (EDFAs) are the essential components of a highly efficient, long distance optical data link.Their design has been refined to give better performance parameters.A novel design approach for erbium-doped fiber amplifiers is proposed based on Matlab and Fortran 77 Programming.In this paper, a combination of fiber intensity distribution, pump and signal power, optimum length and maximum gain are taken into account as objective function
and the results are presented for different core radius, fiber length, pump power and signal power. Dispersion compensating fibers (DCFs) which possess negative dispersion coefficient
equal to or greater than this 17ps/km-nm can be used to overcome this drawback. In order to upgrade the present long haul fiber optic communication system, comprising of CSFs, a
combination of EDFAs and DCFs would be the most feasible choice to compensate the dispersion as well as the loss.
Performance Analysis of Dispersion Compensation in Long Haul Optical Fiber wi...IOSR Journals
Abstract : In this paper, We investigate post, pre and symmetrical/mix dispersion compensation methods for 40
Gb/s non-return to zero link using standard and dispersion compensated fiber through FBG compensator to
optimize high data rate optical transmission. The influence of dispersion of FBG compensator and increases in
the power of CW laser has been studied to evaluate the performance of optical communication systems. The
simulation model of the WDM based on the Optisystem 11.0 is presented according to the above principle. The
simulation results are validated by analysing the Q-factor and Bit error rate (BER) in the numerical simulator.
It is found that post compensation performance is best and the input fiber power is taken as 5-10dB, the
corresponding BER performance is better.
Keywords - BER, Dispersion compensation, Q-factor, WDM.
The attached narrated power point presentation describes the principle of working, various configurations, advantages, disadvantages and applications of Erbium Doped Fiber Amplifiers. The material will be useful to KTU final year B tech students who prepare for the subject EC 405, Optical Communications.
This article illustrates the different types of losses related to optical fibres and optical fibre communication. It highlights scattering and radiation losses. Dispersion is also elaborated in comprehensive depth for rudimentary understanding.
TSSB Brain Initiative - Overview of Nano and Molecular Communications and Bra...Walton Institute
This was a presentation given by Dr. Sasitharan Balasubramaniam, Director of Research at TSSG, in which he presented his current research in developing miniature devices for Brain implants. The talk focused on two types of implants, which includes (i) nanoelectronics that are used to stimulate neutrons, (ii) engineered cells that transfect and communicate to neurons. The talk will also touch on the potential applications for these types of devices.
Optimization of Uniform Fiber Bragg Grating Reflection Spectra for Maximum Re...ijceronline
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
Optical fiber communication Part 1 Optical Fiber FundamentalsMadhumita Tamhane
Optical fiber systems grew from combination of semiconductor technology, which provided necessary light sources and photodetectors and optical waveguide technology. It has significant inherent advantages over conventional copper systems- low transmission loss, wide BW, light weight and size, immunity to interferences, signal security to name a few. One principle characteristic of optical fiber is its attenuation as a function of wavelength. Hence it is operated in two major low attenuation wavelength windows 800-900nm and 1100-1600nm . Light travels inside optical fiber waveguide on principle of total internal reflection. Fiber is available as single mode and multiple mode, step index and graded index depending on applications and expenditures. Principle of fiber can be understood by ray theory or mode theory. ...
The chapter gives knowledge about the fundamentals, theory and applications of optical fiber for the first year Engineering level students. The material is most suitable for the students of first year B.E. and B.Tech.
This article provides a rudimentary understanding of the basic concepts of optical fibres and optical fibre communication, the manufacturing techniques of optical fibres and different terms and terminologies related to optical fibres.
The attached narrated power point presentation describes the principle of working, various configurations, advantages, disadvantages and applications of Erbium Doped Fiber Amplifiers. The material will be useful to KTU final year B tech students who prepare for the subject EC 405, Optical Communications.
This article illustrates the different types of losses related to optical fibres and optical fibre communication. It highlights scattering and radiation losses. Dispersion is also elaborated in comprehensive depth for rudimentary understanding.
TSSB Brain Initiative - Overview of Nano and Molecular Communications and Bra...Walton Institute
This was a presentation given by Dr. Sasitharan Balasubramaniam, Director of Research at TSSG, in which he presented his current research in developing miniature devices for Brain implants. The talk focused on two types of implants, which includes (i) nanoelectronics that are used to stimulate neutrons, (ii) engineered cells that transfect and communicate to neurons. The talk will also touch on the potential applications for these types of devices.
Optimization of Uniform Fiber Bragg Grating Reflection Spectra for Maximum Re...ijceronline
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
Optical fiber communication Part 1 Optical Fiber FundamentalsMadhumita Tamhane
Optical fiber systems grew from combination of semiconductor technology, which provided necessary light sources and photodetectors and optical waveguide technology. It has significant inherent advantages over conventional copper systems- low transmission loss, wide BW, light weight and size, immunity to interferences, signal security to name a few. One principle characteristic of optical fiber is its attenuation as a function of wavelength. Hence it is operated in two major low attenuation wavelength windows 800-900nm and 1100-1600nm . Light travels inside optical fiber waveguide on principle of total internal reflection. Fiber is available as single mode and multiple mode, step index and graded index depending on applications and expenditures. Principle of fiber can be understood by ray theory or mode theory. ...
The chapter gives knowledge about the fundamentals, theory and applications of optical fiber for the first year Engineering level students. The material is most suitable for the students of first year B.E. and B.Tech.
This article provides a rudimentary understanding of the basic concepts of optical fibres and optical fibre communication, the manufacturing techniques of optical fibres and different terms and terminologies related to optical fibres.
In this paper, we utilized optimized C-band and L-band amplifiers to constitute a broadband CA-L erbium-doped amplifier with a parallel structure. This amplifier has a simple configuration, high-flattened gain and low noise. Meanwhile, we have realized an amplification bandwidth of over 70 nm(1 524—1 602 nm)without any broadband gain flattening component. The C-band average gain is over 30 dB and L-band gain variation is less than 2 dB.
Module of fiber coupled diode laser based on 808nm single emitter combinationNaku Technology Co,. Ltd
Because of the good beam quality and heat dissipation of single emitter diode laser, it is more resuitable to be used in the source of electro-optic countermeasure. Aim at the responer curve of charge-coupled device (CCD) spectrum, 808nm single emitter is used as unitsource and 24 single emitters are divided into four groups. In order to increase the output power intensity, space sombination and polarization combination are used in the experiment. Combined beam is focused in an optical fiber through the focused lens group designed by ourself. All the single emittwes are connected inseries. When the drive current is 8.5A, 162W output power is obtained from a 300um fiber core with a numerical aperture of 0.22 at 808nm and coupling efficiency of 84%.
HFSS ANTENNA FOR KU BAND WITH DEFECTED GROUND STRUCTURESAKSHAT GANGWAR
A wide band Microstrip antenna is proposed for Ku band applications with defected groundd structure. A circular shape defect is integrated in the ground plane. A novel equivalent circuit model is proposed for Microstrip patch antenna with defected ground structure. Accurate design equations are presented for the wideband Microstrip antenna and theoretical analysis is done for the proposed structure. The proposed antenna has an impedance bandwidth of 56.67% ranging from 9.8 GHz to 17.55 GHz, which covers Ku-band and partially X-band. The antenna shows good radiation characteristics within the entire band, and has a gain ranging from 5 dBi to 12.08 dBi. Minimum isolation between co-polar and cross-polarization level of 20 dB and 15 dB is achieved in H-plane and E-plane respectively. The simulation of the proposed antenna is done on HFSS v.13, and measured results of fabricated antenna are in good agreement with the theoretical and simulated results
this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a presentation on photo diode it can be very useful for engineering students as well as undergraduate this is a
This ppt describes the ways of designing a fractal antenna , it's limitations and advantages over normal antennas and the applications associated with it.(brief view)...
Similar to A simple high capability c+ l broad bandwidth erbium doped fiber source (20)
1550nm 1MHz narrow linewidth fiber laser is a high-precision, high-performance optical device. It uses optical fiber as the gain medium and generates a laser with a wavelength of 1550 nanometers through the excitation of rare earth elements. It has an extremely narrow linewidth (1MHz), thus ensuring high frequency stability and narrow bandwidth characteristics. This laser has important applications in spectral analysis, optical interference, fiber-optic communication and other fields, and can provide high-resolution and accurate measurement results. At the same time, its high beam quality is suitable for industrial fields such as precision machining and laser cutting. In short, the 1550nm 1MHz narrow linewidth fiber laser is a versatile, high-performance light source that can meet the needs of various precision measurements and industrial applications.
This is a 375nm 30mW polarization-maintaining fiber-coupled laser. Its fiber is pluggable. When installing the fiber, pay attention to align the bayonet.
The laser output power is adjustable from 1 to 30mW. This laser supports CW continuous operation and TTL modulation operation modes, and is equipped with a modulation signal line. When Modulation is connected to an external signal, the laser automatically enters TTL modulation mode.
The 1550nm 10kW pulsed nanosecond fiber laser is a shining star in modern industrial technology. Its high power output and precise nanosecond pulse control make it an ideal choice for material processing, scientific research experiments and other fields. With its unique fiber structure, this laser achieves high efficiency, long life and stability, bringing revolutionary changes to industrial production. In the future, it will continue to lead the new trend of laser technology and contribute to scientific and technological progress and industrial development.
In today's laser technology field, the 980nm 500mW TEM00 semiconductor laser has become the focus of scientific researchers and technicians with its unique optical properties and wide application prospects. This laser provides strong technical support for research and applications in many fields with its high-precision and high-efficiency laser output.
Erbium doped fiber amplifier (EDFA) is a high performance, small size of the fiber amplifier products. The internal use of stability high power semiconductor laser, the high stability of WDM, isolator, and high gain erbium-doped fiber. The product has the advantages of high reliability, high power output, high gain and low noise.
It is a C+L Band 26dBm EDFA Amplifier.The wavelength Range is 1528~1563nm & 1570~1603nm. The EDFA supports two working modes, ACC and APC, and the two working modes can be switched. In APC mode, the output power can be adjusted. In ACC mode, the operating current can be adjusted. Our desktop EDFA can be controlled by buttons. PC control software can be connected through RS232 serial port.
What our laboratory introduces today is a 1550nm 10kW nanosecond pulse fiber laser.
First, let's take a look at the wavelength characteristics of the 1550nm nanosecond fiber laser. 1550nm is located in the infrared spectrum range and belongs to near-infrared light. Laser of this wavelength shows excellent transmission performance in optical communications, which can effectively reduce fiber loss and improve communication efficiency. At the same time, in the fields of medical treatment and material processing, the 1550nm laser has strong penetration and can achieve precise treatment of deep tissues and fine processing of high-hardness materials.
This is a 1550nm fiber-coupled acousto-optic modulator with a driver. The 1550nm acousto-optic modulator is an external modulation technology, and the acousto-optic device that controls the intensity of the laser beam is usually called an acousto-optic modulator. The 1550nm AOM has the advantages of high modulation extinction ratio and high power withstand, and is widely used in the field of optical fiber sensing.
As can be seen from the video, this is a fiber optic coupling device, which is a multi-mode fiber and the fiber is pluggable. The coupling optical fiber can be customized. The one used here is 100μm, 2m in length, and the interface is FC/PC. There is a buckle on the interface. When installing the optical fiber, insert the optical fiber into the buckle and tighten it.
The one shown in our laboratory today is a 1550nm infrared single-mode fiber coupled laser. This is a desktop laser, and the output power can be adjusted directly through the buttons on the panel. The output power is adjustable with an adjustment range of 0.5~5W. The adjustment accuracy is 1mW. The laser can also be controlled through software, and the communication interface is RS232.
This is a 1550nm 200MHz Fiber Coupled AOM with Driver. It is equipped with single-mode fiber, and polarization-maintaining fiber can also be customized. The radio frequency interface is SMA. We provide customized AOM service, different working wavelength and RF frequency can be customized. The rise/fall time of this modulator is 10ns. Let's check it now.
It is a 637nm 15W red laser system. The high-power laser generates a lot of heat when it works, and a heat sink is added at the bottom of the laser module. The radiator is equipped with 3 fans. When the laser is turned on, be careful not to cover the front and rear to avoid affecting the heat dissipation performance.
High power erbium doped fiber amplifier (EYDFA-HP-BA), based on amplification technology of double clad erbium doped fiber, unique optical packaging technology, and with reliable hardware light path protection design, realized high power laser output in C band or L band, It has the advantages of high gain and low noise, and can be widely used in CATV, optical fiber communication, laser radar, etc..
This is a C-Band Erbium Doped Fiber Amplifier, high gain and low noise. It is the latest style of 2023, with a silver shell. The heat sink of the fiber amplifier is upward. This is Polarization-Maintaining Erbium-Doped Fiber Amplifier, SM Fiber EDFA can also be customized.
The power of 60W is very high power, which can instantly ignite the cardboard. Be sure to pay attention to safety when operating, the operator must wear laser protective glasses, and the laser cannot point to other people or other flammable objects.
532nm DPSS green laser is made features of good beam profile, ultra compact, long lifetime and easy operating, which is widely used in collimation, laser medical treatment, scientific experiment, optical instrument, laser display, etc.
The 1550nm band single-wavelength laser (low power) adopts high-stability semiconductor laser chip, polarization maintaining fiber output, professionally designed drive and temperature control circuit control to ensure the safe and stable operation of the laser, and can provide desktop or modular packaging.
This is 808nm 100mW infrared laser system coupled polarization-maintaining fiber. The working voltage is AC 90~240V and supports wide range voltage. Its laser power can be adjusted from 0~100mW, and it supports two working modes of CW/Modulation.
This is a benchtop ASE broadband light source with button control. This is the broadband light source of C+L Band, the wavelength range is 1528~1603nm. The power can be adjusted, and the adjustment accuracy is 1mW. The single-mode fiber is pluggable, and the interface is easily damaged. The fiber here is fixed and cannot be plugged.
It's a high power Ytterbium-doped optical amplifier, its output power is 37dBm. And high power YDFA built-in 3 cooling fans. The software control function can be customized, and the default is button control. The current working mode, current and output power are displayed on the front display.
https://www.civillaser.com/index.php?main_page=product_info&products_id=3049
It's a high power polarization maintaining ytterbium-doped optical amplifier. Civil Laser's 10W high power YDFA include a 'Monitor' fiber. The software control function can be customized, and the default is button control. The working current or output power can be adjusted by the button.
It supports APC and ACC two working modes can be switched. In APC mode, the output power can be adjusted. In ACC mode, the working current can be adjusted.
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
A simple high capability c+ l broad bandwidth erbium doped fiber source
1. A Simple High Capability C+ L Broad Bandwidth
Erbium doped Fiber Source
Abstract: A no vel C+ L band erbium doped fiber broadband light so
urce w ith hig h power w as intr oduced. In the ex periment, a fiber loop mirr
or made fr om 3 dB coupler was employed, meanw hile, pow er controlling
circuit made fiber output steady. Single stage fiber and tw o pump LDs of 980
nm was used, and C band amplified spontaneous emission of backw ard
again enhanced the efficiency of LD and stability o f output of fiber. Meanw
hile, selecting appropriate Erbium doped fiber leng th simultaneously g ot
output of C+ L band w ith pow er higher than 26. 67 mW ( 14.26 dBm) , w
hose averag e w avelength w as 1 550.887 nm.
1 Introduction
SFS (superfluorescent fiber sour ce) is a low-coherence, single-
transverse broadband source. It is based on amplified spontaneous emission
of erbium-doped fiber, with excellent temperature stability and wide
fluorescence. The spectral width, the center wavelength is in the 1 550 nm
band, and the output optical power is large, which has aroused great interest.
More importantly, with the continuous development of fiber optic sensors and
fiber optic detectors, the requirements for broadband sources with low
2. temporal coherence are also increasing. The light source must have not only
a large output power, but also a characteristic of wide frequency band and
high average wavelength stability. Broadband sources also facilitate the
development of wavelength division multiplexing (WDM) systems and
communication networks. Ytterbium-doped light sources have been
extensively studied in recent years. At present, the research on C-band
amplified spontaneous emission broadband light source has been quite
mature. In order to meet the requirements of capacity expansion, the gain
band of EDFA will be adopted.
Widening from the C-band to the L-band, forming a C + L-band wideband
EDFA has become a hot research topic.
The widely used broadband sources are super-radiation diodes, and the
broadband source based on rare earth doped erbium-doped fiber autonomous
emission (A SE) has an inherently broad emission spectrum, high output
power, and easy coupling with fiber systems. Long life and other advantages
make it the best choice for making non-coherent broadband sources. This
makes the research of rare earth doped broadband light sources more urgent.
In this study, a single-stage dual-pumping C+ L-band source model was
designed. The basic structure of the broadband EDFA was analyzed. The
principle of the various bands produced by the erbium fiber, the fabrication
principle of the fiber loop mirror, and a novel design scheme were proposed.
In order to make the output light more stable, the power control circuit is
3. added; and the design is optimized cost-effectively, reducing the pumping
laser diode from two to one without affecting its performance. This design
provides an experimental basis for the study of practical C+ L-band sources.
2 Fiber ring mirror fabrication and reflection principle
The fiber optic ring mirror fuses the two outputs of the 2 # 2 fused-taper
coupler, which is a broadband mirror. The structure is shown in Figure 1. This
structure is called a Sag nac interferometer in optical sensing (such as fiber
optic gyroscopes). When the input optical signal is input from one end of the
ordinary wideband coupler, it is divided into two beams of clockwise and
counterclockwise opposite at the two output ports of the coupler. After
transmission, the two beams are in the coupler. After the coupling region is
coherent, the reflected light is output from the signal input end, and the
transmitted light is output from the other end. The energy splitting ratio of the
coupler is k. Under the premise of ignoring the loss of the coupler itself and
the loss of the fiber, when the incident light power is Pin, the reflected light
power P r and the light transmission power P t are respectively
Pr = 4k( 1 - k)P in ( 1)
P t = ( 1 - 2k)²P in ( 2)
From equations (1) and (2), the reflectivity R and the transmittance T of
the fiber loop mirror can be expressed as
R = 4k ( 1- k) ( 3)
4. T = ( 1 - 2k)² ( 4)
From device symmetry, the device satisfies the relationship:
That is, the transmission matrix A of the device can be written as:
Figure 1 Schematic diagram of the fiber loop mirror structure
The solid and dashed lines in Figure 2 are the theoretical curves of R and
T with k, respectively. Obviously, when the splitting ratio k is 0 or 1, R = 0, P r
= 0, T = 1, P t = P in. In this case, the structure acts as a total transmission
mirror; k ∃0. 147 or k ∃0. 853, that is, at the intersection of the two curves, R =
T = 0.5, Pr = P t , at this time Structure
5. It acts as a semi-transmissive semi-reflection; when k = 1/ 2 (3 dB
coupler), then R = 1, P r = P in , T = 0, Pt = 0, then the structure plays The
role of a total reflection mirror. In practice, the fusion will bring a certain loss,
the splitter ratio of the coupler is not completely consistent with its nominal
value, or the broadband source used has certain fluctuations, environmental
changes and other factors caused by human factors have a certain theoretical
value. Deviation.
Fig. 2 Curve of reflectance and transmittance of fiber loop mirror with
coupling ratio
3 Light source structure analysis
A variety of structures of erbium-doped fiber superfluorescent sources
have been proposed and studied. Among these structures, the two-way
backward structure is considered to be the most ideal structure, which has
high output power, wide line width, and can eliminate the center of the light
6. source caused by the change of pumping power by optimizing the length of
the erbium-doped fiber. Wavelength instability. Through many experiments,
we found that the double pumping structure has higher conversion efficiency
than other two-way two-stage structure, can obtain higher output power, has
better wavelength stability, and more importantly, the experimental device is
simple. Easy to implement. Therefore, the experimental device was finally
selected as a double pumping structure. A 3 dB wideband fiber coupler is
used to form an approximately 100% total reflection mirror, which is used as a
mirror in the light source. The fiber has a erbium-doped concentration of 0.77-
10-3, and the cut-off wavelength is 853.5 nm. The background loss at 1 200
nm is less than or equal to 50 dB/km, and the peak absorption coefficient at
980 nm is 4. 5 毫米。 The mode diameter is greater than or equal to 0. 2, the
mode field diameter is 6.68 ?m. In the experiment, a 980 nm laser diode was
used as the pumping source with a center wavelength of 979.04 nm and a
threshold current of 27.8 mA. The laser diode pigtail output optical power is
substantially linear with the pumping current (from the threshold current point).
In the design of the experimental setup, two 980 nm laser diodes were used
as the pumping source, one as the forward pump and one as the backward
pump. The experimental structure is shown in Fig. 3. In order to reduce the
cost, a 980 nm LD is finally realized, and the forward and backward pumping
optical signals are provided by the coupler to split the light. The simplified
device is shown in Fig.4.
7. Figure 3 Schematic diagram of C + L band source structure
Figure 4 Schematic diagram of the simplified structure of the C+ L-band
source
4 Experimental results and analysis
Broadband source output light characteristics are typically characterized
by three characteristic parameters: spectral bandwidth, center wavelength,
and output power. The doping concentration of erbium fiber is one of the
factors affecting the gain. Choosing a highly doped erbium fiber to produce a
superfluorescent source can achieve superfluorescence with higher output
power. The output light characteristics of the double pumping light source are
8. determined by two major parameters: one is the erbium-doped fiber material
and the waveguide structure parameters, that is, the selected fiber type,
including Er3+ concentration, co-doped ion concentration, absorption and
emission cross-section spectrum, and numerical aperture. , cutoff wavelength,
optical field overlap and fiber core area; the second is the operating mode
parameters, including pump wavelength, pump efficiency, erbium fiber length,
mirror reflectivity.
Usually the simple C-band light source adopts a single-pass backward
structure; the simple L-band light source adopts the single-pass forward
structure directly, and the utilization efficiency is low, or the two-stage two-way
forward direction and other complicated structures are realized, the cost is
increased, and the introduction is further introduced. Many uncertainties.
Therefore, in the experiment, a double-pumping structure is adopted, a high-
concentration erbium-doped fiber is used as a gain medium, and a fiber-optic
total reflector made by a 3 dB coupler is used to redirect the backward-
generated high-power C-band light back into the fiber. The amplified
absorption of the erbium-doped fiber again improves the utilization efficiency
of the light source and improves the stability of the light source.
In the experimental device structure, two 980 nm laser diodes are used
as the pump source, and the output power is up to 26.67 mW ( 14.26 dBm)
with an average wavelength of 1 when the optical power is pumped at both
ends. 550. At 887 nm, the output spectrum is shown in Figure 5. Due to the
9. high cost of the laser diode, from the perspective of cost, changing the two
980 nm laser diodes to one, through a coupler, the performance of the light
source is not affected. Device on top
In the case of a pigtail with a length of about 4 meters, it is not necessary
to connect the pigtails in the repeated test, directly connected to the output
through the coupler, and the number of temporary joints during the test is
reduced, effectively reducing The purpose of the attenuation of optical power
is to improve the utilization of the light source. Add an isolator to the light
output to avoid laser light.
图 5 实验测得的 C+ L 波段光源的输出光谱
The experimental results show that the C+ L-band amplified spontaneous
emission broadband source can be realized by bidirectional pumping single-
10. stage erbium-doped fiber structure. Firstly, the length of the erbium-doped
fiber should be reasonably selected. The length of the fiber has great
influence on the experimental results because of the flatness and blending of
the output spectrum.erbium Fiber length selection has a close relationship. If
the erbium-doped fiber is too short, no matter how the forward and backward
pumping power is adjusted, the L-band spectrum and the C-band spectrum
cannot be matched, so that the spectrally flat C+ L-band amplified
spontaneous emission source cannot be obtained. When the length of the
erbium-doped fiber exceeds a certain value, the L-band and C-band spectra
can be matched by adjusting the control current of the forward-forward
pumping laser diode to adjust the L-band and C-band spectra to obtain a flat
C+L-band amplified spontaneous emission. Spectral output. Moreover, in the
range of suitable fiber lengths, the flatness of the C + L band amplified
spontaneous emission spectrum is basically equal, and the pumping
conversion efficiency of the amplified spontaneous emission source and the
flatness of the spectrum are not necessarily related.
In practical experiments, the connection of erbium-doped fiber with
wavelength division multiplexer, laser diode pigtail and wavelength division
multiplexer, erbium fiber and output pigtail is crucial for the development of
light source. In the experiment, the fusion of the optical fibers was done with a
high precision welding machine.
11. 5 Conclusion
This paper analyzes the formation mechanism and interaction between
C-band and L-band in erbium-doped fiber. The basic principle of simultaneous
output of broadband light source in C+ L band is further analyzed. A simple
and excellent single-stage double-pumped two-pass C+ L-band light source
structure is designed and optimized without affecting its performance. In the
case of changing two laser diodes to one, the cost is reduced and the device
is simplified. The basic principle of erbium ion generating C+ L band while
outputting broadband spectrum is analyzed. In the experiment, we optimized
the length of the erbium fiber to make the output spectrum flatter and the
output optical power higher. At the same time, we changed the concentration
of different erbium and added the power control circuit to further improve the
flatness of the light source to expand its application range.