This document discusses the relevance of studying electromagnetics in modern society. It begins by discussing how electromagnetics was primarily motivated by military defense applications such as radar technology. It then describes how electromagnetics is now crucial for high-speed electronics, photonic integrated circuits, microcavity laser design, and controlling ultrashort optical pulses. Computational solutions of Maxwell's equations are essential for effectively designing technologies across these applications.
Eelctro-Magnetic-Pulse USE AS A WEAPONAshutosh Uke
Seminar Report File - High Power Electromagnetic Pulse generation techniques and High Power Microwave technology have matured to the point where practical EMP Weapon (Electromagnetic pulse) are becoming technically feasible, with new applications in both Strategic and Tactical Information Warfare. The development of conventional EMP devices allows their use in non-nuclear confrontations. This paper discusses aspects of the technology base, weapon delivery techniques and proposes a doctrinal foundation for the use of such devices in warhead and bomb applications.
The wireless power transmission is a great technology that has long history. It has more potential in the near future in various industrial as well as commercial applications.
Seminar report on directed energy weaponsVishal Bait
After decade of research and development, Directed energy weapon are become an operational reality. Such weapons generate streams of electromagnetic energy that can precisely aimed over long distance to disable or destroy target. It is game changing technology in future.
Directed Energy Weapons
===================
Directed energy weapons take many forms. From EMP (electromagnetic pulses) to HPM (high powered microwaves), several weaponized forms of Radio Frequency are being developed.
These .pdf’s from the US Navy Directed Energy Warfare Office (DEWO) show multiple applications for defensive / offensive Radio Frequency weaponry.
Many people have fallen behind the times in regards to understanding what capabilities are being developed, and what current next generation weapons are being deployed.
http://wstiac.alionscience.com/pdf/Vol4Num3.pdf
for many more visit :
hossamozein.blogspot.com/2011/08/laser-wepon.html
electromagnetic pollution , causes of emf pollution , what creates emf pollution , affect of emf pollution , causes and health effects , how to avoid emf pollution
PROJECT DESCRIPTION
DOWNLOAD
The main objective of this project is to develop a device for wireless power transfer. The concept of wireless power transfer was realized by Nikolas tesla. Wireless power transfer can make a remarkable change in the field of the electrical engineering which eliminates the use conventional copper cables and current carrying wires.
Based on this concept, the project is developed to transfer power within a small range. This project can be used for charging batteries those are physically not possible to be connected electrically such as pace makers (An electronic device that works in place of a defective heart valve) implanted in the body that runs on a battery.
The patient is required to be operated every year to replace the battery. This project is designed to charge a rechargeable battery wirelessly for the purpose. Since charging of the battery is not possible to be demonstrated, we are providing a DC fan that runs through wireless power.
This project is built upon using an electronic circuit which converts AC 230V 50Hz to AC 12V, High frequency. The output is fed to a tuned coil forming as primary of an air core transformer. The secondary coil develops a voltage of HF 12volt.
Thus the transfer of power is done by the primary(transmitter) to the secondary that is separated with a considerable distance(say 3cm). Therefore the transfer could be seen as the primary transmits and the secondary receives the power to run load.
Moreover this technique can be used in number of applications, like to charge a mobile phone, iPod, laptop battery, propeller clock wirelessly. And also this kind of charging provides a far lower risk of electrical shock as it would be galvanically isolated.
Automotive Air-Conditioning Service Equipment Mazin Al Ani
Introduction
WOW! Coolius 2700 - Fully Automatic Air-conditioning (A/C) Service Station is a user-friendly tool specifically
designed for the automotive air-conditioning technicians,
Eelctro-Magnetic-Pulse USE AS A WEAPONAshutosh Uke
Seminar Report File - High Power Electromagnetic Pulse generation techniques and High Power Microwave technology have matured to the point where practical EMP Weapon (Electromagnetic pulse) are becoming technically feasible, with new applications in both Strategic and Tactical Information Warfare. The development of conventional EMP devices allows their use in non-nuclear confrontations. This paper discusses aspects of the technology base, weapon delivery techniques and proposes a doctrinal foundation for the use of such devices in warhead and bomb applications.
The wireless power transmission is a great technology that has long history. It has more potential in the near future in various industrial as well as commercial applications.
Seminar report on directed energy weaponsVishal Bait
After decade of research and development, Directed energy weapon are become an operational reality. Such weapons generate streams of electromagnetic energy that can precisely aimed over long distance to disable or destroy target. It is game changing technology in future.
Directed Energy Weapons
===================
Directed energy weapons take many forms. From EMP (electromagnetic pulses) to HPM (high powered microwaves), several weaponized forms of Radio Frequency are being developed.
These .pdf’s from the US Navy Directed Energy Warfare Office (DEWO) show multiple applications for defensive / offensive Radio Frequency weaponry.
Many people have fallen behind the times in regards to understanding what capabilities are being developed, and what current next generation weapons are being deployed.
http://wstiac.alionscience.com/pdf/Vol4Num3.pdf
for many more visit :
hossamozein.blogspot.com/2011/08/laser-wepon.html
electromagnetic pollution , causes of emf pollution , what creates emf pollution , affect of emf pollution , causes and health effects , how to avoid emf pollution
PROJECT DESCRIPTION
DOWNLOAD
The main objective of this project is to develop a device for wireless power transfer. The concept of wireless power transfer was realized by Nikolas tesla. Wireless power transfer can make a remarkable change in the field of the electrical engineering which eliminates the use conventional copper cables and current carrying wires.
Based on this concept, the project is developed to transfer power within a small range. This project can be used for charging batteries those are physically not possible to be connected electrically such as pace makers (An electronic device that works in place of a defective heart valve) implanted in the body that runs on a battery.
The patient is required to be operated every year to replace the battery. This project is designed to charge a rechargeable battery wirelessly for the purpose. Since charging of the battery is not possible to be demonstrated, we are providing a DC fan that runs through wireless power.
This project is built upon using an electronic circuit which converts AC 230V 50Hz to AC 12V, High frequency. The output is fed to a tuned coil forming as primary of an air core transformer. The secondary coil develops a voltage of HF 12volt.
Thus the transfer of power is done by the primary(transmitter) to the secondary that is separated with a considerable distance(say 3cm). Therefore the transfer could be seen as the primary transmits and the secondary receives the power to run load.
Moreover this technique can be used in number of applications, like to charge a mobile phone, iPod, laptop battery, propeller clock wirelessly. And also this kind of charging provides a far lower risk of electrical shock as it would be galvanically isolated.
Automotive Air-Conditioning Service Equipment Mazin Al Ani
Introduction
WOW! Coolius 2700 - Fully Automatic Air-conditioning (A/C) Service Station is a user-friendly tool specifically
designed for the automotive air-conditioning technicians,
Flushing and Cleaning the A/C System
Once an AC system has been contaminated or has suffered a failure, the most important part of the
AC service to restore the cooling performance to the system = FLUSHING
WITHOUT proper flushing procedures, seizing a new or rebuilt compressor is a real possibility.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
An e-bomb (electromagnetic bomb) is a weapon that uses an intense electromagnetic field to create a brief pulse of energy that affects electronic circuitry without harming humans or buildings. At low levels, the pulse temporarily disables electronics systems; mid-range levels corrupt computer data.
A new configuration of patch antenna array for rectenna array applicationsTELKOMNIKA JOURNAL
The performance and advantages of microstrip patch antennas made them a field of interest for wireless power transmission applications, especially for rectenna systems where the choice of the antenna is a crucial step. In this paper, a 5.8 GHz circularly polarized patch antenna has been designed and fabricated, then mounted by using 4 elements to achieve an antenna array to enhance the captured power to be converted by the rectifier circuit. The antenna array is well matched at 5.8 GHz in terms of reflection coefficient and has a directivity of 11 dB and a gain of 6 dB. Results have been confirmed by fabrication.
Electronic circuits provide us with the ability to control the transport and storage of electrons. However, the performance of electronic circuits is now becoming rather limited when digital information needs to be sent from one point to another. Photonics offers an effective solution to this problem by implementing optical communication systems based on optical fibers and photonic circuits. Unfortunately, the micrometer-scale bulky components of photonics have limited the integration of these components into electronic chips, which are now measured in nanometers. Surface plasmon-based circuits, which merge electronics and photonics at the Nano scale, may offer a solution to this size-compatibility problem. Here we review the current status and future prospects of plasmonics in various applications including plasmonic chips, light generation, and nanolithography.
The wireless Power Transmission is a useful and proper technology is used in various fields like electronic devices, implantable medical devices, industry and other fields, and has become a research hotspot at home and abroad. Because it enables the transmission of electrical energy from a power source to an electrical load across an air gap without interconnecting wires. This paper reviews the methods used in the wireless power transmission system, recent technologies, future and its application, merits as well as demerits. Mrs. Yogita Shailesh Kadam "Wireless Power Transmission System- A Review" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-7 | Issue-3 , June 2023, URL: https://www.ijtsrd.com.com/papers/ijtsrd57380.pdf Paper URL: https://www.ijtsrd.com.com/engineering/electrical-engineering/57380/wireless-power-transmission-system-a-review/mrs-yogita-shailesh-kadam
5G wireless network technology is going operate within the environment of other electrical, electronic and electromagnetic devices, components and systems, with capability of high speed data connectivity acting as network transceiver stations with Massive MIMO for Internet of Things (IoT). Considering the level of interoperability, electromagnetic Interference and electromagnetic compatibility to avoid electromagnetic pulse effects (EMP) which is capable of not only causing network malfunctions but total devices and equipments failure in mission critical operations, like hospital MRI scan machines, security profiling and data handling or even personal healthcare devices like heart pacemaker. Electromagnetic energy coupling in PCB due to: radiation, reflection and Crosstalk generates reliability challenges affecting Signal Integrity between traces of multilayer boards stalks, power bus and packaging creating Electromagnetic interference (EMI) in PCB leading false clock response to system failure. Above were considered very essential when deploying 5G wireless network facility as presented in this paper.
Saving of Power in Wireless Power Transmission System using IR Sensor and RelayDr. Amarjeet Singh
As all we know that today’s live is not possible for a moment if we think without electricity after our basic needs that are air, water, food, cloth and shelter. Because without it we can not think about our mobility, But it has also many disadvantages because of the transmission of electricity through wire which cause many time sock due to which living thing may get injured or many time they get unexpected death.
Hence for establishing the transmission of electricity without hazards today’s world started working on the removal of the net of the wires over the world and this is possible only by transmitting electricity wirelessly.
This principle was early given by a charming and mysterious inventor and engineer Nikola Tesla(1891-1898) by inventing Tesla coil. But in wireless electricity transmission, there is a lot of wastage of energy when power is transferred to the load. If there is no loads are available around the receiving antenna(coil), power will be wasted and this is a one of the major disadvantage of this principle.
So by using IR Sensor we can save this power from being waste which will allow the antenna to transmit the power only when the objects are available to receive this transmitted power.
Radiation beam scanning for leaky wave antenna by using slotsTELKOMNIKA JOURNAL
This paper provides an insight of a new, microstrip leaky wave antenna. It holds the ability to continue steer its beam at a swapping frequency. This is done with acceptable impedance matching while scanning and very little gain variation. Investigation is carried out on LWAs’ control radiation pattern in steps at a band frequency via vertical and horizontal slots. The enhancement is realized by etching horizontal and vertical slots on the radiation element. This study also presents a novel half-width microstrip leaky wave antenna (LWA). The antenna is made up of the following basic structures group’s vertical and horizontal slots. The reactance profile at the microstrip’s free edge and thus the main beam direction is changed once the control-cell states are changed. The radiation pattern direction changes by sweeping the operating frequency between 4 GHz to 6 GHz.The main beam may be directed by the antenna between 15o and 55o. C band achieved the measured peak gain of the antenna of 10 dBi at 4.3 GHz beam scanning range.
Design and manufacturing of iris waveguide filters for satellite communicationTELKOMNIKA JOURNAL
We propose in this paper, two bandpass filters in waveguide technology having rectangular symmetrical discontinuities with a half-radius r, designed and operating respectively in the X-Band (9-11.5) GHz and C-Band (3.5-5.5) GHz. These filters consists of eight irises placed symmetrically respectively on standard rectangular waveguides WR90 and WR229 in which resonant irises are inserted. These irises are used to couple the sections very strongly in this filter, which allows the bandwidth to be increased and the matching to be controlled. The comparison between the numerical and electromagnetic results, which we obtained for the filters, constitutes a means of validation of computer simulation technology (CST) environment and Mician for the design of the other circuit elements in the various frequency bands. We observed excellent consistency between the simulation curves and those of the measurements. The results obtained are promising and pave the way for the use of these structures in the fields of telecommunications.
UiPath Test Automation using UiPath Test Suite series, part 4DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 4. In this session, we will cover Test Manager overview along with SAP heatmap.
The UiPath Test Manager overview with SAP heatmap webinar offers a concise yet comprehensive exploration of the role of a Test Manager within SAP environments, coupled with the utilization of heatmaps for effective testing strategies.
Participants will gain insights into the responsibilities, challenges, and best practices associated with test management in SAP projects. Additionally, the webinar delves into the significance of heatmaps as a visual aid for identifying testing priorities, areas of risk, and resource allocation within SAP landscapes. Through this session, attendees can expect to enhance their understanding of test management principles while learning practical approaches to optimize testing processes in SAP environments using heatmap visualization techniques
What will you get from this session?
1. Insights into SAP testing best practices
2. Heatmap utilization for testing
3. Optimization of testing processes
4. Demo
Topics covered:
Execution from the test manager
Orchestrator execution result
Defect reporting
SAP heatmap example with demo
Speaker:
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
Generating a custom Ruby SDK for your web service or Rails API using Smithyg2nightmarescribd
Have you ever wanted a Ruby client API to communicate with your web service? Smithy is a protocol-agnostic language for defining services and SDKs. Smithy Ruby is an implementation of Smithy that generates a Ruby SDK using a Smithy model. In this talk, we will explore Smithy and Smithy Ruby to learn how to generate custom feature-rich SDKs that can communicate with any web service, such as a Rails JSON API.
Builder.ai Founder Sachin Dev Duggal's Strategic Approach to Create an Innova...Ramesh Iyer
In today's fast-changing business world, Companies that adapt and embrace new ideas often need help to keep up with the competition. However, fostering a culture of innovation takes much work. It takes vision, leadership and willingness to take risks in the right proportion. Sachin Dev Duggal, co-founder of Builder.ai, has perfected the art of this balance, creating a company culture where creativity and growth are nurtured at each stage.
Accelerate your Kubernetes clusters with Varnish CachingThijs Feryn
A presentation about the usage and availability of Varnish on Kubernetes. This talk explores the capabilities of Varnish caching and shows how to use the Varnish Helm chart to deploy it to Kubernetes.
This presentation was delivered at K8SUG Singapore. See https://feryn.eu/presentations/accelerate-your-kubernetes-clusters-with-varnish-caching-k8sug-singapore-28-2024 for more details.
Encryption in Microsoft 365 - ExpertsLive Netherlands 2024Albert Hoitingh
In this session I delve into the encryption technology used in Microsoft 365 and Microsoft Purview. Including the concepts of Customer Key and Double Key Encryption.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Smart TV Buyer Insights Survey 2024 by 91mobiles.pdf91mobiles
91mobiles recently conducted a Smart TV Buyer Insights Survey in which we asked over 3,000 respondents about the TV they own, aspects they look at on a new TV, and their TV buying preferences.
UiPath Test Automation using UiPath Test Suite series, part 3DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 3. In this session, we will cover desktop automation along with UI automation.
Topics covered:
UI automation Introduction,
UI automation Sample
Desktop automation flow
Pradeep Chinnala, Senior Consultant Automation Developer @WonderBotz and UiPath MVP
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
2. 2
Fig. 1. False-color snapshot of the computed surface electric currents induced on a prototype military
jet fighter plane by a radar beam at 100 MHz [1]. The impinging plane wave propagates
from left to right at nose-on incidence to the airplane. The surface currents re-radiate
electromagnetic energy which can be detected back at the radar site.
An additional defense need motivating the study of electromagnetics emerged after about
1960 when it became clear that a nuclear bomb detonated above the earth’s atmosphere could
generate a high-level electromagnetic pulse, or EMP. EMP can be sufficiently intense to burn
out electrical and electronic equipment on the earth’s surface located hundreds of miles away
from the point directly below the detonation. Equipment failures on this geographical scale
could leave a nation largely defenseless against subsequent attack. Therefore, substantial efforts
were devoted by the defense community to “harden” key systems to reduce their vulnerability to
EMP. Here, electromagnetics technologies were aimed at predicting the level of EMP
penetration and coupling into potentially vulnerable equipment, and developing cost-effective
means to reduce such coupling to well below the danger point.
A related defense area motivating the study of electromagnetics was explored intensively
after about 1980, when technology developments permitted the generation of steerable, high-
power microwave (HPM) beams. In principle, such beams could neutralize electronics in the
manner of EMP, but be applied on a more selective basis for either tactical or strategic
applications. On the offensive side, electromagnetics technologies were used to design HPM
sources, circuits, and antennas to generate, transport, and radiate high-power beams.
Computational solutions of Maxwell’s equations were also used to understand electromagnetic
wave penetration and coupling mechanisms into potential targets, and means to mitigate these
mechanisms. An example of the complexity of these penetration mechanisms is shown in Fig. 2,
which illustrates the results of applying Maxwell’s equations to calculate the interaction of a 10-
GHz radar beam with a missile radome containing a horn antenna [2].
3. 3
Fig. 2. Two sequential false-color snapshots of a microwave pulse penetrating a missile radome
containing a horn antenna [2]. The impinging plane wave propagates from right to left at the
speed of light and is obliquely incident at 15˚ from boresight. Complicated electromagnetic
wave interactions visible within the radome structure require Maxwell’s equations solutions
to permit effective design.
4. 4
3. Applications in High-Speed Electronics
In undergraduate electrical and computer engineering programs, instructors teaching circuits
courses may, in passing, mention that circuit theory is a subset of electromagnetic field theory.
Invariably, however, the instructors promptly drop this connection. As a result, it is possible for
their graduating seniors (especially in computer engineering, who will likely never take an
electromagnetics course such as this) to have the following rude awakening upon their initial
employment with Intel, Motorola, IBM, and similar manufacturers:
The bedrock of introductory circuit analysis, Kirchoff’s current and
voltage laws, fails in most contemporary high-speed circuits. These
must be analyzed using electromagnetic field theory. Signal power
flows are not confined to the intended metal wires or circuit paths.
Let’s be more specific. High-speed electronic circuits have been traditionally grouped into
two classes: analog microwave circuits and digital logic circuits.
1. Microwave circuits typically process bandpass signals at frequencies above 3 GHz.
Common circuit features include microstrip transmission lines, directional couplers,
circulators, filters, matching networks, and individual transistors. Circuit operation
is fundamentally based upon electromagnetic wave phenomena.
2 . Digital circuits typically process low-pass pulses having clock rates below
2 GHz. Typical circuits include densely packed, multiple planes of metal traces
providing flow paths for the signals, dc power feeds, and ground returns. Via pins
provide electrical connections between the planes. Circuit operation is nominally
not based upon electromagnetic wave effects.
However, the distinction between the design of these two classes is blurring. Microwave
circuits are becoming very complex systems comprised of densely packed elements. On the
digital-circuit side, the rise of everyday clock speeds to 2 GHz implies low-pass signal
bandwidths up to about 10 GHz, well into the microwave range. Electromagnetic wave effects
that, until now, were in the domain of the microwave engineer are becoming a limiting factor in
digital-circuit operation. For example, hard-won experience has shown that high-speed digital
signals can spuriously:
• Distort as they propagate along the metal circuit paths.
• Couple (cross-talk) from one circuit path to another.
• Radiate and create interference to other circuits and systems.
An example of electromagnetic field effects in a digital circuit is shown in Fig. 3, which
illustrates the results of applying Maxwell’s equations to calculate the coupling and crosstalk of a
high-speed logic pulse entering and leaving a microchip embedded within a conventional dual
in-line integrated-circuit package [3]. The fields associated with the logic pulse are not confined
to the metal circuit paths and, in fact, smear out and couple to all adjacent circuit paths.
5. 5
Fig. 3. False-color visualization (bottom) illustrating the coupling and crosstalk of a high-speed
logic pulse entering and leaving a microchip embedded within a conventional dual in-line
integrated-circuit package (top). The fields associated with the logic pulse are not confined
to the metal circuit paths and, in fact, smear out and couple to all adjacent circuit paths [3].
6. 6
4. Applications in Ultrahigh-Speed Photonic Integrated Circuits
Microcavity ring and disk resonators are proposed components for filtering, routing, switching,
modulation, and multiplexing / demultiplexing tasks in ultrahigh-speed photonic integrated
circuits. Fig. 4 is a scanning electron microscope image of a portion of a prototype photonic
circuit comprised of 5.0-µm-diameter aluminum gallium arsenide (AlGaAs) microcavity disk
resonators coupled to 0.3-µm-wide optical waveguides across air gaps spanning 0.1–0.3 µm [4].
Fig. 4. Scanning electron microscope image of a portion of a prototype photonic integrated circuit [4].
The photonic circuit is comprised of 5.0-µm-diameter AlGaAs microcavity disk resonators
coupled to 0.3-µm-wide AlGaAs optical waveguides across air gaps spanning as little as 0.1 µm.
By computationally solving Maxwell’s equations, which are valid literally from dc to light,
the coupling, transmission, and resonance behavior of the micro-optical structures in Fig. 4 can
be determined. This permits effective engineering design. For example, Fig. 5 shows false-color
visualizations of the calculated sinusoidal steady-state optical electric field distributions for a
typical microdisk in Fig. 4 [5]. In the upper-left panel, the optical excitation is at a nonresonant
frequency, 193.4 THz (an optical wavelength, λ, of 1.55 µm). Here, 99.98% of the rightward-
directed power in the incident signal remains in the lower waveguide. In the upper right panel,
the excitation is at the resonant frequency of the first-order radial whispering-gallery mode of the
microdisk, 189.2 THz (λ =1.585 µm). Here, there is a large field enhancement within the
microdisk, and 99.79% of the incident power switches to the upper waveguide in the reverse
(leftward) direction. This yields the action of a passive, wavelength-selective switch.
The lower-left and lower-right panels are visualizations at, respectively, the resonant
frequencies of the second- and third-order whispering-gallery modes, 191.3 THz (λ =1.567 µm)
and 187.8 THz (λ =1.596 µm). A goal of current design efforts is to suppress such higher-order
modes to allow the use of microdisks as passive wavelength-division multiplexing devices
having low crosstalk across a wide spectrum, or as active single-mode laser sources.
7. 7
Fig. 5. False-color visualizations illustrating the sinusoidal steady-state optical electric field
distributions in a 5.0-µm-diameter GaAlAs microdisk resonator coupled to straight
0.3-µm-wide GaAlAs optical waveguides for single-frequency excitations propagating
to the right in the lower waveguide [5]. Upper left—off-resonance signal; Upper right—
on-resonance signal, first-order radial mode; Lower left—second-order radial-mode
resonance; Lower right—third-order radial mode resonance.
8. 8
5. Applications in Microcavity Laser Design
Proposed ultrahigh-speed photonic integrated circuits require microcavity laser sources and
amplifiers in addition to the passive optical waveguides, couplers, and cavities considered in
Section 4. The accurate design of microcavity lasers requires the solution of Maxwell’s
equations for complex semiconductor geometries capable of optical gain. In fact, the ability to
understand electromagnetic fields and waves via the solution of Maxwell’s equations is crucial to
achieve a design capability for all future photonic integrated circuits.
We now consider a recent application of the large-scale solution of Maxwell’s equations to
design the world’s smallest microcavity laser sources. These sources are based upon the physics
of photonic crystals, which are artificial structures having a periodic variation of the refractive
index in one, two, or three dimensions. Analogous to the energy gap in pure semiconductor
crystals in which electrons are forbidden, these structures can have a frequency stopband over
which there is no transmission of electromagnetic waves. Similar to a donor or acceptor state in
a doped semiconductor, a small defect introduced into the photonic crystal creates a resonant
mode at a frequency that lies inside the bandgap. The defect in the periodic array behaves as a
microcavity resonator.
Fig. 6 (top) illustrates how light is contained inside the laser microcavity [6]. First, a λ/2
high-refractive-index slab is used to trap electromagnetic fields in the vertical direction by way
of total-internal reflection (TIR) at the air-slab interface. Second, the laser light is localized in-
plane using a fabricated two-dimensional photonic crystal consisting of a hexagonal array of
0.180-µm-radius air holes (center-to-center spacing of 0.515 µm) etched into the slab.
The periodic variation in the refractive index gives rise to Bragg scattering, which generates
forbidden energy gaps for in-plane electromagnetic wave propagation. Thus, the photonic
crystal provides an energy barrier for the propagation of electromagnetic waves having
frequencies that lie within the bandgap. In the simplest structure, a single air hole is removed
from the photonic crystal, thereby forming a resonant microcavity. The light energy in the
resonant mode is highly spatially localized in the defect region, and can escape only by either
tunneling through the surrounding two-dimensional photonic crystal or by impinging on the
air-slab interface at a sufficiently large angle to leak out in the vertical direction.
The defect laser cavities are fabricated in indium gallium arsenic phosphide (InGaAsP)
using metalorganic chemical vapor deposition. Here, the active region consists of four 9-nm
quantum wells separated by 20-nm quaternary barriers with a 1.22-µm band gap. The quantum-
well emission wavelength is designed for 1.55 µm at room temperature.
Fig. 6 (bottom) is a false-color visualization of the magnitude of the optical electric field
calculated from Maxwell’s equations along a planar cut through the middle of the InGaAsP slab
[6]. These calculations indicate a resonant wavelength of 1.509 µm, a quality factor Q of 250,
and an effective modal volume of only 0.03 cubic microns. Nearly all of the laser power is
emitted vertically due to the bandgap of the surrounding photonic crystal. Experimental
realization of this microcavity laser indicates a lasing wavelength of 1.504 µm, which is very
close to the 1.509 µm predicted value from the electromagnetics model. Ongoing research
involves optimizing this and similar laser cavities by performing Maxwell’s equations
simulations of tailoring the radii and spacing of the etched holes that create the photonic crystal.
The goal is to elevate the cavity Q to above 1,500. This would significantly lower the required
pump power and permit the microcavity laser to operate at room temperature.
9. 9
Fig. 6. Photonic crystal microcavity laser. Top—geometry; Bottom—false-color visualization
of the optical electric field distribution along a planar cut through the middle of the
laser geometry. Source: O. Painter et al., “Two-dimensional photonic band-gap
defect mode laser,” Science, vol. 284, June 11, 1999, pp. 1819–1821 [6].
10. 10
6. Light Switching Light in Femtoseconds
In electrical engineering, the phrase “dc to daylight” has been often used to describe electronic
systems having the property of very wide bandwidth. Of course, no one actually meant that the
system in question could produce or process signals over this frequency range. It just couldn’t
be done. Or could it?
In fact, a simple Fourier analysis argument shows that recent optical systems that generate
laser pulses down to 6 fs in duration approach this proverbial bandwidth. From a technology
standpoint, it is clear that controlling or processing these short pulses involves understanding the
nature of their interactions with materials over nearly “dc to daylight,” and very likely in high-
beam-intensity regimes where material nonlinearity can play an important role. A key factor
here is material dispersion, having two components: (1) linear dispersion, the variation of the
material’s index of refraction with frequency at low optical power levels; and (2) nonlinear
dispersion, the variation of the frequency-dependent refractive index with optical power.
Recent advances in computational techniques for solving the time-domain Maxwell’s
equations have provided the basis for modeling both linear and nonlinear dispersions over
ultrawide bandwidths. An example of the possibilities for such modeling is shown in Fig. 7,
which is a sequence of false-color snapshots of the dynamics of a potential femtosecond all-
optical switch [7]. This switch utilizes the collision and subsequent “bouncing” of pulsed optical
spatial solitons, which are pulsed beams of laser light that are prevented from spreading in their
transverse directions by the optical focusing effect of the nonlinear material in which they
propagate.
Referring to the top panel of Fig. 7, this switch would inject in-phase, 100-fs pulsed signal
and control solitons into ordinary glass (a Kerr-type nonlinear material) from a pair of optical
waveguides on the left side. Each pulsed beam has a 0.65-µm transverse width, while the beam-
to-beam spacing is in the order of 1 µm. In the absence of the control soliton, the signal soliton
would propagate to the right at the speed of light in glass with zero deflection, and then be
collected by a receiving waveguide. However, as shown in the remaining panels of Fig. 7,
a co-propagating control soliton would first merge with and then laterally deflect the signal
soliton to an alternate collecting waveguide. (Curiously, the location of the two beams’ merger
point would remain stationary in space while the beams would propagate at light-speed through
this point.) Overall, the optical pulse dynamics shown in Fig. 7 could provide the action of an
all-optical “AND” gate working on a time scale about 1/10,000th that of existing electronic
digital logic.
Application of the fundamental Maxwell’s equations to problems such as the one illustrated
in Fig. 7 shows great promise in allowing the detailed study of a variety of novel nonlinear
optical wave species that may one day be used to implement all-optical switching circuits (light
switching light) attaining speeds 10,000 times faster than those of the best semiconductor circuits
today. The implications may be profound for the realization of “optonics,” a proposed successor
technology to electronics, that would integrate optical-fiber interconnects and optical microchips
into systems of unimaginable information-processing capability.
11. 11
Fig. 7. Sequential false-color snapshots of the electric field of equal-amplitude, in-phase,
100-fs optical spatial solitons co-propagating in glass [7]. The optical pulses propagate
from left to right at the speed of light in glass. This illustrates the dynamics of a potential
all-optical “AND” gate, i.e., light switching light, that could work on a time scale
1/10,000th
that of existing electronic digital logic.
14. 14
8. Conclusions
Whereas the study of electromagnetics has been motivated in the past primarily by the
requirements of military defense, the entire field is shifting rapidly toward important applications
in high-speed communications and computing and biomedicine that will touch everyone in their
daily lives. Ultimately, this will favorably impact the economic and social well-being of nations
as well as their military security.
In fact, the study of electromagnetics is fundamental to the advancement of electrical and
computer engineering technology as we continue to push the envelope of the ultracomplex and
the ultrafast. Maxwell’s equations govern the physics of electromagnetic wave phenomena from
dc to light, and their accurate solution is essential to understand all high-speed signal effects,
whether electronic or optical. Students who well understand the basis of electromagnetic
phenomena are well-equipped to attack a broad spectrum of important problems to advance
electrical and computer engineering and directly benefit our society.
Availability of This Article on the Internet
The PDF version of this article can be downloaded by accessing the author’s webpage at
http://www.ece.northwestern.edu/ecefaculty/Allen1.html and then clicking on the link
“Why Study E&M” paper. Numerous additional graphics illustrating contemporary applications
of electromagnetics can be obtained on the same webpage by clicking on FDTD presentation.
Please address your email comments to the author at taflove@ece.northwestern.edu.
References and Figure Credits
[1] A. Taflove, Computational Electrodynamics: The Finite-Difference Time-Domain Method. Norwood, MA:
Artech House, 1995, pp. 11, 15, 516, 517.
[2] A. Taflove and S. C. Hagness, Computational Electrodynamics: The Finite-Difference Time-Domain Method,
2nd
ed. Norwood, MA: Artech House, 2000, pp. 9, 20, 687–690. Original graphics courtesy of Dr. James G.
Maloney, Photonex, Inc., Email: jmaloney@photonex.com
[3] Graphics courtesy of Prof. Melinda Piket-May, Dept. of Electrical and Computer Engineering, University of
Colorado–Boulder, Boulder, CO. Email: mjp@boulder.colorado.edu
[4] Graphic courtesy of Prof. Seng-Tiong Ho, Dept. of Electrical and Computer Engineering, Northwestern
University, Evanston, IL. Email: sth@ece.northwestern.edu
[5] A. Taflove and S. C. Hagness op cit, pp. 14, 25, 26, 810–819.
[6] O. Painter, R. K. Lee, A. Scherer, A. Yariv, J. D. O’Brien, P. D. Dapkus, and I. Kim, “Two-dimensional
photonic band-gap defect mode laser,” Science, vol. 284, June 11, 1999, pp. 1819–1821.
[7] A. Taflove and S. C. Hagness op cit, pp. 16, 28, 29, 404–407.
[8] Graphic courtesy of Prof. Susan Hagness, Dept. of Electrical and Computer Engineering, University of
Wisconsin–Madison, Madison, WI. Email: hagness@engr.wisc.edu
[9] S. Davis, E. J. Bond, X. Li, S. C. Hagness, and B. D. Van Veen, “Microwave imaging via space-time
beamforming for early-stage breast cancer detection: Beamformer design in the frequency domain,”
J. Electromagnetic Waves and Applications, in press.
15. 15
About the Author
Allen Taflove (F’90) was born in Chicago, IL on June 14, 1949. He received the B.S., M.S., and
Ph.D. degrees in electrical engineering from Northwestern University, Evanston, IL in 1971,
1972, and 1975, respectively. After nine years as a research engineer at IIT Research Institute,
Chicago, IL, he returned to Northwestern in 1984. Since 1988, he has been a professor in the
Department of Electrical and Computer Engineering of the McCormick School of Engineering.
Currently, he is a Charles Deering McCormick Professor of Teaching Excellence and Master of
the Slivka Residential College of Science and Engineering.
Since 1972, Prof. Taflove has pioneered basic
theoretical approaches and engineering applications of
finite-difference time-domain (FDTD) computational
electromagnetics. He coined the FDTD acronym in a 1980
IEEE paper, and in 1990 was the first person to be named a
Fellow of IEEE in the FDTD area. In 1995, he authored
Computational Electrodynamics: The Finite-Difference
Time-Domain Method (Artech House, Norwood, MA).
This book is now in its second edition, co-authored in 2000
with Prof. Susan Hagness of the University of
Wisconsin–Madison; a third edition is planned for 2005.
In 1998, he was the editor of the research monograph,
Advances in Computational Electrodynamics: The Finite-
Difference Time-Domain Method (Artech House, Norwood,
MA).
In addition to the above books, Prof. Taflove has authored or co-authored 13 invited book
chapters, 77 journal papers, approximately 200 conference papers and abstracts, and 14 U.S.
patents. Overall, this work resulted in his being named in 2002 to the “Highly Cited Researchers
List” of the Institute for Scientific Information (ISI).
Prof. Taflove has been the thesis adviser of 16 Ph.D. recipients who hold professorial,
research, or engineering positions at major institutions including University of Wisconsin–
Madison, University of Colorado–Boulder, McGill University, MIT Lincoln Laboratory,
Jet Propulsion Laboratory, Argonne National Laboratory, and U.S. Air Force Research
Laboratory. Currently, he is conducting research in a wide range of computational
electromagnetics modeling problems including the propagation of bioelectric signals within the
human body, laser-beam propagation within samples of human blood, UHF diffraction by
buildings in urban wireless microcells, electrodynamics of micron-scale optical devices, novel
wireless interconnects for ultrahigh-speed digital data buses, and extremely low-frequency
geophysical phenomena.