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Krishna Thyagarajan

Bio: Krishna Thyagarajan is an academic researcher from Indian Institute of Technology Delhi. The author has contributed to research in topics: Optical fiber & Waveguide. The author has an hindex of 29, co-authored 254 publications receiving 4220 citations. Previous affiliations of Krishna Thyagarajan include Indian Institutes of Technology & Ravenshaw College.


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01 Dec 2007
TL;DR: In this article, the authors present a detailed analysis of planar optical waveguide and a step-index fiber model for optical fiber communication and demonstrate the properties of a step index fiber.
Abstract: 1. Introduction 2. Basic optics 3. The optical fiber 4. Ray analysis of planar optical waveguide 5. Graded index optical fibers 6. Material dispersion 7. Planar waveguides 8. Characteristics of a step-index fiber 9. Graded Index fibers 10. Waveguide dispersion and design considerations 11. Sources for optical fiber communication 12. Detectors for optical fiber and communication 13. Fiber optic communication system design 14. Optical fiber Amplifiers 15. Dispersion compensation and chirping phenomenon 16. Optical solitons 17. Single-mode fiber optic components 18. Single mode optical fiber sensors 19. Measurement methods in optical fiber: I 20. Measurement methods in optical fibers: II 21. Periodic interactions in waveguides 22. Ray equation in Cartesian coordinates 23. Ray paths 24. Leaky modes.

843 citations

Journal ArticleDOI
TL;DR: In this article, a simple matrix method for obtaining propagation characteristics, including losses for various modes of an arbitrarily graded planar waveguide structure which may have media of complex refractive indices, is presented.
Abstract: We present here a simple matrix method for obtaining propagation characteristics, including losses for various modes of an arbitrarily graded planar waveguide structure which may have media of complex refractive indices. We show the applicability of the method for obtaining leakage losses and absorption losses, as well as for calculating beat length in directional couplers. The method involves straightforward 2 × 2 matrix multiplications, and does not require the solutions of any transcendental or differential equations.

244 citations

Journal ArticleDOI
TL;DR: The exact solution of the scalar-wave equation for a rectangular-core waveguide structure is reported and a perturbation analysis for evaluating accurately the propagation characteristics of practical integrated-optical structures is developed.
Abstract: We report the exact solution of the scalar-wave equation for a rectangular-core waveguide structure and develop a perturbation analysis for evaluating accurately the propagation characteristics of practical integrated-optical structures. We show that the present method gives results that are more accurate than other analytical methods reported earlier.

213 citations

Journal ArticleDOI
TL;DR: In this paper, a novel dispersion compensating fiber design consisting of two highly asymmetric concentric cores was proposed, which can have very large negative dispersion values with larger mode field diameter.
Abstract: We propose a novel dispersion compensating fiber design consisting of two highly asymmetric concentric cores. We show that the fundamental mode of the proposed fiber can have very large negative dispersion values [/spl sim/-5100 ps/(nm.km)] with larger mode field diameter (/spl sim/8-9 /spl mu/m) relative to the existing dispersion compensating fibers.

166 citations

Journal ArticleDOI
TL;DR: In this paper, a numerical technique that allows straightforward determination of bound-state and quasi-bound-state energy eigenvalues (and lifetimes of the latter) for arbitrary one-dimensional potentials is presented.
Abstract: A numerical technique that allows straightforward determination of bound-state and quasi-bound-state energy eigenvalues (and lifetimes of the latter) for arbitrary one-dimensional potentials is presented. The method involves straightforward multiplication of 2*2 matrices and does not involve any iterations. The applicability of the technique to analysis of the quantum-well structures is also shown. Since the Schroedinger equation for a spherically symmetric potential can be transformed to a one-dimensional equation, all such problems can also be solved using this method. >

151 citations


Cited by
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Journal Article
TL;DR: AspectJ as mentioned in this paper is a simple and practical aspect-oriented extension to Java with just a few new constructs, AspectJ provides support for modular implementation of a range of crosscutting concerns.
Abstract: Aspect] is a simple and practical aspect-oriented extension to Java With just a few new constructs, AspectJ provides support for modular implementation of a range of crosscutting concerns. In AspectJ's dynamic join point model, join points are well-defined points in the execution of the program; pointcuts are collections of join points; advice are special method-like constructs that can be attached to pointcuts; and aspects are modular units of crosscutting implementation, comprising pointcuts, advice, and ordinary Java member declarations. AspectJ code is compiled into standard Java bytecode. Simple extensions to existing Java development environments make it possible to browse the crosscutting structure of aspects in the same kind of way as one browses the inheritance structure of classes. Several examples show that AspectJ is powerful, and that programs written using it are easy to understand.

2,947 citations

Journal ArticleDOI
TL;DR: In this paper, the authors reviewed recent research on fiber optic long-period gratings (LPGs) with emphasis placed upon the characteristics of LPGs that make them attractive for applications in sensing strain, temperature, bend radius and external index of refraction.
Abstract: Recent research on fibre optic long-period gratings (LPGs) is reviewed with emphasis placed upon the characteristics of LPGs that make them attractive for applications in sensing strain, temperature, bend radius and external index of refraction. The prospect of the development of multi-parameter sensors, capable of simultaneously monitoring a number of these measurands will be discussed.

1,203 citations

Journal ArticleDOI
01 Oct 1991
TL;DR: In this paper, the authors give a brief historic perspective of the coupled mode theory and the development and applications of the theory in microwaves in early years and in optoelectronics and fiber optics in recent years.
Abstract: The authors give a brief historic perspective of the coupled mode theory. The development and applications of the theory in microwaves in early years and in optoelectronics and fiber optics in recent years are described. They then consider lossless coupling of two modes in time. Two coupled resonance circuits, or two coupled microwave or optical resonators, are the physical examples. The start-up of a parametric oscillator is another example. Then they look at the formal derivation of coupled mode theory and consider the more general case when the modes are not energy-orthogonal and the energies are not necessarily positive. A more detailed account of the nonorthogonal coupled mode theory developed in the last five years for optical waveguides is given. >

853 citations

Journal ArticleDOI
TL;DR: A detailed mechanism of the surface plasmon resonance (SPR) technique for sensing purposes has been discussed in this paper, where different new techniques and models in this area that have been introduced are discussed in quite a detail.
Abstract: Since the introduction of optical fiber technology in the field of sensor based on the technique of surface plasmon resonance (SPR), fiber-optic SPR sensors have witnessed a lot of advancements. This paper reports on the past, present, and future scope of fiber-optic SPR sensors in the field of sensing of different chemical, physical, and biochemical parameters. A detailed mechanism of the SPR technique for sensing purposes has been discussed. Different new techniques and models in this area that have been introduced are discussed in quite a detail. We have tried to put the different advancements in the order of their chronological evolution. The content of the review article may be of great importance for the research community who are to take the field of fiber-optic SPR sensors as its research endeavors.

824 citations

Journal ArticleDOI
TL;DR: A study was undertaken to develop a simple, rapid, and reliable method for the experimental determination of the index of refraction n of the many mammalian tissues using the ubiquitous quartz optical fiber.
Abstract: The index of refraction n of the many mammalian tissues is an important but somewhat neglected optical constant. Archival and oral papers have quoted the use of values of n for tissue generally ranging from 1.35 to 1.55. However, these values are frequently without experimental basis. They have arbitrarily used values near that of water, which is a major component of mammalian tissue, or have calculated a theoretical n from the weighted elemental composition of tissue. Since these values have not been precise and little information is available on specific indices for each tissue, a study was undertaken to develop a simple, rapid, and reliable method for the experimental determination of n. This was done using the ubiquitous quartz optical fiber. By substituting the usual cladding found on commercial quartz optics by the tissue in question and utilizing the principle of internal reflection, the value of n for the specific tissue can be calculated. This is done by utilizing the known indices for air and quartz and measuring the angle of the emergent cone of light from the output of the optical fiber. A number of indices for mammalian tissue (bovine, porcine, canine, and human) have been determined at 632.8 nm. With few exceptions, for tissues at this wavelength, n was in the 1.38-1.41 range. The species type did not appear to be a factor. Bovine muscle showed normal dispersion characteristics through the visible wavelengths. The denaturation of tissue was shown to alter significantly the refractive index.

574 citations