The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform

Kin Seng Chiang - One of the best experts on this subject based on the ideXlab platform.

  • Calculation of confinement factors for multiple‐quantum‐well optical amplifiers by the Effective‐Index model
    Microwave and Optical Technology Letters, 2000
    Co-Authors: W. P. Wong, Kin Seng Chiang
    Abstract:

    The Effective-Index model is examined for the calculation of the confinement factors of the TE and TM modes of a multiple-quantum-well (MQW) waveguide amplifier. When the confinement factors for the barrier and well layers of the MQW structure are calculated separately, the Effective-Index model, when applied to the TM mode, must be corrected with the actual refractive Indexes of the corresponding layers. The usefulness of the model is demonstrated with a design of a polarization-insensitive MQW optical amplifier. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 25: 275–278, 2000.

  • e Effective-Index Method for the Vector ctangular-Core Dielectric Waveguides
    1996
    Co-Authors: Kin Seng Chiang
    Abstract:

    The approximations involved in the Effective-Index method for analyzing the vector modes of rectangular-core di- electric waveguides are examined in detail. It is shown that the Effective-Index method does not solve the full vector-wave equation that governs the modes. Instead, it solves the reduced vector-wave equation, which is accurate only for approximately linearly polarized waves. Furthermore, in solving the reduced vector-wave equation, the method of separation of variables is used, which leads to additional errors as the waveguide being analyzed is a mathematically nonseparable structure. To charac- terize the performance of the Effective-Index method, asymptotic expressions are derived for the errors in the calculation of prop- agation constants. Apart from separating the effects of different approximations involved, these expressions show explicitly how the accuracy of the method depends on the mode type, the normalized frequency, the mode orders, the dimensions of the waveguide, and the relative refractive-Index differences between the core and the surrounding media. With the help of these expressions, it is demonstrated that more accurate results can be obtained by combining various Effective-Index solutions. of optical fibers with the Effective-Index method, Chiang (12) presented the reduced vector-wave equation (in contrast with the full vector-wave equation) that the method actually solved, and pointed out which terms in the equation were ignored in the application of the method. This study reveals, in the most fundamental way, the basic assumptions made in the method. Considering only the scalar modes, Kumar et al. (19) derived the rectangular structure that was exact for the Effective-Index method. By treating this structure as a perturbation of the original structure, Chiang developed an asymptotic theory for the Effective-Index method for rectangular waveguides (20) and waveguide arrays (SI. This theory fully characterizes the performance of the method for the scalar modes in the far- from-cutoff region. In this paper, a detailed analysis of the Effective-Index method for the vector modes of rectangular-core waveguides is presented. It is shown that the solution obtained from the Effective-Index method in general contains errors arising from the use of the reduced vector-wave equation to approximate the full vector-wave equation, and from the use of a different structure to approximate the original structure. Analytical asymptotic expressions for these errors are derived to describe explicitly the performance of the method. Based on these expressions, a procedure to obtain more accurate solutions from combining various Effective-Index solutions is proposed. The results presented in this paper should provide a much clearer picture of the nature of the Effective-Index method for the analysis of rectangular-core waveguides.

  • Effective-Index method with built-in perturbation correction for integrated optical waveguides
    Journal of Lightwave Technology, 1996
    Co-Authors: Kin Seng Chiang, Kam Shing Kwok
    Abstract:

    It is well known that the conventional Effective-Index method for the analysis of rectangular-core waveguides can in general produce accurate results only when the modes of the waveguides are operated in the far-from-cutoff region. In this paper, an improved Effective-Index method, called the Effective-Index method with built-in perturbation correction, is described. This method is as efficient as the conventional method pet produces much more accurate results. Numerical examples for single waveguides and directional couplers are presented to demonstrate the accuracy of the method with results obtained from an improved Fourier decomposition method as the references.

  • Analysis of the Effective-Index method for the vector modes of rectangular-core dielectric waveguides
    IEEE Transactions on Microwave Theory and Techniques, 1996
    Co-Authors: Kin Seng Chiang
    Abstract:

    The approximations involved in the Effective-Index method for analyzing the vector modes of rectangular-core dielectric waveguides are examined in detail. It is shown that the Effective-Index method does not solve the full vector-wave equation that governs the modes. Instead, it solves the reduced vector-wave equation, which is accurate only for approximately linearly polarized waves. Furthermore, in solving the reduced vector-wave equation, the method of separation of variables is used, which leads to additional errors as the waveguide being analyzed is a mathematically nonseparable structure. To characterize the performance of the Effective-Index method, asymptotic expressions are derived for the errors in the calculation of propagation constants. Apart from separating the effects of different approximations involved, these expressions show explicitly how the accuracy of the method depends on the mode type, the normalized frequency, the mode orders, the dimensions of the waveguide, and the relative refractive-Index differences between the core and the surrounding media. With the help of these expressions, it is demonstrated that more accurate results can be obtained by combining various Effective-Index solutions.

  • Effective-Index analysis of optical waveguides
    Physics and Simulation of Optoelectronic Devices III, 1995
    Co-Authors: Kin Seng Chiang
    Abstract:

    The operation and the theory of the Effective-Index method for the analysis of a wide range of optical waveguides are reviewed. The asymptotic results that characterize the performance of the method for rectangular waveguides and waveguide arrays are discussed. An accurate version of the method, namely the Effective-Index method with a built-in perturbation correction, is described. The applications of the Effective-Index method to nonrectangular waveguides and nonlinear waveguides are also discussed.

Samir Kumar Lahiri - One of the best experts on this subject based on the ideXlab platform.

  • Design of Single Mode Annealed Proton Exchanged LiNbO^3 Waveguides by Effective-Index Based Matrix Method
    Journal of Optics, 2006
    Co-Authors: Pranabendu Ganguly, Juran Chandra Biswas, Samir Kumar Lahiri
    Abstract:

    Effective-Index based matrix method is used to analyse annealed proton exchanged (APE) LiNbO_3 waveguides. The variation of refractive Index with the fabrication parameters, such as, exchange time, annealing time, waveguide width, and transmitting wavelength is studies. The computed surface refractive Index changes of the waveguides are compared with the published experimental results. The 2D transverse refractive Index profile of the APE lithium niobate waveguide is transformed to the laterial 1D Effective Index profile by WKB method, which is then disc reused using a partitioning scheme. The matrix method is then applied to obtain the propagation constants of the guided modes. Variation of propagation constant with the fabrication parameters of APE waveguide is studied and the single mode APE lithim niobate channel waveguides are designed.

  • Design of Single Mode Annealed Proton Exchanged LiNbO^3 Waveguides by Effective-Index Based Matrix Method
    Journal of Optics, 2006
    Co-Authors: Pranabendu Ganguly, Juran Chandra Biswas, Samir Kumar Lahiri
    Abstract:

    Effective-Index based matrix method is used to analyse annealed proton exchanged (APE) LiNbO_3 waveguides. The variation of refractive Index with the fabrication parameters, such as, exchange time, annealing time, waveguide width, and transmitting wavelength is studies. The computed surface refractive Index changes of the waveguides are compared with the published experimental results. The 2D transverse refractive Index profile of the APE lithium niobate waveguide is transformed to the laterial 1D Effective Index profile by WKB method, which is then disc reused using a partitioning scheme. The matrix method is then applied to obtain the propagation constants of the guided modes. Variation of propagation constant with the fabrication parameters of APE waveguide is studied and the single mode APE lithim niobate channel waveguides are designed.

Sang-yung Shin - One of the best experts on this subject based on the ideXlab platform.

  • On the validity of the Effective-Index method for rectangular dielectric waveguides
    Journal of Lightwave Technology, 1993
    Co-Authors: Jae-suk Lee, Sang-yung Shin
    Abstract:

    The Effective-Index method (EIM) for rectangular dielectric waveguides is derived as an approximation from an exact equivalent-network formulation. It is explained why EIM gives accurate results for the fundamental modes in near cutoff region as well as for all the guided modes in well-guiding region. As a direct improvement on EIM a simple eigenvalue equation is presented, which takes into account the shape of the predominant slab-waveguide mode. It is shown that EIM overestimates propagation constants compared to the improved results. >

Pranabendu Ganguly - One of the best experts on this subject based on the ideXlab platform.

  • Design of Single Mode Annealed Proton Exchanged LiNbO^3 Waveguides by Effective-Index Based Matrix Method
    Journal of Optics, 2006
    Co-Authors: Pranabendu Ganguly, Juran Chandra Biswas, Samir Kumar Lahiri
    Abstract:

    Effective-Index based matrix method is used to analyse annealed proton exchanged (APE) LiNbO_3 waveguides. The variation of refractive Index with the fabrication parameters, such as, exchange time, annealing time, waveguide width, and transmitting wavelength is studies. The computed surface refractive Index changes of the waveguides are compared with the published experimental results. The 2D transverse refractive Index profile of the APE lithium niobate waveguide is transformed to the laterial 1D Effective Index profile by WKB method, which is then disc reused using a partitioning scheme. The matrix method is then applied to obtain the propagation constants of the guided modes. Variation of propagation constant with the fabrication parameters of APE waveguide is studied and the single mode APE lithim niobate channel waveguides are designed.

  • Design of Single Mode Annealed Proton Exchanged LiNbO^3 Waveguides by Effective-Index Based Matrix Method
    Journal of Optics, 2006
    Co-Authors: Pranabendu Ganguly, Juran Chandra Biswas, Samir Kumar Lahiri
    Abstract:

    Effective-Index based matrix method is used to analyse annealed proton exchanged (APE) LiNbO_3 waveguides. The variation of refractive Index with the fabrication parameters, such as, exchange time, annealing time, waveguide width, and transmitting wavelength is studies. The computed surface refractive Index changes of the waveguides are compared with the published experimental results. The 2D transverse refractive Index profile of the APE lithium niobate waveguide is transformed to the laterial 1D Effective Index profile by WKB method, which is then disc reused using a partitioning scheme. The matrix method is then applied to obtain the propagation constants of the guided modes. Variation of propagation constant with the fabrication parameters of APE waveguide is studied and the single mode APE lithim niobate channel waveguides are designed.

Jae-suk Lee - One of the best experts on this subject based on the ideXlab platform.

  • On the validity of the Effective-Index method for rectangular dielectric waveguides
    Journal of Lightwave Technology, 1993
    Co-Authors: Jae-suk Lee, Sang-yung Shin
    Abstract:

    The Effective-Index method (EIM) for rectangular dielectric waveguides is derived as an approximation from an exact equivalent-network formulation. It is explained why EIM gives accurate results for the fundamental modes in near cutoff region as well as for all the guided modes in well-guiding region. As a direct improvement on EIM a simple eigenvalue equation is presented, which takes into account the shape of the predominant slab-waveguide mode. It is shown that EIM overestimates propagation constants compared to the improved results. >