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    Extension of unified formulation for the FDTD simulation of nonlinear dispersive media

    , Article IEEE Photonics Technology Letters ; Volume 22, Issue 16 , 2010 , Pages 1214-1216 ; 10411135 (ISSN) Naqavi, A ; Miri, M ; Mehrany, K ; Khorasani, S ; Sharif University of Technology
    A simple approach is extended for the simulation of Kerr-nonlinear and/or dispersive media through the finite-difference time-domain method. The scheme is able to include different types of linear and nonlinear dispersion in a single and unified formulation. It also provides a method for the simulation of nonlinear dispersive media in such a way that saving time is possible. Also, a new simple technique is presented for the implementation of sources having arbitrary profiles and arbitrary radiation angles. The technique is particularly suited for easy modeling of unidirectional sources like Gaussian beams  

    Wave propagation in metallic slab waveguides undergoing arbitrary temporal variations of permittivity

    , Article 27th Iranian Conference on Electrical Engineering, ICEE 2019, 30 April 2019 through 2 May 2019 ; 2019 , Pages 1529-1533 ; 9781728115085 (ISBN) Chegnizadeh, M ; Memarian, M ; Mehrany, K ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    A general and closed form solution of wave propagation in a metallic slab waveguide undergoing any arbitrary, time-varying function of permittivity is presented. The formulation is general and accurate to account for all temporal variations of permittivity. Parametric amplification and frequency conversion is demonstrated using this closed form formulation. Moreover, all results are validated and confirmed using full wave FDTD simulation. The in-house FDTD MATLAB code takes into account time variations of the permittivity  

    On the power-bandwidth trade-off in bistable photonic switches

    , Article Photonic and Phononic Crystal Materials and Devices IX, San Jose, CA, 27 January 2009 through 29 January 2009 ; Volume 7223 , 2009 ; 0277786X (ISSN) Naqavi, A ; Abediasl, H ; Mehrany, K ; Khorasani, S ; Chamanzar, M. R ; Adibi, A ; Sharif University of Technology
    Low power operation and high speed have always been desirable in applications such as data processing and telecommunications. While achieving these two goals simultaneously, however, one encounters the well-known powerbandwidth trade-off. This is here discussed in a typical bistable switch based on a two-dimensional photonic crystal with Kerr type nonlinearity. The discussion is supported by the nonlinear finite difference time domain (FDTD) simulation of a direct coupled structure with a home-developed code. Two cases of working near resonant and off- resonant are simulated to compare the power and the speed of the device in the two cases. It is shown that working nearresonance reduces the... 

    FDTD analysis of distributed amplifiers based on the fully distributed model

    , Article 2007 Asia-Pacific Conference on Applied Electromagnetics, APACE2007, Melaka, 4 December 2007 through 6 December 2007 ; 2007 ; 1424414350 (ISBN); 9781424414352 (ISBN) Mirzavand, R ; Abdipour, A ; Shishegar, A. A ; Sharif University of Technology
    In this paper a wave approach has been introduced to study the performance of a distributed amplifier. The time domain response of a FET is obtained by means of the fully distributed model. By applying the procedure to a pi-gate GaAs MESFET, the S matrix is computed from time domain results over a frequency range of 2-20 GHz. Scattering parameters of gate and drain lines are extracted from three-dimensional FDTD simulation. The result obtained by this wave approach is compared with device lumped model and Quasi static approach of transmission line. © 2007 IEEE