Adibi, Ali

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Now showing 1 - 5 of 5
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    Absorbing boundary conditions for low group velocity electromagnetic waves in photonic crystals
    (Georgia Institute of Technology, 2011-03) Askari, Murtaza ; Momeni, Babak ; Reinke, Charles M. ; Adibi, Ali
    We present an efficient method for the absorption of slow group velocity electromagnetic waves in photonic crystal waveguides (PCWs). We show that adiabatically matching the low group velocity waves to high group velocity waves of the PCW and extending the PCW structure into the perfectly matched layer (PML) region results in a 15 dB reduction of spurious reflections from the PML. We also discuss the applicability of this method to structures other than PCWs.
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    Systematic Design of Wide-Bandwidth Photonic Crystal Waveguide Bends With High Transmission and Low Dispersion
    (Georgia Institute of Technology, 2010-06) Askari, Murtaza ; Momeni, Babak ; Soltani, Mohammad ; Adibi, Ali
    We identify factors affecting transmission and dispersive properties of photonic crystal waveguide (PCW) bends, using 2-D simulations and present a method for systematic design of PCW bends to achieve high transmission and low dispersion over large bandwidths. The bends presented here have higher bandwidth and lower dispersion than bends already reported.
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    Strong angular dispersion using higher bands of planar silicon photonic crystals
    (Georgia Institute of Technology, 2008-09) Momeni, Babak ; Chamanzar, Maysamreza ; Hosseini, Ehsan Shah ; Askari, Murtaza ; Soltani, Mohammad ; Adibi, Ali
    We present experimental evidence for strong angular dispersion in a planar photonic crystal (PC) structure by properly engineering the modes in the second PC band. We show that by using the second photonic band of a square lattice PC, angular dispersion of 4°/nm can be achieved. We also show that major challenges in designing practical PC devices using second band modes can be addressed by engineering the lattice and adding input/output buffer stages designed to eliminate unwanted effects.
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    Planar photonic crystals infiltrated with nanoparticle/polymer composites
    (Georgia Institute of Technology, 2007-11) Tay, Savaş ; Thomas, Jayan ; Momeni, Babak ; Askari, Murtaza ; Adibi, Ali ; Hotchkiss, Peter J. ; Jones, Simon C. ; Marder, Seth R. ; Norwood, Robert A. ; Peyghambarian, Nasser
    Infiltration of planar two-dimensional silicon photonic crystals with nanocomposites using a simple yet effective melt processing technique is presented. The nanocomposites that were developed by evenly dispersing functionalized TiO₂ nanoparticles into a photoconducting polymer were completely filled into photonic crystals with hole sizes ranging from 90 to 500 nm. The infiltrated devices show tuning of the photonic band gap that is controllable by the adjustment of the nanoparticle loading level. These results may be useful in the development of tunable photonic crystal based devices and hybrid light emitting diodes and solar cells.
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    Compact wavelength demultiplexing using focusing negative index photonic crystal superprisms
    (Georgia Institute of Technology, 2006-03) Momeni, Babak ; Huang, Jiandong ; Soltani, Mohammad ; Askari, Murtaza ; Mohammadi, Saeed ; Rakhshandehroo, Mohammad ; Adibi, Ali
    Here, we demonstrate a compact photonic crystal wavelength demultiplexing device based on a diffraction compensation scheme with two orders of magnitude performance improvement over the conventional superprism structures reported to date. We show that the main problems of the conventional superprism-based wavelength demultiplexing devices can be overcome by combining the superprism effect with two other main properties of photonic crystals, i.e., negative diffraction and negative refraction. Here, a 4-channel optical demultiplexer with a channel spacing of 8 nm and cross-talk level of better than -6.5 dB is experimentally demonstrated using a 4500 μm² photonic crystal region.