1 September 2004 Microgenetic algorithm design of hybrid conventional waveguide and photonic crystal structures
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We previously proposed the hybrid integration of photonic crystals (PhCs) and conventional index-guided waveguides (CWGs) as a potentially attractive method of realizing compact waveguide elements for large-scale planar lightwave circuits (PLCs). We now examine 90-deg bends and beamsplitters in PhC/CWG structures in which the waveguide core has a high refractive index (3.25) and yet a low refractive index contrast (1.54%) with the clad material. A PhC structure composed of a triangular or square array of air holes is placed at the intersection of input and output waveguides to obtain high efficiency 90-deg bends. We find that diffraction from the boundary of the PhC region with CWG limits the optical efficiency of the bend. To overcome this we use a rigorous design tool based on a microgenetic algorithm (µGA) and a finite difference time domain (FDTD) method to optimize the boundary layer to suppress the unwanted diffraction. We find that this approach yields improvements in the bend efficiency at a wavelength of 1.55 µm from 56.2 to 92.5% (for a triangular PhC structure, TE polarization) and from 72.0 to 97.4% (square PhC structure, TM polarization).
© (2004) Society of Photo-Optical Instrumentation Engineers (SPIE)
Seunghyun Kim, Seunghyun Kim, Gregory P. Nordin, Gregory P. Nordin, Jianhua Jiang, Jianhua Jiang, Jingbo Cai, Jingbo Cai, } "Microgenetic algorithm design of hybrid conventional waveguide and photonic crystal structures," Optical Engineering 43(9), (1 September 2004). https://doi.org/10.1117/1.1780546 . Submission:

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