1 September 2004 Microgenetic algorithm design of hybrid conventional waveguide and photonic crystal structures
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Optical Engineering, 43(9), (2004). doi:10.1117/1.1780546
Abstract
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).
Seunghyun Kim, Gregory P. Nordin, Jianhua Jiang, Jingbo Cai, "Microgenetic algorithm design of hybrid conventional waveguide and photonic crystal structures," Optical Engineering 43(9), (1 September 2004). http://dx.doi.org/10.1117/1.1780546
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KEYWORDS
Waveguides

Diffraction

Polarization

Finite-difference time-domain method

Beam splitters

Photonic crystals

Refractive index

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