guided waves, integrated optics, optical devices, photonics


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.

Original Publication Citation

S. Kim, G. P. Nordin, J. Jiang, and J. Cai, "Micro-genetic algorithm design of hybrid conventional waveguide and photonic crystal structures," Opt. Eng., 43(9), pp. 2143-2149 (24)

Document Type

Peer-Reviewed Article

Publication Date


Permanent URL


SPIE -- Society of Photo-Optical Instrumentation Engineers




Ira A. Fulton College of Engineering and Technology


Electrical and Computer Engineering