Design and Simulation of Photonic Crystal Based Polarization Converter

A periodic asymmetrically loaded photonic-crystal (PC) based polarization converter has been designed and fabricated. The polarization converter structure consists of a single defect line square hole PC slab waveguide with asymmetrically loaded top layer. The design methodology consists of finding the birefringence induced by geometrical asymmetry through full-wave modal analysis. The proposed design methodology can be extended to arbitrary air hole shape photonic-crystal-based polarization converter. The length and total number of top loaded layers are determined upon full-wave modal analysis. The thickness of the loaded top layer has been optimized to provide wideband and low loss polarization conversion. The optimized thickness of the top loaded layer is 0.2a for which polarization conversion takes place over the propagation distance of 13lambda₀. For this distance, the coupling efficiency higher than 90% is achieved within the normalized frequency band of 0.258-0.267 corresponding to 584-604.5 GHz for the design example presented in III.