The Theoretical Study Of Chalcogenide Photonic Crystal Slab Waveguide

Photonic crystal (PhC) which is periodic dielectric materials can provide light confinement by photonic band gap (PBG). The light having frequency within the PBG is not allowed to travel in the ideal crystal. Based on this kind of property, PhC has led to novel methods for many important applications, and the photonic crystal waveguide (PCW) is the best important one of these applications. By introducing linear defect, light within the PBG can travel along the defect. In recent years, chalcogenide glass has become a promising novel waveguide material and received the comprehensive research, due to many significant advantages, such as high refractive index, ultra-low linear absorption, light-sensitive characteristics and low two-photon absorption, etc. In our paper, the chalcogenide material we research is gallium lanthanum sulfide (GaLaS refractive index n=2.4), and nontoxicity and easy dopping for rare-earth ions also are its key characters.In this paper, we theoretically designed and studied the band structures and defect modes on 2D chalcogenide PhC slab waveguides.The preparation of 3D photonic crystal has complex operation, high preparation cost and high requirement on the process precision. Preparation of 2D photonic crystal on planar film optical waveguide reduces the difficulty of the technology and cost. Photonic crystal slab waveguide confines light by photonic crystal band gap on the slab plane and refractive index difference in the third dimension. The main contents of paper are as follows:1. The photonic crystal Slab waveguide with the hexagonal air hole lattice was designed based on chalcogenide material GaLaS. By using the modules BandSOLVE of the RSoft Photonic Suite based on the plane wave expansion method, the optimum design parameters of waveguide were obtained by having a scanning calculation for band gap distribution of suspended photonic crystals slab. The optimum slab thickness and air hole radius of waveguide respectively are 0.90a and 0.41a.2. We have a full zone analyze for two-dimensional photonic crystal slab waveguide, the constrained linear defect modes field distribution were obtained by air light cone filtering out radiation modes. The complete band gap of the designed photonic crystal slab structure exist in the range of guided wave, two kinds of polarization guide mode were constrained well.3. And by using the modules FullWAVE based on the finite difference time domain method, we described the propagation information in the waveguide at wavelength 1.53μm Through local structure optimizing for bend waveguide, optical transmission characteristics of 120° bend waveguide and Y waveguide have been improved dramatically.