Research On Design Of Silicon-based Photonic Crystal Slow Light Waveguide And Measuring Methods

With the rapid development of silicon photonics, silicon-based photonic crystaldevices have attracted people’s great attention, and research on slow light waveguide isespecially promising. Slow light is not just a mysterious phenomenon. It can offersuperior solutions for optical signal buffering and processing in the time domain, orenhance the light-material interactions and improve the optical nonlinear effects. Formedby arranging two or more dielectric materials periodically in space and also introducingdefects particularly, photonic crystal waveguides can be easily integrated, flexiblydesigned and operated in room temperature. Thus, wide band and low dispersion slowlight can be achieved through fine adjusting the structure and band of the photonic crystalwaveguides.Focusing on silicon-based photonic crystal slow light waveguides, this thesis mainlyincludes the following contents:(1) Based on the investigations and discussions of the mechanism of slow light inphotonic crystal and Maxwell Equations, the waveguides can be precisely simulated withplane wave expansion method, finite-difference time-domain method and so on.Compared to conventional line defect photonic crystal waveguide, two differentoptimizations, zero dispersion slow light and dispersion-compensated slow light, areillustrated. Taking advantages from both lattice-shift and slot designs, a novel lattice-shiftslot structure is proposed and then simulated with plane wave expansion method. Byoptimizing structural parameters and finely tuning the dispersion curves, wide band andlow dispersion slow light is achieved, centered at wavelength of1550nm. The slow lightoperation bandwidths of25.72nm,15.6nm,5.1nm are got corresponding to grouprefractive index(ng) of15.5,19,31respectively. It additionally offers a possible fielddensity enhancement for strengthen optical nonlinear effect.(2) Based on the investigations of slow light measuring methods and the currentfacilities in our laboratory, a simple Mach-Zehnder interferometer (MZI) has been builtby using adjustable optical delay line as alternative of photonic-crystal slow lightwaveguide. And experimental results and data analysis are provided. The experimentalresults confirm the rationality and feasibility of measuring ngof slow light waveguide byMZI system.