Research On Band Structure And Slow Light In Photonic Crystal Waveguide

Controlling the speed of light has become a hot topic in the field of optics. Slow light abstracts widespread attention because of its applications in optical delay line, all-optical buffer, optical communications and other areas. Compared to traditional optical technology, the slow light in photonic crystal defect waveguide depends entirely on waveguide structure, and it can be formed at room temperature, result in a very low group velocity, so it provides opportunities for the integrated and smaller optoelectronic devices.This paper deeply analyzes the structure and properties of two-dimensional photonic crystal waveguide. The main work done as follows:(1) Taking two-dimensional square lattice and two-dimensional triangular lattice for example, it calculates band structure of perfect photonic crystal using PWE, and uses MPB to analyze the field distribution of every band in the formation process of band structure. We can see that the field has some requirements on the symmetry of the photonic crystal structure.(2) It analyzes the structure of photonic crystal waveguide with a single line defect. Taking two-dimensional triangular lattice waveguide with line defect for example, it analyzes its band structure, dispersion relation, group velocity and other characteristics, proposes the method of dynamically adjusting the group velocity based on the effect of thermo-optic and thermal expansion and contraction. Else, by changing the medium dielectric constant, dielectric cylinder radius, refractive index and defect location, it gives the result that the fundamental factor affecting group velocity is the change of defect frequency. Based on above, the theory of photonic crystal waveguide parameters are optimized, and group velocity can be adjusted to0.02c at room temperature.(3) By the analysis of a single defect cavity and coupled transmission characteristics of conventional waveguide and photonic crystal waveguide, it optimizes the original structure of two-defect coupled waveguide with the symmetric single-defect. The single defective part is adjusted to asymmetry, and the air hole is not determined. It analyzes the effect of different m, n values on quality factor, resonance frequency and resonance transmission rates, and finds that m=3is the optimal index for the waveguide, then calculates the distribution of defect modes when the waveguide length is d=8.00a, d=8.30a and m=3. The location of waveguide defect mode frequency determines the characteristics of the transmission after the coupling of general waveguides and line defect waveguide; different waveguide length will make the transmission spectra of the peak position shift, can be used as a phase shifting regulator. The results have important significance for the design and study on defects in optoelectronic devices based on symmetry constraints.