The Simulation Analysis Of Controllable Group-Velocity Of Two Dimension Photonic Crystal Waveguides

Recently, to control the velocity of light in medium has been widely investigated on in the field of optics. As far as now, there are many kinds of methods to reduce light propagation. Relative to other slow-light technologies, the biggest advantage of slow light in photonic crystal waveguides is that it can produce slow light at room temperature in compact in size, and it's great prospect of applications in optical delay line, optical buffering, all-optical storage, optical communication and etc.In this paper, we introduce the applications, the preparation methods and development situation of photonic crystal, with emphases on the band theory based on plane wave expansion method. The effects of forbidden band's location and width by different lattice structures, magnitudes of dielectric constant, ratios of filling rate and shapes of dielectric rod are studied in detail, which provide theoretic support to the optimization of photonic crystal waveguides.By adding line defect to photonic crystal, we could lead in waveguide in former forbidden band region, and use BandSOLVE to perform the simulation of dispersion relation of waveguides, and get velocity of the waveguides by group velocity theory, and point out the linear relation between the wavelength and lattice constant, in other words, we can achieve specific wavelength by altering lattice constant. For slow light in photonic crystal waveguides, large group velocity dispersion makes it difficult apply to the field of optical communication, especially to wavelength division multiplex system. The emphases of this paper is to realize the group velocity controllable in photonic crystal waveguides. By controlling the parameters of waveguides including the width of the waveguide and the size of air rods and etc, we achieved waveguides with different group velocity and different waveguide width at the wavelength of1.55μm . Shifting the first row of air rods refer to waveguide center, we obtained large bandwidth of 10.74nm with group velocity at0.087c₀ , and variating the second row of air rods refer to waveguide center, we obtained bandwidth of 0.95nm with group velocity at 0.0083c₀. At last, we come to the result that the bandwidth and group velocity exclude each other, it's difficult to achieve low group velocity with large bandwidth, there is an idea point at group velocity of 0.035c₀ with the bandwidth of 7.1nm.