Study and analysis on slow light in photonic crystal waveguide

Abstract

Slow light is to reduce the light propagation speed in the medium. In recent years, because slow light technology is the key to achieving all-optical network technologies constitute optics, it attracted people's attention. Compared with other methods, photonic crystal waveguides provide slow light with many adventages, especially we can fine tune the structure to control the performance of the slow-light. Because the two-dimensional triangular lattice photonic crystal is easier to form band gaps than two-dimensional cubic lattice photonic crystal, the circular dielectric rod is easier to form band gaps than square dielectric cylinder, when the photonic crystal lattice vector angle is greater than 60 degrees, it can make the performance of slow light more excellent. So in this paper,we will rotate the cubic lattice 45 degrees counterclockwise. By reducing the radius of middle row of medium column to form the line defect; Additionly, we design a coupled cavity waveguide. Using the plane wave expansion method (PWE), we have analyzed the dispersion curves of the guided mode, the corresponding group refractive index and group velocity dispersion of slow light. For the line defected waveguide, we have realized the group refractive index changing from 8.1 to 84.8 by fine tuning the radius of the defective rod, the position and radius of the first row of the dielectric cylinder close to the waveguide. For the coupled cavity waveguide, we have realized the group refractive index changing from 16 to 79 by fine tuning the radius of the defective rod.