Transmission properties of defect modes in one-dimensional photonic crystals containing gradient refractive index defects

The gradient refractive index (GRIN) defect layer is introduced into one-dimensional photonic crystal (1D PC) to develop the optical filters needed. The transmission properties of 1D PC with GRIN defect layer were investigated based on the finite difference time domain (FDTD) method. Defect mode was obtained according to the GRIN distribution functions. With a GRIN structure in the defect layer, simulation results show that the position and width of the photonic band gap can be effectively modulated by varying the thickness and GRIN distribution functions of defect layer and the parameters of symmetrical layers. The new study provides a certain reference for photonic band gap engineering and designing the photonic-based devices.