Optics and Photonics Society of Iran

In this paper, we use two-dimensional photonic crystals (PCs) for designing gradient index (GRIN) structures. In order to implement graded refractive index, we propose changing the filing factor. In this way, the radius of dielectric rods along the transverse direction to propagation is altered. The response of the structure to wide incident beam is investigated. The spatially wide input beam enters to the structure and bends toward the central area. The input beam reduces its spatial width considerably and focuses to the focal point outside the structure. The propagation of electric and magnetic fields is calculated by the finite-difference time-domain method. For frequency analyzing of photonic crystal structure with gradient index we plot iso-frequency curves for different value of dielectric rods radius.