BROADENING OF OMNIDIRECTIONAL PHOTONIC BAND GAP IN SI-BASED ONE DIMENSIONAL PHOTONIC CRYSTALS
Progress In Electromagnetics Research M
A simple design of one dimensional gradual stacked photonic crystal (GSPC) structure has been proposed. The proposed structure consists of a periodic array of alternate layers of SiO 2 and Si as the materials of low and high refractive indices respectively. The structure considered here has three stacks of periodic structures with five layers each. The lattice period of successive stack is increased by a certain multiple (say gradual constant, γ) of the lattice period of the just preceding
... just preceding stack. For numerical computation, the transfer matrix method (TMM) has been employed. It is found that such a structure has wider reflection bands in comparison to a conventional dielectric PC structure, and the width of the omni-directional reflection (ODR) bands can be enlarged by increasing the value of the gradual constant. Hence, a GSPC structure can be used as a broadband omnidirectional reflector, and the bandwidth of omni-directional gaps can be tuned to a desired wavelength region by choosing appropriate value of γ.