Tunable frequency and angular photonic crystal filter

Abstract

We investigate the influence of structure parameters to the band structures of one-dimensional photonic crystals stacking of alternating positive and negative refractive index materials. The refractive index of these two materials has the same given absolute value. We find that the layers' thickness of the photonic crystals determines the frequency and angle of the transmission peaks, and when the thickness is given, the permittivity and permeability of the negative index material determine the width of frequency peak and angular peak. For realizing ultra-narrow band frequency and sharp angular filer, we add a defect layer with positive refractive index in the middle of the photonic crystals. Setting its structure parameters satisfying some special conditions, there will be a narrow peak in the middle of the band gap. When electromagnetic wave incident on such PC, only those portions with special frequency and special angle can pass though, and the accuracy can be very high. Such filter will have wide applications in microwave and optical communications.