Wavelength Filter Based on Photonic Crystal Resonant Cavity
Alok Kumar and Sarang Medhekar
An optical wavelength filter employing a resonant cavity (RC) in 2-D photonic crystal (2DPC) is proposed in this paper. Photonic band gap (PBG) of the considered structure (wavelength filter) is calculated by Plane Wave Expansion (PWE) method and the simulation results of light propagation in the proposed wavelength filter are obtained using Two Dimensional Finite Difference Time Domain (2DFDTD) method. The effect of changing (i) radius of defect rods of RC (ii) refractive index of defect rods of RC (iii) refractive index of rods of the whole structure (iv) radius of the coupling rods (v) radius of the central rod of RC on resonant wavelength (and hence, filtered wavelength of the wavelength filter) is investigated. The results of the investigations give an intuitive idea of manipulating the resonant wavelength to a desired value. Further, It is found in our investigations that sharp wavelength filtering is possible with transmission efficiency as high as 90%. A scheme to realize wavelength de-multiplexer is also given at the end.
Keywords: Photonic crystals, resonant cavity