Very compact photonic crystal resonant cavity for all optical filtering

In this paper, an all-optical filter is proposedwhich employs a resonant cavity localized between inputand output waveguides as wavelength selecting part of thefilter. We study the impact of different parameters on thefiltering of the structure using plane wave expansion andfinite difference time domain methods. We also study theeffect of the output waveguide position on the performanceof the filter and results show that the proper position of theoutput waveguide is straight to the center of the resonantcavity. The initial form of filter is capable of selecting theoptical waves at λ = 1,554.2 nm and the transmissionefficiency of the filter is obtained about 100 %. The totalfootprint of the filter is<76 lm(2). High transmission efficiency,simplicity of design and compact size are the mostsignificant advantages of filter.