Channel drop filters using photonic crystal Fabry–Perot resonators

We have proposed channel drop filters based on a combination of Fabry–Perot (F–P) resonators in a two-dimensional photonic crystal with a triangular lattice of air holes. By tuning the separation, the radii of air holes between F–P resonators, and the length of two F–P resonators, we can selectively improve filter characteristics and obtain a forward-dropping efficiency of 95% and a backward-dropping efficiency of 90% at desired resonance frequencies. For the case where two F–P resonators are directly connected without separation, it forms a ring behavior and has a backward-dropping efficiency of 75% at resonance. Moreover, we investigate the dependence of optical bistability in one of the optimized resonators on initial frequency detunings. A switching speed of 2ps is obtained. By decreasing the initial frequency detuning, overshoot on the switching-on power can be greatly suppressed. ► Nearly 100% dropping efficiency. ► Both backward- and forword- directional dropping. ► Short switching speed about 2ps for optical bistability. ► The suppression of overshooting and instability phenomenom.