Compact in-plane channel drop filter design using a single cavity with two degenerate modes in 2D photonic crystal slabs

Abstract

A compact in-plane channel drop filter design in 2D hexagonal lattice photonic crystal slabs is presented in this paper. The system consists of two photonic crystal waveguides and a single cavity with two degenerate modes. Both modes are able to confine light strongly in the vertical dimension and prove to couple equally into the waveguides. Three dimensional finite difference time domain simulations show that the quality factor is around 3,000. At resonance, power transferred to the drop waveguide is 78% and only 1.6% remains in the bus waveguide. We also show that by carefully tuning the drop waveguide boundary, light remaining in the bus can be further reduced to below 0.4% and thus the channel isolation is larger than 22dB.