Photonic crystal channel drop filters based on circular-shaped cavities

This paper presents a novel photonic crystal-based channel drop filter in a silicon-on-insulator platform. The proposed structure consists of two line-defect waveguides and a special circular cavity between them. The effects of structural parameters and fabrication errors on resonant wavelength and drop efficiency of output signal are analyzed. Band structure calculations and propagation of electromagnetic field through device are done by plane wave expansion and finite-difference time-domain methods, respectively. In our design, drop efficiency of more than 81% and quality factor of about 2246 are achievable. Simulation results show the effectiveness of the proposed filter for narrowband applications in photonic communication systems.