Photonic crystal circular-shaped microcavity and its uniform cavity-waveguide coupling property due to presence of whispering gallery mode

In this report, we investigate a photonic crystal circular- shaped microcavity ( removing seven air holes) sustaining whispering- gallery mode ( WGM) by shifting the 12 nearest air holes according to the concept of cavity- shaping in micro- disk and micro- gear lasers. The WGM modal characteristics are investigated by three- dimensional ( 3D) finite- difference time- domain ( FDTD) simulations. From well- fabricated devices and simulated results, we obtain and identify WGM single- mode lasing with low threshold and high measured quality factor. By inserting additional waveguides, we also investigate its uniform coupling behaviors in different waveguide- cavity- waveguide geometries in both FDTD simulations and experiments. (c) 2007 Optical Society of America.