High-Q microcavities in 2D photonic crystal slabs studied by FDTD techniques and Pade approximation

A series of microcavities in 2D hexagonal lattice photonic crystal slabs (PCS's) are studied. A combination of FDTD techniques and Pade approximation with Baker's algorithm is used to accurately determine the resonant frequencies and quality factors of the cavity modes simultaneously. Q factor larger than 10(6) is obtained for a one missing hole cavity. Another cavity with smaller and simpler design keeps Q factor larger than 10(5). Microcavities in silicon-on-insulator-type (SOI-type) PCS's are also Studied. Simulations show that Q factors of cavities in SOI-type PCS's are much smaller than those in the membrane PCS's. Deep etching of air holes is still required to obtain relatively high Q cavities in SOI-type PCS's.