Photonic band-gap waveguide microcavities: Monorails and air bridges

Photonic band-gap monorail and air-bridge waveguide microcavities, operatin g at the wavelength regime of 1550 nm, are fabricated using GaAs-based comp ound semiconductors. The fabrication process involves gas-source molecular beam epitaxy, electron-beam lithography, reactive ion etching, and thermal wet oxidation of Al0.93Ga0.07As. The fabrication of the air-bridge microcav ity, in particular, also entails the sacrificial wet etch of AlxOy to suspe nd the micromechanical structure. The monorail and air-bridge microcavities have been optically characterized and the transmission spectra exhibit res onances in the 1550 nm wavelength regime. Tunability of the resonant wavele ngth is demonstrated through changing the defect size in the one-dimensiona l photonic crystal. The quality factors (Q) of the microcavities are about 140 for the monorail and 230 for the air bridge, respectively. (C) 1999 Ame rican Vacuum Society. [S0734-211X(99)03303-X].