Optical losses in plasma-etched AlGaAs microresonators using reflection spectroscopy

The optical losses in dry-etched monolithic microresonators have been studi ed as a function of their lateral dimensions. Cylindrical microresonators w ith various radii have been etched from a planar GaAlAs/GaAs microcavity wi th a very high quality factor (Q congruent to 11 700). Measurements of the resonance linewidth, using Ti-sapphire laser spectroscopy allowed to study the degradation of the Q factor at small radii. The Q factor is four times smaller in 1.1 mu m radius microresonators, compared to the unprocessed cav ity. This degradation is attributed to optical scattering from sidewalls, w hose efficiency is shown to scale with the guided mode intensity at the mic roresonator edge. (C) 1999 American Institute of Physics. [S0003-6951(99)01 007-4].