High-finesse AlxOy/AlGaAs nonabsorbing optical cavity

Abstract

We report the measured finesse value of similar to 390 in nonabsorbing AlxOy/AlGaAs cavities. The nonabsorbing cavity consisting of a bottom AlxOy/AlGaAs distributed Bragg reflector (DBR), an AlxOy spacer layer, and a top AlxOy/AlGaAs DBR is prepared by a wet-oxidation process. The measured resonance linewidth agrees well with that of calculation, indicating very small overall losses in the cavity. The wet-oxidation process does not seem to degrade the interface of the epitaxial layers significantly. The lower bound of maximum achievable reflectivity from the AlxOy DBR is estimated to be >99.95%, assuming an average interface roughness of about 0.6 nm. The maximum achievable finesse of this type of cavity is expected to be larger than that of the all-epitaxial counterpart assuming the same roughness. (C) 1998 American Institute of Physics.