Abstract

Novel microcavities are fabricated that consist of GaAs microdisks (~3 μm diameter) sandwiched between AlAs cladding, bounded by a circular grating of deeply etched air trenches. An emitting layer of InAs quantum dots is inserted in GaAs. The grating acts as a 4th-order Bragg reflector for the in-plane cavity, so that some 2nd-order diffraction towards air can occur. This allows to observe upwards the horizontal resonances through the mode leakage. Microdisks modes usually require high azimuthal number l to be confined through total internal reflection, while drum-like modes with low-azimuthal number l only see the poorer normal reflection at the semiconductor-air interface (30%). In our cavity, the circular Bragg mirror is highy reflective for these low-l modes. Peaks with Q’s up to 650 are observed, and modes are tentatively identified up to l=6. The cavity finesse peaks at 50, corresponding to a reflectivity in excess of 85%.

© 1998 IEEE