Polarization degenerate micropillars fabricated by designing elliptical oxide apertures

A method for fabrication of polarization degenerate oxide apertured micropillar cavities is demonstrated. Micropillars are etched such that the size and shape of the oxide front is controlled. The polarization splitting in the circular micropillar cavities due to the native and strain induced birefringence can be compensated by elongating the oxide front in the [110] direction, thereby reducing stress in this direction. By using this technique, we fabricate a polarization degenerate cavity with a quality factor of 1.7 × 104 and a mode volume of 2.7 μm3, enabling a calculated maximum Purcell factor of 11.