Single-mode operation of a large optically pumped triangular laser with lateral air trenches

A triangular resonator has fewer modes than other polygonal lasers such as microdisk and square lasers with similar areas. However, a large resonator with a side of 8 μm can still resonate at many distinct wavelengths. We show experimentally that the introduction of air trenches to the sides of the triangular resonator can lead to single-mode operation of the laser device. The air trenches will considerably increase the radiation losses of most of the resonant modes, except for a mode with weak magnetic fields at the position of the trenches. This high quality factor mode will be the only mode able to reach lasing in the modified structure, as we show experimentally.