Large Square Resonator Laser With Quasi-Single-Mode Operation

A large square resonator with a size of 8.3 mum can support many resonant modes, including whispering gallery modes. The inclusion of trenches at judicious node positions of a selected mode will not significantly affect this mode (i.e., its quality factor will not be significantly reduced) while the remaining modes will drastically lose power through radiation. Since most of the modes will not be able to overcome their radiation losses, only a single mode will resonate in the modified structure. We demonstrate, experimentally, single-mode operation of this device at a temperature of 4.2 K.