SINGLE-FREQUENCY CONTINUOUS-WAVE OPERATION OF RING RESONATOR DIODE-LASERS

We report continuous-wave room-temperature operation of a semiconductor ring resonator diode laser with a single Y-junction outcoupling waveguide. This device with a 150-mu-m radius and 8-mu-m-wide etched-rib waveguide has a threshold current of 72 mA and emits up to 1 mW of single-frequency output. The side-mode-rejection ratio of this laser exceeds 22 dBm over a > 50 mA current range corresponding to a stable operating mode of the laser. Studies of the emission behavior in this and other similar ring lasers suggest that the ring is lasing in "whispering gallery" modes, and also that the Y junction is affecting mode selection in the ring.