Compact microgear reflector-based laser heterogeneously integrated on a SiN platform

We report on heterogeneously integrated continuous-wave (CW) lasers on a SiN platform that employ a microgear as a wavelength-selective reflector. Heterogeneous integration is realized through micro-transfer printing (µTP), enabling compact, robust, and frequency-stable on-chip lasers without the need for phase shifters. The devices achieve up to 12.1 mW of on-chip optical output power and intrinsic linewidths as narrow as 3.7 kHz, highlighting the tradeoff between output coupling and coherence. The laser devices operate in single mode with side-mode suppression ratios exceeding 45 dB, and have a compact footprint of 4000 × 250 µm². These results demonstrate a promising path to integrated lasers for coherent communications and LiDAR.