High-repetition-rate GaAs-on-SiN mode-locked laser using a Fabry-Pérot cavity

We demonstrate a 23.3 GHz GaAs-on-SiN mode-locked laser heterogeneously integrated on a commercial SiN platform using micro-transfer printing. A compact Fabry-Pérot cavity with a central saturable absorber enables colliding-pulse, second-harmonic mode locking. The device delivers up to 1 mW on-chip optical power from a single output port and generates eight comb lines within a 10 dB optical bandwidth. The pulse-forming operation is confirmed by autocorrelation measurements, yielding a deconvolved pulse width of 4.8 ps. This approach provides a scalable route toward electrically pumped high-repetition-rate pulse sources for nonlinear SiN photonic circuits.