Stabilization of heterogeneous silicon lasers using Pound-Drever-Hall locking to Si₃N₄ ring resonators

Recent results on heterogeneous Si/III-V lasers and ultra-high Q Si₃N₄ resonators are implemented in a Pound-Drever-Hall frequency stabilization system to yield narrow linewidth characteristics for a stable on-chip laser reference. The high frequency filtering is performed with Si resonant mirrors in the laser cavity. To suppress close in noise and frequency walk off, the laser is locked to an ultra-high Q Si₃N₄ resonator with a 30 million quality factor. The laser shows high frequency noise levels of 60 × 10³ Hz²/Hz corresponding to 160 kHz linewidth, and the low frequency noise is suppressed 33 dB to 10³ Hz²/Hz with the PDH system.