Pound-Drever-Hall Laser Frequency Stabilization of Tunable 1.55 µm Monolithically Integrated Semiconductor Lasers Using an Integrated Phase Modulator

Report on the advancement in the integration of the Pound-Drever-Hall (PDH) stabilization scheme on a single InP photonic integrated circuit by monolithically integrating a tunable laser and an electro-optic phase modulator (EOPM). A semi-insulating substrate allows a sufficiently reduced electrical cross-talk between the laser and the external EOPM to allow PDH stabilization. A novel implementation of the PDH lock is demonstrated, whereby an EOPM internal to the integrated lasing cavity is modulated. The frequency noise suppression of both implementations is measured and compared to those achieved with a bulk phase modulator. A 58 dB frequency noise suppression at 10–100 Hz is achieved.