Towards frequency stabilization of a chip-based, ultra-narrow linewidth InP-Si3N4 hybrid laser

Recently, hybrid integration of an InP semiconductor optical amplifier with a low-loss Si3N4 feedback circuit has enabled an ultra-narrow intrinsic linewidth of below 300 Hz. Such high intrinsic frequency stability is of benefit for short-time measurements, such as for coherent optical data transmission. The intrinsic stability is a central advantage also for achieving long-term stability, via stabilizing the laser to an absolute frequency reference, specifically here, to ro-vibrational transitions of acetylene (C2H2) in the 1.55 μm telecom wavelength range. We present the noise characteristics of the laser and discuss a stabilization scheme for a hybrid laser that is frequency-controlled with two integrated microring resonators and a phase-tuning section. We show that the laser possesses a sufficiently large mode-hop-free tuning range to efficiently stabilize the laser. Preliminary experimental data on performance of the stabilization will be presented.