Analysis of the phase-locking dynamics of a III-V-on-silicon frequency comb laser

Abstract

We present the detailed characterization of the phase dynamics of a telecom hybrid III-V-onsilicon passively mode-locked laser with a ring cavity. We explore the various regimes of operation as a function of gain current and saturable absorber bias voltage. We use a stepped-heterodyne measurement to quantify the spectral chirp and reconstruct the pulse envelop. With this technique we are able to identify regimes of near-transform-limited operation and we assess the degradation of mode-locking in the comb phase relationship when saturable absorber bias voltage is changed. Finally, we present a preliminary study of the phase-locking in hybrid mode-locked operation and demonstrate transform-limited pulses.FIG. 1: Layout of the hybrid 8 GHz ring frequency comb laser. Semiconductor Optical Amplifier (SOA) and Saturable Absorber (SA) are integrated within the active Indium Phosphide (InP) material. The long spiral waveguide is etched in the underlying Si membrane that is bonded to InP. Light is evanescently coupled between active and passive layers.