Coupled Cavity Single-Mode Laser Based on Regrowth-Free Integrated MMI Reflectors

A photonic integrated circuit is demonstrated that couples three Fabry-Pérot (FP) lasers together via an integrated star coupler. The FP lasers rely on a common cleaved facet and individual multimode interference reflectors (MIRs) for lasing operation. The MIRs are monolithically integrated with each FP laser using a single growth step, which allows for epitaxial regrowth-free processing. By suitable independent tuning of each Fabry-Pérot, a single mode operation and a mode selection can be attained from the coupled cavity system. The mode selectivity and side-mode suppression ratios of ~40 dB are demonstrated.