Injection-locking dynamics of two self-pulsing nanocavities optically coupled on photonic integrated circuit

Pulse generation in nanostructure devices underpins all-optical spiking neurons, on-chip communication, and sampling. Synchronizing such devices provides insights for implementing analog all-optical machines, at the cost of adding complexity to the system. Mutual synchronization at nanoscale is typically achieved via evanescent coupling, which limits control over coupling strength and tunability. Injection locking offers an alternative based on drive-driven mechanism, but its nanoscale implementation has so far been limited to phase noise reduction in electro/opto-mechanical systems. Here, we experimentally explore an integrated platform to realize injection locking between non-identical nanophotonic oscillators, i.e., two thermo-optical self-pulsing Indium Phosphide (InP) photonic crystal cavities integrated on silicon-on-insulator waveguides. A train of amplitude pulses, imprinted on a laser carrier by the first oscillator, drive the second oscillator. The temporal dynamics, supported by numerical simulations, reveal complex features, such as multi-frequency locking, phase slips, and asynchronous responses, all dependent on optical parameters. Our platform is a valid alternative to study high-dimensional dynamics in complex on-chip architectures.