High-frequency all-optical oscillators based on silicon photonic crystal nanobeam cavities

Integrated all-optical oscillators are essential building blocks for optical computing, communications, and neuromorphic processing. However, current resonator-based designs are limited to low MHz frequencies by slow thermal dynamics and often require high power or electrical biasing. Here, we develop a compact silicon photonic crystal nanobeam cavity (PCNBC) platform that simultaneously manages both optical and thermal dynamics to generate high-frequency self-sustained oscillations. The high quality factor (Q) and small mode volume (V_mode) of this device enhance optothermal nonlinearities, while its nanoscale geometry ensures rapid heat dissipation. Supported by FEM simulations, our experimental results demonstrate oscillation frequencies up to 45 MHz at a low threshold power of 223 μW. Furthermore, we show wide tunability of both frequency and duty cycle through optical control of the input power and wavelength detuning. This fully passive and bias-free platform offers a compelling solution for chip-scale optical clocks, neuromorphic photonic circuits, and low-power signal processing.