Multi-state dynamically switchable frequency combs in cavity optomechanical-thermal systems

We numerically demonstrate dynamically multi-state switchable optomechanical optical frequency combs (OFCs) in whispering-gallery-mode cavity optomechanical-thermal (OMT) systems by exploiting the intrinsic staircase effect and bistability rooted in thermal instability. Under a moderate pump power of 480 μW, forward laser detuning sweeping enables switching among 4 discrete OFC states, with the number of valid comb teeth increasing from 15 to 27. By raising the pump power to 2 mW, the strengthened OMT coupling expands the controllable dimensions, allowing switching among 6 discrete states during forward sweeping, where the valid comb teeth count increases from 23 to 43. Robust bistable switching is achieved in both pump power regimes, supporting two stable and distinguishable OFC states at an identical laser detuning. The physical mechanism of discrete-state switching is attributed to the thermal-instability-driven staircase effect and the synchronized positive feedback loop among optical, mechanical, and thermal fields. This work provides a flexible and versatile scheme for multi-state manipulation of optomechanical OFCs, with promising prospects in adaptive spectroscopy, multichannel optical communication, and reconfigurable integrated photonic systems.