Independently reconfigurable internal loss and resonance-shift in an interferometer-embedded optical cavity

Optical cavities find diverse uses in lasers, frequency combs, optomechanics, and optical signal processors. Complete reconfigurability of the cavities enables development of generic field programmable cavities for achieving the desired performance in all these applications. We propose and demonstrate a simple and generic interferometer in a cavity structure that enables periodic modification of the internal cavity loss and the cavity resonance to reconfigure the Q-factor, transmission characteristics, and group delay of the hybrid cavity, with simple engineering of the interferometer. We also demonstrate methods to decouple the tuning of the loss from the resonance-shift, for resonance-locked reconfigurability. Such devices can be implemented in any guided-wave platform (on-chip or fiber-optic) with potential applications in programmable photonics and reconfigurable optomechanics.