Self-Stabilization by Negative Feedback of Whispering Gallery Mode Resonators Based on Optical Fiber With Active Core

A new mechanism for self-stabilizing microcavities of whispering gallery modes based on optical fibers is proposed. For this, an optical fiber with a core doped with rare-earth elements is used to build up a microresonator. Light launched into the core heats the fiber through nonradiative relaxation of the excited states and thus tunes the microresonator. We propose using an optical closed loop that couples waves circulating within the microcavity and within the core to create feedback for stabilization of the resonances.