Feedback control of ultra-high-Q microcavities: application to micro-Raman lasers and microparametric oscillators
We demonstrate locking of an on-chip, high-Q toroidal-cavity to a pump laser using two, distinct methods: coupled power stabilization and wavelength locking of pump laser to the microcavity. In addition to improvements in operation of previously demonstrated micro-Raman and micro-OPO lasers, these techniques have enabled observation of a continuous, cascaded nonlinear process in which photons generated by optical parametric oscillations (OPO) function as a pump for Raman lasing. Dynamical behavior of the feedback control systems is also shown including the interplay between the control loop and the thermal nonlinearity. The demonstrated stabilization loop is essential for studying generation of nonclassical states using a microcavity optical parametric oscillator.