Frequency Locking of an Optical Cavity using LQG Integral Control
For quantum optics researchers, this provides a practical control method for cavity locking, but it is an incremental application of existing control theory.
The paper applies integral LQG control to lock an optical cavity's frequency to a laser, achieving stable locking and low-frequency noise rejection with experimental validation.
This paper considers the application of integral Linear Quadratic Gaussian (LQG) optimal control theory to a problem of cavity locking in quantum optics. The cavity locking problem involves controlling the error between the laser frequency and the resonant frequency of the cavity. A model for the cavity system, which comprises a piezo-electric actuator and an optical cavity is experimentally determined using a subspace identification method. An LQG controller which includes integral action is synthesized to stabilize the frequency of the cavity to the laser frequency and to reject low frequency noise. The controller is successfully implemented in the laboratory using a dSpace DSP board.