Frequency Locking of an Optical Cavity using LQG Integral Control

TL;DR

This paper applies integral LQG control to stabilize an optical cavity's frequency, demonstrating effective noise rejection and experimental implementation in a quantum optics setup.

Contribution

It introduces an LQG control approach with integral action for cavity locking, including system identification and practical laboratory implementation.

Findings

Successful stabilization of cavity frequency using LQG control

Effective rejection of low-frequency noise

Experimental validation with real-time control hardware

Abstract

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.