Methods of Feedback Control for Adaptive Counter-Phase Optical Interference Cancellation

We describe two methods of automatically tuning the optical parameters of the optical counter-phase interference-cancellation system. The methods not only achieve signal cancellation automatically but also permit that cancellation to be maintained in the presence of dynamic amplitude and phase fluctuations in the input signal. The purpose of this paper is twofold: First, we show that this conceptually simple optical method of interference cancellation readily lends itself to a simple method of closed-loop control and second, we introduce a novel method of optical closed-loop control. This work has allowed for fully adaptive operation of the opto-cancellation system in proof-of-principle laboratory experiments while also exposing issues to be addressed so that adaptive operation may be realized in more realistic situations.