System-Level Performance and Characterization of Counter-Phase Optical Interference Cancellation

In this paper, we report on the performance of the second implementation of the optical counter-phase RF interference cancellation technique. Referred to as the opto-cancellation system, it has demonstrated narrowband-signal cancellation exceeding 80 dB. Also, broadband signals of 80-MHz bandwidth, whose center frequencies ranged from 1 GHz-20 GHz, were cancelled down to the system noise floor; where that cancellation was approximately uniform over the full bandwidth of each signal. It is not known that other interference cancellation systems can achieve such low cancellation depths, over such a wide frequency bandwidth, at the time of this writing. In addition to describing the system's performance in terms of experimental results, we also characterize the system's performance analytically. Although the sensitivity, gain, linearity, and noise figure of the current system implementation are known, the analysis presented here will be useful for future implementations of the optical counter-phase RF interference cancellation technique. The analysis will also aid in understanding the trade-offs and limitations of the current system implementation, as well as future implementations.