Co-site interference mitigation using optical signal processing

Co-site interference is a problem found everywhere from wireless systems and environmental sensors to military communications; it refers to the difficulty of extracting or detecting a weak signal in proximity to a strong transmitter. Traditional interference cancellation techniques are electronics-based and their performance is consequently bandwidthlimited; electronic interference cancellation is also inhibited by the inability to cancel in-band interference. Our group has developed an optical technique for interference cancellation, and our signal processor, called the Opto-Cancellation System (OCS), is capable of cancelling both in-band interference as well as broadband signals over a wide range of frequencies. The OCS has demonstrated >70 dB cancellation of narrowband signals while also cancelling 20 MHz-wide signals by at least 40 dB cancellation over a full 20 MHz range. Proof-of-concept cancellation performance has been previously demonstrated, and to better understand cancellation performance, we explore a theoretical model of our optical interference cancellation. The theoretical model and its projected performance will be compared to experimental results, and various performance parameters will be used to evaluate the limitations and advantages of our RF photonic link approach.