Demonstration of Over-the-Air RF Self-Interference Cancellation Using an Optical System

We demonstrate an analog optical self-interference cancellation system for over-the-air multipath cancellation in radio-frequency communications. Self-interference cancellation is achieved by subtracting a matched copy of the self-interference signal from the corrupted received signal. The system uses optical signal processing instead of traditional radio-frequency approaches to achieve wide instantaneous bandwidth and high precision. Channel matching is performed entirely in the optical domain with variable optical attenuators and tunable optical delays. A singlemode to multimode combiner enables the cancellation of up to six multipath components using just two optical sources. The system achieved 35 dB of narrowband cancellation and 30 dB of cancellation across 20 MHz of instantaneous bandwidth, with multipath cancellation contributing more than 10 dB of cancellation at the signal of interest frequency.