Optical Analog Self-Interference Cancellation Using Electro-Absorption Modulators

An optical analog self-interference cancellation system for radio-frequency communications is proposed and experimentally demonstrated. The system uses two electro-absorption modulators, an optical attenuator and delay, and a balanced photodetector to subtract strong self-interference from a corrupted received signal and recover a weak signal of interest. The system achieves > 65 dB narrowband cancellation and > 30 dB broadband cancellation across more than 40 MHz bandwidth for interference in both the 900 MHz and 2.4GHz bands. Both narrowband and broadband cancellation are frequency tunable, and can be combined with other forms of interference cancellation to achieve even higher levels of cancellation.