SNR Enhancement Receiver Based on Dual-Comb Microwave Photonic Channelization

Signal to noise ratio (SNR) is one of the key parameters in the communication, radar and spectrum perception systems. In this paper, we propose and demonstrate a SNR enhancement receiver with wide processing bandwidth and tunability, where two coherent optical frequency combs (OFCs) based on multi-channel microwave source and electro-optic modulators are incorporated to accomplish simultaneous frequency down-conversion and channelization. By exploiting a dual frequency microwave source as a comb driver, the FSR tunable OFC is demonstrated. The FSR of the laser can be tuned flexibly from 8 GHz to 12 GHz by controlling the controlling the frequency of the microwave source. Multi-frequency microwave signal is generated from a 0-10GHz microwave signal source and cloned to the optical domain by a carrier suppressed single sideband modulator (CS-SS) and then down-converted and channelized to the same IF. The IF signals are digitalized and then added in the digital domain. With the proposed receiver a 7.2 dB SNR enhancement has been achieved.