Ultra-broadband microwave frequency downconversion based on optical frequency comb

Based on optical frequency comb (OFC), a photonic-assisted ultra-broadband microwave signal down-converting method is proposed. In the proposed scheme, microwave signal at 2∼20GHz can be downconverted to 0∼1GHz intermediate frequency (IF) signals by an OFC of 2GHz frequency space at different order of comb lines. By slightly switching the frequency space of OFC, the frequency of the signal to be measured can be retrieved through the frequency shift of the downconverted IF signal. The validity of this proposed unknown signal detection method is verified by the experiments. The proposed method is proven to be flexible, low-cost and easily implemented, which requires only a lowfrequency tunable microwave source while provides ultra-broadband downconverting frequency range.