A coherent photonic RF scanning receiver based on a flat optical frequency comb

A coherent photonic-assisted radio-frequency (RF) receiver is proposed and experimentally demonstrated. In this receiver, a laser light is modulated by an input broadband RF signal through an intensity modulator (IM) in one optical branch; simultaneously, it is used as a seed to generate an optical frequency comb (OFC) in another optical branch. The OFC generator consists of two cascaded IMs, and can produce 5 lines with a spectral flatness less than 1.1 dB over a broad bandwidth of 3-12 GHz. By scanning the frequencies of the OFC, the input broadband RF tone can be directly down-converted to a given intermediate frequency (IF) band. We experimentally demonstrate the down-converting scheme for the input RF tones from 2 GHz to 12 GHz. The RF signals are successfully down-converted to several IF bands, respectively.