Fuzz-free ultra-wideband multitone signal instantaneous frequency measurement system based on simple optical frequency combs

The instantaneous frequency measurement (IFM) for wideband and multi-tone radio frequency (RF) signals are necessary for electronic reconnaissance and countermeasure systems, but conventional methods often suffer from the electronic bottlenecks on the instantaneous bandwidth, and timeliness. To solve this problem, a fuzz-free ultra-wideband multi-tone IFM scheme based on frequency shift analysis is proposed, which is mainly implemented based on three simple optical frequency combs (OFCs). The system is very simple, the dual-drive Mach-Zehnder modulator (MZM) is used to realize the modulation of the signal to be measured and the generation of the optical frequency comb, and the optimal phase control is achieved by adjusting the bias voltage. After passing through the photodetector, the frequency of the RF signal can be calculated by analyzing the frequency shifts of the beat frequency terms in the three channels. In a proof-of-concept experiment, the measurements for multiple-tone RF signals are demonstrated, indicating a large frequency range from 0.1 to 40 GHz, a low measurement error less than 10 kHz, and the second- and third-order spurious-free dynamic ranges (SFDRs) of 83.8 dB·Hz¹/² and 98.8 dB·Hz²/³, respectively.