Frequency-Agile Coherent Multiple Bands Generation Based on an Asymmetrically-Coupled Optoelectronic Dual-Loop With Recirculating Frequency-Shifting

We propose and demonstrate a frequency-agile coherent multiple bands generator based on an asymmetrically-coupled optoelectronic dual-loop framework with recirculating frequency-shifting. The two loops convert two seed signals into different frequency-shifted signals and respectively replace the original seed signals through feedback modulation, achieving repetitive frequency-shifting in the optical- and the electric-domains. When the two loops are coupled through delivering one continuously frequency-shifted light wave into the other loop to participate in the recirculating frequency-shifting, a carrier-frequency agile multiple bands signal is obtained. By properly controlling the parameters of the seed signals and the two optoelectronic loops, highly reconfigurable and coherent multiple bands can be obtained. A proof-of-concept experiment is carried out. Coherent multiband signals with stepped frequency and hopped frequency covering C- and X-bands are generated. Additionally, using the generated signals, a series of microwave imaging experiments under complex electromagnetic interference (EMI) are demonstrated, showing the advantages of the proposed method in anti-interference and high-resolution imaging.