Flexible Broadband Frequency Hopping Signal Generation Based on a Filter-Free Optoelectronic Conversion Loop

We propose and experimentally demonstrate a photonics method for generating broadband frequency hopping (FH) microwave signals based on an optoelectronic conversion (OEC) loop. In the proposed scheme, FH signals are generated after feedback modulation when low-frequency seed pulses are applied to the MZM in the OEC loop. The scheme can achieve a large-scale frequency hopping between S/C/X bands and C/X/Ku frequency bands. The experimental results indicate that 3-level FH signals with frequencies of 3/6/12 and 4/8/16 GHz have been successfully generated. Frequency-hopped linear frequency modulation (FH-LFM) signals from 2.5 GHz to 4.5 GHz, 5 GHz to 9 GHz and 10 GHz to 18 GHz with different chirp rates can also be generated. The achievable time-bandwidth product (TBWP) is as high as 15400. The autocorrelation results indicate that FH-LFM has good pulse compression ability. The pulse width, period and bandwidth of the FH signal can be adjusted flexibly. The proposed system does not require any optical filters or high-frequency RF signal source. It has potential to apply in radar, electronic warfare and wireless communication systems.