Multioctave and reconfigurable frequency-stepped radar waveform generation based on an optical frequency shifting loop.

A photonic method for multioctave and reconfigurable frequency-stepped radar waveform generation is proposed and experimentally demonstrated based on an optical frequency shifting loop (OFSL). When a rectangular optical pulse is applied to the OFSL, a frequency-stepped optical signal can be generated. Beating the signal with another continuous-wave optical carrier, an electrical frequency-stepped waveform can be obtained. By meticulously adjusting the relations between the time duration of the rectangular optical pulse and the loop delay of the OFSL, the frequency-hopping rate (or the frequency-hopping period) of the generated frequency-stepped signal can be reconfigured. An experiment is carried out. The generation of frequency-stepped signals with frequency intervals of 1 GHz, 3 GHz, 5 GHz, 8 GHz, and 10 GHz is realized. The reconfigurability of the frequency-hopping period is also investigated and different frequency-hopping periods of 189, 10.2, 5.1, and 2.42 ns are achieved.