High-Speed and wideband multilevel Frequency-Hopping microwave signal generation based on a Sagnac loop

An approach for photonic generation of multilevel frequency-hopping (FH) microwave signal based on a Sagnac loop is proposed and investigated. In the Sagnac loop, several Mach-Zehnder Interferometers (MZI), driven by the coding signals, are connected in series to act as a tunable photonic filter. By carefully adjusting the coding signals, the photonic filter can select the specific frequency component from the input optical frequency comb (OFC), so as to generate multilevel FH microwave signal. Theoretical analysis and simulation works are per-formed to demonstrate a 7-level FH microwave signal generator, and the discussion about the impact of non-ideal factors is given. The approach features high FH speed, wideband and amenable to photonic integration. In addition, the Sagnac loop ensures the equal optical path for clockwise and counterclockwise lights, which can enhance signal performance due to the better phase stability.