Fig. 1. Schematic of wideband dual-chirp microwave signal generation based on fiber Bragg grating (LD: laser diode; MZM: Mach‒Zehnder modulator; LFM: linear frequency modulation; OC: optical coupler; PD: photodetector; RF: radio frequency; FBG: fiber Bragg grating; OSA: optical spectrum analyzer; OCS: oscilloscope)

Fig. 2. Experimental setup diagram for signal generation scheme (TOF: tunable optical filter; PC: polarization controller; EDFA: erbium-doped optical fiber amplifier; OSA: optical spectrum analyzer; AWG: arbitrary waveform generator; SA: spectrum analyzer; EA: electrical amplifier; MSG: microwave signal generator; TLD: tunable laser diode)

Fig. 3. Output spectrum after the tunable optical filter (TOF). (a) Output spectrum after filtering; (b) transmission and reflection response of the FBG

Fig. 4. Output spectra of the optical coupler

Fig. 5. Waveform diagrams of the PD output signal. (a) Electrical spectrum; (b) temporal waveform

Fig. 6. Instantaneous frequency-time diagrams. (a) Input signal; (b) output signal

Fig. 7. Auto-correlation function of the output signal

Fig. 8. Instantaneous frequency-time diagrams of the dual-chirp microwave waveform with different center frequencies. (a) 16 GHz; (b) 22 GHz; (c) 28 GHz

Fig. 9. Fuzzy functions and contour maps. (a) Fuzzy function of the dual-chirp microwave signal; (b) contour map of the dual-chirp microwave signal, where the inset showing the -3 dB contour map; (c) fuzzy function of the single chirp microwave signal; (d) contour map of the single chirp microwave signal, where the inset showing the -3 dB contour map

Fig. 10. Schematic diagram of a high-speed motion target detection radar system (LO: local oscillator)

Fig. 11. Match-filter result of the radar system