Fig. 1. (a) Schematic diagram of the phase array antenna. (b) Schematic diagram of beam forming using phase shifters.

Fig. 2. (a) Schematic of a multi-channel, multi-bit programmable photonic beam former. (b) Schematic of a delay subnetwork. DWDM, dense wavelength division multiplexing; MZM, Mach–Zehnder modulator; EDFA, erbium-doped fiber amplifier; PTTD, photonic true-time delay; PD, photodetector; MEMS, micro-electro mechanical switch.

Fig. 3. PAA radiation patterns based on photonic beam former.

Fig. 4. (a) Beam forming based on FG. (b) The time delay curves of the nine channels. TLS, tunable laser source; PC, polarization controller; EOM, electro-optical modulator; FG, fiber grating; PD, photodetector.

Fig. 5. (a) Beam forming based on CFG. (b) Time delay measurement results for four channels. TLS, tunable laser source; MZM, Mach–Zehnder modulator; WDM, wavelength division multiplexing; PD, photodetector.

Fig. 6. Schematic architecture of the optically steered phased array radar. TLS, tunable laser source; MZM, Mach–Zehnder modulator; LNA, low noise amplifier; EDFA, erbium-doped fiber amplifier; SMF, single-mode fiber; DCF, dispersion compensation fiber; PD, photodetector; ATT, attenuator; PT, phase trimmer.

Fig. 7. (a) Time delays of the DCF-based TTD units. (b) Amplitude characteristics for eight paths through the TTD device. (c) Beam steered angles at different frequencies.

Fig. 8. Measurement result for a single target.

Fig. 9. (a)–(d) Measurement result for the double target.

Fig. 10. (a) Schematic architecture of the photonic-based PAA system with an ultra-fast wavelength-swept laser source. LD, laser diode; AWG, arbitrary waveform generator; MZM, Mach–Zehnder modulator; DCF, dispersion compensation fiber; LNA, low noise amplifier; EDFA, erbium-doped fiber amplifier; SMF, single-mode fiber; PD, photodetector; ATT, attenuator; PT, phase trimmer. (b),(c) Principle of the ultra-fast wavelength-swept laser source.

Fig. 11. (a) Measured spectrum. (b) The waveform of the electrical pulse. (c) The received signals of the PAA system with wavelength spacing of 2.4 nm.