Fig. 1. Beam deflection principle of liquid crystal optical phased array^[19]. (a) No voltage condition; (b) applied voltage condition

Fig. 2. Schematic of the experiment and the 3-layer stackable optical phased array^[21]. (a) The 3-layer stackable optical phased array; (b) schematic of the method of measuring response time

Fig. 3. Experimental data of beam deflection^[21]. (a) Relationship between the voltage on the left and right sides and the deflection angle; (b) steering efficiency curve of SOPA; (c) photos of the spot from a CCD camera in the range of -100 μrad to100 μrad deflection angle

Fig. 4. Liquid-crystal-polymer based polarization gratings^[22]. (a) Polarizing microscope image of liquid-crystal-polymer based polarization gratings (633 nm); (b) polarizing microscope image of liquid-crystal-polymer based polarization gratings (1064 nm); (c) physical photos of the liquid-crystal-polymer based polarization grating (1064 nm); (d) diffraction efficiency and diffraction angle test data and grating equation curves for polarization grating (1064 nm) ; (e) flexible polarization grating; (f) white light diffraction of the sample

Fig. 5. Dual-terminal communication experiments^[23]. (a) Experiment system of dual-terminal tracking; (b) far-field spots image of double-terminal tracking experiment

Fig. 6. SEMS of the MEMS OPA^[26]. (a) Top view of the micromirrors arrays; (b) close-up view of the anchor area; (c) close-up view of the mirrors and perforated springs

Fig. 7. Photos of 160×160 MEMS phased array device prepared by the University of California research group^[27]. (a) Photo of the OPA on a coin; (b) micrograph of the optical aperture; (c) SEM of OPA; (d) close-up view of a single MEMS grating element; (e) hidden combdrive actuator underneath the grating; (f) cross-sectional SEM of an OPA unit

Fig. 8. High-precision tracking system and test results^[28]. (a) High-precision tracking system; (b) curves of tracking accuracy; (c) comparison of the receiving power with and without tracking system; (d) comparison of BER with and without tracking system

Fig. 9. Laser communication system based on MEMS OPA^[29]

Fig. 10. Schematic diagram of integrated optical waveguide OPA

Fig. 11. Optical phased array containing 512 channels^[30]. (a) Schematic diagram of optical phased array; (b) optical microscope image of the silicon waveguide layer; (c) physical photo of the packaged chip

Fig. 12. Silicon nitride integrated optical phased array^[31]. (a) Layout of the OPA; (b) enlarged image of the phase shifters; (c) last three stages of multi-mode interferometers; (d) enlarged image of the emitters

Fig. 13. Nonuniform phased array^[32]

Fig. 14. 8192-channel OPA^[33]. (a) OPA photonic integrated circuits with flip-chip CMOS; (b) photograph of the chip after packaged

Fig. 15. Photograph of 1024-channel SiN optical phased array^[34]. (a) Full image of the SiN OPA; (b) SEM photo of last seven stages of multi-mode interferometers; (c) SEM photo of emitters with upper cladding removed; (d) SEM photo of last stage of multi-mode interferometers; (e) schematic layout of phase compensation

Fig. 16. Silicon-photonic optical phased array^[35]. (a) The 8 × 8 optical phased array antenna with only 16 phase shifters; (b) antenna array structure diagrams; (c) antenna unit structure diagram

Fig. 17. Physical photos of the 2D optical phased array^[36]. (a) Microscope image of the packed chip; (b) zoom-in of the output antenna arrays; (c) SEM image of the antenna unit

Fig. 18. Spatial optical communication from OPA to OPA^[37]. (a) Example of OPA-to-OPA free-space optical communication; (b) received eye diagram of point-to-point communication; (c) point-to-point sweep time of the transmitter OPA; (d) received data in sequence from OPA1 to OPA2; (e) local zoom-in of Fig. (d)

Fig. 19. One-to-three targets communication^[38]

Fig. 20. Physical photos of the 128-channel nonuniform-space optical phased array^[41]