Fig. 1. (a) Schematic of the 4×4 Butler MOPA chip. (b) Detailed illustration of the 4×4 BM with the corresponding port labels. (c) Schematic diagram of the emitting grating coupler.

Fig. 2. (a) Phase response and (b) power splitting ratio of the 2×2 MMI output ports. The blue and orange lines indicate the bar and cross ports, respectively.

Fig. 3. Phase response of the TO phase shifter w.r.t. heating power and operating wavelength.

Fig. 4. Results of wavelength transparency simulation when the laser wavelength of the OPA is adjusted sequentially from 1.5 to 1.6 μm in 0.01 μm steps. (a) Distribution of simulated peak directions, (b) FWHM, and (c) SLSR of each beam of the multi-beam OPA, with pink, red, black, and blue points representing beams from In1, In2, In3, and In4 in simulation. (d) Far-field intensity distribution of the multi-beam pattern after beamforming at the central operating wavelength of 1.55 μm.

Fig. 5. (a) Microscope image of the chip after packaging. (b) Picture of the packaged chip, including the PCB and the FA.

Fig. 6. Schematic diagram of the multi-beam imaging system.

Fig. 7. (a) Normalized far-field intensity distributions in the phase scanning direction of beam1. (b)–(d) Measured multi-beam far-field patterns when beam1 is steered at (b) −5°, (c) 0°, and (d) 5° at the input wavelength of 1550 nm. (e) Measured multi-beam patterns with the input wavelengths at 1520 nm, 1550 nm, and 1570 nm.

Fig. 8. Results of wavelength transparency validations when the wavelengths of the input lasers of OPA were adjusted sequentially from 1520 to 1570 nm in 10 nm steps. (a) FWHM and (b) SLSR of each beam of the multi-beam OPA.

Fig. 9. Schematic diagram of FMCW ranging system. EDFA: erbium-doped fiber amplifier; AWG: arbitrary waveform generator; OSC: oscilloscope; APD: avalanche photodetector.

Fig. 10. (a) Power spectral density of the beat signal for a target at the optical path difference of 9.18 m, 11.51 m, 13.74 m, 15.32 m, and 16.91 m. The beam emitting angle is 7.44°. (b) Linear regression of the measured range versus the optical path difference.

Fig. 11. (a) Power spectral density of beam1 at the emitting angle of 7.44°. (b) Power spectral density of beam3 at the emitting angle of −7.83°. (c) Error summary of multiple ranging experiments. (d) Linear fitting of measured distances with real distances at different angles.

Fig. 12. (a) Picture of the C-shaped target object. (b) Superimposed far-field beam patterns for the scanned beams used for target illumination. (c) Point cloud of the C-shaped target object in the Descartes coordinate system.