Solid-state FMCW LiDAR with two-dimensional spectral scanning using a virtually imaged phased array

Abstract

The beam-steering device is a critical component in LiDAR systems for 3D imaging. Solid-state beam-steering devices attract the most attention for their advantages of robustness, fast beam-steering speed, and stability. However, solid-state beam-steering devices, such as optical phased arrays (OPAs), are challenging to realize 2D scanning ability. Here we employed a virtually imaged phased array (VIPA) in the LiDAR system to realize all solid-state two-dimensional (2D) beam-steering based on dispersion only. A frequency swept laser source is used for performing optical frequency-modulated continuous-wave (FMCW) ranging and 2D beam steering simultaneously. The 2D disperser is compact and can be easily implemented owing to its simple structure. The mechanism of continuous scanning and ranging is beneficial for obtaining high lateral resolution, and a lateral resolution of 0.06° is achieved. 3D maps of the object at a distance of 2 m are obtained with cm-level ranging precision. The frame rate of the proposed LiDAR system only depends on the wavelength-tuning speed of the swept laser source, with the potential to realize ultrafast solid-state LiDAR systems.

Video-rate high-precision time-frequency multiplexed 3D coherent ranging

“…In our current prototype, solid-state scanning is only achieved along the grating axis, while the other axis still relies on mechanical scanning. However, 2D solid-state spectral scanning can potentially be achieved by using cascaded gratings 35 , array waveguide grating 36 , and virtually imaged phased array 37 .…”

>20 dB phase noise reduction by locking an off-the-shelf external cavity laser having sub-kHz linewidth to an on-chip wavelength reference in Si3N4 using an electronic feedback loop on the diode injection current

“…The wavelength of the presented laser can be freely tuned across the c-telecom bandwidth, and similar designs prove to scan at much broader wavelength ranges, yet providing tens of mW of output power [4,5]. In this work we also briefly show modulation of the lasers wavelength, making in an attractive candidate for Frequency-Modulated Continues Wave Lidar applications (FMCW Lidar) [6].…”

Spatio-spectral 4D Coherent Ranging Using a Flutter-wavelength-swept Laser

“…Conventional beam scanners based on mechanical movements are widely used, whereas solid-state beam scanners have gained attention recently because of their rapid, stable, and flexible performance. Although various coherent LiDARs with solidstate beam scanning have been extensively reported, the spatio-spectral mapping approach is receiving interest because of the easy implementation of the 1:1 mapping between the lateral position of the beam movement and the central wavelength sweep of the light source based on the driving of a single light source [20][21][22][23][24] . Considering the characteristics of the light source for coherent LiDAR, whose wavelength must be swept, it is an efficient strategy to simultaneously achieve both coherent axial ranging and lateral beam scanning by utilizing the broad wavelength bandwidth of the light source.…”