  Light detection and ranging (LiDAR) have emerged as a crucial tool for
high-resolution 3D imaging, particularly in autonomous vehicles, remote
sensing, and augmented reality. However, the increasing demand for faster
acquisition speed and higher resolution in LiDAR systems has highlighted the
limitations of traditional mechanical scanning methods. This study introduces a
novel wavelength-multiplexed code-division multiple access (CDMA) parallel
laser ranging approach with a single-pixel receiver to address these
challenges. By leveraging the unique properties of Gold-sequences in a
direct-sequence spread spectrum (DSSS) framework, our design enables
comprehensive parallelization in detection and ranging activities to
significantly enhance system efficiency and user capacity. The proposed coaxial
architecture simplifies hardware requirements using a single avalanche
photodiode (APD) for multi-reception, reducing susceptibility to ambient noise
and external interferences. We demonstrate 3D imaging at 5 m and 10 m, and the
experimental results highlight the capability of our CDMA LiDAR system to
achieve 40 parallel ranging channels with centimeter-level depth resolution and
an angular resolution of 0.03 degree. Furthermore, our system allows for user
identification modulation, enabling identity-based ranging among different
users. The robustness of our proposed system against interference and speckle
noise and near-far signal problems, combined with its potential for
miniaturization and integration into chip-scale optics, presents a promising
avenue to develop high-performance, compact LiDAR systems suitable for
commercial applications.
