Light Detection And Ranging (LiDAR) is the main solution to provide high-precision and high-rate optical detection and sensing. In LiDAR system, the laser light source that scans the space effectively is the core to realize the radar detection and sensing function. The technical solutions to realize beam scanning are divided into passive beam scanning and active beam scanning. Passive beam scanning includes semi-solid-state Micro-Electro-Mechanical System (MEMS) LIDAR, which realizes spatial beam scanning through mechanical rotation, and all-solid-state Optical Phased Array (OPA), which realizes spatial beam scanning by changing the waveguide. (OPA), which deflects the beam and achieves mechanical-free scanning by changing the geometry or refractive index distribution of the waveguide. Unlike existing passive scanning schemes such as MEMS and OPA, active beam scanning (ABS) uses an actively emitted light source for scanning, which can effectively improve the energy conversion efficiency of the system, increase the output power and reduce the complexity of the space system.
Recently, a team of academician Zheng Wanhua from the Institute of Semiconductors, Chinese Academy of Sciences, together with a team of Peking University's Peng Chaojieqing, realized electrically injected active laser spatial beam scanning based on a Photonic Crystal Surface Emitting Laser (PCSEL). The structure takes AlGaInAs quantum well as the gain medium, and uses a finite size photonic crystal to quantize the continuous energy bands into discrete modes, obtaining multi-order modes corresponding to the excitation of different dispersion angles in the far-field; combined with carrier modulation, different order modes are excited under different injection currents, thus realizing active beam scanning. The electrically injected PCSEL provides component support for 2D active laser space scanning radar.
The current source is used to drive the laser at high speed to realize beam scanning at up to 1 MHz rate, which is one to two orders of magnitude improvement in scanning rate compared with the traditional MEMS scheme. The laser is able to increase the concurrent scale of sensing, flexibility, and reduce power consumption. On the one hand, the laser is one of the most promising technology routes for LIDAR, laser imaging, and laser sensing, and provides a new control mechanism for active phased array radar; on the other hand, its surface emission characteristics have unique advantages in the fields of sensing detection, photonic integration, and large-scale arrays.
The results, titled "Active Beam Steering Enabled by Photonic-Crystal Surface Emitting Laser", were published on July 11 in American Chemical Society Nano (ACS Nano). -Nano (DOI: 10.1021/acsnano.3c09793). Mingjin Wang, a young researcher of Institute of Semiconductors (ISS), and Feifan Wang, a postdoctoral fellow of Peking University (Peking University), are the co-first authors of the paper, and Wanhua Zheng, an academician of ISS, and Chao Peng, a professor of Peking University, are the co-corresponding authors.
This work was supported by the National Key Research and Development Program of China and the National Natural Science Foundation of China.
Fig. 1 PCSEL quantization of continuous energy bands into discrete modes
Fig. 2 High-speed beam scanning
