Researchers from the Danish University of Technology have developed a chip based beam steering device to reduce the size and cost of high-performance LiDAR technology. This device can be applied to autonomous diving, free space optical communication, 3D holography, biomedical sensing, and virtual reality.

Research group leader Hu Hao said that the traditional mechanical beam control in LiDAR systems is bulky, expensive, vibration sensitive, and has limited speed. He said that although chip based optical phased arrays (OPA) can quickly and accurately guide light non mechanically, these devices often suffer from poor beam quality and limited field of view.

OPAs achieve beam steering by electronically controlling the phase profile of light to form specific patterns. Most use waveguide arrays to emit multiple beams of light. Apply interference in the far field to form a pattern. However, due to the fact that waveguides are usually far apart from each other and interference occurs in the far field, aliasing is introduced. In order to obtain a 180 º field of view, the transmitter must be placed close to it. However, this approach may introduce crosstalk, thereby reducing beam quality.

Researchers did not use multiple emitters, but instead used flat gratings to create a single emitter. Eliminates aliasing as adjacent channels can be placed close to each other. In addition, the coupling between adjacent channels is not harmful in a flat grating, as it can achieve interference and beamforming in the near field. Then, light can be emitted at the desired angle in the far field. The team also introduced other optical technologies to reduce background and other optical artifacts, such as sidelobes.

Senior researcher Hu Hao and doctoral student Liu Yong from the Danish University of Technology have developed a chip based OPA that can achieve wide field of view beam control without affecting beam quality. This device can achieve a small, cost-effective, and high-performance LiDAR system.

To test the device, the team constructed an imaging system to measure the average far-field optical power along the horizontal direction in a 180 º field of view. It demonstrates non aliasing beam steering in this direction, including steering exceeding ± 70 °, although researchers have observed some beam degradation.

Then, the researchers characterized the vertical beam direction by tuning the wavelength from 1480 nm to 1580 nm, achieving a tuning range of 13.5 °. Finally, they demonstrated the versatility of OPA by using it to form 2D images of the three letters in the alphabet, which are achieved at 60 °, 0 °, and 60 ° by tuning the wavelength and phase shifter. They conducted experiments with a beam width of 2.1 °, and the researchers observed

Efforts are currently being made to reduce this width to achieve higher resolution and longer range beam steering.