A team of researchers at Japan's Yokohama National University claim to have developed a method to obtain such a sensor by taking advantage of slow light, an unexpected move in a field where speed is often valued above other variables.
Light detection and ranging also called LiDAR sensors can be used to map the distance between distant objects by using laser light. In modern LiDAR sensors, many of the systems are composed of a laser source; a photodetector, which converts light into current; and an optical beam steering device, which directs the light into the proper location.
"Currently existing optical beam steering devices all use some kind of mechanics, such as rotary mirrors," said Toshihiko Baba, a professor in the Department of Electrical and Computer Engineering at Yokohama National University. "This makes the device large and heavy, with limited overall speed and a high cost. It all becomes unstable, particularly in mobile devices, hampering the wide range of applications."
As a result engineers have turned toward optical phased arrays, which direct the optical beam without mechanical parts. According to Baba, however, such an approach can become complicated due to the sheer number of optical antennae that are required, as well as the time and precision needed to calibrate each piece.
"We have employed another approach -- what we call 'slow light,'" Baba said.
This has involved using a special waveguide "photonic crystal," aimed through a silicon-etched medium. Light is slowed down and emitted to the free space when forced to interact with the photonic crystal. The researchers engaged a prism lens to then direct the beam in the desired direction.
"The non-mechanical steering is thought to be crucial for LiDAR sensors," Baba said.
The resulting method and device are small-sized, free of moving mechanics, setting the stage for a solid-state LiDAR. Such a device is considered smaller, cheaper to make and more resilient, especially in mobile applications such as autonomous vehicles.
Baba and his team are now planning to more fully demonstrate the potential of a solid-state LiDAR, as well as work on improving its performance with the aim of commercialising the device.
Image credit: Yokohama National University
