The researchers say they are one of the first to demonstrate a low-power large-scale optical phased array (OPA) at near infrared and the first to demonstrate optical phased array technology on-chip at blue wavelength for autonomous navigation and augmented reality, respectively. In addition, say the researchers, they also developed an implantable photonic chip based on an optical switch array at blue wavelengths for precise optogenetic neural stimulation.
"This new technology that enables our chip-based devices to point the beam anywhere we want opens the door wide for transforming a broad range of areas," says Michal Lipson, Eugene Higgins Professor of Electrical Engineering and Professor of Applied Physics at Columbia Engineering. "These include, for instance, the ability to make LiDAR devices as small as a credit card for a self-driving car, or a neural probe that controls micron scale beams to stimulate neurons for optogenetics neuroscience research, or a light delivery method to each individual ion in a system for general quantum manipulations and readout."
The researchers designed a multi-pass platform that reduces the power consumption of an optical phase shifter while maintaining both its operation speed and broadband low loss for enabling scalable optical systems. They let the light signal recycle through the same phase shifter multiple times so that the total power consumption is reduced by the same factor it recycles.
They demonstrated a silicon photonic phased array containing 512 actively controlled phase shifters and optical antenna, consuming very low power while performing 2D beam steering over a wide field of view. Their results, say the researchers, are a significant advance towards building scalable phased arrays containing thousands of active elements.
Phased array devices were initially developed at larger electromagnetic wavelengths. By applying different phases at each antenna, researchers can form a very directional beam by designing constructive interference in one direction and destructive in other directions. In order to steer or turn the beam’s direction, they can delay