In three recent papers, Columbia engineers report the first demonstration of optical phased array technology on-chip at both near infrared and blue wavelength with applications in a broad range of research areas

MCS, AM, KW, ML are listed as inventors in a patent application related to this work, filed by Columbia University. The remaining authors declare no competing interests.

A.M., Q.L., M.A.T., X.J., A.K. and M.L. are listed as inventors in a patent application related to this work, filed by Columbia University. The remaining authors declare no competing interests.

S. A. M., C. T. P., M.L. holds individual ownership in a commercial entity; Y. C. C., S. P. R., B. S., M. L. are listed as inventors in a patent application related to this work, filed by Columbia University.

Blue optical phased array for augmented reality, trapped ion quantum computer and optogenetic neural stimulation.

New York, NY—March 19, 2020—While beam steering systems have been used for many years for applications such as imaging, display, and optical trapping, they require bulky mechanical mirrors and are overly sensitive to vibrations. Compact optical phased arrays (OPAs), which change the angle of an optical beam by changing the beam’s phase profile, are a promising new technology for many emerging applications. These include ultra-small solid-state LiDAR on autonomous vehicles, much smaller and lighter AR/VR displays, large-scale trapped-ion quantum computers to address ion qubits, and optogenetics, an emerging research field that uses light and genetic engineering to study the brain. Long-range, high-performance OPAs require a large beam emission area densely packed with thousands of actively phase-controlled, power-hungry light-emitting elements. To date, such large-scale phased arrays for LiDAR have been impractical since the technologies in current use would have to operate at untenable electrical power levels. Researchers led by Columbia Engineering Professor Michal Lipson have developed a low-power beam steering platform that is a non-mechanical, robust, and scalable approach to beam steering. The team is one of the first to demonstrate low-power large-scale optical phased array 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 collaboration with Adam Kepecs' group at Washington University in St. Louis, the team has also developed an implantable photonic chip based on an optical switch array at blue wavelengths for precise optogenetic neural stimulation. The research has been recently published in three separate papers in Optica, Nature Biomedical Engineering, and Optics Letters.

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. Michal Lipson Eugene Higgins Professor of Electrical Engineering and Professor of Applied Physics

“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 Lipson, Eugene Higgins Professor of Electrical Engineering and Professor of Applied Physics. “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.” Lipson’s team has 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 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 light in one emitter or shift a phase relative to another.