SWEEPER technology is to be developed further through DARPA’s Electronic-Photonic Heterogeneous Integration (E-PHI) program, which has already successfully integrated billions of light-emitting dots on silicon to create an efficient silicon-based laser.

Current laser-scanning technologies such as LIDAR require mechanical assemblies to sweep the laser back and forth. These large, slow opto-mechanical systems are both temperature- and impact-sensitive and often cost tens of thousands of dollars each—all factors that limit widespread adoption of current technologies for military and commercial use.

By finding a way to steer lasers without mechanical means, we’ve been able to transform what currently is the largest and most expensive part of laser-scanning systems into something that could be inexpensive, ubiquitous, robust and fabricated using the same manufacturing technology as silicon microchips. This wide-angle demonstration of optical phased array technology could lead to greatly enhanced capabilities for numerous military and commercial technologies, including autonomous vehicles, robotics, sensors and high-data-rate communications.

—Josh Conway, DARPA program manager

Phased arrays—engineered surfaces that control the direction of selected electromagnetic signals by varying the phase across many small antennas—have revolutionized radio-frequency (RF) technology by allowing for multiple beams, rapid scanning speeds and the ability to shape the arrays to curved surfaces. DARPA pioneered radar phased array technologies in the 1960s and has repeatedly played a key role in advancing them in the decades since.

Transitioning phased-array techniques from radio frequencies to optical frequencies has proven exceptionally difficult, however, because optical wavelengths are thousands of times smaller than those used in radar. This means that the array elements must be placed within only a few microns of each other and that manufacturing or environmental perturbations as small as 100 nanometers can hurt performance or even sideline the whole array. The SWEEPER technology sidesteps these problems by using a solid-state approach built on modern semiconductor manufacturing processes.

Under SWEEPER funding, four teams of DARPA-funded researchers have used advanced manufacturing techniques to demonstrate optical phased array technology. These performers include the Massachusetts Institute of Technology; the University of California, Santa Barbara; the University of California, Berkeley; and HRL Laboratories.

SWEEPER research is drawing to a close and DARPA is seeking potential transition partners.