Sandia Labs invents method to integrate micro-optical devices on silicon

07 Aug 2023

New Mexico-based lab awarded patent for technique of integrating multiple materials onto silicon.

A novel type of silicon-integrated micro-laser, developed by scientists at Sandia National Laboratories, based in Albuquerque, NM, can be combined with other micro-scale optical devices. Its developers say it promises improvements for self-driving cars safer, data centers, biochemical sensors, and defense technologies.

Sandia has been awarded a patent for its new method of integrating many different materials onto silicon.

The new method enables the creation of high-bandwidth, high-speed optical devices, including indium phosphide lasers, lithium niobate modulators, germanium detectors and low-loss acousto-optic isolators.

Sandia’s statement of August 1st notes, “Building a laser on silicon is a challenging and unusual feat that could extend America’s leadership in semiconductor technology. Other organizations, including the University of California, Santa Barbara, and Intel, have built similar lasers, but Sandia has broadened the class of devices that can be integrated. For the first time, these devices could work together on optical microchips, also called photonic integrated circuits.”

Sandia scientist Patrick Chu explained, “This [development] allows the U.S. to lead and have less dependency on foreign manufacturing capabilities.” Chu co-leads the U.S. National Security Photonics Center, a group of more than 60 photonics scientists and engineers based at Sandia’s Microsystems Engineering, Science and Applications complex.

Integration with silicon

“Silicon is the lifeblood of the semiconductor industry and a great material for making computer chips. However, by itself, it’s a lousy material for making lasers,” commented Sandia research scientist Ashok Kodigala, a co-inventor of the new integration process.

Kodigalala’s challenge was to design a way for optical components made from a variety of materials to coexist on a silicon microchip. Kodigala fused them to silicon in complex layers, in a process also called heterogeneous integration.

The Sandia team successfully demonstrated heterogenous integration techniques to create hybrid silicon devices: hybrid lasers and amplifiers made from both indium phosphide and silicon, and similarly modulators made of both lithium-niobate and silicon, which encode information in light generated from the lasers.

Now Sandia says that semiconductor fabs could exploit its new integration technique. The lab built its chip-scale lasers with a goal of transferring the technology to industry. The team used many of the same tools found at commercial semiconductor plants, and the lasers generate light in wavelengths commonly used in the telecommunications industry, known as C-band and O-band.

Kodigala said, “Once we demonstrate this photonic platform at a national lab, we can then pass this technology on to U.S. companies, where they can focus on even larger-scale production for commercial and U.S. government applications.”

He conceived his method with funding from Sandia’s Laboratory Directed Research and Development program and developed it under a Defense Advanced Research Projects Agency program called Lasers for Universal Microscale Optical Systems.

Supporting the CHIPS and Science Act

In 2022, U.S. President Joe Biden signed the CHIPS and Science Act – a nonpartisan, $52.7 billion boost for the semiconductor industry. While the legislation is expected to increase production of American-made computer chips, it also directs funding for photonic semiconductors.

Sandia added that it is also investing in optical microchips because they transmit more information than conventional ones. But manufacturing challenges have prevented their widespread adoption, Chu said: “Even though the technology is well known in scientific circles, on most microchips, he said, electronic technologies still reign supreme.”

Sandia has positioned itself to support industry and other institutions performing photonics research and development in the coming years, although Sandia research is not currently funded by the CHIPS Act.

Chu added, “We know our process is scalable, so that’s one way we’re supporting the CHIPS Act mission. Sandia is eager to collaborate with others and start building new technologies together.”