ARPA-E grant supports UCSC research on high-power solar energy

Innovative "sun to fiber" device to enable efficient, flexible use of concentrated sunlight


The principal investigators in the "sun to fiber" project are (left to right): Nobuhiko Kobayashi, UCSC; R. Ernest Demaray, Antropy; Ravi Mullapudi, Tango Systems.

A $1.6 million grant from the U.S. Department of Energy's Advanced Research Projects Agency - Energy (ARPA-E) will support research at UC Santa Cruz on the development of an innovative optical device for harvesting concentrated sunlight into an optical fiber for applications such as thermal storage, photovoltaic conversion, or solar lighting.

The device will enable efficient and flexible use of sunlight collected by solar concentrators, according to principal investigator Nobuhiko Kobayashi, associate professor of electrical engineering in the Baskin School of Engineering at UC Santa Cruz. It is based on a unique thin-film waveguide that collects sunlight and transforms it to match an optical fiber with minimum losses compared to traditional light-concentrating optics.

The project is a collaboration between the Baskin School of Engineering and two Silicon Valley companies, Antropy Inc. and Tango Systems Inc. Antropy, founded in 2007 by Ernest Demaray, is based in Portola Valley, Calif. Demaray, who earned his Ph.D. in chemistry at UC Santa Cruz in 1978 and has been a Silicon Valley entrepreneur for several decades, is the inventor and owner of a portfolio of more than 50 patents. Tango Systems, based in San Jose, is an equipment company specializing in production sputtering systems and thin-film deposition services.

The project involves a new way to use solar concentrators, which are typically deployed in massive projects in which a large array of mirrors concentrates solar energy on a linear absorber or a tower, where absorbed heat is collected for generating electricity. Kobayashi's plan is to collect concentrated sunlight and transmit it through optical fibers to be stored or used remotely without significant losses.

"The problem is that when you look at these two optical components, a gigantic mirror and a tiny optical fiber, the coupling efficiency is very low," Kobayashi said. "We are developing a very special optical coupling device that enables efficient collection of high-power, concentrated solar energy. This optical coupling device could change the way we handle solar light."

The novel optical coupling device is enabled by special optical thin films based on Demaray's patents. He began collaborating with Kobayashi in 2010 to develop applications for optical films with high refractive index and low extinction coefficient. Tango Systems is providing the specialized thin-film deposition system needed to manufacture the optical coupling device.

"This thin-film technology allows us to design an efficient optical coupling device that can't be made with existing materials," Kobayashi said. "People have been trying to make an efficient optical coupling device for decades, and now we have the technology and knowledge in materials science, as well as the manufacturing technology to do it."

Kobayashi's project is among 66 cutting-edge research projects funded by the highly competitive ARPA-E program this year. ARPA-E seeks out transformational, breakthrough technologies that show fundamental technical promise but are too early for private-sector investment. These projects have the potential to produce game-changing breakthroughs in energy technology, form the foundation for entirely new industries, and have large commercial impacts.

"With ARPA-E and all of the Department of Energy’s research and development efforts, we are determined to attract the best and brightest minds at our country's top universities, labs and businesses to help solve the energy challenges of this generation," said energy secretary Steven Chu in announcing the awards. "The 66 projects selected today represent the true mission of ARPA-E: swinging for the fences and trying to hit home runs to support development of the most innovative technologies and change what’s possible for America’s energy future."