Illuminating the Future of Photonics

Finding Photonics

Fainman didn’t always intend to go into photonics, an ever-evolving discipline that harnesses light for communication, computing and imaging

As a master’s student at the Technion–Israel Institute of Technology in Israel, where he emigrated from the Soviet Union in 1974, he was still unsure of his exact direction. But then a visiting researcher from Bell Labs delivered a presentation on fiber optics.

“I thought, ‘Oh, this is an interesting area to focus my future studies on,’” Fainman said, noting that the presentation was one of his first encounters with photonics. “Then I discovered it’s fun to understand the basics. I’ve stayed here since!”

Fainman later received his Ph.D. at Technion in 1983, where he researched electromagnetic wave scattering. He joined UC San Diego later that year as a postdoctoral researcher studying optical interconnects and photorefractive effects, before moving to the University of Michigan as an associate professor.

By 1990, he was back at UC San Diego — this time to launch his own research group focused on photonic devices and ultrafast optics.

From Nanolasers to Cryptography

Fainman directs the Ultrafast and Nanoscale Optics group at UC San Diego; the group investigates silicon photonics, active nanophotonics and optical sensing and imaging.

Fainman’s research centers on nanophotonics, which looks at how light interacts with matter on a nanoscale.

“We make optical structures at deeply sub-wavelength scales and investigate how light interacts on incredibly short timescales,” he explained.

His lab was among the first to develop nanolasers. These tiny devices — smaller than a micron in all three dimensions — can emit and manipulate light with incredible precision.

Nanolasers are essential to improving miniaturized optical circuits used in advanced computing, as they can reduce energy consumption and increase processing speeds in optical interconnects.

Beyond nanolasers, Fainman has also worked extensively on polarization-selective holograms. These optical elements, which were introduced in the 1990s, control how light waves interact with nanoscale engineered surfaces and are fundamental components of high-resolution imaging and sensing applications.

In parallel, Fainman partnered with Ramesh Rao, the director of QI, to initiate his work in quantum cryptography, a field that utilizes quantum mechanics to develop unbreakable encryptions.

Fainman explained that quantum information technology was just beginning in the mid-90s.

“We worked on quantum cryptography and improving security through optical methods,” he said. Fainman’s team helped pioneer quantum information encoding, a now-vital technology for quantum-secure communication networks.

Fainman also spent time developing a method to map optical information across time and space domains.

“Let’s say I have a sequence of a hundred femtosecond pulses; these are so fast that no detector can capture them,” he explained. “But if I spread them into a one-dimensional array where these signals appear for a much longer time, I can use an array of existing detectors to observe all of them at once.”

Essentially, his technique transforms ultrafast pulses of light into spatial data arrays that can be more easily analyzed and evaluated for patterns and signals.

The Next Frontier in High-Speed Computing

Applications of Fainman’s research are wide-spanning — they’ve even reached Google.

As part of the National Science Foundation’s Engineering Research Center, Fainman worked with Amin Vahdat, a former SAIC Professor of Computer Science and Engineering at UC San Diego, and other colleagues to develop new techniques for optical circuit switching. This type of optical networking is critical for high-speed data centers, which require fast and efficient data transmission.

Vahdat is now an engineering fellow and vice president of machine learning, systems and cloud AI at Google. Years later, Fainman learned that Google had put the findings from the pair’s Helios project on circuit switching into action.

“When I heard they deployed our technique, I emailed Amin to confirm,” Fainman said. Vahdat did indeed affirm that Google’s methodology and overall concept was inspired by their paper.

"I wanted to use it as propaganda for our recruitment of graduate students,” he added with a grin.

Optical switching now plays a crucial role in Google’s AI infrastructure and high-bandwidth computing.

Fainman explained that photonics offers a path to faster, more energy-efficient processing, reducing the power consumption of massive data centers running complex AI models.

He sees the future of photonics in computing as inevitable.

“The semiconductor industry is looking at optical interconnects for chiplets because electrical wiring becomes inefficient over long distances,” he said.

‘Be Passionate’

Despite his intense research schedule, Fainman has a lighter side. He once played the violin and piano, though he admits those skills have faded over time.

“I try from time to time, but it’s rusted,” he said with a chuckle.

Even so, his dedication to his work is clear.

When asked about hobbies outside of research, he said: “Work is my hobby.”

That doesn’t mean he doesn’t enjoy himself. Fainman couldn’t pinpoint a favorite project from his 40 years of research. He’s like a parent, he explained. He doesn’t have favorites because he loves them all equally.

“Every project has its own interesting aspects and challenges,” he said.

Still, one of his most rewarding projects was with QI, where he and his group created an integrated photonics education kit.

This hands-on learning tool packages a silicon photonics chip with fiber optic and electrical connections. When his team developed it in 2019, Fainman never could have imagined the impact it would have a year later.

“During COVID, students could access it remotely to conduct experiments,” he explained. “It was a fun project that’s drawn a lot of interest beyond UC San Diego.”

For those looking to follow in his footsteps in photonics or enter the research community more broadly, Fainman has simple but profound advice.

“Be passionate about what you are doing.”