In the “Star Wars” universe, characters harness the power of light through iconic lightsabers. Here on Earth, researchers are tapping into a similarly transformative phenomenon, aiming to build technology that uses beams of light to perform ever-faster computing.
A team co-led by Lawrence Berkeley National Laboratory (Berkeley Lab), Columbia University, and Universidad Autónoma de Madrid has developed a new optical computing material from “photon avalanching” nanoparticles. Their findings, recently reported in the journal Nature Photonics, could pave the way for optical memory and transistor components at sizes comparable to today’s microelectronics — offering a route toward smaller, faster systems for future computers.
Postdoctoral research fellow Xiao Qi in the laser room at the Molecular Foundry. Qi used the setup to develop a new optical computing material from nanoparticles that exhibit photon avalanching. A small increase in laser power led to a giant surge in light emitted by the nanoparticles. (Credit: Marilyn Sargent/Berkeley Lab)
“This is the first practical demonstration of intrinsic optical bistability in nanoscale materials,” said Emory Chan, a staff scientist and co-lead author at Berkeley Lab’s Molecular Foundry. “The fact that we can reproducibly make these materials and understand their unintuitive properties is critical for making optical computers at scale a reality.”
The research is part of Berkeley Lab’s broader push to advance smaller, more energy-efficient microelectronics through new materials and techniques. For decades, scientists have investigated how to use light instead of electrical signals to run computer operations. Materials that display intrinsic optical bistability (IOB)—the ability to switch between two distinct light-emitting states—have been considered key building blocks for optical computing. However, IOB was usually found in large “bulk” materials that were too big for modern chips and impractical to mass produce. Earlier efforts at the nanoscale offered limited insights, with most assuming that heat caused the switching.
Chan’s team considered “photon avalanching” nanoparticles as a potential solution. During experiments at the Molecular Foundry, a nanoscale science user facility at Berkeley Lab, the researchers crafted 30-nanometer particles from a potassium-lead-halide material, incorporating neodymium, a rare-earth element often used in lasers. When hit by light from an infrared laser, these particles unleashed a dramatic, disproportionate burst of light in response to a relatively small increase in laser power.
The phenomenon, known as photon avalanching, had already been documented in a 2021 paper by some of the same researchers. They found that doubling the laser power could increase emitted light intensity by a factor of 10,000. In the newest study, the particles proved to be more than three times as “nonlinear” as before, showcasing what Chan described as “the highest nonlinearities that anyone has ever observed in a material.”
Further tests revealed a crucial property: once the nanoparticles surpass a certain laser power threshold and start emitting brightly, they continue to glow even if the laser’s intensity is slightly reduced. They only switch “off” at much lower power levels. That trait — staying on or off based on their recent exposure — means the particles act as genuine nanoscale optical memory.
The team then used computer models to show, for the first time, that the IOB effect in these nanoparticles doesn’t stem from heat but instead results from photon avalanching itself and a unique particle structure that minimizes vibrations. This mechanism points toward potentially more efficient and controllable optical devices.
Looking ahead, the researchers plan to explore how these bistable nanoparticles might be refined for broader medical or technological uses, such as advanced data storage, wearable electronics, and more. They also aim to develop new formulations that offer even greater environmental stability and bistability.
The Molecular Foundry is a nanoscale science user facility at Berkeley Lab. This work received support from the Department of Energy’s Office of Science, as well as funding from the Defense Advanced Research Projects Agency (DARPA) and the National Science Foundation.
