Reviewed by Lexie CornerJan 6 2025
Scientists from Oregon State University have identified luminescent nanocrystals capable of quickly switching between light and dark states, representing a step forward in the development of next-generation optical computing and memory. The findings were published in Nature Photonics.
Optically bistable nanocrystals can store information that is written and read entirely through light, making them useful for building small and scalable optical memory units. These nanocrystals are controlled by lasers: one delivers continuous power, while the other triggers them to emit light after a brief pulse. This functionality mimics the behavior of electronic transistors and paves the way for devices where light controls light. Image Credit: Artiom Skripka, OSU College of Science
The extraordinary switching and memory capabilities of these nanocrystals may one day become integral to optical computing–a way to rapidly process and store information using light particles, which travel faster than anything in the universe. Our findings have the potential to advance artificial intelligence and information technologies generally.
Artiom Skripka, Assistant Professor, Oregon State University
The study by Skripka and collaborators from Lawrence Berkeley National Laboratory, Columbia University, and the Autonomous University of Madrid focuses on a specialized class of materials known as avalanching nanoparticles.
Nanomaterials are extremely small particles, ranging from one billionth to one hundred billionths of a meter in size. Avalanching nanoparticles exhibit highly non-linear light-emission properties, where a slight increase in laser intensity causes a substantial increase in light emission.
The researchers studied neodymium-doped potassium, chlorine, and lead nanocrystals. While potassium lead chloride nanocrystals do not interact with light independently, they act as hosts that enhance the ability of neodymium guest ions to process light signals. This makes them suitable for applications in laser technology, optoelectronics, and other optical systems.
Normally, luminescent materials give off light when they are excited by a laser and remain dark when they are not. In contrast, we were surprised to find that our nanocrystals live parallel lives. Under certain conditions, they show a peculiar behavior: They can be either bright or dark under exactly the same laser excitation wavelength and power.
Artiom Skripka, Assistant Professor, Oregon State University
This phenomenon is known as intrinsic optical bistability.
If the crystals are dark to start with, we need a higher laser power to switch them on and observe emission, but once they emit, they remain emitting, and we can observe their emission at lower laser powers than we needed to switch them on initially. It is like riding a bike–to get it going, you have to push the pedals hard, but once it is in motion, you need less effort to keep it going. And their luminescence can be turned on and off really abruptly, as if by pushing a button.
Artiom Skripka, Assistant Professor, Oregon State University
The nanocrystals' low-power switching capabilities align with global efforts to reduce energy consumption amid the growing demand from data centers, electronic devices, and artificial intelligence applications.
AI systems often face limitations due to hardware constraints and their significant processing power requirements. This research could help address these challenges.
Skripka said, “Integrating photonic materials with intrinsic optical bistability could mean faster and more efficient data processors, enhancing machine learning algorithms and data analysis. It could also mean more efficient light-based devices of the type used in fields like telecommunications, medical imaging, environmental sensing, and interconnects for optical and quantum computers.”
He emphasized that the study underscores the importance of basic research in driving innovation and economic growth while supporting efforts to develop robust optical computers that leverage light and matter interactions at the nanoscale.
“Our findings are an exciting development, but more research is necessary to address challenges such as scalability and integration with existing technologies before our discovery finds a home in practical applications,” Skripka concluded.
The study was funded by the US Department of Energy, the National Science Foundation, and the Defense Advanced Research Projects Agency. It was led by Bruce Cohen and Emory Chan of Lawrence Berkeley, P. James Schuck of Columbia University, and Daniel Jaque of the Autonomous University of Madrid.
Journal Reference:
Skripka, A., et al. (2025) Intrinsic optical bistability of photon avalanching nanocrystals. Nature Photonics. doi.org/10.1038/s41566-024-01577-x.