Scientists including an Oregon State University chemistry researcher have taken a key step toward next-generation optical computing and memory with the invention of luminescent nanocrystals that will be quickly toggled from light to dark and back again.
“The extraordinary switching and memory capabilities of those nanocrystals may in the future turn into integral to optical computing — a option to rapidly process and store information using light particles, which travel faster than anything within the universe,” said Artiom Skripka, assistant professor within the OSU College of Science. “Our findings have the potential to advance artificial intelligence and knowledge technologies generally.”
Published in Nature Photonics, the study by Skripka and collaborators at Lawrence Berkeley National Laboratory, Columbia University and the Autonomous University of Madrid involves a variety of material generally known as avalanching nanoparticles.
Nanomaterials are tiny bits of matter measuring between one-billionth and one-hundred-billionths of a meter, and avalanching nanoparticles feature extreme non-linearity of their light-emission properties — they emit light whose intensity can increase massively with a small increase within the intensity of the laser that is exciting them.
The researchers studied nanocrystals composed of potassium, chlorine and lead and doped with neodymium. By themselves, the potassium lead chloride nanocrystals don’t interact with light; nevertheless, as hosts, they allow their neodymium guest ions to handle light signals more efficiently, making them useful for optoelectronics, laser technology and other optical applications.
“Normally, luminescent materials give off light once they are excited by a laser and remain dark once they are usually not,” Skripka said. “In contrast, we were surprised to search out that our nanocrystals live parallel lives. Under certain conditions, they show a peculiar behavior: They will be either vivid or dark under the exact same laser excitation wavelength and power.”
That behavior is known as intrinsic optical bistability.
“If the crystals are dark to start out with, we want a better laser power to modify them on and observe emission, but once they emit, they continue to be emitting and we will observe their emission at lower laser powers than we would have liked to modify them on initially,” Skripka said. “It’s like riding a motorbike — to get it going, you might have to push the pedals hard, but once it’s in motion, you would like less effort to maintain it going. And their luminescence will be turned on and off really abruptly, as if by pushing a button.”
The low-power switching capabilities of the nanocrystals align with the worldwide effort to cut back the quantity of energy consumed by the growing presence of artificial intelligence, data centers and electronic devices. And never only do AI applications require substantial computational power, they are sometimes constrained by limitations related to existing hardware, a situation this recent research could also address.
“Integrating photonic materials with intrinsic optical bistability could mean faster and more efficient data processors, enhancing machine learning algorithms and data evaluation,” Skripka said. “It could also mean more-efficient light-based devices of the sort utilized in fields like telecommunications, medical imaging, environmental sensing, and interconnects for optical and quantum computers.”
Moreover, he said, the study complements existing efforts to develop powerful, general-purpose optical computers, that are based on the behavior of sunshine and matter on the nanoscale, and underscores the importance of fundamental research in driving innovation and economic growth.
“Our findings are an exciting development, but more research is obligatory to handle challenges corresponding to scalability and integration with existing technologies before our discovery finds a house in practical applications,” Skripka said.
The U.S. Department of Energy, the National Science Foundation and the Defense Advanced Research Projects Agency supported the research, which 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.
