Scientists including an Oregon State University chemistry researcher have taken a key step toward next-generation optical computing and memory with the discovery of luminescent nanocrystals that can be quickly toggled from light to dark and back again.
"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," said Artiom Skripka, assistant professor in the OSU College of Science. "Our findings have the potential to advance artificial intelligence and information 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 type of material 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 in their light-emission properties – they emit light whose intensity can increase massively with a small increase in the intensity of the laser that’s exciting them.
The researchers studied nanocrystals composed of potassium, chlorine and lead and doped with neodymium. By themselves, the potassium lead chloride nanocrystals do not interact with light; however, as hosts, they enable 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 when they are excited by a laser and remain dark when they are not," Skripka said. "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."
That behavior is referred to as intrinsic optical bistability.
