New graphene photodetector could improve night vision, thermal sensing and medical imaging

Using graphene, one of science's most versatile materials, engineers from the UCLA Samueli School of Engineering have invented a new type of photodetector that can work with more types of light than its current state-of-the-art counterparts. The device also has superior sensing and imaging capabilities.

Photodetectors are light sensors; in cameras and other imaging devices, they sense patterns of elementary particlescalledphotons, and create images from those patterns. Different photodetectors are built to sense different parts of the light spectrum. For example, photodetectors are used in night vision goggles to sense thermal radiation that is invisible to the naked eye. Others are used in cameras that identify chemicals in the environment by how they reflect light.

How versatile and usefulphotodetectorsare depends largely on three factors: their operating speed, their sensitivity to lower levels of light, and how much of the spectrum they can sense. Typically, when engineers have improved a photodetector's capabilities in any one of those areas, at least one of the two other capabilities has been diminished.

The photodetector designed by the UCLA team has major improvements in all three areas – it operates across a broad range of light, processes images more quickly and is more sensitive to low levels of light than current technology.

"Our photodetector could extend the scope and potential uses of photodetectors in imaging and sensing systems," said Mona Jarrahi, a professor of electrical and computer engineering, who led the study. "It could dramatically improve thermal imaging in night vision or in medical diagnosis applications where subtle differences in temperatures can give doctors a lot of information on their patients. It could also be used in environmental sensing technologies to more accurately identify the concentration of pollutants."

The study was published in the journal Light: Science and Applications.