Programmable pixels could advance infrared light applications
Full control over mid-infrared wavelengths enables advancements in applications ranging from chip security to personalized health monitoring.
Without the ability to control infrared light waves, autonomous vehicles wouldn’t be able to quickly map their environment and keep “eyes” on the cars and pedestrians around them; augmented reality couldn’t display realistic 3D displays; doctors would lose an important tool for early cancer detection. Dynamic light control allows for upgrades to many existing systems, but complexities associated with fabricating programmable thermal devices hinders availability.
A new active metasurface, the electrical-programmable graphene field effect transistor (Gr-FET), from the labs of Sheng Shen and Xu Zhang in Carnegie Mellon University’s College of Engineering, enables the control of mid-infrared states across a wide range of wavelengths, directions, and polarizations. This enhanced control enables advancements in applications ranging from infrared camouflage to personalized health monitoring.
“For the first time, our active metasurface devices exhibited the monolithic integration of the rapidly modulated temperature, addressable pixelated imaging, and resonant infrared spectrum.” said Xiu Liu, postdoctoral associate in mechanical engineering and lead author of the paper published in Nature Communications. “This breakthrough will be of great interest to a wide range of infrared photonics, materials science, biophysics, and thermal engineering audiences.”
The two-dimensional device is made up of gold array pixels that either directly interface with a single graphene layer or are separated by an insulation layer.
Video: Dynamic thermal mapping capture of experimental pixel sweeping of the pixelated 2D metasurface array illuminating each pixel sequentially and following a letter “L” shape.
“It has low crosstalk, meaning the signals transmitted from one channel do not interfere with another,” said Zexiao Wang, Ph.D. candidate in mechanical engineering, “This breakthrough allows for scalable 2D electrical writing for densely packed, independently addressable pixels.”
Tianyi Huang, also a Ph.D. candidate in mechanical engineering, led the development of a specially-designed circuit that powers the device. This allows the device to operate on its own or integrate into existing products.
“This device is scalable. It could be used on a chip to prevent side channel attacks by camouflaging existing thermal emission with misleading, programmed emissions. On the other side it could be worn in a garment to detect breast cancer cells,” explained mechanical engineering Ph.D. candidate Yibai Zhong.
This device is scalable. It could be used on a chip to prevent side channel attacks … or worn in a garment to detect breast cancer cells.
Yibai Zhong, Ph.D. Candidate, Mechanical Engineering
Side channel attacks are a way to exploit sensitive information, like encryption keys, by analyzing subtle temperature variations caused by computing device operations. By monitoring temperature fluctuations with a thermal imaging camera, an attacker can potentially piece together information. Shen’s device could act as an added level of security by camouflaging thermal emissions.
“We aren’t too far off from seeing this technology integrated into our lives,” said Shen. “We could be using it in the next five to 10 years.”
Pictured, top: Rendering of active metasurface, the electrical-programmable graphene field effect transistor.