UCF researcher Debasis Chanda, a professor in the UCF Nanoscience and Technology Center, has developed a new technique to detect long-wave infrared (LWIR) photons of different wavelengths, or “colors.”
The research was recently published in Nano Letters,a prestigious scientific journal published by the American Chemical Society
The findings are the result of a $1.5 million project funded through the Defense Advanced Research Projects Agency’s Extreme Photon Imaging Capabilities program and awarded about two years ago.
New detection and imaging techniques will be applied to the analysis of materials based on their spectral properties, i.e. spectroscopic imaging, and thermal imaging applications.
Humans can see primary and secondary colors, but not infrared. Scientists theorize that snakes and nocturnal animals may be able to sense different wavelengths of near-infrared light in the same way that humans can see color.
Chanda said detecting infrared light, especially LWIR, at room temperature has long been a challenge due to the low photon energy.
According to the researchers, LWIR detectors can be classified as cooled or uncooled.
Cooled detectors offer high detection capabilities and fast response times, but their reliance on cryogenic cooling significantly increases their cost, limiting their practical applications.
In contrast, uncooled detectors such as micro-thermometers can operate at room temperature and are relatively low cost, but they have low sensitivity and slow response times, Chanda said.
Neither type of LWIR detector has dynamic spectral tuning capability and therefore cannot distinguish between different “color” photon wavelengths.
Hoping to push the limits of existing LWIR detectors, Chanda and his team of postdoctoral researchers set out to demonstrate a highly sensitive, efficient, and dynamically tunable method based on nanopatterned graphene.
Tianyi Guo ’23PhD is the lead author of the study. Guo completed his doctorate at UCF in 2023 under Chanda’s mentorship. He has received an international paper award from Springer Nature, and his paper exploring potential LWIR detection methods was published in the high-impact Springer Theses series.
Chanda said the newly discovered method is the result of work conducted by Guo, Chanda and other researchers in Chanda’s lab.
“Current cooled and uncooled detectors do not offer such dynamic spectral tuning and ultrafast response,” Chanda said. “This demonstration highlights the potential of our engineered single-layer graphene LWIR detector, which operates at room temperature and offers high sensitivity and dynamic spectral tuning for spectral imaging.”
The detector exploits the temperature difference between materials (known as the Seebeck effect) inside an asymmetrically patterned graphene film. Upon illumination and interaction, the patterned half generates hot carriers with greatly enhanced absorption, while the unpatterned half remains cool. Diffusion of the hot carriers generates a photothermal voltage, which is measured between the source and drain electrodes.
By patterning graphene into specialized arrays, the researchers were able to achieve improved absorption and further electrostatic tuning in the LWIR spectral range, resulting in better infrared detection that significantly outperforms conventional uncooled infrared detectors, also known as microbolometers .
“The proposed detection platform paves the way for a new generation of graphene-based uncooled LWIR photodetectors for a wide range of applications, including consumer electronics, molecular and space sensing,” Chanda said.
Researchers in Chanda’s group include postdoctoral researchers Aritra Biswas (21MS, 24PhD), Sayan Chandra, Arindam Dasgupta and Muhammad Waqas Shabbir (16MS, 21PhD).
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UCF Nanoscience Center
