Devasis Chanda, a professor at the University of Central Florida’s (UCF) Nanoscience and Technology Center, has developed a new technique to detect long-wave infrared (LWIR) photons of different wavelengths, or “colors.”
The breakthrough is the result of a $1.5 million project funded by the Defense Advanced Research Projects Agency’s (DARPA) Extreme Photon Imaging Capabilities program, awarded nearly two years ago.
This new detection and imaging method is used for spectroscopic imaging (the analysis of materials based on their spectral properties) and thermal imaging applications.
While humans can see primary and secondary colors, infrared light is beyond the range of human vision, but scientists believe that some animals, such as snakes and nocturnal animals, can sense different wavelengths of infrared light in the same way that humans can see visible colors.
According to Chanda, detecting infrared light, especially LWIR, at room temperature is difficult due to the low energy of the photons.
The study explains that LWIR detectors generally fall into two categories: cooled and uncooled. Cooled detectors have high sensitivity and fast response times but require cryogenic cooling, making them expensive and limiting their practical use. Uncooled detectors, such as microbolometers, on the other hand, operate at room temperature and are more affordable, but have lower sensitivity and slower response.
Neither type of detector can be dynamically tuned across different wavelengths, and therefore cannot distinguish between photons of different “colors.”
To address these limitations, Chanda and his postdoctoral research team developed a highly sensitive, efficient and dynamically tunable technique based on nanopatterned graphene.
The lead author of the study is Tianyi Guo, who completed his doctorate at UCF in 2023 under Chanda’s mentorship. Guo received an international paper award from Springer Nature, and his research on LWIR detection methods was published in the prestigious Springer Theses series .
Guo, Chanda and other members of Chanda’s team conducted the research that led to this new detection method.
No currently available cooled or uncooled detectors offer such dynamic spectral tuning and extremely fast response. This demonstration highlights the potential of the engineered single-layer graphene LWIR detector to operate at room temperature and provide high sensitivity and dynamic spectral tuning for spectral imaging .
Debasis Chanda, Professor, University of Central Florida
The detector exploits the temperature difference between materials, known as the Seebeck effect, within asymmetrically patterned graphene layers. When light shines on the graphene, the patterned areas create a highly absorbing heat carrier, while the unpatterned areas remain cool. The movement of these heat carriers generates a photothermal voltage, which is measured between the source and drain electrodes.
To enhance absorption, the researchers patterned the graphene into specific arrays that could be electrostatically tuned in the LWIR spectrum, enabling superior infrared detection. As a result, the detector significantly outperforms traditional uncooled infrared detectors such as microbolometers.
Chanda further said , ” The proposed sensing platform paves the way for a new generation of graphene-based uncooled LWIR photodetectors for various applications such as consumer electronics, molecular and space sensing
Postdoctoral researchers Aritra Biswas (21MS, 24Ph.D.), Sayan Chandra, Arindam Dasgupta and Muhammad Waqas Shabbir (16MS, 21Ph.D.) were among the researchers in Chanda’s group.
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University of Central Florida
