Researcher discovers new technique for infrared ‘color’ detection and imaging

The research was recently published in nanolettersa journal published by the American Chemical Society.

New detection and imaging technologies will be used to analyze materials through their spectral properties, or for spectral imaging and thermal imaging applications.

Humans perceive primary and secondary colors, but not infrared. Scientists speculate that animals like snakes or nocturnal animals can detect various wavelengths in infrared light, much like how humans perceive color.

Chanda said that detection of infrared light at room temperature, especially long-wavelength infrared light, has been a long-standing challenge due to the weak energy of photons.

The researchers said that long-wave infrared detectors can be roughly divided into cooled detectors and uncooled detectors.

Cooled detectors have the advantages of high detection rates and fast response times, but their reliance on cryogenic cooling significantly increases their cost and limits their practical applications.

In comparison, Chanda said, uncooled detectors, such as microbolometers, can operate at room temperature and are relatively low-cost, but have lower sensitivity and slower response times.

Both types of long-wave infrared detectors lack dynamic spectral tunability, so they cannot distinguish between different “colors” of photon wavelengths.

Chanda and his team of postdoctoral scholars sought to push the limits of existing long-wavelength infrared detectors, so they worked to demonstrate a highly sensitive, efficient, and dynamically tunable method based on nanopatterned graphene.

Tianyi Guo ’23, Ph.D., is the lead author of this study. Guo completed his PhD at UCF in 2023 under the supervision of Chanda. He is the recipient of the Springer Nature International Dissertation Award, and his paper exploring potential long-wave infrared detection methods was published in the Springer Dissertation Series.

Chanda said the newly discovered method is the culmination of research conducted by Guo, Chanda and others in Chanda’s lab.

“No current cooled or uncooled detector can provide such dynamic spectral tunability and ultrafast response,” Chanda said. “This demonstration highlights the potential of engineered single-layer graphene long-wavelength infrared detectors operating at room temperature to provide high sensitivity and dynamic spectral tunability for spectral imaging.”

The detector relies on temperature differences in the material within a thin film of asymmetrically patterned graphene (called the Seebeck effect). Under light illumination and interaction, the patterned half generates hot carriers whose absorption is greatly enhanced, while the unpatterned half remains cooler. The diffusion of hot carriers generates a photothermal voltage, which is measured between the source and drain.

By patterning graphene into specialized arrays, the researchers achieved enhanced absorption and could further perform electrostatic tuning in the long-wave infrared spectral range and provide better infrared detection. The detector’s capabilities significantly exceed traditional uncooled infrared detectors (also known as microbolometers).

“The proposed detection platform paves the way for a new generation of uncooled graphene long-wave infrared photodetectors with a wide range of applications such as consumer electronics, molecular sensing, and space,” said Chanda.

Researchers in Chanda’s group include postdoctoral scholars Aritra Biswas ’21MS ’24PhD, Sayan Chandra, Arindam Dasgupta and Muhammad Waqas Shabbir ’16MS ’21PhD.

The findings are the result of a $1.5 million program funded by the Defense Advanced Research Projects Agency’s Extreme Photon Imaging Capabilities Program awarded nearly two years ago.