New technique for photon detection developed

University of Central Florida (UCF) researcher Debashis Chanda, a professor at UCF’s NanoScience Technology Center, has developed a new technique to detect photons — elementary particles that span from visible light to radio frequencies and are instrumental in carrying cellular communication. Described in the journal Advanced Functional Materials, the breakthrough could lead to more precise and efficient technologies in various fields, from improving medical imaging and communication systems to enhancing scientific research and even potentially bolstering security measures.

Photon detection has typically relied on change/modulation of voltage or current amplitude — but Chanda has developed a way to detect photons by modulating the frequency of an oscillating circuit, paving the path for ultrasensitive photon detection. His method uses a phase-change material (PCM) that changes its form when light touches it, making an electrical rhythm that stays steady, or a stable electrical circuit oscillation. When a photon hits the material, it changes how fast the rhythm goes, or shifts the oscillation frequency. How much the rhythm changes depends on how strong the light is.

Long wave infrared (LWIR) detection in the 8–12 µm wavelength range is extremely important in astronomy, climate science, materials analysis and security. However, LWIR detection at room temperature has been a longstanding challenge due to the low energy of photons. LWIR detectors that are currently available can be broadly categorised into two types — cooled and uncooled — with both having their own limitations.

While cooled detectors offer excellent detectivity, they require cryogenic cooling, making them expensive and limiting their practical utility. On the other hand, uncooled detectors can operate at room temperature but suffer from low detectivity and slow response due to the higher thermal noise intrinsic to room temperature operation. This is the main reason LWIR cameras are not widely used, except in Department of Defense and space-specific applications.

“Unlike all present photon detection schemes where light power changes the amplitude of voltage or current (amplitude modulation — AM), in the proposed scheme, hits, or incidents of photons, modulate the frequency of an oscillating circuit and are detected as a frequency shift, offering inherent robustness to noises, which are AM in nature,” Chanda said.

“Our FM-based approach yields an outstanding room temperature noise equivalent power, response time and detectivity. This general FM-based photon detection concept can be implemented in any spectral range based on other phase-change materials.

“Our results introduce this novel FM-based detector as a unique platform for creating low-cost, high-efficiency uncooled infrared detectors and imaging systems for various applications such as remote sensing, thermal imaging and medical diagnostics. We strongly believe that the performance can be further enhanced with proper industry-scale packaging.”

Image caption: Debashis Chanda.