The low energy of photons makes long-wave infrared (LWIR) light detection at ambient temperature a longstanding issue. Decades of effort have gone into developing an affordable, high-performing LWIR detector or camera that can function in such environments. Presently, all accessible detectors act through amplitude modulation (AM), and their efficiency is restricted by AM noises such as background fluctuation noise, shot noise, and Johnson noise.
To address this challenge, UCF researcher Debashis Chanda, a professor at the NanoScience Technology Center, has developed a new technique to detect photons. The technique has inherent robustness against different types of AM noises.
In the past, people usually detected photons (tiny particles of light) by measuring changes in voltage or current. But now, Chanda has come up with a new way. Instead of looking at changes in electricity, they detected photons by modulating the frequency of an oscillating circuit.
The technique uses a unique phase-change material (PCM) that alters its shape in response to light, creating a stable electrical circuit oscillation or constant rhythm. A photon of light striking the substance causes the oscillation frequency to alter, or how quickly the rhythm beats. Just as a person’s voice alters the sound on the radio, the intensity of the light affects how much the rhythm changes.
Chanda said, “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.”
“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 the performance can be further enhanced with proper industry-scale packaging.”
This new concept offers a paradigm shift to susceptible, uncooled LWIR detection as noise limits detection sensitivity. This finding suggests a new way to detect long-wave infrared (LWIR) radiation without needing cooling. It is susceptible, doesn’t cost much, and can be easily combined with electronic circuits for reading without complicated setups.
Journal Reference:
Tianyi Guo, Arindam Dasgupta, Sayan Chandra et al. Frequency Modulation Based Long-Wave Infrared Detection and Imaging at Room Temperature. Advanced Functional Materials. DOI: 10.1002/adfm.202309298
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