Frequency Modulation Based Long-Wave Infrared Detection and Imaging at Room Temperature

Detection of long wave infrared (LWIR) light at room temperature is a long-standing challenge due to the low energy of photons. A low-cost, high-performance LWIR detector or camera that operates under such conditions is pursued for decades. Currently, all available detectors operate based on amplitude modulation (AM) and are limited in performance by AM noises, including Johnson noise, shot noise, and background fluctuation noise. To address this challenge, a frequency modulation (FM)-based detection technique is introduced, which offers inherent robustness against different types of AM noises. The FM-based approach yields an outstanding room temperature noise equivalent power (NEP), response time, and detectivity (D*). This result promises a novel uncooled LWIR detection scheme that is highly sensitive, low-cost, and can be easily integrated with electronic readout circuitry, without the need for complex hybridization. In summary, an frequency modulation-based uncooled long wave infrared (LWIR) detector is demonstrated using a cavity-coupled phase change material. The measured detectivity of the proposed detector is higher than commercially-available uncooled LWIR detectors with a faster response time. There is also great potential for the presented detection scheme with the implementation of other phase change materials with unique light responses.image