Uncooled infrared imaging using a single trampoline-based optomechanical thermal detector

Uncooled optomechanical infrared (IR) detectors with high sensitivity and fast response that outperform traditional thermal detectors have been developed for diverse emergent applications. Nevertheless, scaling the high-performance optomechanical detectors to focus plane array cameras for IR imaging remains a great challenge. This work reports uncooled IR imaging using a single optomechanical thermal detector, in which the IR radiation induced photothermal frequency shift of a high-quality trampoline-type mechanical resonator is read out optically within a fiber-based micro-cavity. The trampoline resonator, featuring low thermal mass and excellent thermal isolation, exhibits a responsivity of 12,227 W −1 for the fundamental mechanical mode with a thermal response time constant of 12 ms. Leveraging the fast thermal response, we implement a modulation-demodulation scheme to achieve an optimal IR detection sensitivity with a noise equivalent power reaching 4.48 pW · Hz −1/2 . And a minimum detectable IR power of 1.40 pW is achieved for an integration time of 10 s. Because the scheme is inherently robust against slowly varying temperature fluctuations, high-spatial-resolution thermal imaging of a 10.6 μm IR beam spot is demonstrated using the optomechanical detector through pixel-by-pixel scanning. Notably, this proof-of-principle demonstration is fully compatible with advanced single-pixel imaging techniques, offering the possibility of a significant acceleration in imaging speed.