Long-Wave Infrared Spintronic Poisson Bolometers with High Sensitivity

Abstract: High-sensitivity long-wave infrared (LWIR) detection is crucial for observing weak thermal radiation. Recently, the spintronic Poisson bolometer was proposed as a promising platform for uncooled infrared detection. The Poisson bolometer operates in a probabilistic regime dominated by Poissonian noise, establishing a new detection paradigm. In contrast to traditional analog detectors, where signal and noise are continuous currents or voltages, the Poisson bolometer has both signal and noise governed by Poissonian counting statistics regardless of the light source, with the mean count rate modulated by incident radiation. In this work, we integrate a broadband plasmonic absorber optimized for LWIR absorption onto a spintronic Poisson bolometer to enhance thermal coupling and temperature rise in the sensing layer. The plasmonic absorber achieves over 60\% absorptance across the LWIR spectrum, matching the blackbody radiation peak at room temperature. The device exhibits a best noise-equivalent temperature difference (NEDT) of 35 mK at a 50 Hz frame rate and multiple results close to or below 100 mK, demonstrating room-temperature performance among the most sensitive uncooled LWIR detectors reported to date. This work advances uncooled infrared detection toward cryogenic-level sensitivity through the innovation of integrating spintronic materials and plasmonic materials, opening pathways to high-sensitivity LWIR sensing and imaging applications such as remote sensing, high-speed imaging, cryogenic system diagnostics, and industrial monitoring.