Dual-mode resonant infrared detector based on film bulk acoustic resonator toward ultra-high sensitivity and anti-interference capability

Abstract

Here, we demonstrate an uncooled, miniaturized, and high resolution infrared (IR) detector based on an aluminum nitride (AlN) film bulk acoustic resonator with dual resonant modes. Due to temperature dependence of the resonance frequency of the resonator and charge carrier generation effect of the AlN piezoelectric material, both the resonant frequency and valley value in reflection coefficient S11 are found responsive to IR irradiation at each resonant mode, thus realizing four IR sensing signal concurrence in a single device. The four sensing signals achieved IR responsivities of 3.32 Hz/nW, 561.21 μdB/nW, 43.17 Hz/nW, and 53.70 μdB/nW, respectively. The second sensing signal even realized a noise equivalent power down to 108 pW/Hz1/2, which is the lowest value among resonant infrared detectors reported in literature studies till now. More importantly, these four sensing signals lie in two separate frequency bands up to GHz, thus enabling the detector to operate normally by the frequency-hopping sensing method when one of the frequency bands suffers from strong electromagnetic interference. The presented device shows a great potential for ultra-sensitive and anti-interference infrared detection in civilian and military fields.