Metamaterial microbolometers for multi-spectral infrared polarization imaging

Vanadium oxide (VOx) microbolometers enable the construction of high-performance yet low-cost and uncooled imaging detectors in the mid-infrared spectrum. Typical microbolometers are broadband sensors with no polarization selectivity. Thus, imaging detectors based on microbolometers have to use separate spectral and polarization filters to select the target spectral bands and polarization states, and the resulting systems are complicated and bulky. Here we demonstrate that by using metamaterial absorbers (MAs), which are arrays of optical resonators with sub-wavelength dimensions and spacing, we simultaneously tailor the VOx microbolometers' spectral and polarization responses, the need for separate spectral filters and polarizers can be mitigated. The MAs selectively absorb the TM polarization component of the incident light in a spectral band with tunable central wavelength and bandwidth while rejecting the TE polarization component. Two MAs with average TM absorption of 0.8322 in the 5.150 mu m - 6.422 mu m band and 0.7720 in the 5.867 mu m - 7.467 mu m band are fabricated, and the polarization extinction ratio (PER) are 42.24 and 42.65, respectively. The MAs are applied to VOx micro-bolometers, and the measured detector responses agree well with the absorption spectra of the MAs. The achieved peak responsivities of two fabricated detectors are 1.0 V/W at 6.0 mu m and 1.46 V/W at 6.8 mu m, respectively. And the two detectors achieve a D* of 6.94x10(5) cm.Hz(1/2)W(-1) at 11 Hz and 9.95x10(5) cm.Hz(1/2)W(-1) at 36Hz, respectively. Our work paved the way towards large format room temperature multi-spectral infrared polarization imaging detector. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing