Surface plasmon-enhanced dual-band infrared absorber for -based microbolometer application**Project supported by the One Hundred Talents Program of the Chinese Academy of Sciences, the National Natural Science Foundation of China (Grant Nos. 61376083 and 61307077), the China Postdoctoral Science Foundation (Grant Nos. 2013M530613 and 2015T80080), and the Guangxi Key Laboratory of Precision Navigation Technology and Application (Grant Nos. DH201505, DH201510, and

Abstract

We propose a periodic structure as an extra absorption layer (i.e., absorber) based on surface plasmon resonance effects, enhancing dual-band absorption in both middle wavelength infrared (MWIR) and long wavelength infrared (LWIR) regions. Periodic gold disks are selectively patterned onto the top layer of suspended SiN/VO2/SiN sandwich-structure. We employ the finite element method to model this structure in COMSOL Multiphysics including a proposed method of modulating the absorption peak. Simulation results show that the absorber has two absorption peaks at wavelengths and with the absorption magnitudes more than 0.98 and 0.94 in MWIR and LWIR regions, respectively. In addition, the absorber achieves broad spectrum absorption in LWIR region, in the meanwhile, tunable dual-band absorption peaks can be achieved by variable heights of cavity as well as diameters and periodicity of disk. Thus, this designed absorber can be a good candidate for enhancing the performance of dual band uncooled infrared detector, furthermore, the manufacturing process of cavity can be easily simplified so that the reliability of such devices can be improved.