Quasi-three-dimensional nanopost array integrated Type-II superlattice photodetectors for infrared multispectral filtering

Angle-insensitive and high-transmission infrared spectral filters, comprising periodic quasi-three-dimensional (quasi-3D) nanopost arrays, are fabricated using a nanoimprint lithography technique and directly integrated onto an InAs/GaSb type-II superlattice (T2SL) photodetector. Simulation results of the plasmonic filters reveal that the transmission peak wavelength is linearly adjusted by tuning the filter period as a result of the propagated and localized surface plasmon resonances of the quasi-3D nanopost array structure. Additionally, the transmission peak wavelength of the array structure is measured to increase with decreasing nanopost height owing to stronger field coupling between the Au hole and disk arrays. A tunable bandpass filtering function of the quasi-3D nanopost-integrated T2SL photodetector is successfully demonstrated with narrow bandwidths in the spectral range of 2–6 μm. Our findings offer a significant potential for a scalable low-cost manufacturing method of compact snapshot multispectral infrared imagers for portable-field imaging or airborne-platform-based imaging applications.