Hybrid SWM-IR narrow bandpass filters with high optical density

Narrow bandpass filters (NBFs), which are designed to accept a narrow wavelength range and simultaneously reject a much wider range, show great potential in applications such as spectral imaging, lidar detection, fluorescence microscopy, and others. In this paper, we propose and numerically simulate NBF technology for infrared (IR) optical applications. The filter is a combination of plasmonic nanostructures and improved induced transmission layers. The operating wavelength range is from 1360 to 5000 nm [short wave mid-infrared radiation(SWM-IR)], with a FWHM of less than 10 nm and maximum optical density of around 10. Therefore, our SWM-IR hybrid filter can distinguish much smaller differences in terms of spectrum information and reduce the background noise level even if using an optical amplifier.