Design and preparation of LWIR narrow-band filter with wide rejection band

In this letter, using mult-half-wave structure and some chosen films optimized method, the long-wave infrared （LWIR） narrow-band pass filter is investigated, meanwhile the opposite of the substrate coated with long-wavelength pass film. The transmittance of design spectrum is more than 80% at wavelength region of 8.05 8.35 μm, and the average transmittance is less than 0.5% at wavelength region of less than 7.95 and 8.45 14 pro. The filter is prepared by thermal evaporation method, and plasma-assisted deposition technology. The experiment result shows that the average transmittance is about 75% in the transmission wavelength range, and the average transmittance of cut-off band is about 0.3%. The results show that multi-half-wave structure and some chosen films optimized method for the preparation LWIR narrow-band pass filter are feasible. The film system is simplified and is convenient to prepare the film.