Insertion Layer in a Mid-Ir Band-Pass Filter Structure to Improve Optical Transmittance

Abstract

Insertion of a single Ge layer deposition (denoted as layer xGe) has been carried out to the band-pass filter structure to improve optical transmittance in a mid-IR region. The filter structure was of Air/[Ge/ZnS]^N xGe/Quartz constructed from Ge/ZnS period layer deposition. From the modeling done, by introducing a layer period, N = 10, each layer thickness of Ge and ZnS prepared is 500 nm, the optical transmittance was found to improve significantly about 0.9 for xGe = 0.80 (layer thickness of 80% of Ge thickness) compare than that of the greater value.

Keywords : band-pass filter, infrared, transmittance, Ge, ZnS