Spectral characteristics of MWIR band-pass filters at cryogenic temperature

Citation

陈凤金 (Chen Fengjin), 马胜昔 (Ma Shengxi), 苏现军 (Su Xianjun), & 经 凌 (Jing Ling). (2015年7月). 低温对中波红外带通滤光片光谱特性的影响 [Spectral characteristics of MWIR band-pass filters at cryogenic temperature]. 应用光学 [Journal of Applied Optics], 36(4), 635-638. doi: 10.5768/JAO201536.0406002.

Keywords

• 低温 / Low Temperature / Cryogenic
• 中波红外 / Mid-Wave Infrared - MWIR
• 带通滤光片 / Bandpass Filter
• 光谱特性 / Spectral Characteristics
• 透过率 / Transmittance
• 中心波长 / Center Wavelength
• 截止波长 / Cut-off Wavelength
• Ge / Germanium
• 宝石 / Sapphire
• 基底 / Substrate
• 液氮 / Liquid Nitrogen
• 膜层 / Thin Film/Coating
• 膜层牢固度 / Film Layer Adhesion / Fastness
• 膜层脱落 / Film Layer Delamination
• 分光光度计 / Spectrophotometer

Brief

This article investigates the impact of cryogenic temperatures on the spectral properties of mid-wave infrared bandpass filters with Ge and sapphire substrates, revealing that transmittance decreases and the center wavelength slightly shifts with prolonged exposure to low temperatures, while the film layers remain intact.

Summary

This article explores how cryogenic temperatures (using liquid nitrogen) affect mid-wave infrared (MWIR) bandpass filters made with Ge and sapphire substrates. The study found that as the filters were exposed to low temperatures for longer durations (up to 300 minutes), their passband transmittance gradually decreased, with Ge-based filters showing a larger initial drop. The center wavelength experienced a minor shift of 5nm to 13nm, likely due to changes in the refractive indices of the film materials at low temperatures. However, the film layers of both Ge-based and sapphire-based MWIR bandpass filters remained intact even after 300 minutes of cryogenic exposure.

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