中短波红外双带通低温滤光片的设计与制备

双带通滤光片可以在元件的任意一个几何位置上同时透过两个光谱通道，从而实现双光谱通道的同时探测。文中研制了一种在100 K低温下使用的短波和中波红外双带通滤光片，选用Ge和SiO分别作为高低折射率膜层，在蓝宝石（Al₂O₃）基片上设计了具有Fabre-Perot(F-P)结构的短波通道滤光膜系和中波通道滤光膜系，它们在另一通带位置兼具增透能力，组合形成了包含短波通道(2.60~2.85 μm)和中波通道(4.10~4.40 μm)的双带通滤光片。Ge和SiO薄膜分别以电子束和电阻热蒸发的方式在高真空环境中完成沉积。测试结果显示，在100 K低温下，短波和中波通道的平均透射率分别达到91.2%和87.7%，顶部波纹幅度分别为2.1%和3.8%，波长3.00~3.95 μm光谱区域内的截止深度低于0.1%。该双带通滤光片在低温下的光学性能满足光学成像仪器的光谱应用要求，有利于更加精确的红外遥感和探测。

Design and fabrication of short and middle wavelength infrared dual band-pass filter at cryogenic temperature

Dual band-pass filter can simultaneously form two spectral channels to transmit at any position of the element, so as to realize simultaneous detection of dual spectral channels. In this paper, an infrared dual band-pass filter used at 100 K temperature was developed. Sapphire (Al₂O₃) was used as substrate, and Ge and SiO were used as high (H) and low (L) refractive index thin films respectively. An infrared dual band-pass filter combined with a shorter wavelength channel (2.60-2.85 μm) and a longer wavelength channel (4.10-4.40 μm) was designed and fabricated. Based on Fabre-Perot (F-P) filter structure, Ge and SiO thin films were deposited by electron beam evaporation and resistance thermal evaporation on the two sides of the substrate. At the working temperature (100 K), the filter transmittance of shorter channel is 91.2%, and the top ripple amplitude is 2.1%; the average transmittance of longer channel is 87.7%, and the top ripple amplitude is 3.8%. Between the two channels (wavelength 3.00-3.95 μm), the cut-off depth is less than 0.1%. The optical performance of the infrared dual band-pass filter can meet the spectral requirements and contribute to more accurate infrared remote sensing and detection.