Han Molong, Smith Daniel, Ng Soon Hock, Vilagosh Zoltan, Anand Vijayakumar, Katkus Tomas, Reklaitis Ignas, Mu Haoran, Ryu Meguya, Morikawa Junko, Vongsvivut Jitraporn, Appadoo Dominique, Juodkazis Saulius
Optical Sciences Centre and ARC Training Centre in Surface Engineering for Advanced Materials (SEAM), School of Science, Swinburne University of Technology, Hawthorn, VIC 3122, Australia.
Melbourne Centre for Nanofabrication, 151 Wellington Road, Clayton, VIC 3168, Australia.
Micromachines (Basel). 2022 Jul 25;13(8):1170. doi: 10.3390/mi13081170.
THz band-pass filters were fabricated by femtosecond-laser ablation of 25-μm-thick micro-foils of stainless steel and Kapton film, which were subsequently metal coated with a ∼70 nm film, closely matching the skin depth at the used THz spectral window. Their spectral performance was tested in transmission and reflection modes at the Australian Synchrotron's THz beamline. A 25-μm-thick Kapton film performed as a Fabry-Pérot etalon with a free spectral range (FSR) of 119 cm-1, high finesse Fc≈17, and was tuneable over ∼10μm (at ∼5 THz band) with β=30∘ tilt. The structure of the THz beam focal region as extracted by the first mirror (slit) showed a complex dependence of polarisation, wavelength and position across the beam. This is important for polarisation-sensitive measurements (in both transmission and reflection) and requires normalisation at each orientation of linear polarisation.
太赫兹带通滤波器是通过飞秒激光烧蚀25微米厚的不锈钢微箔和聚酰亚胺薄膜制成的，随后对其进行金属镀膜，镀膜厚度约为70纳米，与所用太赫兹光谱窗口的趋肤深度紧密匹配。在澳大利亚同步加速器的太赫兹光束线中，对它们的光谱性能进行了透射和反射模式测试。一层25微米厚的聚酰亚胺薄膜表现为法布里-珀罗标准具，其自由光谱范围（FSR）为119厘米-1，精细度Fc≈17，并且在β = 30°倾斜时，在约10微米（在约5太赫兹频段）范围内可调谐。由第一反射镜（狭缝）提取的太赫兹光束聚焦区域的结构显示出极化、波长和光束位置之间的复杂依赖关系。这对于极化敏感测量（透射和反射）很重要，并且需要在每个线性极化方向上进行归一化。
