Bolakis C, Grbovic D, Lavrik N V, Karunasiri G
Department of Physics, Naval Postgraduate School Monterey, CA 93943, USA.
Opt Express. 2010 Jul 5;18(14):14488-95. doi: 10.1364/OE.18.014488.
A terahertz-absorbing thin-film stack, containing a dielectric Bragg reflector and a thin chromium metal film, was fabricated on a silicon substrate for applications in bi-material terahertz (THz) sensors. The Bragg reflector is to be used for optical readout of sensor deformation under THz illumination. The THz absorption characteristics of the thin-film composite were measured using Fourier transform infrared spectroscopy. The absorption of the structure was calculated both analytically and by finite element modeling and the two approaches agreed well. Finite element modeling provides a convenient way to extract the amount of power dissipation in each layer and is used to quantify the THz absorption in the multi-layer stack. The calculation and the model were verified by experimentally characterizing the multi-layer stack in the 3-5 THz range. The measured and simulated absorption characteristics show a reasonably good agreement. It was found that the composite film absorbed about 20% of the incident THz power. The model was used to optimize the thickness of the chromium film for achieving high THz absorption and found that about 50% absorption can be achieved when film thickness is around 9 nm.
一种包含介质布拉格反射器和薄铬金属膜的太赫兹吸收薄膜堆叠结构，被制备在硅衬底上，用于双材料太赫兹（THz）传感器。布拉格反射器用于在太赫兹光照下对传感器变形进行光学读出。使用傅里叶变换红外光谱法测量了薄膜复合材料的太赫兹吸收特性。通过解析计算和有限元建模两种方法计算了该结构的吸收情况，两种方法结果吻合良好。有限元建模提供了一种方便的方法来提取各层中的功率耗散量，并用于量化多层堆叠结构中的太赫兹吸收。通过在3 - 5太赫兹范围内对多层堆叠结构进行实验表征，验证了计算结果和模型。测量和模拟的吸收特性显示出相当好的一致性。发现复合薄膜吸收了约20%的入射太赫兹功率。该模型用于优化铬膜厚度以实现高太赫兹吸收，发现当膜厚度约为9纳米时可实现约50%的吸收。
