Kappa Jan, Sokoluk Dominik, Klingel Steffen, Shemelya Corey, Oesterschulze Egbert, Rahm Marco
Department of Electrical and Computer Engineering, Research Center OPTIMAS, Technische Universität Kaiserslautern, Kaiserslautern, Germany.
Department of Experimental Physics, Physics and Technology of Nanostructures, Nano Structuring Center, Technische Universität Kaiserslautern, Kaiserslautern, Germany.
Sci Rep. 2019 Feb 22;9(1):2597. doi: 10.1038/s41598-019-39152-y.
We report the design, fabrication and experimental investigation of a spectrally wide-band terahertz spatial light modulator (THz-SLM) based on an array of 768 actuatable mirrors with each having a length of 220 μm and a width of 100 μm. A mirror length of several hundred micrometers is required to reduce diffraction from individual mirrors at terahertz frequencies and to increase the pixel-to-pixel modulation contrast of the THz-SLM. By means of spatially selective actuation, we used the mirror array as reconfigurable grating to spatially modulate terahertz waves in a frequency range from 0.97 THz to 2.28 THz. Over the entire frequency band, the modulation contrast was higher than 50% with a peak modulation contrast of 87% at 1.38 THz. For spatial light modulation, almost arbitrary spatial pixel sizes can be realized by grouping of mirrors that are collectively switched as a pixel. For fabrication of the actuatable mirrors, we exploited the intrinsic residual stress in chrome-copper-chrome multi-layers that forces the mirrors into an upstanding position at an inclination angle of 35°. By applying a bias voltage of 37 V, the mirrors were pulled down to the substrate. By hysteretic switching, we were able to spatially modulate terahertz radiation at arbitrary pixel modulation patterns.
我们报告了一种基于768个可驱动微镜阵列的光谱宽带太赫兹空间光调制器（THz-SLM）的设计、制造及实验研究，每个微镜的长度为220μm，宽度为100μm。为了减少太赫兹频率下单个微镜的衍射并提高THz-SLM的像素间调制对比度，需要几百微米的微镜长度。通过空间选择性驱动，我们将微镜阵列用作可重构光栅，在0.97THz至2.28THz的频率范围内对太赫兹波进行空间调制。在整个频带内，调制对比度高于50%，在1.38THz时峰值调制对比度为87%。对于空间光调制，通过将作为一个像素集体切换的微镜进行分组，几乎可以实现任意的空间像素尺寸。对于可驱动微镜的制造，我们利用了铬 - 铜 - 铬多层膜中的固有残余应力，该应力使微镜以35°的倾斜角直立。通过施加37V的偏置电压，微镜被拉到基板上。通过滞后切换，我们能够以任意像素调制模式对太赫兹辐射进行空间调制。
