A Suspended Metamaterial Mirror for Hyperspectral Shortwave Infrared Fabry-Perot Filters
A Suspended Metamaterial Mirror for Hyperspectral Shortwave Infrared Fabry-Perot Filters
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DOI：
10.1109/jmems.2022.3180701
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发表时间：
2022-08-01
影响因子：
2.7
通讯作者：
Faraone, Lorenzo
中科院分区：
文献类型：
--
作者：
Mao, Haifeng;Dong, Xianshan;Faraone, Lorenzo
报道了一种基于拉伸单层硅超材料膜的宽带高反射、结构平坦的大面积二维亚波长光栅(SWG)反射器的研制。超材料反射器的设计采用了严格的耦合波分析，得到了600 nm(1.9-2.5微米)的波长范围，反射率为99%，这是已报道的最大带宽分数带宽Delta lambda/lambda(C)为27%。研究了设计参数偏差对SWG反射镜反射率的影响，结果表明该反射镜设计具有较好的加工公差。制作了高精度的自立式2 mm尺寸二维SWG反射器，光学测量表明，在1.91-2.49微米的波长范围内，与偏振无关的平均反射率为99%，与模型结果吻合较好。本文还首次研究了悬挂式单层二维SWG反射面的表面平坦度特性。自支撑反射器在硅栅薄膜中的拉应力为10+/-5 Mpa，可获得纳米级的表面平坦度，这与需要应力平衡的多层DBR相比具有显著的优势。在此基础上，首次提出了一种基于顶部悬置二维SWG反射器和底部4对Si/SiO_2分布布拉格反射器(DBR)的高光谱法布里-珀罗短波红外滤光片。该滤光片的峰值透过率为80%，半高宽窄(FWHM)约为4 nm。这种光谱分辨率比其他已报道的基于MEMS/DBR的法布里-珀罗滤光片高一个数量级，非常适合于高要求的高光谱短波红外成像应用。
This paper reports the development of a broadband highly reflective and structurally flat large-area 2-D subwavelength grating (SWG) reflector, based on a tensioned single-layer silicon metamaterial membrane. Rigorous coupled-wave analysis is adopted to design the metamaterial reflector, resulting in a wavelength range of 600 nm (1.9-2.5 mu m) with >99% reflectivity, which represents the largest reported fractional bandwidth Delta lambda/lambda(c) of 27%. Effects of design parameter deviations on the SWG reflector reflectivity are studied, showing that the reflector design has good fabrication tolerances. A freestanding 2-mm dimension 2-D SWG reflector has been fabricated with high precision, and optical measurements indicate polarization-independent average reflectivity of 99% over the wavelength range of 1.91-2.49 mu m, which agrees well with the modeled result. This paper also, for the first time, examines the surface flatness characteristics of a suspended single-layer 2-D SWG reflector. With a tensile stress of 10 +/- 5 MPa in the silicon grating membrane, the freestanding reflector achieves nanometer-scale surface flatness, which provides a significant advantage over multilayer DBRs requiring stress-balancing. Furthermore, a hyperspectral Fabry-Perot shortwave infrared filter based on a top suspended 2-D SWG reflector and a bottom 4-pair Si/SiO2 distributed Bragg reflector (DBR) has been experimentally demonstrated for the first time. The filter is measured to have a peak transmission of 80% with a narrow full-width at half-maximum (FWHM) of about 4 nm. This spectral resolution is one order of magnitude higher than that of other reported MEMS/DBR-based Fabry-Perot filters and is well-suited to highly demanding hyperspectral shortwave infrared imaging applications.