Nano-convergence Mechanical Systems Research Division, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Daejeon, 305-343, Republic of Korea.
Microelectronics Research Center, Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, 78712-1024, USA.
Sci Rep. 2017 Mar 27;7(1):430. doi: 10.1038/s41598-017-00586-x.
We demonstrate an infrared broadband metasurface absorber that is suitable for increasing the response speed of a microbolometer by reducing its thermal mass. A large fraction of holes are made in a periodic pattern on a thin lossy metal layer characterised with a non-dispersive effective surface impedance. This can be used as a non-resonant metasurface that can be integrated with a Salisbury screen absorber to construct an absorbing membrane for a microbolometer that can significantly reduce the thermal mass while maintaining high infrared broadband absorption in the long wavelength infrared (LWIR) band. The non-dispersive effective surface impedance can be matched to the free space by optimising the surface resistance of the thin lossy metal layer depending on the size of the patterned holes by using a dc approximation method. In experiments a high broadband absorption was maintained even when the fill factor of the absorbing area was reduced to 28% (hole area: 72%), and it was theoretically maintained even when the fill factor of the absorbing area was reduced to 19% (hole area: 81%). Therefore, a metasurface with a non-dispersive effective surface impedance is a promising solution for reducing the thermal mass of infrared microbolometer pixels.
我们展示了一种适用于通过降低热质量来提高微测辐射热计响应速度的红外宽带超表面吸收体。在具有非色散有效表面阻抗的薄耗金属层上的周期性图案中制造大量孔。这可用作非共振超表面，可与 Salisbury 屏吸收体集成以构造微测辐射热计的吸收膜，从而在长波红外 (LWIR) 波段显著降低热质量同时保持高红外宽带吸收。非色散有效表面阻抗可以通过优化薄耗金属层的表面电阻来匹配自由空间，具体取决于使用直流近似方法的图案化孔的尺寸。在实验中，即使在吸收面积的填充因子降低到 28%（孔面积：72%）时，仍保持高宽带吸收，并且即使在吸收面积的填充因子降低到 19%（孔面积：81%）时，仍在理论上保持高宽带吸收。因此，具有非色散有效表面阻抗的超表面是降低红外微测辐射热计像素热质量的有前途的解决方案。
