Lee Jae-Hwang, Leung Wai, Kim Tae Guen, Constant Kristen, Ho Kai-Ming
Ames Laboratory U.S .DOE, Iowa State University, Ames, IA, 50011, USA.
Opt Express. 2008 Jun 9;16(12):8742-7. doi: 10.1364/oe.16.008742.
Metallic thermal emitters consisting of two layers of differently structured nickel gratings on a homogeneous nickel layer are fabricated by soft lithography and studied for polarized thermal radiation. A thermal emitter in combination with a sub-wavelength grating shows a high extinction ratio, with a maximum value close to 5, in a wide mid-infrared range from 3.2 to 7.8 mum, as well as high emissivity up to 0.65 at a wavelength of 3.7 microm. All measurements show good agreement with theoretical predictions. Numerical simulations reveal that a high electric field exists within the localized air space surrounded by the gratings and the intensified electric-field is only observed for the polarizations perpendicular to the top sub-wavelength grating. This result suggests how the emissivity of a metal can be selectively enhanced at a certain range of wavelengths for a given polarization.
通过软光刻技术制备了由均匀镍层上两层结构不同的镍光栅组成的金属热发射器，并对其偏振热辐射进行了研究。与亚波长光栅相结合的热发射器在3.2至7.8微米的宽中红外范围内显示出高消光比，最大值接近5，并且在波长为3.7微米时发射率高达0.65。所有测量结果与理论预测吻合良好。数值模拟表明，在由光栅包围的局部空气空间内存在高电场，并且仅在垂直于顶部亚波长光栅的偏振方向上观察到增强的电场。这一结果表明了对于给定偏振，如何在特定波长范围内选择性地提高金属的发射率。
