Qian Qinyu, Ti Sun, Wang Chinhua
Opt Lett. 2019 Aug 15;44(16):3984-3987. doi: 10.1364/OL.44.003984.
An all-dielectric double-layer grid grating is proposed and demonstrated theoretically and experimentally to realize the angular filtering effect. The theoretical results show that the transmission of the double-layer grid grating drops sensitively, as the incident angle increases under TM incidence at the designed resonant wavelength. The transmission is almost 0 (i.e., the entire incident light is reflected) when the incident angle increases to over 12°, which exhibits excellent angular filtering behavior. Double-beam interference lithography and sputter coated depositions are utilized to fabricate the proposed angular filter. The experimental results show that the divergent angle of the transmitted beam through the angular filtering sample at the wavelength of 633 nm is 7.76°, and the transmission is as high as 0.936 at normal incidence. The ultra-thin all-dielectric angular filter is very easy to fabricate in a large area, which has important applications in directional lighting and image processing.
提出了一种全介质双层栅格光栅，并通过理论和实验证明其可实现角度滤波效果。理论结果表明，在设计的共振波长下，当TM入射时，随着入射角增加，双层栅格光栅的透射率会敏感下降。当入射角增加到超过12°时，透射率几乎为0（即所有入射光都被反射），这表现出优异的角度滤波特性。利用双光束干涉光刻和溅射镀膜工艺制作了所提出的角度滤波器。实验结果表明，在波长633 nm时，通过角度滤波样品的透射光束发散角为7.76°，在正入射时透射率高达0.936。这种超薄全介质角度滤波器非常易于大面积制作，在定向照明和图像处理方面具有重要应用。
