傳統上利用雙折射晶體(birefringent crystal)製作的偏振元件，可以用次波長金屬光柵來達到同樣的功能，這種具有雙折射特性的光柵稱之為人造雙折射光柵(form-birefringent gratings)。一般而言次波長金屬光柵僅能應用於微波與遠紅外光波段，然而隨著微影技術的進步，我們可以利用電子束微影技術，製作出可應用於可見光與近紅外光波段的次波長金屬光柵。 本文對電子束微影系統有簡單的介紹，並且利用電子束微影技術製作出次微米結構，光阻的最小線寬可以達到0.1μm。並且製作出可見光範圍的次波長金屬光柵。在特性上，次波長金屬光柵的確產生了零階光柵的效應，對於TE與TM不同偏振方向的入射光有敏感的選擇性。然而，最後量測的結果並不能得到預期之相位延遲的效應。光柵金屬的厚度也是影響反射效率的重要一環，當金屬薄膜厚度低於肌膚深度時，會造成反射效率的下降。 One method for influencing the polarization of light is the use of wire-grid polarizers. For the visible region, this type of element can be realized as a metal-stripe grating with periods less than the wavelength. We fabricate metal-stripe gratings with periods down to 0.3um in thin gold layers of 98nm thickness using electron-beam lithography technology. A detailed investigation of the influence of grating period and duty cycle on the polarization effect is carried out to verify the conformity of rigorous diffraction theory and experimental results. The comparison between the two indicates good performance. Polarization ratios of the order of 2.3 with reflection efficiencies of about 60% in TM polarization are obtained. .
