以含不對稱十字架孔洞金屬膜實現兆赫波段相位延遲器

Abstract

本論文實現一種兆赫波段的相位延遲器。此元件由不對稱十字架孔洞以正方形陣列排列成一金屬網狀結構。我們利用微機電製程中的電鑄技術來製作獨立型的金屬網狀結構。我們製作兆赫波段的金屬線柵偏振片，以建立一套紅外偏極光譜系統來量測相位延遲器。我們利用史托克向量與穆勒矩陣描述此系統，以分析光源穿透樣品後的強度與相位差的關係。藉由改變十字架的長軸長度與短軸長度，我們可以控制穿透頻譜的峰值頻率並且調變元件的相位差。量測數據與理論計算可在定性上獲得一致結果。

We implemented a new kind of phase retarders operating at terahertz frequencies. The retarders were made of a free standing metallic film perforated with arrays of cross-shaped holes with asymmetric arms in a square lattice. We fabricated the devices by electroforming processes. We also fabricated a terahertz wire-grid polarizer to setup a spectropolarimeter for characterizing the phase retarders. We used Stokes vectors and Mueller matrix to describe the measurement system and to analyze the relation between the intensity of transmitted light and the phase shift of the retarders. We adjusted the main peak frequency and the phase shift by changing the length of long arms and of short arms of the cross-shaped holes. The experimental data were in qualitative agreement with theoretical results.