以頻域有限差分法分析金屬光柵之穿透特性

Abstract

本文使用修正的頻域有限差分方法分析一維週期性金屬光柵結構，有效處理金屬的色散性質及介面邊界條件，以避免可能的發散問題。我們使用Drude模型模擬金屬材質，並在可見光-紅外光頻段驗證在不同幾何形狀的對稱結構中，共振腔模態及耦合模態造成的效應將影響穿透與反射頻譜。另外我們以色彩濾波器為目標，應用窄頻寬的表面電漿波與金屬狹縫共振腔耦合模態，設計出一個非對稱的一維週期金屬光柵結構，可作為白光LED的電極以及三原色的色彩濾波器。

A modified finite-difference frequency-domain method is used to analyze the one-dimensional periodic metallic gratings. The dispersion of metal and the boundary conditions at material interfaces are properly treated to circumvent the possible difficulty of divergence. In the visible light or infrared regime, the dielectric constant of a metal is described by Drude model. It is demonstrated that the effects of cavity modes and coupled modes can influence the transmittance and reflectance spectra of symmetric metallic grating structures. As a result from our simulation about the interaction of narrow-band coupled modes, an asymmetric metallic grating structure is designed as an electrode and a color filter for the white-light LED.