金屬光柵之偏光性質與光學模擬

Polarization property and optical simulation of metal grating

余星睿(Hsing-Jui Yu)

指導教授 ： 林清彬

淡江大學/工學院/機械與機電工程學系碩士班/碩士(2015年)

https://doi.org/10.6846/TKU.2015.00093

摘要

本文使用Comsol的光學軟體對次波長矩形金屬光柵與梯形金屬光柵進行光學模擬，模擬參數包含不同金屬材料(Cu、Ag、Ti、Al)、光柵週期(120、150、200、250nm)、金屬厚度(50、120、200、250nm)、碳層厚度(100、120nm)、入射角(0、15、30、45°)與氧化鋁厚度(0、15、20、25nm)，藉由電場與功流率的分佈圖進行偏光性質之探討。由光學模擬結果可知，鋁在可見光波長中阻擋TE偏振光的穿透率效果最好。當增加金屬厚度時會使TM偏振光穿透率呈現紅移的趨勢。另外，在可見光波長下，矩形金屬光柵之TE偏振光穿透率是高於梯形金屬光柵約30%，然而TM偏振光穿透率則低於約20%。隨著入射角的增加至45° 時，矩形金屬光柵之消光比下降了80 %。TE與TM偏振光穿透率分別隨氧化鋁厚度增加而上升及下降。

關鍵字

次波長金屬光柵 ； 光學模擬 ； 偏振光

並列摘要

The main purpose of this paper is to simulate the sub-wavelength rectangle metal grating and trapezoid metal grating by optical software of Comsol. The simulation parameters comprise different metal materials (Cu, Ag, Ti and Al), grating period (120, 150, 200 and 250nm), metal thickness (50, 120, 200 and 250 nm), carbon thickness (100 and 120 nm), aluminum oxide thickness (0, 15, 20 and 25 nm), and incident angles (0, 15, 30 and 45 degrees). However, we can study the polarization properties of them by electric field and power flow distribution. According to the optical simulate result, aluminum which in the visible wavelengths could block the best effect of TE-polarized light transmittance. If increase the thickness of the metal, TM-polarized light transmittance will appear tends of red-shifted. To compare with rectangle metal grating and trapezoid metal grating, the TE polarized visible light transmittance of rectangle metal grating is higher than trapezoid metal grating about 30% and TM polarized visible light transmittance of rectangle metal grating is lower than trapezoid metal grating about 20%, respectively. By the incident angle increase to the 45 degree, the extinction ratio of the rectangle metal grating has been reduced by 80%. When increase the aluminum oxide thickness, the TE-polarized light transmittance will increase, but TM-polarized light transmittance will decrease.

並列關鍵字

Sub-wavelength metallic grating ； optical simulation ； polarized light

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