具偏極化之波導/電漿子窄頻紅外線熱發射器與吸收窄頻紅外線偵測器

Abstract

本文為研究具有偏極化特性之窄頻紅外線發射器及可室溫操作之窄頻紅外線偵測器。首先我們在一個波導型窄頻紅外線發射器上方製作一金屬銀光柵，利用金屬銀光柵對於不同偏極化光具有不同穿透與反射的特性，實現一具有高偏極化特性之窄頻紅外線發射器。我們也發展出一個可同時發射雙波長窄頻紅外線之波導型熱輻射發射器，且這兩個不同波長的紅外線之偏極化方向相互垂直。此元件所發射的波長可藉由位在金屬光柵上下之二氧化矽層厚度所調變。我們也研究在一金屬光柵埋藏於一個金/二氧化矽/金三層結構中之侷域型表面電漿子共振模態。這個侷域型共振模態的共振波長亦可由位在金屬光柵上下之二氧化矽層厚度所調變。我們在一個金/二氧化矽/金/二氧化矽/金之堆疊結構中，在同樣金屬光柵寬度的條件下利用不同二氧化矽層的厚度創造出兩個不同波長的侷域型表面電漿子共振模態，發展出具有雙波段窄頻紅外線發射之侷域型表面電漿子熱輻射發射器。我們也實現了一個可攜式的窄頻紅外線發射器。我們將窄頻紅外線發射晶片安裝於一個外殼大小約為2.5x5x12立方公分的可攜式加熱裝置中，並使用一個鋰電池當作是加熱的電流源。操作時可利用電池所提供的電流流經環繞於窄頻紅外線發射晶片之電阻絲加熱晶片。 我們研究了一個具有窄頻紅外線吸收之電漿子窄頻紅外線偵測器。此偵測器的結構為一非晶矽薄膜覆蓋於一金/氧化鋁/金之三層結構，其中最上層金為具有指叉狀電極及金圓盤之圖形化結構。在此偵測器中，我們利用存在於金圓盤/氧化鋁/金結構中之侷域型表面電漿子的共振來達到窄頻紅外線的吸收，被吸收的能量會加熱覆蓋於元件上方的非晶矽薄膜進而降低其薄膜電阻值，藉由量測電阻值的改變我們即可偵測到元件所吸收的紅外線能量。

The polarized infrared thermal emitter with narrow bandwidth infrared emission and the uncooled narrow bandwidth infrared photodetector were studied. At first, a polarized infrared thermal emitter consisting of a waveguide thermal emitter and top silver grating structure were studied. The polarized ratio with different grating thickness was investigated and the high polarization ratio was achieved. A waveguide thermal emitter that can generate two infrared emission modes with different wavelengths and orthogonal polarization was developed. A localized surface plasmon resonance in a tri-layer Au/SiO2/Au stacked structure with Au-grating embedded in the SiO2 layer was also investigated. The resonant wavelength can be adjusted by controlling the grating width and dielectric layer thicknesses on both sides of the metallic grating. A double wavelength infrared emission by plasmonic thermal emitter using stacked Au/SiO2/Au/SiO2/Au structure was investigated. The effective refractive index of sandwiched SiO2 is higher than normal value due to the coupling of surface plasmons at the top and bottom Au/SiO2 interfaces. Two different localized surface plasmon modes were excited with the same metal width, but different SiO2 layer thicknesses in top and bottom Au/SiO2/Au tri-layer structures. A portable narrow bandwidth infrared emission instrument was realized. The narrow bandwidth infrared emission chip was fixed on the portable heating instrument which is installed in a plastic case with a size around 2.5x5x12 cm3. A lithium battery was used as the current source. The narrow bandwidth infrared emission chip can be heated by sending the current through the resistive wire surrounding the chip. A plasmonic infrared photodetector with narrow bandwidth infrared absorption was investigated. The structure is constructed by a hydrogenated amorphous silicon (a-Si:H) film covered on a patterned Au layer consisting of the Au disk resonators and Au interdigitated electrodes on an Al2O3/Au substrate. This device exhibited narrow bandwidth infrared absorption corresponded to the localized surface plasmon resonance in the Au-disk/Al2O3/Au tri-layer resonators. The absorption of infrared energy heats up the top a-Si:H film and reduces the film resistance which can be detected.