低邊帶之波導模態共振濾光片的設計與模擬

Abstract

本篇論文以增透膜的特性為基礎，分析具有寬頻寬的多層增透膜之設計方法，再將該結構與波導模態共振濾波器進行結合，設計出能夠在特定波長具有高反射率，且在該波長區段以外的波長之反射率接近為零的濾波器。 在設計增透膜結構的時候，為了使結構能有寬頻寬的低反射率，在結構之中加入了虛設層，以增加增透膜結構低反射波段，並且計算增透膜結構之等效折射率，設定光柵週期。為了防止結構在可見光波段(400nm至700nm)產生複數模態，調整多層膜結構的中心波長與厚度，使結構在可見光波段僅有單模態。為了增加反射頻譜的半高全寬，分析最適合應用於濾光片的多層增透膜結構，使用了上下交錯型的雙層光柵。 在完成增透膜與光柵結構的設計之後，分析入射角與光柵厚度、占空率、位移距離對於反射率造成的影響與原因，並且針對三色光的濾波器進行光柵的調整。最後我們會計算濾波器可達到的色彩飽和度，與現今顯示器所要求的色彩飽和度進行比較。

In this thesis, we are going to design the multilayer anti-reflective coatings with broad bandwidth, combine the multilayer anti-reflective coatings with guided-mode resonant filter, and design the filter which is highly reflective at the center wavelength, but nearly zero reflective at the sideband. In order to keep low reflectance in broad bandwidth, we add absentee layer into the anti-reflective coatings, then calculate the effective refractive index of the structure and set the period of the gratings. To prevent multiple modes from appearing at visible light (400nm to 700nm,) we adjust the thickness of the structure, so there is only one mode at visible light (400nm to 700nm.) For the purpose of increasing the FWHM (Full width at half maximum) of reflectance, we analyze the structure which is the most suitable of the color filters, and decide to use two layers of gratings, which is staggered to each other. After deciding the structure and parameters of the color filters, we are going to analyze how incident angle, the grating thickness, duty cycle and displacement of the grating affect the reflectance of the color filter, and design three different structures corresponded to primary colors of light. At the end, we will calculate the color saturation of the color filters, and compare them to the standard of saturation of the monitors.