可調式窄頻液晶濾波器

Tunable Narrow-bandwidth Liquid Crystal Spectral Filter

吳佳龍(Jia-long Wu)

指導教授 ： 戴朝義 ； 徐桂珠

國立中央大學/理學院/光電科學研究所/碩士(2012年)

摘要

本論文主要目的在開發窄頻(<5nm)且於可見光範圍內(400~800nm)大範圍可調之光濾波器。Fabry-Perot濾波器主要優點在於當膜層反射率夠高時，能獲得較佳的半高寬(FWHM)；串接液晶波板組成的Lyot濾波器主要優點在於第一級穿透波長具有大的FSR。本文結合兩種濾波器之優點，以Fabry-Perot濾波器串接Lyot濾波器來達到大範圍可調窄頻光濾波器之目的。
　　藉由薄膜光學理論與瓊斯矩陣(Jones matrix)運算分別模擬計算Fabry-Perot濾波器與Lyot濾波器的FWHM與FSR。Fabry-Perot濾波器要求FSR要大但需保持在可調範圍內，模擬結果為可行空間層厚度為2μm。Lyot濾波器作用為圈選出Fabry-Perot濾波器中的主穿透波長，須確保半高寬夠小，可行參數為4組液晶波板所組成Lyot濾波器，其液晶層厚度分別為5、10、20、40μm。將兩種濾波器模擬結果結合，可得到符合設計目的之濾波器。
　　我們實際製作了鍍製鋁膜的Fabry-Perot濾波器，並驗證了光程和反射率對於濾波器的影響。另實際製作了Lyot濾波器，其實際量測結果與模擬結果相符合。

關鍵字

可調 ； 窄頻 ； 液晶 ； 濾波器

並列摘要

In this thesis, we propose a filter that has narrow FWHM(<5nm) and large tunable range(400nm ~ 500nm). Because Fabry-Perot filter can achieve narrow resolution and Lyot filter has large FSR, we combine Fabry-Perot filter and Lyot filter to be a new filter that has narrow FWHM and large FSR.

We use thin film theory and Jones matirx to calculate the spectral response. In simulation, we design 2μm cell gap for Fabry-Perot filter and 5μm, 10μm, 20μm, 40μm cell gap for 4-stage-Lyot filter. By using these parameters, we can get a filter which reaches the target.

Finally, we manufacture Fabry-Perot filter that uses Al film and verify the theory. We also make 4-stage-Lyot filter that show an identical result with the simulation.

並列關鍵字

tunable ； narrow-bandwidth ； liquid crystal ； spectral filter

參考文獻

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