在論文中，我們利用單模光纖SMF-28去掉纖衣再利用皮秒雷射加工製作以
雷射光中心波長1064nm為準特定週期LPBG模態轉換元件。由於雷射模態在量測
端出口端是個別模態電場間的干涉，為了求得轉換效率，我們也特別設計模態逆
運算系統，利用MATLAB最佳化指令幫我們找出個別模態比例組成，對於模擬與
實驗數據上的逆運算，我們也做了不同的角度與多重指令細部設定分析，讓量測
端實驗數據逆運算上更趨準確。

In this thesis, we use picosecond laser to fabricate long period Bragg grating on cladding stripped single mode SMF-28 fiber as mode converter for 1064nm. Because of modal interference in the measurement setup, we design the modal simulation using the “fminsearch” command in MATLAB to find modal composition in order to obtain conversion efficiency. In order to achieve better fitting between experiment and simulation, we rotate experimental data and optimize the parameters in “fminsearch” in our analysis. We are able to obtain the precise modal composition.

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