本文提出以三維入口流道及具平緩變化的圓弧形側壁的主流道構成的微光流體分光器，它利用漸進式折射率梯度，使經過主流道的光束，會往主流道兩側分光，並向中央平面 匯聚以增加傳輸效率。本研究將氯化鈣水溶液(A，核心流體)及去離子水(B，包覆流體)由左右對稱的六個入口注入分光器，其中上下四個入口為去離子水入口，包覆中間深度較淺的氯化鈣水溶液入口，所以會在入口匯流處截面呈現一顆圓形的核心流體被包覆流體包覆的分布，左右兩側流體匯流於主流道後，入射光會隨著此折射率分布向兩側分光，如此一來可以藉由調整上下去離子水入口的流體流率，改變核心流體被包覆的位置，進而改變分光器的分光角度。本研究利用數值模擬軟體ANSYS Fluent模擬分光器的速度及濃度場，再寫作C++程式進行光線追跡，模擬光線在不同幾何參數及流率參數的情況下，因折射率分布差異影響之軌跡。接著，以田口法調整參數：主流道圓弧的曲率半徑、後段主流道長度、混合流體總流率及A、B流體匯流處與主流道圓弧形流道壁端點距離，進行最佳化。同時，使用微影製程製作微分光器，基於最佳參數組合進行實驗，用配有顯微轉接鏡及可變焦顯微觀察系統的數位單眼相機，從流道上方觀察及拍攝流道中的濃度交界位置及光線分光情形，並在主流道後 處放置光纖量測光束分光後在光纖處聚焦的能量大小，且因實驗所得的結果與數值模擬的結果相符，故可知本文使用的電腦數值模擬相當可靠。由模擬結果可知：三維流道由於其折射率分布亦呈現三維分布，傳輸效率比二維流道大。上下B流體入口流率的比例可以用來調整光線經過微分光器的分光角度。A流體與B流體入口流率的比例可以用來改變光線開始匯聚的位置。

In this work, we proposed a micro optofluidic beam splitter with three-dimensional (3D) inlets and gently varying curved side walls of main channel. Calcium chloride solution (A fluid) and deionized water (B fluid) are applied as the core and cladding fluids, respectively. Two deionized water inlets lie on both sides of the calcium chloride solution inlet. The latter is shallower than the former in depth. By the diffusion between the A fluid and B fluid, the gradient refractive index (GRIN) is formed. The beam passing through the main channel will be split into two beams on both sides of the main channel and converged toward the central horizontal plane by the GRIN. Furthermore, we can adjust the inlet flow rate to change the GRIN, and so change the split angle. ANSYS Fluent and self-developed codes are used to simulate the flow field and the light trajectory under different geometry and flow rate parameters. Taguchi method is used to optimize the parameters to enhance the performance. The validity of simulations is confirmed by the experiment. And we can find the following trends from the results. (i) The 3D structure of the splitter improves the transmission. (ii) The ratio of the flow rates at the two B inlets can be used to adjust the split angle. (iii) The ratio of the A fluid flow rate and the total flow rate can be used to change the location where the light begins to converge.

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