整合微液珠光學共振腔及液態波導應用於微流體染料雷射

Integration of Micro-Droplet Resonators and Liquid Waveguides Applied for Microfluidic Dye Lasers

沈達緯(Da-Wei Shen)

指導教授 ： 李明昌

國立清華大學/電機資訊學院/光電工程研究所/碩士(2012年)

摘要

近年來微流體(microfluidic)技術因為具有容易製作、低成本以及整合性高等特點，被廣泛的整合並運用於實驗室晶片(Lab-on-chip)系統上，為了將微流體與光學系統進一步的整合加以應用，我們提出一個微液珠液態雷射的構想，利用微流體技術產生摻有染料的液態球形光學共振腔，結合部分結構化的微流道做為光波導包覆層，形成動態可調光學共振腔與液態波導的組合，其中液態波導是用來將液珠所產生的光學共振模態WGM (Whispering Gallery Mode)向外耦合，以萃取特定波段的受激發雷射光。實驗中的液珠材料為苯甲醇其折射率為1.54並將其摻入增益介質(gain medium)R6G(Rhodamine 6G)，摻入濃度控在3mM，而液態波導核心材料則選用折射率較低的礦物油其折射率為1.48，當材料選定後，先利用有限元素法模擬設計幾組不同的液珠大小以及單模液態波導結構尺寸，再分別加以實驗測試。本實驗我們設計了三種不同結構，分別量測比較，發現具有光波導結構的設計能有較佳的雷射出光效能，間接證明了液態波導的作用性，是可以利用液態波導將液珠雷射耦合出來，以及量測到的液珠雷射其閾值(lasing threshold)約為0.32mJ。

關鍵字

微流體 ； 液珠雷射 ； 流體聚焦結構 ； 單模脊狀波導 ； 液態波導

並列摘要

Microfluidic technology has been widely applied in lab-on-chip because of easy fabrication, low cost and easy manipulation of fluid in microscopic scale. To integrate microfluidics with photonics, we propose and demonstrate microfluidic dye lasers by combining flow-focusing microfluidic channels to generate micro-droplets (laser cavity) with liquid waveguides to couple the light out from the droplet laser. The droplet material is 3mM R6G dye in benzyl alcohol (n=1.54), and the single-mode liquid waveguide is made by mineral oil (n=1.48). We used the finite element method (FEM) to simulate the characteristics of the droplet cavity with different radii and the mode profile of the single-mode liquid waveguide, and used the simulation result to implement the experiment. We designed three different structures to compare the photoluminescence, and verified the lasing modes coupled from the microdroplets to the liquid waveguide. The threshold pump energy for micro-droplet lasing was about 0.32 mJ.

並列關鍵字

microfluidic ； dye laser ； flow-focusing ； single mode rib waveguide ； liquid waveguide

參考文獻

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