我們設計雙錐形結構於單模光纖(Single-mode)，並探討其雙錐形光纖潛在應用，例如感測器。利用單模光纖製作雙錐形設計，將光纖移除光纖外衣(Jacket)及緩衝區(Buffer)，使其光纖裸露出包層(Cladding)及核心(Core)，使用火炬加熱及電控平移台進行光纖拉伸成為錐形光纖。雙錐形光纖區域之參數可由光學顯微鏡觀察得知，錐形光纖長度及錐形光纖腰部直徑分別為10 毫米及30微米到80微米，重複上述兩次拉伸步驟可得雙錐形光纖感測器。奈米金屬薄膜附著於雙錐形光纖區域部分，我們採用物理氣相沉積，將金、銀碇片放置真空腔體並加熱至高溫蒸鍍，使金屬薄膜覆蓋於雙錐形光纖表面，其薄膜厚度約為80奈米，經由兩次的物理氣相沉積處理使光纖表面覆蓋一層金屬薄膜。
光學系統上，我們使用白光雷射當光源，白光光源波段落於可見光及近紅外光，波長範圍為450奈米到2400奈米，主要優點為快速辨識錐形光纖於某個波長下之響應及特徵。我們也藉由單頻可調雷射當其光源，可調之中心波長範圍為840奈米到868奈米，其外腔雷射之可調波長精細度為0.1奈米，精確檢測其光源經雙錐形光纖之細節變化。

根據理論預測，我們預期光源經過雙錐形光纖時，能增加特定波長之干涉現象，並由奈米金屬薄膜覆蓋於雙錐形區域，利用表面電漿共振特性影響特定波長之強度使干涉現象明顯。在未鍍金屬部分其明顯干涉現象在於可見光區域，其波長範圍為550奈米到750奈米；鍍金屬後之干涉現象落於750奈米到920奈米。最後，我們成功利用雙錐形光纖在折射率液體上進行感測，其感測趨勢為線性變化。

We reported the design of dual-tapered shape in single-mode fiber and explore the potential applications on sesnors, and band-pass filters. After fiber is removed the jacket and buffer, the core and cladding of fiber is heated and extruded. The fiber shape is changed to a taper tye. The related parameters are obtained such as length and waist diameter of dual-tapered fiber is about 10 mm and 30 μm to 80 μm, respectively. The surface of tapered region is coated with metallic film by physical vapor deposition (PVD). The thickness of metallic film is about 80 nm. We can get our dual-tapered fibers with the different metallic films from above process.

About the optical system, we use a white light laser as a light source that the wavelength range is from visible to near-infrared bewteen 450 nm to 2400 nm. The advantage is rapid identification that the phenomenon is generated for specific wavelengths. We also employ the single-frequency tunable laser as another light source that central wavelength can be tuned between 840 nm to 868 nm. The wavelength resolution of infrared laser is below 0.1 nm.

According to theoretical predictions, we expect the interference is generated when the light passes through the dual-tapered fiber. The result of interference is obviously in visible light without metallic film. After the surface with metallic film, the interference is obviously in near-infrared. The SPR affects the intensity for specific wavelengths on tapered region. Finally, we are successful to identify the different refractive index by our design.

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