光纖式粒子電漿共振感測器：感測區波導與其消散光譜之特性研究

Fiber-Optic Particle Plasmon Resonance Sensor:Characteristics of Waveguide Sensing Region and Extinction Spectra

陳建興(Chen Chien-Hsing)

指導教授 ： 魏台輝 ； 吳瑋特

國立中正大學/理學院/物理學系/博士(2013年)

摘要

本研究目的，在於研發感測靈敏度佳，且適合應用於生化檢測技術的光學式折射率感測器，而光纖式粒子電漿共振感測器具有高感測靈敏度且易於結合免標定生物感測技術，使其提高感測靈敏度的關鍵技術有兩點分別是，提升光纖感測區多次全內反射產生漸逝波的比例及分析光纖感測區修飾的貴金屬奈米粒子所誘發的粒子電漿共振特性。本研究以飛秒雷射於通訊用62.5 μm多模光纖及CO2雷射於400 μm多模光纖，分別製作出視窗式D形光纖及環切式光纖感測器，並採用光學檢測法及機械強度檢測法分析感測區的波導品質，建構一套有系統的方法，研發高折射率靈敏度之光纖式感測器。再將此光纖式感測器修飾球狀金奈米粒子，開發成光纖式粒子電漿共振折射率感測器，並以光纖式光譜儀進行消散光譜的量測分析研究。
結果顯示，以飛秒雷射加工製作視窗式D形光纖感測器，其感測靈敏度及折射率感測解析度可達9.62/RIU及5.13×10-5 RIU。而CO2雷射加工製作環切式光纖感測器，以三種光學檢測法(尺寸量測法、光傳遞缺陷檢測法、數值孔徑量測法)及機械強度檢測法(韋伯拉伸試驗法)，分析感測區的波導品質，篩選出垂直光軸加工掃描路徑、雷射加工功率為4 W、雷射加工掃描速率為9.45 cm/s，為最佳之雷射加工參數。以此最佳參數加工製作的環切式光纖感測器。在折射率感測實驗方面，感測靈敏度及折射率感測解析度可達-1.25/RIU及6.17×10-5 RIU。最後將環切式光纖，進行光纖表面球狀金奈米粒子修飾，開發成光纖式粒子電漿共振感測器後，利用光纖式光譜儀，進行光纖式粒子電漿共振感測器的消散光譜量測及共振波長、吸收度及半高全寬參數分析，結果顯示在球狀金奈米粒子溶液濃度為在abs.= 1.0 - 1.5、表面覆蓋率為15.2% - 17.2%間，都有不錯的折射率感測靈敏度。說明以光纖式光譜儀，進行光纖式粒子電漿共振感測器消散光譜量測分析(共振波長、吸收度(消散度)及半高全寬)，確實有機會開發出高感測靈敏度及折射率感測解析度的光纖式粒子電漿共振感測器。

關鍵字

折射率 ； 粒子電漿共振 ； 波導 ； 光纖 ； 感測器 ； 消散光譜

並列摘要

In this study, we aim to develop highly sensitive optical refractive index sensors used in the biochemical sensing techniques. A novel fiber-optic particle plasmon resonance (FO-PPR) sensor is found to have a high sensitivity and allow label-free detection of biomolecules. The sensor sensitivity of FO-PPR can be enhanced by optical fiber sensing which is based on the evanescent wave via multiple total internal reflections and the extraordinary optical properties (known as particle plasmon resonance) of noble metal nanoparticles. In this research, we fabricated the trench type D-shaped fiber and cladding-off cylindrical fiber by femtosecond(fs) laser and CO2 laser micromachining system, respectively. In order to develop highly sensitive optical refractive index sensors, the waveguide sensing region of the fiber fabricated with laser machining must be analyzed. The quality analysis includes optical detection techniques and the mechanical strength detection techniques (tensile test). After quality analysis, we modified the gold nanoparticles on optical fiber sensors for detection of refractive index by the FO-PPR sensors. Furthermore, a fiber-optic spectrometer is used to measure the extinction spectra of FO-PPR sensors. Accordingly, we propose a methodology for parameter analysis of extinction spectra.
This study first demonstrates the feasibility of fabricating a highly sensitive trench type D-shaped fiber sensor by the fs laser. The refractive index measurement results of sucrose solution of different concentrations show the sensor sensitivity can reach 9.62/RIU and the sensor resolution can reach 5.13×10-5 RIU for refractive indices in the range of 1.333 to 1.403.
Afterwards, this study demonstrates the feasibility of fabricating a highly sensitive cladding-off cylindrical fiber by the CO2 laser and establishes a quality analysis method for laser processed fiber-optic sensors. After quality analysis, a perpendicular scanning path, a laser power of 4 W and a scanning speed of 9.45 cm/s was selected as the optimum processing parameter in this study. The refractive index measurements of sucrose solution at different concentrations show a sensitivity of 1.25/RIU and a resolution of 6.17×10-5 RIU pertaining to the sensor for refractive indices in the range of 1.333 to 1.383. Finally, we modified the gold nanoparticles on the cladding-off cylindrical fiber for detection of refractive index by the FO-PPR sensors. The fiber-optic spectrometer is used to measure the extinction spectra of FO-PPR sensors and analyze the parameters (resonance wavelength, absorbance(extinction) and absorption spectrum of full width at half maximum) involved in extinction spectra. The experimental demonstrates the high sensor sensitivity for the surface coverage in the range of 15.2% to 17.2% of FO-PPR sensors. Such a highly sensitive FO-PPR refractive index sensor can be developed to analyze of the relation between the refractive index sensor resolution and extinction spectra in order to optimize the sensor capability.

並列關鍵字

refractive index ； particle plasmon resonance ； waveguide ； Optical fiber ； sensor ； extinction spectra

參考文獻

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