SENSITIVITY ENHANCEMENT OF SURFACE PLASMON RESONANCE FIBER SENSORS BASED ON A DOUBLE-LAYER OF POLYVINYL ALCOHOL/Au STRUCTURE

• Main Authors: Chieh-wen Teng, 鄧傑文
• Other Authors: Wu-hu Tsai
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/79328116091268504739

碩士 === 大同大學 === 光電工程研究所 === 102 === The multi-mode fiber which has core diameter of 62.5μm has been applied in my experiments. We polished one side of the fiber down to core center and deposited a 50 nm thickness of Au thin film on the fiber side-polished surface. After we had deposited the Au film, we also coated different thickness of polyvinyl alcohol thin films on Au surface, then we baked the fiber in the oven at temperature of 85℃ for 90 minutes. We finally applied the SPR sensors we proposed, to measure the concentration of methyl yellow solutions and analyze the SPR resonance absorption responses in the optical spectrum observed by the optical spectrum analyzer. The experimental results show that the SPR fiber sensor with the film thickness of 171.1 nm fabricated by 5.39 wt% polyvinyl alcohol solution exhibits the best performance in the SPR measurements. The sensitivity was improved from 14.625 nm/wt% to 48.750 nm/wt% in the low concentration SPR measurements of methyl yellow solutions. The sensitivity of organic-thin-film/Au double-layer structure of the SPR fiber sensor we proposed is better than the traditional Au SPR sensor with easy fabrication and lower cost facilities compared to other double-layer structures with oxide/Au structure by sputtering method.