| Summary: | 碩士 === 國立臺灣大學 === 光電工程學研究所 === 104 === To date, fabricating metallic submicron structures on an optical fiber facet and applying to the surface plasmon resonance (SPR) sensing have drawn a lot of attentions, and have led to many applications. Therefore, the need of SPR fiber probes increases steadily. The method for mass production of the SPR fiber probes is the main focus of this work.
In this work, we first introduced the processes for the fabrication of the SPR fiber probes. The mass production of the probes was realized by fiber bundles. However, even if the bundle was polished, it could not generate a suitable plane for the spin-coating process of the resists. The nanotransfer printing (nTP) technique was adopted to overcome this problem. The technique relied on the different surface energies between the materials to transfer the metallic structures. PDMS was chosen as the material for the stamps used in nTP process. In the process of the fabrication of the stamps patterned with periodic structures, the patterns were designed by our unique two-beam interference lithography (IL) system. Nevertheless, it was found that the patterns on the stamps buckled up during the replication of the patterns to the stamps. The problem resulted from the uncured low molecular weight (LMW) chains, which could be removed by some organic solutions or a longer curing time. After a metallic layer was deposited on the treated stamps, we first applied the nTP process on the glass substrates and optimized the parameters. Then the optimized parameters were applied on the fiber bundles.
To study the optical characteristics of the SPR fiber probes, two commercial software, FDTD Solutions and Comsol, were used in this study. The simulated results revealed the trends of the reflection and transmission spectra and the characteristics of SPR were also confirmed and discussed. In the simulation of different surroundings, the resonant position in the transmission spectrum shifted as the surroundings changed while the resonant position in the reflection spectrum remained still due to the structures’ insensitivity to the surroundings. In experiment, the measured results showed very good consistency with the simulated, which verified the reliability of the models used in the simulation. Based on the spectra obtained from different probes, the potential for mass production of the SPR fiber probes is found by utilizing fiber bundles and nTP technique. The transmission spectra showed good performance in refractive index sensing with a sensitivity of 265.7 nm/RIU for the resonant position. Finally, biosensing of bovine serum albumin (BSA) with the SPR fiber probes was demonstrated.
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