| Summary: | 碩士 === 國立臺灣大學 === 光電工程學研究所 === 94 === The proposed corrugated fiber gratings by our group do not need fiber photosensitivity to make long period fiber gratings. Besides, the corrugated structure offers flexibility on adjusting coupling strength and resonant conditions. However, making the corrugated structure on a fiber by thermal coating method is not convenient and time consuming. Multiple metal layers need be coated on a fiber for protecting the etching of hydrofluoric acid. Hence, a new method based on photo-lithography is proposed for fabricating corrugated structures on a fiber. The proposed
method can increase the production yield and save time. Since SU8 epoxy resin is a negative photoresist used in the process, it can generate a large aspect ratio and is inert to chemical properties. Hence, SU8 can be used to cover and protect a fiber during the etching process.
In addition to confirming its being intact of wavelength and loss tunability when mechanical forces such as stress and torsion are applied, the corrugated fiber gratings thus fabricated are also tested in a different environment. Because only first few cladding modes and the core mode are involved for the optical characteristics of the corrugated fiber grating, the refractive index of the surrounding material is found to affect little on its resonant conditions. This may help the selection of an appropriate material to package such fiber gratings.
The proposed photo-lithographical method may improve the generalization of the corrugated fiber gratings, which may find useful applications in optical fiber communication and fiber sensing.
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