Design and Research of Y-Junction Couplers with Multi-Step Index Fiber and Arc-Branch Structure
| Autor: | Chang, Che-Chia, 張哲嘉 |
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| Rok vydání: | 2019 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 107 The thesis mainly applies a multi-step index (MSI) fiber and arc-branch structure to the design and research of a Y-junction coupler in a distributed illumination system. Generally, an optical fiber illumination system usually needs to combine multiple light-source beams into one beam or divide one beam into multiple beams, and the used beam combining or splitting elements are usually the Y-junction coupler. In previous researches, most of couplers were designed and fabricated with a single material of step-index (SI) fibers; however, the efficiency of the couplers is declined due to the susceptibility of a taper region formed by multi-branch stacks. Therefore, this thesis uses a MSI plastic optical fiber (POF), which is similar to a graded-index (GRIN) fiber having property of self-focus, to design the Y-junction coupler and improve the light loss caused by the taper region so that the coupling efficiency can be increased, the output beam-angle becomes more convergent, and the size of the coupler is greatly reduced. Optical simulation results show that the combining and splitting efficiencies of the MSI-POF Y-junction coupler designed in this thesis can reach 74 and 85%, respectively, and corresponding minimum output half-beam angles can be respectively reduced to 67 and 45% of the original half source-beam angle. As compared with a high efficient SI-POF Y-junction coupler, the MSI-POF Y-junction coupler has good coupling efficiency even at a smaller bending radius, and the associated convergence angle is less than that of the SI-POF coupler even up to 78% that the volume of the coupler can be greatly reduced. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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