Using a Tapered Fiber Probe to Excite the Fundamental Mode in a Multimode Fiber

• Main Authors: Yao-Hsuan Wang, 王耀萱
• Other Authors: Fang-Wen Sheu
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/11478246180045958158

碩士 === 國立嘉義大學 === 電子物理學系光電暨固態電子研究所 === 103 === In the experiment, we heated up the red-light single-mode fiber for extending to a slender tapered fiber probe. And then, we connected it with a flat end multimode fiber to receive the light and used a camera to observe the output modal image of such multimode fiber end. We used the red helium-neon laser as the light source. A beam expander lens set was used for adjusting the laser light source into a parallel beam, and then we coupled the laser light into the red-light single-mode tapered fiber probe with a focusing objective, and then connected it to a flat end multimode light receiving fiber. At the end of the light receiving fiber, we used an imaging lens and a camera to observe the output modal image of the light receiving fiber end cross-section. We used the lateral distance and vertical distance movement of the tapered fiber probe to find out the output image closest to the fundamental mode. In addition, we used different types of multimode light receiving fibers and changed the slope of the red-light single-mode tapered fiber probe to observe the changes of the modal images transmitted to the multimode light receiving fiber. In the end, we used computer software to perform the numerical simulation, discussing if the bigger the slope or the opening is, the more modes would be transmitted to the multimode light receiving fiber when the tapered fiber probes with different slopes and different openings connected to a multimode light receiving fiber. We also testify the specification condition of the tapered fiber probe that is able to excite the single fundamental mode in a multimode fiber.