Semiconductor Laser Microlens Fiber Coupling Technology Research

Because of the rapid development of optoelectronic devices, especially the performance of the semiconductor lasers, semiconductor lasers have been used in more and more areas, including optical communication, solid-state laser pumping, laser processing, laser printing and medical applications. But the poor output beam quality of the edge-emitting semiconductor laser limits its further applications. The coupling of semiconductor laser and the optical fiber has vital significance to the semiconductor laser light beam quality improvement. How to improve the coupling efficiency between the edge-emitting semiconductor laser and the optical fiber becomes a widely concerned problem.This thesis focuses on the coupling between semiconductor laser and the optical fiber. The laser with the optical fiber outputs is needed in the laser processing, the solid laser pump, and medical domains. Its advantage is that the light beam quality is good, the light beam emitting direction and position can be changed optionally. The technique to improve the coupling efficiency of edge-emitting semiconductor laser and optical fiber is adding optical elements in front of the laser beam. The mostly used techniques to improve the coupling efficiency and alignment tolerance include using micro single lens, micro lens group and lensed fiber.The main topic in the thesis is the coupling the coupling between the high power single emitter broad area diode laser and micro lensed multimode fiber. The use of the lensed fiber can improve the coupling efficiency and alignment tolerance greatly. In the first part, a novel paraboloidal lensed multimode fiber has been analyzed amply in the coupling between the high power single emitter broad area diode laser and multimode fiber, which has been verified in the experiment. In the second part, the coupling between the high power single emitter broad area diode laser and cylindrical lensed multimode fiber has been discussed detailedly.The thesis includes six chapters. The first chapter introduces the development, application of the semiconductor lasers and the relatively research of coupling between semiconductor lasers and optical fiber. The characteristics of diode laser, the transmitted characteristics of optical fiber and the influence factor of coupling efficiency are discussed in the second chapter. The third chapter of the thesis discusses a novel paraboloidal lensed multimode fiber used in the fiber coupling of the high power single emitter broad area diode laser, and the results of the computer aided simulation of the coupling have been described too, the results verified the theory of paraboloidal lensed multimode fiber. The coupling efficiency and alignment tolerance between the high power single emitter broad area diode laser and thecylindrical lensed multimode fiber has been discussed in the forth chapter; in addition, the simulation and the experiment have been done to support the theoretical results. In the fifth chapter, a novel technique using Thermally Expanded Core Fiber (TEC Fiber) to get high brightness laser has been discussed theoretically. The last chapter summarizes the works which have been done and the forecast research directions which are deserved to study deeply.