Research On Fiber Coupling Technique For405nm Fiber Coupled LD

Due to the property of the semiconductor laser, the divergence angle is larger along the fast axis while smaller in the slow axis direction. The asymmetry of the light’s of the fast and slow axis leads to a bottleneck in widespread use which is the large divergence angle of the laser beam and serious seastigmatic.Based on the above consideration, the fiber coupling technique is a proper way to simply the application conditions, and improve the asymmetry of output beam. It can also be designed to achieve the output coupling of multiple laser source, thereby obtaining higher output power, which have been widely used in many areas, such as laser printing, health care, display and so on.In this paper, we investigate the property of the semiconductor laser, fiber and the fiber coupling technique, and then design the405nm Fiber Coupled LD with a better coupling-performance.This submitted work is divided into five chapters. The first chapter is the introduction, which briefly discusses the history of the semiconductor laser、GaN LD and the research on the current fiber coupling technique and the405nm Fiber Coupled LD. Chapter two introduces the major structure of semiconductor laser, showing its beam characteristics and the key factors determining its quality. Then a short synopsis of the applied domain of the405nm Fiber Coupled LD is given, as well as the problems during the growth and fabrication of the GaN LD. Chapter three introduces the basic characteristics of the fiber including the basic structure, categorization and the sources of energy loss. In chapter four, the basic method of the coupling between semiconductor laser and fiber are introduced, and then the influences of butt coupling error on the coupled efficiency are discussed in detail. In addition the basic concepts of optics of thin film are also introduced in this part. In the last chapter, experiments aiming to obtain better coupling efficiency are done and the405nm Fiber Coupled LD are designed based on the parameters from the above experiments.