Design Of A Coupler For Semiconductor Laser And Fiber Without Laser Ablation

Since the fiber was made, it has been considered as the most competitive waveguide medium. The laser diode (LD) is widely used in the optical communications since its launch, because of its light weight, small size, simple structure, and other advantages. As semi-monomer laser luminous area is very small, it has great divergence angle, fast axis of up to 30°-40°, the LD beam is often been shaped to improve the beam quality when coupling into the fiber. Using the system of micro-lens (for example, the core diameter fiber) and the sphere-end optical fiber to shaping LD beam is an easy and inexpensive way. However, with the successful promotion and development of the high-power LD, laser ablation of the optical fiber has become an increasingly prominent problem. Currently, there are very few studies on it, which mostly concentrate on the military aspects, so the study on the laser ablation of high-power LD has practical significance.This paper, on the basis of in-depth study of the various coupling method and its applied conditions, mainly does the following work:1. A more detailed analysis of the LD output light and the basic optical transmission theory of single-mode, multimode optical fiber has been done, and the theoretical coupling model of the LD and fiber has been expounded.2. The LD and fiber coupling system dividing into direct and indirect coupling system is discussed. The structure and coupling characteristics of the common micro-lens fiber end has been introduced and analyzed, as well as the existing coupled devices. Considering the process and coupling efficiency, optical fiber with sphere-end is easy to achieve, because its production technology is simple and mature.3. Against the problems, that is, the sphere-end fiber and cylindrical lens combination coupling system is difficult to package and debug as well as the high-power LD has laser ablation on the coupling interface, we put forward: a section of fiber with 400μm diameter instead of the cylindrical lens to shape the LD output beam; sphere-end fiber with large diameter ball focuses the beam after collimation, and realizes the direct fiber coupling, so it can take place of focusing lens and optical fiber coupling link. The sphere-end fiber with large diameter ball is melded and burnt or by standard multimode optical fiber and large core diameter multimode optical fiber.4. A coupling device of LD and sphere-end fiber is designed. The device divides the traditional five-dimensional adjustment modes into two-dimensional and three-dimensional adjustment modes, experiments proved that the device can greatly reduce the difficulty of regulating coupling system, and the machining accuracy of the installation is not particularly high.5. The new coupling system put forward in 3 is studied. Firstly, the parameters of the ball lens that of sphere-end fiber is measured, the analysis shows that the technology of sphere-end fiber production using automatic welding machines is stable. Experimental analysis, how about the coupling effect of the sphere-end fiber with large diameter ball lens, is made, the results show that: the coupling efficiency of the system is long-term stable around 80.0 percent; the difficulty of the sphere-end fiber and cylindrical lens combination coupling system in package and debug is significantly reduced, and the laser ablation can effectively reduced as well.