Design And Fabrication On High Performance 980nm Fiber Grating External Cavity Semiconductor Laser

980nm pump laser is widely used in the design of erbium doped fiber amplifier(EDFA).With the rapid development of high speed and high capacity fiber communication and optoelectronic components, the coupling efficiency of 980 pump laser and single mode fiber (SMF) has become the most fundamental problem for engineers and researchers to solve. Coupling efficiency not only affects fiber communication relay distance, but also affects the performance of EDFA. So it is very important to improve coupling efficiency and reduce its cost.According to coupling theory, the coupling of 980nm pump laser to SMF is to meet the mode field diameter match and the phase match. For the technology of butting laser to a fiber, the coupling efficiency is very low for the serious phase mismatch and mold field diameter mismatch. So it is necessary to minimize the mismatch. Recently various coupling techniques have been used to achieve a low-loss coupling between a semiconductor laser and a single mode fiber. The experimental results in these studies have been reported for lasers with either circular or near circular beam profiles, however, 980nm pump laser has a highly elliptical beam profile because of its special structure, and there are a few studies about it. A theoretical and experimental study of a new, efficient technique to couple a laser, emitting a highly elliptical beam, to a single-mode fiber without the use of bulk optical components is presented. The technique involves butt coupling the laser to a wedge-shaped cylindrical lensed fiber(CLF). Such lensed fiber tip corrects for the phase front mismatch between the curved laser beam wave front and the planar fiber beam. In this paper, a theoretical model is presented to calculate the fiber coupling efficiency for the case of a 980nm pump laser directly coupled to a wedge-shaped CLF. Both radius and wedge angle of the wedge-shaped CLF are optimized for maximal coupling efficiency. It is found that with proper design by matlab software, a coupling efficiency up to 97.38% may be obtained theoretically. And comparisons indicate that theoretical results are in good agreement with the experimental results.In order to get a stable wavelength, we improve coupling efficiency by using a wedge-shaped CLF tip spliced to a SMF then fused a fiber bragg grating (FBG) to form an external cavity laser. At present, the coupling efficiency between 980nm pump laser and wedge-shape CLF is high to some extent, and further work which is benefit for coupling efficiency is going on.