Design And Study On Fiber-coupled Diode Laser Module

During the recent years, high-power diode lasers have gained more importance in industrial applications such as optical fiber communication, solid-state laser pumping, materials processing and medical treatments. But the output beam of the laser diodes is highly divergent and asymmetric, which limits the applications in many fields. Commonly, it is necessary to use collimation, beam shaping optics or coupling system in most applications of high-power diode lasers. Accordingly, many institutions internal and abroad have been doing much research on this problem, and a lot of optical structures have been presented.On the basis of summarizing various methods from those reports, a fiber-coupled diode laser module has been designed by considering the situation of the internal optical processing. The large divergence in the fast axis is corrected by using a cylindrical lens, the beam asymmetry between fast axis and slow axis is adjusted by using isosceles right-angled prisms beam-shaping technique, the divergence in the slow axis is also collimated by cylindrical lens after beam shaping, and the shaped beam is focused and coupled into a fiber with the diameter of 400μm and the numerical aperture of 0.22. This module can be applied in pumping high-power fiber laser, processing materials and medical treatments.The optical system of the module is discussed by collimation, beam shaping and fiber coupling. Each optical structure is described in detail and each parameter which can affect the efficiency of the system is also discussed. The whole system is simulated and optimized in computer by using some optical designing software and the experiment is performed according to the finally result of optimization. The efficiency of the collimation is more than 92%, the efficiency of the beam shaping is more than 95% and the coupling efficiency of 76% is obtained. At last, the experimental result is compared with the simulating result, the physical and practical limitation is discussed and the method which can improve the whole efficiency is presented.To demonstrate the adaptability of the beam-shaping module, the module is tested by six environmental tests——the lowest environmental temperature test, the highest environmental temperature test, the vibration test, the impulsion test, the circular temperature test and the life time test in high temperature. The results illuminate that the beam-shaping module has a strong capability for different environmental conditions, can be used out of the laboratory and the quantity production of this module can be achieved.