在半导体激光器的光纤耦合系统中, bar条的各发光点指向偏差(偏向角)会恶化光束整形效果, 显著降低光纤耦合效率。针对该现象提出利用引入修正角的楔形整形镜补偿发光点的指向偏差, 改善激光束的指向性和光束整形效果。通过ZEMAX软件模拟与实验验证,在光纤耦合系统中使用引入修正角后的楔形整形镜片, 其整形效果显著改善, 测量的光束参数积(BPPs)在快轴和慢轴方向分别为7.25 mm·mrad和5.05 mm·mrad, 聚焦光斑为148 μm×135 μm(包含90%能量)。该系统将单个bar条耦合进芯径200 μm、数值孔径(NA)0.2的光纤中, 在注入电流60 A时, 获得稳定输出功率53 W, 对应电-光转换效率为47%, 光纤耦合效率为87%, 相对于使用修正前的楔形整形镜片, 光纤耦合效率提高了7%。

In fiber coupling system of diode laser bars, directivity deviation of emitters deteriorates the beam shaping seriously, thus leading to the degradation of fiber coupling efficiency. In order to solve this problem properly, in this paper, a wedge-shaped lens with calibrated angle is proposed to compensate the directivity deviation of the emitters and then improve the directivity of the laser beam and shaping effect. Both ZEMAX simulation and experiments are conducted. The results show that significant improvements of the beam shaping are obtained by using such wedge-shaped lens with calibrated angle. The beam parameter products(BPPs) calculated in the fast and slow axis are 7.25 mm·mrad and 5.05 mm·mrad respectively, and the focal spot dimension is 148 μm×135 μm(with 90% energy enclosed). After coupled the laser beams into a standard fiber with 200 μm core diameter and 0.2 numerical aperture(NA), the output power is measured to be 53 W and the electrical-to-optical conversion efficiency is 47% at the inject current of 60 A. Finally, the fiber coupling efficiency of 87% is achieved, increased by 7% compared to that of the conventional wedge-shaped lens.