Fiber Coupling of Semiconductor Laser Based on Wedge-shaped Lens

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. © 2021, Science Press. All right reserved.