Beam shaping method to improve power density of semiconductor laser diodes

To solve the problem that the power density of laser beam attenuated along the propagation direction, which was caused by large beam divergence angle (14-46) of semiconductor laser diode, a beam shaping optical system to improve power density was proposed. An X type planoconvex cylindrical lens and a Y type planoconvex cylindrical lens were selected to collimate the laser beam. Then, a pair of planoconvex spherical lenses were applied to improve the parallelism. Finally, a single planoconvex spherical lens focused the laser beam to a spot with high power density. The lenses were chosen and optimized through Light Tools simulation. A real beam shaping optical system was mounted and built. Test results show that 67% laser power is converged into a cycle with diameter of 1 mm, and the power density is over 30 W/cm2.