Beam reshape of high power laser diode stack
Based on the ray tracing method the laser intensity distribution of single DL bar collimated with micro spherical cylindrical lens was analyzed in detail. We found that the intensity distribution of output laser have a better flat shape when the divergence angle is about 5. A beam reshape system was designed for a 25-bar DL stack. The system includes microlens of fast axis collimating, coupling lens of fast axis and coupling lens of slow axis. The laser medium to be pumped was designed at the focus plane of fast axis coupling lens and close to the imaging plane of slow axis coupling lens. A 7 mm8 mm pump beam was obtained with intensity uniformity of 90%. The coupling efficiency of the beam reshaping system reached 85%.