As the increasing applications of the semiconductor lasers in the laser processing, the single 2-D stack optic-power
density has not satisfied the actual requirements. It demands to couple several diode laser stack beams to one to improve
the brightness, and it becomes the central issue to adopt the appropriate beam coupling technology which would offer
high quality and high efficiency. In this paper, it mainly introduces the beam shaping and the technology of spatial
coupling, polarization coupling, and wavelength coupling. The coupling key elements are presented and indicated.
Finally, the development of the diode laser on beam coupling in our country fell behind through analyzing the statement
of the world. Our lab is studying on polarization coupling and wavelength coupling. We gain some results by phase,d
which the polarization coupling efficiency can achieve 90% for two LD stacks with seven bars whose luminous
wavelength is 975nm and980nm. By two 808nm diode laser coupling effeice the efficiency of 60% can be achieved after
focusing to the beam size of 2x2mm<sup>2</sup>.