Using of Broadened Asymmetric Waveguide Structure for 980nm Diode Laser

Laser diode beam divergence is the main parameter for beam shaping and fiber optic coupling. Increasing the waveguide layer thickness is the conventional method to decrease the beam divergence. In this paper, the broadened asymmetric waveguide is introduced to decrease the divergence without increasing the optical power. The asymmetric waveguide was used to shift the vertical optical field to n-section, which has lower free carrier loss. The main target in this research is to minimize the internal loss to avoid the disadvantage of the broadened waveguide. Finally the beam divergence was decreased to 35 degrees that is very suitable for the conventional multi-mode optical fiber coupling and the optical power was increased to 2400mW in the laser diode with 100μm stripe width and 1mm cavity length. In addition to the fiber coupling, this improvement can be used for other direct applications that need beam shaping.