GaInAs/AlGaAs comprehensive-strained three-quantum-well lasers with asymmetric waveguide are designed and optimized.With this design,the optical field in the transverse direction is extended,and a semiconductor laser with large spot is obtained.For a 300-μm cavity length and 100-μm aperture device under continuous wave（CW） operation,the measured vertical and horizontal far-field divergence angles are 12.2？ and 3.0？,respectively.The slope efficiency is 0.44 W/A and the lasing wavelength is 917 nm.The equivalent transverse spot size is 3 μm for the fundamental transverse mode,which is a sufficiently large value for the purpose of coupling and manipulation of light.
