Fig. 1. （a）Refractive index and calculated optical field distribution diagram of 980 nm semiconductor laser；（b）schematic diagram of MOPA structure

Fig. 2. （a）The variation of the optical confinement factor of TE₀₀-mode and TM₀₀-mode in ridge waveguide with etched depth；（b）the trend of degree of polarization variation of ridge section under different etching depths；（c）the total power and TE-mode power varing from etching depths.

Fig. 3. （a）The trend curve of the power，polarization angle and degree of polarization of tapered waveguide with stress；（b）emission spectrum of taper section with different stress

Fig. 4. （a）The influence of PN metal thickness difference on DOP and polarization angle of MOPA；（b）Dop and polarization angle of ridge，toper and MOPA

Fig. 5. （a）The power and DOP（b）voltage and efficiency of MOPA lasers as a function of PA current before and after enhancement

Fig. 6. The impact of heat sink temperature on the power and DOP of MOPA device