Effect of transverse and longitudinal current modulation on beam quality in broad area semiconductor lasers

Beam filamentation limits the beam quality of broad-area semiconductor lasers (BASLs), and effective mitigation strategies remain an open issue. We investigate the impact of spatial modulation of the injected current using a spatio-temporal traveling-wave model that describes the coupled longitudinal and transverse dynamics of the optical field and carrier density. The modulation is implemented as a two-dimensional current pattern, producing simultaneous variations of gain and refractive index compatible with structured electrodes. Transverse modulation alone stabilizes the near-field profile but introduces far-field side lobes associated with out-of-phase modes. The addition of longitudinal modulation modifies this behavior and can suppress these side lobes for modulation periods near Talbot-type resonance conditions. These effects persist, although reduced, in the presence of thermal refractive index variations. The results provide a realistic assessment of spatially structured current injection for beam shaping in BASLs and clarify its limitations and potential for practical implementations.