Fig. 1. Schemes of popular SLD waveguide geometries: (a) tilted facet, (b) tilted waveguide, (c) waveguide with an absorber section, and (d) bent waveguide (used in this study).

Fig. 2. Simulated changes in emission spectra shape resulting from light amplification in medium with a linear profile of indium.

Fig. 3. Example of a calculated emission spectrum of an SLD with a step-like indium content profile along the waveguide.

Fig. 4. Fabricated step vicinal angle profile. The inset presents a 3D scheme of the surface pattern.

Fig. 5. Scheme of the epitaxial structure design of the examined samples (indium content estimated for a non-patterned wafer).

Fig. 6. Microphotoluminescence maps of central emission wavelength measured for substrate areas with three types of patterns: (a) flat, (b) linear, and (c) step.

Fig. 7. Optical power versus current curves measured for all types of devices.

Fig. 8. Comparison of emission spectra measured for three types of SLDs: fabricated on a substrate with constant vicinal angle (flat), with a linear profile of vicinal angle (linear), and with a step-like profile (step). The measurement was performed under 250 mA of operating current.

Fig. 9. Evolution of the emission spectrum with applied current measured for SLD fabricated on a substrate with step-like indium content profile.