Strain compensated 1120 nm GaInAs/GaAs vertical external-cavity surface-emitting laser grown by molecular beam epitaxy

We report on the development of high quality, strain compensated gain mirror for 1120 nm vertical external-cavity surface-emitting lasers (VECSELs). The gain mirror was grown by molecular beam epitaxy and comprised a total of six Ga0.69In0.31As quantum wells. The effect of the strain compensation has been assessed by measuring the curvature of the wafer and by mapping the photoluminescence to identify the non-emissive dark areas. We demonstrate that ∼91% strain compensation with GaAs0.85P0.15 is sufficient to remove the dark lines corresponding to areas with structural defects in the gain mirror structure. Rapid thermal annealing studies revealed that the strain compensation is efficient in preventing the appearance of dark lines even for samples that were annealed at temperatures as high as 700 °C for a considerable time. The strain compensated gain mirror was used to demonstrate a VECSEL emitting at 1120 nm.

► We developed a strain compensated gain mirror for 1120 nm VECSELs.
► The gain region contained Ga0.69In0.31As QWs and GaAs0.85P0.15 strain compensation layers.
► The strain was assessed by measuring the wafer curvature and dark lines.
► ∼91% strain compensation is sufficient to remove the dark lines.
► The appearance of dark lines was also avoided for thermally annealed samples.