High-power AlGaAs laser with a thin tapered-thickness active layer

A laser whose active layer is thinner near the mirror facet than the inner region is fabricated. Lasers with narrow beam divergence perpendicular to the junction, as narrow as 10°-20°, are obtained with little increase of threshold current. For lasers emitting at 780 nm, stable 30 mW operation at 50°C has been confirmed without obvious degradation over 4000 h.