Planar native-oxide buried-mesa Al x Ga1− x As-In0.5(Al y Ga1− y )0.5P- In0.5(Al z Ga1− z )0.5P visible-spectrum laser diodes

Data are presented demonstrating the continuous (cw) room-temperature (23 °C) operation of planar index-guided ‘‘buried-mesa’’ AlxGa1−xAs-In0.5(AlyGa1−y)0.5P- In0.5Ga0.5P heterostructure visible-spectrum laser diodes. The planar ‘‘mesa’’ structure is formed by ‘‘wet’’ oxidation (H2O vapor+N2 carrier gas, 550 °C) of the AlxGa1−xAs on the composite AlxGa1−xAs-In0.5(AlyGa1−y)0.5P upper confining layer (outside of the active stripes). The oxidation process results in a ∼0.5-μm-thick native oxide located (in depth) within ∼3000 Å of the active layer in the region outside of the laser stripes themselves. The oxide possesses excellent current-confinement properties and a low refractive index (n≊1.60), resulting in relatively low-threshold laser operation for narrow-stripe devices. In addition, these devices exhibit transverse-mode confinement and small beam astigmatism because of the refractive index step provided by the deep native oxide.