Blue-green buried-ridge laser diodes

An attempt is being made to develop short wavelength (green and blue) laser diodes with performance suitable for use in optical data storage systems. Buried-ridge laser diodes operating in the blue-green ( lambda =511 nm) are reported. The starting material is a separate-confinement heterostructure consisting of a strained, pseudomorphic CdZnSe quantum well, ZnSSe light-guiding layers, and MgZnSSe cladding layers. The II-VI layers are grown by MBE (molecular beam epitaxy) and are nominally lattice-matched to the GaAs substrate. Ridges, typically 2 or 3 mu m wide, are formed using ion beam etching, and are subsequently buried with ZnS in a self-aligned process that results in a planar surface. Laser diodes with room-temperature pulsed threshold currents of 2.5 mA have been obtained. Single lateral model operation is indicated by the far-field pattern of these devices.