500 W QCW red laser

Numerous applications exist for high power red laser diodes including laser pointers, solid state laser pumping, printing, medicine, bar code scanning, and optical data storage. We have previously reported output powers as high as 140 W from a single 1 cm quasi-continuous wave (QCW) bar. Other workers have reported output powers >70 W QCW from a laser diode bar. In this work we report the results of further improvements which have led to power conversion efficiencies greater than 40% and output powers >500 W from a six-bar stack. The lasers described here use AlGaInP epitaxial layers grown lattice-matched on n-type GaAs substrates. Epitaxial layers are deposited via metal organic chemical vapor deposition (MOCVD). The active layer consists of a single Ga_0.4In_0.6P quantum well (QW) surrounded by (Al _0.6Ga_0.4)_0.5In_0.5P waveguiding layers. The QW is intentionally compressively strained by adding excess In. Compressive strain modifies the valence band structure resulting in a reduced effective mass for holes in the quantum well leading to a reduced threshold current. Cladding layers of AlInP are used in order to obtain maximum carrier confinement in the active region. The growth technique and layer design used insures that the material has high quantum efficiency and low series resistance