Semiconductor laser with unstable resonator consisting of negative cylindrical lenses

We have obtained high power single-lateral-mode operation in wide-stripe InGaAs/GaAs/A1GaAs semiconductor lasers using a monolithic unstable resonator (consisting of diverging elements incorporated above an asymmetric GRIN-SCH). The fabrication involves MOCVD regrowth after wet-chemical etching of lens-like patterns in a GaAs layer above the active region. Pulsed output powers of 175 mW and 490 mW have been obtained in 170 p.m and 100 tm wide lasers respectively, with spatial coherence in the near-field exceeding 60%. We observe good lateral mode discrimination upto 3.5 times threshold in 100 .tm stripes with a round-trip magnification of 6.4.