Dresden 2006 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 16: Semiconductor laser I
HL 16.6: Vortrag
Dienstag, 28. März 2006, 12:15–12:30, BEY 154
Low divergence single-mode edge emitting 650 nm lasers based on longitudinal photonic bandgap crystal — •Kristijan Posilovic1, Thorsten Kettler1, Leonid Ya. Karachinsky2, Vitaly A. Shchukin1,3, Vladimir P. Kalosha4, Udo W. Pohl1, Nikolai N. Ledentsov1,3, and Dieter Bimberg1 — 1Institut für Festkörperphysik, Technische Universität Berlin — 2Ioffe Physico-Technical Institute, St.Petersburg — 3NL Nanosemiconductor GmbH, Dortmund — 4Department of Physics, University of Ottawa
Conventional edge-emitting lasers suffer from large vertical beam divergence due to a narrow modal spot size of the optical mode, and therefore are seriously limiting practical applications. We present a novel approach to achieve large optical spot size and low divergence. The waveguide is broadened and a one-dimensional photonic bandgap crystal is used to filter higher order modes. The structure was realised in the GaInP-AlGaInP material system grown on GaAs-substrates and processed into narrow ridge waveguide lasers using standard techniques. The devices show fundamental mode emission over a wide range of injection currents proved by near field as well as far field measurements. The lasing wavelength remained stable at 650 nm over all injection currents. The measured vertical beam divergence is below 10∘ for all stripe widths investigated. A 4 micron stripe shows lateral beam divergence of 8∘, resulting in a circular shaped far field emission.