B. Sumpf, P. Adamiec, J. Fricke, P. Ressel, H. Wenzel, G. Erbert, G. Tränkle

Published in:

Proc. SPIE, vol. 7616, no. 7616H (2010).

Abstract:

650 nm tapered laser diodes with nearly diffraction limited beam quality are requested for laser display applications. In this paper, results for 2 mm long 650 nm tapered lasers diodes with different lateral geometries will be presented. The vertical structure is based on a 5 nm thick InGaP single quantum well embedded in AlGaInP waveguide and n-AlInP and p-AlGaAs cladding layers. The ridge waveguides of lengths L_RW = 200 µm, 300 µm, 500 µm, and 750 µm were fabricated using selective etching. The contact window for the tapered section was defined applying ion implantation. Devices with a taper angle of 4° were manufactured. The facets were passivated. The rear side was high reflection coated and the taper side anti reflection coated. The devices were mounted p-side down on CVDdiamond heat spreaders and standard C-mounts.
All devices reached a maximal output power larger than 1 W. They had a threshold current density of about 700 A/cm² and a slope efficiency of 0.8 W/A. The best conversion efficiency was 20%. The devices with the shortest RW-length L_RW = 200 µm had the best beam quality (beam waist width 7 µm, far field angle 8.8°, 85% of the emitted power in central lobe, M² of 1.3 (all values measured at 1/e²-level)) at P = 1 W. The beam quality for devices with longer RW-section deteriorates up to M² = 4.4 for a L_RW = 750 µm laser.

Keywords:

Semiconductor lasers, Tapered lasers, Red emitting lasers, High-Brightness.

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