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HL: Fachverband Halbleiterphysik

HL 26: Lasers and LEDs II

HL 26.1: Vortrag

Montag, 11. März 2013, 16:45–17:00, H16

Beam steering in mid-IR external cavity quantum cascade lasers — •Verena Blattmann, Frank Fuchs, Stefan Hugger, Jan Jarvis, Michel Kinzer, Quankui Yang, Ralf Ostendorf, Wolfgang Bronner, Rachid Driad, Rolf Aidam, and Joachim Wagner — Fraunhofer-Institut für Angewandte Festkörperphysik IAF, Tullastr. 72, D-79108 Freiburg, Germany

Quantum cascade (QC) lasers have been established as Watt-level coherent light sources in the mid-infrared of the electromagnetic spectrum. Applying band structure engineering, the gain spectrum of a QC laser can be designed according to the specific needs of the given application. Control over the emission wavelength over the entire gain spectrum can be obtained by an external cavity (EC) setup, making QC lasers interesting for broad-band spectroscopy. Such sensing applications require a stable far-field intensity distribution in order to realize a high signal-to-noise ratio during the measurement. However, it has been shown that QC lasers are likely to show lateral multi-mode emission. In particular when operated at higher output power, they show far-field beam instabilities and beam steering effects due to coherent coupling of different lateral modes. In order to understand these effects, we investigate the dependence of far-field characteristics of EC-QC lasers on parameters such as laser current, temperature, emission wavelength as well as the precise alignment of the components of the external cavity. In addition, the influence of lateral optical confinement is evaluated by using laser chips differing in ridge width and processing technology (double trench, buried heterostructure).