High efficiency, 8W narrow-stripe broad-area lasers with in-plane beam-parameter-product below 2 mm mrad
European Conf. on Lasers and Electro-Optics and Int. Quantum Electronics Conf. (CLEO®/Europe-IQEC), Munich, Germany, May 12-16, paper CB-9.1-THU (2013).
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High power diode lasers are the most efficient technology for converting electrical input power into optical output power. Their efficiency and low manufacturing cost lead to their being the preferred source for industrial material processing applications, where kilowatt-class diode laser systems are produced by combining the output of many diode lasers into an optical fibre, with a beam parameter product, BPP, around 20-30 mm mrad . Although this is sufficient for many applications, deep cutting of metals requires sources with BPP <; 2 mm mrad, as delivered by fibre, solid state and CO2 lasers. Sophisticated beam combination schemes can increase the overall power level of diode laser systems [1,2,3], but BPP is ultimately limited by the semiconductor devices. A typical high power broad area laser used in a material processing system has a stripe width W = 90...100 μm and operates with a continuous wave output power, Pout = 10 W, an efficiency at the operation power, ηE(Pout) > 60% and an in-plane BPP > 3 mm mrad . Therefore, improved diode laser performance is required.
Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, 12489 Berlin, Germany