Simple design for fiber coupled 9xx nm kW-QCW pump module with high duty cycle based on customized chips and lateral heat removal

Wolfgang Pittroff; Bernd Eppich; Götz Erbert; René Platz; Dieter Tyralla; Günther Traenkle

doi:10.1117/12.2036949

7 March 2014 Simple design for fiber coupled 9xx nm kW-QCW pump module with high duty cycle based on customized chips and lateral heat removal

Wolfgang Pittroff, Bernd Eppich, Götz Erbert, René Platz, Dieter Tyralla, Günther Traenkle

Author Affiliations +

Proceedings Volume 8965, High-Power Diode Laser Technology and Applications XII; 896515 (2014) https://doi.org/10.1117/12.2036949
Event: SPIE LASE, 2014, San Francisco, California, United States

Abstract

High power 9xxnm QCW- pump modules are very interesting for high- and ultra-high-energy laser systems. Main relevant issues beside price and power conversion efficiency are long term stability of the mounting scheme and stable fiber coupling. We present a design based on diode laser stacks with lateral heat removal. A single stack element consists of a diode laser, which is soldered on both sides to CuW carriers using AuSn. Life test over 1000 h showed no degradation. DCB coolers are subsequently soldered onto both outer sides of the stack. The thermal resistance of a single stack element is about 1.7 K/W. For >3 J pulse energy the stack contains 28 elements. ≥60% power conversion efficiency of the used 940 nm diode laser chips at 120 W output power allows ≥20% duty cycle without substantial heating (maximum measured output power >200 W). The light is collimated in vertical direction for each stack element. We choose a size for the FAC which allows staggering the beams of two stacks. The diode laser chips have an aperture width of 1.2 mm and a lateral divergence <14° (95 % power) at 120 W. Fiber coupling is performed by cylindrical lenses in both directions. For 6 J pump energy two stacks are used, coupled into 1.9 mm diameter fiber with a high optical coupling efficiency of >90 %. The principle design is very flexible to match other demands in fiber size and output power.

Citation Download Citation

Wolfgang Pittroff, Bernd Eppich, Götz Erbert, René Platz, Dieter Tyralla, and Günther Traenkle "Simple design for fiber coupled 9xx nm kW-QCW pump module with high duty cycle based on customized chips and lateral heat removal", Proc. SPIE 8965, High-Power Diode Laser Technology and Applications XII, 896515 (7 March 2014); https://doi.org/10.1117/12.2036949

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