Characterization of tapered diode laser bars for the use in high-power diode laser systems

Alexander Knitsch, Martin Traub, Karsten Rotter, Dieter Hoffmann, Peter Loosen, Reinhart Poprawe, Mark S. Zediker
2004 High-Power Diode Laser Technology and Applications II  
For further development in beam quality of high power diode laser systems a new type of diode laser bars has been realized recently. Compared to commercially available broad area diode laser bars the lateral design of tapered diode laser bars consists of a ridge waveguide and a tapered section, where the tapered structure determines high output power and the high brightness is provided by the ridge waveguide structure. Unfortunately the different lateral structure leads to astigmatism effects
more » ... ich are also thermally affected in continous wave operation. Hence in terms of diode laser systems with essentially fast-and slow-axis collimation microoptics the full characterization of tapered diode laser bars is necessary. Where the wavelengths and divergences of tapered diode laser bars are relatively easy to measure, the beam profile with it's apparently inside the tapered structure located lateral source is not. With telecentric optics the caustic of the individual emitters of the bars are detected by the use of a fiber sensor with a resolution of 10 µm in fastand slow-axis direction. Subsequently with beam analysis software the astigmatism can be calculated. As a result of several measurements of tapered bars of different wavelengths we detected good homogeneity over the bar concerning the amount of astigmatism but a slight current dependency. So particularly with regard to beam shaping microoptics the application to high power diode laser systems seems to be sophisticated so far. Keywords: tapered diode laser bars, characterization of high power diode lasers, astigmatism, fiber sensor, birefringent-multiplexing, beam displacer *; http://www.ilt.fhg.
doi:10.1117/12.529086 fatcat:upag2n5xfzhj3kch7siaxahr7m