Berlin 2018 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 5: Semiconductor Lasers

HL 5.3: Talk

Monday, March 12, 2018, 10:00–10:15, EW 202

Beam Analysis of Semiconductor Lasers by their Wavefront Structure — •Inga-Maria Eichentopf and Martin Reufer — Hochschule Ruhr West, Institut Naturwissenschaften, Mülheim an der Ruhr, Germany

For many applications of semiconductor lasers like high precision engraving, cutting and additive manufacturing a constant beam quality during processing is essential. But even if the intensity distribution is perfectly Gaussian for a certain set of laser parameters, blur effects can occur due to a slight shift of working conditions during the process. To forecast a loss of beam quality the analysis of the wavefront structure of the processing laser over the typical diode current range can be a helpful tool to choose a suitable parameter window or to correct the beam parameters using optical elements like deformable mirrors. In our research we use a Shack-Hartmann Sensor to record the wavefront and intensity distribution of single and multimode semiconductor lasers based on GaAs composites emitting at wavelengths in the near infrared. Over the parameter range electrical as well as thermal effects inside the laser resonator strongly influence the modal composition of the intensity distribution causing a deformation of the wavefront. To determine the impact of these effects a Gaussian telescope setup is used to detect the wavefront structure during the spatial and current depending evolution of the beam. This approach shall be used to forecast the beam stability.