Dresden 2009 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 35: Semiconductor Laser

HL 35.1: Talk

Wednesday, March 25, 2009, 14:00–14:15, BEY 154

Crystal length dependency of the generation of the second harmonic with non-diffraction limited radiation — •Mirko Uebernickel, Gunnar Blume, Christian Fiebig, Katrin Paschke, Bernd Eppich, Reiner Güther, and Götz Erbert — Ferdinand-Braun-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, 12489 Berlin, Deutschland

The direct second harmonic generation (SHG) of high power, infrared semiconductor diode lasers is a possible candidate for the replacement of established visible laser systems, like Argon-Ion lasers or frequency doubled solid-state lasers. To achieve high optical output power in the visible wavelength range the length of nonlinear crystal needs to be considered. The SHG power scales linear with the length of the crystal in single path configuration for a Gaussian beam.

We determine the crystal length dependency for non-diffraction limited radiation of diode lasers in experiment and theory. Different semiconductor lasers with increasing beam propagation factor (second order moments) from 1.1 to 3 were used to examine the SHG power of four periodically poled MgO doped lithium niobate crystals with lengths of 10, 18, 22 and 50mm. It was found that the SHG power is indeed linearly dependent on the crystal length, but only if the focusing conditions are adjusted to the non-diffraction limited radiation. Theoretical calculations based on a Gauss-Shell model could verify these experimental results. The model can thus be used to predict optimised focussing conditions for SHG with non-diffraction limited beams.