Product Code: ICAL09_P158

Frequency Doubling (SHG) of a 200 W cw Fiber Laser in Kaliumtitanylphosphat (KTP)
Authors:
Markus Mundus, Laser Center, Muenster University of Applied Sciences; Steinfurt Germany
Jürgen Gröninger, Laser Center, Muenster University of Applied Sciences; Steinfurt Germany
Klaus Dickmann, Laser Center, Muenster University of Applied Sciences; Steinfurt Germany
Presented at ICALEO 2009

Since most metals are high reflective in case of fiber laser wavelengths these materials often can't be processed ideally. Therefore the wavelength of the beam is modified by frequency conversions in order to optimize the interaction of laser and
material. In most state-of-the-art publications single-frequency and/or pulsed laser sources are used for conversion processes, since the conversion efficiency rises with decreasing bandwidth and increasing intensity of the beam. Unfortunately these lasers are rather costly and/or the Harmonics modulation is limited. A solution to this problem was developed at the Laser Center (LFM), Muenster
University of Applied Sciences. In contrast to recently published results, in this study a cw fiber laser (YLR-200-LP/IPG) with 1.6 nm FWHM-bandwidth and 200 W maximum output power was used for single-pass Second Harmonic Generation (SHG) in KTP (KTiOPO4). Thus the application possibilities of this laser source were extended and the operator can choose between the infrared beam and the Second
Harmonic in order to optimize the interaction of laser and material. In first experimental studies 3.7 W output power of the Second Harmonic was reached at 3.2 % optic-optical efficiency. The crystal temperature, crystal length and angular dependences of the output power were researched. Furthermore the crystal structure was analyzed by using the Laue-method and thermal lenses of the optical
components were observed.