A 57 W radially polarized SESAM mode-locked thin-disk oscillator

The advantages of radially and azimuthally polarized laser beams for various applications in material processing, e.g. cutting and drilling, over circularly or linearly polarized beams has been reported among others in [1]. Furthermore, for micro material processing ultrafast lasers with pulse durations in the order of 1 ps have gained tremendous interest. The oscillator we present here is a promising candidate to seed thin-disk multipass amplifier without the need of a complex multi-stages pre-amplification scheme reported in [2]. The cavity of the oscillator we present here is designed such that the LG01 transversal mode has a sufficient overlap with the pump spot. Radial polarization is preferred over azimuthal polarization by the use of a circular Grating Waveguide Output Coupler (GWOC) which supresses the fundamental Gaussian mode at the same time. Mode-locking is achieved by the implementation of a Semiconductor Saturable Absorber Mirror (SESAM) as cavity end mirror.