A quantitative comparison of conventional absorption line (940 nm) pumping and zero phonon line (ZPL) (969 nm) pumping of a Yb:YAG thin disk laser is reported. Characteristics of an output beam profile, surface temperature, and deformation of a thin disk under the different pump wavelengths are evaluated. We found that a nonlinear phonon relaxation (NPR) of the excited state in Yb:YAG, which induces nonlinear temperature rise and large aspheric deformation, did not appear in the case of a ZPL pumped Yb:YAG thin disk. This means that the advantage of ZPL pumping is not only the reduction of quantum defect but also the suppression of NPR. The latter effect is more important for high power lasers.
© 2014 Optical Society of America
Lasers and Laser Optics
Original Manuscript: May 22, 2014
Revised Manuscript: July 10, 2014
Manuscript Accepted: July 14, 2014
Published: August 14, 2014
Martin Smrž, Taisuke Miura, Michal Chyla, Siva Nagisetty, Ondřej Novák, Akira Endo, and Tomáš Mocek, "Suppression of nonlinear phonon relaxation in Yb:YAG thin disk via zero phonon line pumping," Opt. Lett. 39, 4919-4922 (2014)