Abstract
In this paper, we present a FEM-model that can be used to investigate the effects of thermally induced natural convection at the thin-disk laser crystal. Based on this simulation, we calculated the distribution of the refractive index of the ambient gas for the case of air and helium. By evaluating the optical path difference of a beam at normal incidence, the angular tilt (gas wedge) in the plane of the direction of convection as well as the spherical contribution (gas lens) was calculated for a set of different pump spot geometries and temperatures of the pumped area on the surface of the laser disk. Equations were derived that allow to simply calculate the tilt angle and the focal length of the gas lens for different temperatures of the disk and pump spot diameters for air as ambient medium.
Highlights
A major limitation for power scaling of solid-state lasers with good beam quality (M2 < 1.3) are thermally induced effects within and at the surface of the laser active medium
To quantitatively determine the thermally induced linear (‘gas wedge’) and spherical (‘gas lens’) contributions to the wave front distortion of a transmitted laser beam, we have modelled the heated laser crystal and the surrounding atmosphere using the finite-element method (FEM) and the software COMSOL [14]
The linear part of the wavefront aberration occurring in the YZ-plane shown in Fig. 4a was extracted by applying a Modelling of natural convection in thin‐disk lasers
Summary
A major limitation for power scaling of solid-state lasers with good beam quality (M2 < 1.3) are thermally induced effects within and at the surface of the laser active medium. While the effects inside the crystal, e.g. thermal expansion and dispersion, are well understood [1, 2], wavefront aberrations of the transmitted beam caused by thermally induced natural convection near the surface of the laser crystal so far have been investigated less extensively. This effect starts to play a significant role when it comes to laser oscillators and amplifiers with very high output powers (kW-class) and good beam quality. 47 Page 2 of 7 on the angular and the spherical contribution to the wave front distortions is essential to be able to adapt the design of the laser cavity more precisely
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
