Structural and optical behavior due to thermal effects in end-pumped Yb:YAG disk lasers

Abstract

We employ a Monte Carlo ray-tracing code along with the ANSYS package to predict the optical and structural behavior in end-pumped CW Yb:YAG disk lasers. The presence of inhomogeneous temperature, stress, and strain distributions is responsible for many deleterious effects for laser action through disk fracture, strain-induced birefringence, and thermal lensing. The thermal lensing, in turn, results in the optical phase distortion in solid-state lasers. Furthermore, the dependence of optical phase distortion on variables such as the heat transfer coefficient, the cooling fluid temperature, and crystal thickness is discussed.

Analytical model of thermal effect and optical path difference in end-pumped Yb:YAG thin disk laser

“…At the same time, the maximum temperature would be observed at the center of the disk crystal depending on the pumping intensity, and the temperature difference along the radial direction is small in the pumping zone. The simulation results from analytical calculation agree with the finite element simulations from relational literature [6,9].…”

“…The spherical deformation of the OPD could be compensated by the resonator design, while the aspherical part of the thermo-optical aberrations has to reduce to improve the brightness of the output laser. In order to investigate the OPD, thermal lensing, and compensation techniques, various models and experiments have been carried out by Speiser and Geisen [5], Milani et al [6], Perchermeier and Wittrock [7], Shang et al [8], Sazegari et al [9], and others. Many numerical models were built and calculated using finite element analysis (FEA) software.…”

7kW direct-liquid-cooled side-pumped Nd:YAG multi-disk laser resonator

“…With the direct-liquid-cooled configuration, the linear arrangement of multiple thin disks is can be realized since the oscillating laser passes through dozens of thin disks transmissively [3,4], while a high pump intensity is allowed due to its efficient thermal management [5]. Furthermore, a flexible support is easy to realize and the awful wavefront aberration existing in the conventional thin disks that are welded on coolers can be avoided [6][7][8]. The study of direct-liquid-cooled multi-disk SSL has attracted much attention [9,10].…”

3kW liquid–cooled elastically-supported Nd:YAG multi-slab CW laser resonator

“…Thermal effects remain to be one of the main limiting factors for raising the output power from the solid-state lasers while keeping good beam quality [1][2][3]. For the conventional liquid-conduction-cooled configuration, in order to make room for the propagation path of pump light, the pump surface of the gain medium that the pump light injects into, is not directly attached to the heat sink in most cases [4][5][6][7].…”