Author:
Reich Stefan,Schäffer Sebastian,Lueck Martin,Wickert Matthias,Osterholz Jens
Abstract
AbstractWhen laser beams propagate through media with non-vanishing absorption, the media is heated resulting in a change of the refractive index, which can lead to thermal lensing and thermal blooming. However, experimental details about both phenomena for propagations in water are lacking, especially for high-power lasers in the kilowatt range. We show that significant thermal lensing occurs only for high input powers before the onset of convective flow, while for low input powers, no strong thermal lens arises. After the onset of water flow, thermal blooming occurs at low input powers comparable to that known for propagations over kilometres in the air. However, for high input powers a thermal blooming on a qualitatively higher level is shown. By wavefront sensing, the change of refractive index distribution in water is investigated. This clearly shows the fast development of a strong thermal lens for high input powers and the onset of convection. Furthermore, a qualitatively good agreement of the accompanying simulations is observed. It is found that the absorption coefficient is linear with a value of $$\mu ={13.7}\,{\mathrm{m}^{-1}}$$
μ
=
13.7
m
-
1
at least up to 7.5 kW, i.e. 8 $$\mathrm{kW/cm}^2$$
kW
/
cm
2
. However, the directed transmission into an aperture is only constant before any thermal lensing of blooming occurs.
Funder
Fraunhofer Institute for High Speed Dynamics (EMI)
Publisher
Springer Science and Business Media LLC
Cited by
4 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献