Page 261 - High Power Laser Handbook

230 So l i d - S t at e La s e r s Thin-Disc Lasers 231

Host Material
YAG Yb , Nd (3+) 9–11 , Tm (3+) 12,13 , Ho (3+) 14
3+
YVO Yb (3+) 15–17 , Nd (3+) 18–21
4
Sc O 3 Yb (3+) 22
2
Lu O 3 Yb (3+) 22,23
2
KY(WO ) Yb (3+) 22
4 2
KGd(WO ) Yb (3+) 22
4 2
NaGd(WO ) Yb (3+) 15,17
4 2
LaSc (BO ) Yb (3+) 24
3 3 4
Ca YO(BO ) Yb (3+) 25
4 3 3
GdVO Nd (3+) 21
4
ZnSe Cr (2+) 26
Table 10.1 Examples for Successful Combinations of Host
and Active Ions in the Thin-Disc Laser Setup

With neodymium-doped materials, not only the four-level transi-
tions could be used but also the quasi-three-level transitions, result-
ing in 5.8 W laser power at 914 nm with Nd:YVO and 25 W laser
20
power at 938 nm and 946 nm with Nd:YAG. 11

10.5 Numerical Modeling and Scaling

10.5.1 Average Temperature
Because the disc is very thin and the pump spot is large, one can assume
one-dimensional heat conduction. If we apply a pump power P pump on
a pump spot with radius r , absorption efficiency η , and heat genera-
p
abs
tion η heat to a disc with thickness h, that is made of a material with
thermal conductivity l , we will get as heat load per area:
th
P ηη
I = pump absheat (10.1)
heat π r p 2

This heat load will result in a parabolic temperature profile along the
axis inside the disc of
 z 1 z 2 
Tz() = T + I R  −  (10.2)
0 heat th disk h 2 2
,
 h 