The thin-disk laser technology is the key to laser systems delivering high pulse energy (several 100 mJ up to the Joule level) in
combination with high repetition rate on the kHz level. At MBI we started the work on thin-disk lasers to setup a driver for
an X-ray laser. We aimed at laser parameters of more than 500 mJ at 100 Hz repetition rate. As laser medium Yb doped YAG was chosen.
The required fiber coupled pump laser diodes emitting at 940 nm wavelength were developed at the
Ferdinand Braun Institut who was our partner in this project supported by
Pro FIT . Further
partners were the group of A. Giesen from the
Institut für Strahlwerkzeuge (IFSW)
as well as Trumpf Laser Technology and
Dausinger & Giesen.
Motivated by the success of the first project the subsequent development step aimed at more than 1 Joule laser pulse energy. This
project was financed by
Several thin-disk laser amplifiers have been developed. The amplifier that has been set up most often is a regenerative amplifier.
In this type of amplifier a very weak laser pulse of several nano-Joule pulse energy is amplified as long as an electro-optical switch
opens the amplifier for the laser pulse to leave. The latest version of this amplifier can be used to amplify laser pulse to more than 300 mJ
pulse energy at a repetition rate of 100 Hz. In general these regenerative amplifiers are used as pre-amplifiers. The laser pulses are then
further amplified in a multi-pass or a ring amplifier. The multi-pass amplifiers we have set up could be operated with up
to 500 mJ laser pulse energy. Also a ring amplifier had been developed amplifying a laser pulse to more than 1 J at 100 Hz
One of the most important element in thin-disk laser development is the thin-disk itself. A large portion of the time was invested in
the manufacturing of the thin-disks. Since the laser beam is reflected from the backside of the disk the optical quality of the
laser disk must be as good as the optical quality of a mirror, but the thin-disk is only a few hundred micrometer thick!
Therefore, attaching the thin-disk to a heat-sink is a very sophisticated process.