High Power Laser Science and Engineering, (2018), Vol. 6, e62, 10 pages.
© The Author(s) 2018. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/
licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.
doi:10.1017/hpl.2018.58
Overview of ytterbium based transparent ceramics for
diode pumped high energy solid-state lasers
Samuel Paul David, Venkatesan Jambunathan, Antonio Lucianetti, and Tomas Mocek
HiLASE Centre, Institute of Physics of the Czech Academy of Sciences, Za Radnic
´
ı 828/5, 25241, Doln
´
ı B
ˇ
re
ˇ
zany, Czech Republic
(Received 25 July 2018; revised 6 September 2018; accepted 9 November 2018)
Abstract
Development of high energy laser sources with nanosecond pulses at several hertz values for repetition rate has been very
attractive in recent years due to their great potential for practical applications. With the recent advancement in fabricating
large size laser quality transparent ceramics, diode pumped solid-state laser generating pulse energy of 100 J at 10 Hz
has been recently realized at HiLASE center using Yb:YAG ceramic with Cr:YAG cladding. This review discusses Yb
based high energy lasers, specific laser geometries for efficient thermal management and the role of transparent ceramics
in such diode pumped high-energy-class solid-state lasers around the world.
Keywords: diode pumped solid-state lasers; high energy lasers; laser materials; transparent ceramics
1. Introduction
High power diode pumped solid-state lasers have gained
more attention in recent years due to their potential scientific
and technological applications ranging from laser fusion
research to industrial materials processing. In addition,
efficient, high energy, pulsed laser systems operating at
high pulse repetition rates (10 Hz and beyond) are the ideal
pump sources for ultra-high intensity femtosecond petawatt-
class lasers generating high-brightness secondary radiation
(X-ray, gamma-ray) and particle (electron, proton, ion,
muon) sources. These have potential applications for novel
medical therapies, and in high-resolution radiography and
advanced imaging for industrial and security sectors. The
improvements in semiconductor technology result in high
power semiconductor laser diodes with high efficiency
and power over long life times. High power laser diodes
coupled by coupling optics or optical fiber are efficient
pump sources for solid-state lasers based on materials such
as crystals, glasses or ceramics. Compactness, portability
and high efficiency make diode pumped solid-state lasers
more desirable for wide range of applications. Such high
energy compact lasers generating an average output power
exceeding 100 kW with pulse energy of 500 J were chosen
for military purposes as a high energy laser weaponry
due to the ease of mounting them on moving vehicle or
even on an aircraft
[1]
. Northrop Grumman demonstrated
Correspondence to: S. Paul David, HiLASE Centre, Institute of Physics
of the Czech Academy of Sciences, Czech Republic.
Email: Samuel-Paul.David@hilase.cz
105 kW output power by phase locking seven laser chain
slabs (15 kW building blocks) pumped by high power
laser diodes. In the field of plasma physics, laser–plasma
interactions under high energy lasers can help scientists to
understand relativistic plasma physics including compact
particle accelerators and fast ignition of fusion targets.
Extreme light infrastructure (ELI) will provide fs laser pulses
with tens of joules of energy allowing generation of high
energy density plasmas that are characterized by pressures
above 1 Mbar (1 bar = 10
5
Pa) or energy densities above
10
11
J/m
3[2]
. High-energy-class lasers with nanosecond
pulses are in general limited to very low repetition rate in
the order of few shots per minute or per hour, resulting
in low average power. Such low average power lasers
do not satisfy the requirements for advanced applications
such as laser-driven inertial confinement fusion (ICF).
Highly repetitive pulses >10 Hz with multi-joule energy are
important for several applications
[3]
such as laser induced
damage threshold (LIDT) of optics
[4]
and in aerospace
industries to improve the fatigue life of metals and alloys
by laser shock peening (LSP) technique
[5]
. With such
wide application fields, several research groups around the
world have been involved in prototyping high repetition high
energy lasers. Bottlenecks to obtain high energy are laser
gain media, pump sources and the cooling mechanism. A
large size gain medium is necessary and such sizes can be
easily made in glasses rather than crystalline form. The most
common high energy laser based facilities such as National
Ignition Facility (NIF) in USA, Shenguang-III in China, and
Laser Mega Joule (LMJ) in France are based on Nd: glass
[6]
.
1