High Power Laser Science and Engineering, (2019), Vol. 7, e35, 7 pages.
© The Author(s) 2019. 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.2019.16
High-repetition-rate and high-power picosecond
regenerative amplifier based on a single bulk
Nd:GdVO
4
crystal
Jie Guo
1
, Wei Wang
1,2
, Hua Lin
1
, and Xiaoyan Liang
1
1
State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences,
Shanghai 201800, China
2
Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
(Received 19 January 2019; revised 21 March 2019; accepted 4 April 2019)
Abstract
We report on a high-repetition-rate, high-power continuously pumped Nd:GdVO
4
regenerative amplifier. Numerical
simulations successfully pinpoint the optimum working point free of bifurcation instability with simultaneous efficient
energy extraction. At a repetition rate of 100 kHz, a maximum output power of 23 W was obtained with a pulse duration
of 27 ps, corresponding to a pulse energy of 230 µJ. The system displayed an outstanding stability with a root mean
square power noise as low as 0.3%. The geometry of the optical resonator and the pumping scheme enhanced output
power in the TEM
00
mode with a single bulk crystal. Accordingly, nearly diffraction-limited beam quality was produced
with M
2
≈ 1.2 at full pump power.
Keywords: diode-pumped solid state laser; high repetition rate regenerative amplifier; picosecond laser
1. Introduction
Compact, stable and high-power diode-pumped short-
pulse laser amplifier systems with excellent spatial qual-
ity are ideal sources for high-power optical parametric
chirped pulse amplification (OPCPA) and efficient laser
processing
[1–5]
. Among various configurations, regenerative
amplifiers (RAs) are routinely used to enhance the output of
mode-locked oscillators because of their ability to provide
gains of several orders of magnitude and a resonator
structure that maintains the spatial quality of the seed
[6–9]
.
In the past two decades, various solutions and architectures
have been proposed for power scaling of regenerative am-
plifiers. The thin-disk geometry was particularly impressive
for heat dissipation. Nubbemeyer et al. employed a Kerr-
lens mode-locked thin-disk oscillator to seed two stages of
regenerative amplifiers, including a thin-disk preamplifier
and a main amplifier comprising two thin-disk modules,
generating >200 mJ pulses at a 5 kHz repetition rate and
>100 mJ at a 10 kHz repetition rate
[10]
. The cryogenic
cooling technique offered another alternative to obtain a high
pulse energy at a 1 kHz repetition rate, although measures
were necessary to mitigate the reduced gain bandwidth
[11]
.
Correspondence to: X. Liang, No. 390 Qinghe Road, Jiading, Shanghai
201800, China. Email: liangxy@siom.ac.cn
Although not so aggressive in heat removal, laser systems
based on bulk materials generally employ simpler structures
and work more efficiently. These characteristics make bulk
materials favored choices as laser media in high-power
diode-pumped solid state lasers
[12–14]
. An average output
power of 34 W with pulses as short as 140 fs at a 500 kHz
repetition rate has been achieved by a bulk Yb:CALGO re-
generative amplifier with the implementation of the chirped
pulse amplification (CPA) technique
[15]
.
High-repetition-rate regenerative amplifiers are beneficial
for promoting industrial throughput and reducing data ac-
cumulation or processing time in scientific applications.
However, high repetition rates come with bifurcation and
even chaotic pulse train dynamics, in which the pulse en-
ergy is unstable
[16]
. This bifurcation-termed phenomenon
constitutes a major impediment for RAs operated at high
repetition rates
[3]
, where the operating parameters of the
laser systems have to be carefully optimized to maintain
equilibrium
[17–20]
. A detailed analysis concerning this prob-
lem is elaborated in the following section. For more than
a decade, several methods have been proposed to eliminate
this deleterious effect. The methodologies include raising
the seed energy
[19, 21]
, pumping at higher intensity
[17]
, op-
erating at the second operating point outside the unstable
region if the effect could not be thoroughly avoided
[22]
,
1