Low-timing-jitter high-power mode-locked
1063 nm Nd:GdVO
4
master oscillator
power amplifier
ZHI-MIN WANG,FENG-FENG ZHANG,JUN-WEI ZUO,JING YANG,LEI YUAN,QIN-JUN PENG,*
D
A-FU CUI, AND ZU-YAN XU
Research Center for Laser Physics and Technology, Key Laboratory of Functional Crystal and Laser Technology,
Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
*Corresponding author: pengqinjun@163.com
Received 28 May 2015; revised 31 August 2015; accepted 7 September 2015; posted 8 September 2015 (Doc. ID 241975);
published 29 September 2015
A low-timing-jitter high-power semiconductor saturable absorber mirror mode-locked picosecond (ps) 1063 nm
Nd:GdVO
4
master oscillator power ampl ifier is presented. Using a single-pass Nd:GdVO
4
amplifier, an ampli-
fied laser with 21.5 W output power and 8.3 ps pulsewidth was achieved at 250 MHz repetition rate. Employing a
servo control, an average RMS timing jitter of ∼222 fs was realized. This laser can be used as a drive laser for
photocathode injectors in free-electron lasers.
© 2015 Optical Society of America
OCIS codes: (140.3425) Laser stabilization; (140.4050) Mode-locked lasers; (140.3280) Laser amplifiers; (140.2600) Free-electron
lasers (FELs).
http://dx.doi.org/10.1364/AO.54.008425
1. INTRODUCTION
In free-electron lasers (FELs), high-power picosecond (ps) lasers
with narrow pulsewidth and low timing jitter are desired and
are good drive sources for photocathode injectors [1,2]. For
ps lasers, Nd
3
-doped crystal materials (such as Nd:YAG,
Nd:YVO
4
, Nd:YLF, and Nd:GdVO
4
) are always adopted as
the main active elements. Among these laser crystals, neodym-
ium-doped gadolinium vanadate (Nd:GdVO
4
) crystal is a rela-
tively new one that was first introduced as a laser crystal in 1992
[3]. It has attracted much interest from researchers because of
its advantages to achieve passive mode-locked lasers, such as
high thermal conductivity, a large absorption coefficient, a large
stimulated-emission cross section, and a short upper-state life-
time. For instance, its thermal conductivity (11.7 W∕m∕K)
is higher than that of Nd:YVO
4
(5.1 W∕m∕K), and com-
parable to that of Nd:YAG (14 W∕m∕ K). Meanwhile, atten-
tion should be paid to the fact that Nd:GdVO
4
crystal has a
broader gain bandwidth (1.3 nm) than those of Nd:YVO
4
(0.96 nm) and Nd:YAG (0.45 nm) [4], which makes it a
potential crystal to produce high-power mode-locked lasers with
narrow pulsewidth.
Nd:GdVO
4
crystal used for mode locking with a semicon-
ductor saturable absorber mirror (SESAM) was reported for the
first time in 2003 [5], and 0.6 W output power with a pulse-
width of 7.7 ps was obtained. Subsequently, the higher average
power of passively mode-locked Nd:GdVO
4
lasers has been
presented [6–10]. For example, a 3.46 W passively mode-
locked Nd:GdVO
4
laser with 18.9 ps pulsewidth by using a
GaAs single crystal wafer simultaneously as the saturable
absorber and the output coupler (OC) was reported in 2004
[6]. A 6.3 W SESAM mode-locked Nd:GdVO
4
laser with a
pulsewidth of 6.2 ps was obtained in 2007 [7]. An up to 30 W
Nd:GdVO
4
laser with a pulsewidth of ∼20 ps was demon-
strated based on the nonlinear mirror technique [8]. Though
numerous studies relating to mode-locked ps Nd:GdVO
4
lasers
have been reported, surprisingly, there is very little information
available in the literature about low timing jitter. In 2004, the
first low-timing-jitter (∼146 fs) SESAM mode-locked 12 ps
Nd:GdVO
4
laser was reported; however, the average output
power generated was only around 0.5 W [9]. Later, a 5.68 W
SESAM mode-locked 7.4 ps Nd:GdVO
4
laser with a low
timing jitter of 286 fs was obtained in 2013 [10]. However,
to the best of our knowledge, no group has yet published
on a low-timing-jitter ps Nd :GdVO
4
laser with output power
more than 10 W.
In this paper, we present a 21.5 W SESAM mode-locked ps
Nd:GdVO
4
master oscillator power amplifier (MOPA) laser
with low timing jitter at pulsewidth of 8.3 ps. By stabilizing
the laser based on a servo control, an average RMS timing jitter
of ∼222 fs was realized at the repetition rate of 250 MHz.
To our knowledge, this is the highest average output power
for low-timing-jitter ps Nd:GdVO
4
lasers.
Research Article
Vol. 54, No. 28 / October 1 2015 / Applied Optics 8425
1559-128X/15/288425-04$15/0$15.00 © 2015 Optical Society of America