ISSN 1054660X, Laser Physics, 2009, Vol. 19, No. 11, pp. 2082–2085.
© Pleiades Publishing, Ltd., 2009.
Original Russian Text © Astro, Ltd., 2009.
2082
1
1. INTRODUCTION
The ps or fs laser pulses are needed in several ways,
such as micromachining, laser ranging, surgery and
spectroscopy. It is well known that this kind of laser
pulses can be generated by diode pumped systems with
Qswitching and mode locking (QML). It usually
occurs in the modelocked lasers using saturable
absorbers, such as Cr
4+
:YAG [1–3], GaAs [4–7],
LiF:F
2
[8], or LTIn
0.25
Ga
0.75
As [9]. However, the
pulse train was usually unstable. In order to obtain
more stable QML pulses, actively QML was intro
duced. Especially, the actively QML by using an
acoustooptic (AO) modulator can lead to a stable
QML regime of operation with considerable enhance
ment in peak power. By now, this kind of stable pulses
have been realized in a variety of lasers, like Nd:YVO
4
[10, 11] and Nd:GdVO
4
[12].
As we know, the neodymiumdoped vanadate crys
tals, Nd:YVO
4
and Nd:GdVO
4
, play an important role
in diodepumped laser system. Recently, Nd:LuVO
4
,
whose physical properties are similar to those of the
Nd:YVO
4
and Nd:GdVO
4
, has emerged as a promising
laser crystal for diode pumping. This kind of crystal
possesses even greater absorption cross section (6.9
×
10
–19
cm
2
) at 0.8
μ
m and emission cross section
(14.6
×
10
–19
cm
2
) at 1.06
μ
m and even wider fluores
cence line width (
Δλ ≈
1.5 nm) than those of both
Nd:YVO
4
and Nd:GdVO
4
. Compared to Nd:YVO
4
and
Nd:GdVO
4
, Nd:LuVO
4
lasers have higher slope effi
ciency and higher output power [2, 5, 6, 12–15]. So it
has attracted more interests.
1
The article is published in the original.
In this work, we report the results of an actively
Qswitched and mode locked Nd:LuVO
4
laser in order
to get better results than before. By using AO modula
tor only, a stable pulse train with great average output
power is obtained. Also we used a Ztype cavity,
because this kind of cavity is longer than threemirror
cavity and can strength the photon intensity in the
cavity. The higher average output power and deeper
modulation depth can be obtained.
2. EXPERIMENTAL SETUP
The schematic setup of our laser is depicted in
Fig. 1. The pump source employed was a fibercou
pled laserdiode array (FAP system, COHERENT
Inc., USA) which worked at the maximum absorption
wavelength (808 nm) of the Nd
3+
ions. The pump
beam was focused into the laser crystal with a spot
SOLID STATE
AND LIQUID LASERS
Simultaneous Mode Locking in an AcoustoOptic
QSwitched Nd:LuVO
4
Laser
1
G. Zhang
a
, S. Z. Zhao
a
,
*, Y. F. Li
a
, G. Q. Li
a
, D. C. Li
a
, K. J. Yang
a
,
K. Cheng
a
, H. B. Ge
a
, and Z. G. Yu
b
a
School of Information Science and Engineering, Shandong University, Jinan, 250100 China
b
Shandong Bright Optronics Inc., Jinan, 250100 China
*email: shengzhi_zhao@sdu.edu.cn
Received June 10, 2009; in final form, June 12, 2009; published online September 23, 2009
Abstract
—Simultaneous mode locking had been obtained in acoustooptic Qswitched Nd:LuVO
4
laser by
using a Ztype cavity. Pulses with great average output power and narrow pulse width were observed in our
experiment. The modulation depth is nearly 90% and the width of Qswitched envelope is about 70 ns, and
both maintained constant with the increase of pump power. The maximum average output power of 1.83 W
was obtained when the incident pump power was 6.78 W and the Qswitched envelop repetition frequency
was 30 kHz. Also the average pulse width of the mode locking among the Qswitched envelope is estimated
to be about 200 ps.
PACS numbers: 42.55.Px
DOI:
10.1134/S1054660X09210178
Fig. 1.
Configuration of actively Qswitched and mode
locked Nd:LuVO
4
laser.
M1
M2
M3 M4
Fibercoupled
laser diode
Focusing
optics
Nd:LuVO
4
AOM
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