High-power PPMgLN-based optical parametric
oscillator pumped by a linearly polarized,
semi-fiber-couple d acousto-optic
Q-switched fiber master oscillator
power amplifier
Tao Chen, Peipei Jiang, Dingzhong Yang, Chengzhi Hu, Bo Wu, and Yonghang Shen*
State Key Laboratory of Modern Optical Instrumentation, Department of Optical Engineering,
Zhejiang University, Hangzhou 310027, China
*Corresponding author: physyh@zju.edu.cn
Received 28 May 2013; revised 26 July 2013; accepted 31 July 2013;
posted 1 August 2013 (Doc. ID 191252); published 28 August 2013
We have experimentally demonstrated a periodically poled magnesium-oxide-doped lithium niobate
(PPMgLN)-based, fiber-laser-pumped optical parametric oscillator (OPO) generating idler wavelength
of 3.82 μm. The pump fiber laser was constructed with a linearly polarized, semi-fiber-coupled
acousto-optic Q-switched fiber oscillator and a polarization-maintaining fiber amplifier with pulse du-
ration of 190 ns at the highest output power. The OPO was specifically configured in single-pass, singly
resonant linear cavity structure to avoid the damage risk of the pump fiber laser, which is always a seri-
ous issue in the fiber-laser-pumped, double-pass, singly oscillating structured OPOs. Under the highest
pump power of 25 W, an idler average output power of 3.27 W with one-hour peak-to-peak instability of
5.2% was obtained. The measured M
2
factors were 1.98 and 1.44 for horizontal and vertical axis, respec-
tively. The high power stability and good beam quality demonstrated the suitability of such technology for
practical application. © 2013 Optical Society of America
OCIS codes: (140.3615) Lasers, ytterbium; (190.4970) Parametric oscillators and amplifiers.
http://dx.doi.org/10.1364/AO.52.006316
1. Introduction
Laser emissions around 3–4 μm, which are typically
produced from periodically poled magnesium-oxide-
doped lithium niobate (PPMgLN)-based optical
parametric oscillators (OPOs), are versatile sources
for environmental monitoring, missile counter-
measures, and medical diagnostics [
1,2]. In terms
of environmental monitoring, robust portable mid-
infrared (IR) sources with high wall-plug efficiencies
and small dimensions are beneficial, though usually
beyond the abilities of OPOs pumped by conventional
bulky solid state lasers with water cooling systems.
As for missile countermeasures, IR sources with high
average power as well as high peak power at the
wavelength from 3.8 to 4 μm are favorable to saturate
the IR detectors with little atmospheric absorption.
In both cases, good beam quality is required to en-
hance the working distance. According to these
requirements, fiber lasers are supposed to be the best
candidates among all the OPO pump sources due to
their compactness, robustness, excellent beam qual-
ity, and simple thermal management schemes [
3].
Therefore, fiber-laser-pumped OPOs have been ex-
tensively investigated from continuous wave (CW)
to ultrashort pulsed operation schemes [
4–13].
Among all these pump sources, fiber lasers with tens
1559-128X/13/256316-06$15.00/0
© 2013 Optical Society of America
6316 APPLIED OPTICS / Vol. 52, No. 25 / 1 September 2013