Amplified random fiber laser-pumped mid-infrared
optical parametric oscillator
Yaping Shang (尚亚萍)
1,2,3
, Meili Shen (沈梅力)
1,2,3
, Peng Wang (王 鹏)
1,2,3
,
Xiao Li (李 霄)
1,2,3,4,
*, and Xiaojun Xu (许晓军)
1,2,3,
**
1
College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha 410073, China
2
Hunan Provincial Key Laboratory of High Energy Laser Technology, Changsha 410073, China
3
Hunan Provincial Collaborative Innovation Center of High Power Fiber Laser, Changsha 410073, China
4
State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
*Corresponding author: crazy.li@163.com; **corresponding author: xuxj@21cn.com
Received July 14, 2016; accepted October 14, 2016; posted online November 14, 2016
In this Letter, we report, for the first time to our knowledge, on a continuous-wave, singly resonant optical
parametric oscillator using an MgO: PPLN crystal pumped by an all-fiberized master-oscillator power amplifier
structured amplified random fiber laser. An idler output power of 2.46 W at 3752 nm is achieved with excellent
beam quality, and the corresponding pump-to-idler conversion efficiency is 9.6% at room temperature. The idler
output power exhibits a peak-to-peak power stability better than 12.7%, and the corresponding standard
deviation is better than 3.6% RMS in about 20 min at the maximum output power. Meanwhile, other character-
istics of the generated signal and idler laser are studied in detail and not only offered an effective guide in the
research of optical parametric processes in the case of a continuous spectrum, but also broadened the range of
random fiber laser applications.
OCIS codes: 190.4975, 190.4970.
doi: 10.3788/COL201614.121901.
Many applications, such as environmental monitoring,
high-resolution molecular spectroscopy, and infrared
countermeasures, require mid-infrared (MIR) sources
operating in the 3–5 μm wavelength range
[1–3]
. Optical
parametric oscillators
[4–20]
(OPOs), especially fiber laser-
pumped MgO: PPLN OPOs
[10–20]
, provide an effective ap-
proach to generate MIR lasers for their compact volume,
electrical operation, and high conve rsion efficiency, which
have attracted the interest of many researchers. In 2014,
we reported the highest continuous-wave (CW) output
power of 34.2 W at 3.35 μm from an MgO: PPLN OPO,
which was pumped by a homemade quasi-si ngle-frequency
(SF) Yb-doped fiber laser
[21]
. A higher idler laser is hard to
obtain. One potential reason for this is that the nonline-
arity effect (such as the self-pulsation effect) has a signifi-
cant influence on the performances of conventional fiber
lasers under high power output scaling, such as spectral
broadening, temporal instability, and intensity fluctua-
tions
[22,23]
. All of these would have unfavorable influences
on the following optical parametric processes, including
the power instability and low pump-to-idler conversion
efficiency, which prevents OPOs from further power scaling.
Recently, the concept of random fiber lasers (RFLs) has
attracted a great deal of attention for its ability to gener-
ate incoherent light free from mode competition without a
traditional laser resonator and ensure the stationary nar-
row-band continuous modeless spectrum
[24–30]
. The RFLs
took a big step forward when, in the year 2010
[24]
, a random
distributed feedback (RDFB) fiber laser based on Raman
amplification and distributed Rayleigh scattering feed-
back in a single-mode fiber (SMF) was reported. Since
then, more and more scholars have been committed to
the research in this field. In 2015, Du et al.
[29]
demonstrated
a kW-class fiber amplifier seeded by an RFL with a spec-
tral-broadening-free property caused by the temporal sta-
bility of the RFL seed, which was quite different from a
traditional high-power fiber amplifier. Early this year,
Dontsova et al.
[30]
reported the first experimental study
of frequency doubling an RFL in an MgO: PPLN crystal,
and by contrast, the highest second harmonic generation
(SHG) efficiency was obtained for the RDFB Raman fiber
laser with the fiber Bragg grating (FBG). On these bases,
the corresponding experiments of a singly resonant optical
parametric oscillator (SRO) pumped by a high-power,
all-fiberized, master oscillator power amplifier (MOPA)-
configuration-amplified RFL were carried out.
In this Letter, we reported on, to our knowledge, what
was the first experimental demonstration of an SRO
pumped by an amplified RFL. The characteristics of the
generated signal and idler laser have been studied in detail.
The experimental results were of great interest in terms of
both the investigation of optical parametric processes in
the case of a continuous spectrum and the extension of
the range of RFL applications.
An experimental schematic diagram of the amplified
RFL-pumped MIR OPO system is illustrated in Fig.
1.
The OPO was pumped by a homemade high-power non-
linearly polarized 1070 nm amplified RFL, which was com-
posed of a half-cavity structure, tempo rally stable RDFB
Raman fiber laser and a high-power fiber amplifier stage,
similar to the MOPA described in Ref. [
29], except that
the gain fiber used in the amplifier was characterized
COL 14(12), 121901(2016) CHINESE OPTICS LETTERS December 10, 2016
1671-7694/2016/121901(4) 121901-1 © 2016 Chinese Optics Letters
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