High-power MoTe
2
-based passively Q-switched
erbium-doped fiber laser
Mengli Liu (刘孟丽)
1
, Wenjun Liu (刘文军)
1,2,
*, Peiguang Yan (闫培光)
3
,
Shaobo Fang (方少波)
2
, Hao Teng (滕 浩)
2
, and Zhiyi Wei (魏志义)
2
1
State Key Laboratory of Information Photonics and Optical Communications, School of Science,
Beijing University of Posts and Telecommunications, Beijing 100876, China
2
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences,
Beijing 100190, China
3
Shenzhen Key Laboratory of Laser Engineering, College of Optoelectronic Engineering, Shenzhen University,
Shenzhen 518060, China
*Corresponding author: jungliu@bupt.edu.cn
Received October 30, 2017; accepted December 22, 2017; posted online January 26, 2018
Materials in the transition metal dichalcogenide family, including WS
2
, MoS
2
, WSe
2
, and MoSe
2
, etc., have
captured a substantial amount of attention due to their remarkable nonlinearities and optoelectronic properties.
Compared with WS
2
and MoS
2
, the monolayered MoTe
2
owns a smaller direct bandgap of 1.1 eV. It is beneficial
for the applications in broadband absorption. In this letter, using the magnetron sputtering technique, MoTe
2
is
deposited on the surface of the tapered fiber to be assembled into the saturable absorber. We first implement the
MoTe
2
-based Q-switched fiber laser operating at the wavelength of 1559 nm. The minimum pulse duration and
signal-to-noise ratio are 677 ns and 63 dB, respectively. Moreover, the output power of 25 mW is impressive
compared with previous work. We believe that MoTe
2
is a promising 2D material for ultrafast photonic devices
in the high-power Q-switched fiber lasers.
OCIS codes: 160.4330, 140.3540, 140.3510.
doi: 10.3788/COL201816.020007.
Q-switched fiber lasers have been extensively applied in
optical telecommunications, environmental sensing, and
industrial processing due to their characteristics of narrow
pulse duration and high peak power
[1–4]
. Employing
saturable absorbers (SAs) as optical modulator devices
is a preferred implementation method for the passively
Q-switched system because the quality factor Q of the
optical resonance can be expediently regulated by the
intensity-dependent nonlinearity of SAs. At present, semi-
conductor saturable absorber mirrors (SESAMs) are the
mature SAs in commercial applications due to the precise
control of the absorption wavelength, saturation thresh-
old, modulation depth, and relaxation time
[5]
. However,
limited bandwidth and high cost become the problems
to be sol ved, which partly restricts the further develop-
ment of SESAMs
[6]
. Graphene, as one of representative
two-dimensional (2D) nanomaterials, shows extraordi-
nary talents in fiber lasers because of its ultrafast recovery
time, high damage threshold, and broadband absorption
properties
[7–9]
. Inspired by graphene, the topological
insulators are also found to be excellent saturated absorp-
tion materials
[10,11]
. They have a great advantage in the
regulation of light due to their large modulation depth.
Black phosphorus has a direct bandgap from 0.3 eV
(body structure) to 1.5 eV (single layer)
[12,13]
. The direct
bandgap structure can guarantee ultrafast electronic
relaxation, and it is especially beneficial to the field of
ultrafast photonics and high-frequency optoelectronics
[14]
.
Gold nanorods have the advantages of high nonlinear
coefficient, good optical fiber compatibility, ultrashort
response time, and easy preparation. Therefore, the SAs
based on gold nanomaterials have also attracted much
attention
[15]
.
Meanwhile, investigations on transition metal dichalco-
genides (TMDs) are emerging at a fast pace because of
their preeminent nonlinear effects and physical proper-
ties
[16–20]
. In TMDs, the atoms in-plane are covalently
bonded, while the atoms between each layer are connected
by weak van der Waal forces, which is beneficial to the
exfoliation of few-layer nanosheets
[21]
. In the past few
years, WS
2
has been employed for the generation of ultra-
short optical pulses and exhibited large second-order non-
linear susceptibility
[22–25]
.MoS
2
, as the analogue of WS
2
,
is also proved to have saturable absorption properties.
Moreover, MoS
2
-based Q-switched and mode-locked fiber
lasers have been implemented at 1, 1.5, and 2 μm. Those
properties indicate that WS
2
and MoS
2
can be both
used as broadband SAs
[26–29]
. The further exploration s of
WSe
2
and MoSe
2
are also gradually strengthened and
developed
[30]
. The substantial researches on the members
of the TMD family indicate that they all exhibit broad-
band absorption properties and have a great potential
in electroopti c applications, which paves the way for
the exploration of new members of the TMD family.
Recently, the preparations and electrooptic properties
of MoTe
2
have been reported
[31–34]
, but the applications
in Q-switched fiber lasers have hardly been realized.
The layer-dependent bandgap is the typical feature of
COL 16(2), 020007(2018) CHINESE OPTICS LETTERS February 10, 2018
1671-7694/2018/020007(5) 020007-1 © 2018 Chinese Optics Letters