516 mW, nanosecond Nd:LuAG laser Q-switched by
gold nanorods
Guangju Zhang (张光举)
1
, Tinghao Liu (刘廷昊)
1
, Yijie Shen (申艺杰)
1
,
Chujun Zhao (赵楚军)
2
, Bin Huang (黄 斌)
2
, Zhe Kang (康 喆)
3
, Guanshi Qin (秦冠仕)
3
,
Qiang Liu (柳 强)
1
, and Xing Fu (付 星)
1,
*
1
State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments,
Tsinghua University, Beijing 100084, China
2
Key Laboratory for Micro-/Nano-Optoelectronic Devices of Ministry of Education, IFSA Collaborative Innovation
Center, School of Physics and Electronics, Hunan University, Changsha 410082, China
3
State Key Laboratory on Integrated Opto-electronics, College of Electronic Science & Engineering, Jilin University,
Changchun 130012, China
*Corresponding author: fuxing@mail.tsinghua.edu.cn
Received September 8, 2017; accepted October 27, 2017; posted online December 27, 2017
Q-switched operation of an Nd:LuAG laser using gold nanorods (GNRs) as the saturable absorber (SA) is
reported, which also produces the highest average power among the nanosecond Nd-doped Q-switched lasers
by GNRs-based SA. The applied GNRs are prepared using a seed-mediated growth method and then dropped
onto the quartz substrate to fabricate the SA. The average power of the Q-switched laser is 516 mW with the
shortest pulse duration of 606.7 ns and the repetition rate of 265.1 kHz.
OCIS codes: 160.3380, 140.3540, 160.4236, 140.3580.
doi: 10.3788/COL201816.020011.
Solid-state pulsed lasers with ultrashort duration as well
as high peak power are effective optical sources widely
used in multiple areas, such as medicine, sensing, telecom-
munications, material processing, and scientific research.
Considerable efforts have been devoted to obtain pulses
with higher energy, shorter duration, and controllable rep-
etition rate. Ultra-short pulsed have been generated from
different Nd-doped lasers such as Nd:YAG, Nd:YVO
4
,
Nd:GdVO
4
, Nd:LGGG, and Nd:LuAG have been utilized
in the solid-state pulsed laser systems. Among them,
Nd:LuAG is a recently grown one, which is believed to
be very promising as the laser active media because of
its attractive physical and chemical properties. An
Nd:LuAG crystal has a long fluorescence lifetime
(277 μs
[1]
), combined with high thermal conductivity
(9.6 W∕m· K
[2]
), and moderate saturation fluence, indi-
cating its potential in obtaining high-energy pulses using
techniques such as passively Q-switching. By now, several
reports have been presented on Q-switched Nd:LuAG
lasers with different saturable absorbers (SAs)
[3–8]
.
As the key element in the passively Q-switching, the SA
periodically modulates the Q factor of the laser cavity to
achieve the pulsed operation. Therefore, the properties of
the SA intensively determine the performance of a pulsed
laser, and the demo nstration of the novel SA is also of
significance besides the gain medium. A semiconductor
SA mirror (SESAM) is a successful type of SA that is
widely applied in commercial pulsed lasers
[9]
. However,
its drawbacks, such as complex fabrication, narrow oper-
ation band, and high costs, limit further investigations
[10]
.
Compared to SESAM, a single-walled carbon nanotube
(SWCNT) exhibits several advantages of fast recovery
time, low saturation intensity, and high damage thresh-
old
[11,12]
. Moreover, SWCNT has a broadband oper ation,
and its fabrication is easy with a low cost
[12]
. In recent
years, the research focused on two-dimensional (2D)
materials has brought rapid development of the SA
family. These materials, including graphene
[13,14]
, topologi-
cal insulators
[15–18]
, transition metal dichalcogenides
[19,20]
,
and black phosphorus
[21,22]
, possess unique electronic and
photonic properties and demonstrate distinguished satu-
rable characteristics that are even more advantageous
than SWCNT.
More recently, gold nanorods (GNRs), which are the
typical metal nanoparticles investigated intensively in
biology and medicine, have demonstrated excellent SA
performance. This nanomaterial has special third-order
nonlinearity as determined by its surfac e plasmon reso-
nance (SPR)
[23]
. GNRs normally have two SPR absorption
bands defined as the transverse absorption band and the
longitudinal absorption band
[23]
. As to the longitudinal
absorption band, the corresponding absorption peak has
a flexible location by designing the aspect ratio of GNRs,
leading to a wide wavelength range of GNRs-based SA
[24]
.
The fast recovery time of a few picoseconds also contrib-
utes to the performance of GNRs as the SA, which will
facilitate the ultrashort pulse generation
[25]
. To date,
several reports have been presented on the GNRs
Q-switched and mode-locked lasers at a number of wave-
lengths from the visible band to 2 μm with the
pulse duration from femtoseconds to microseconds
[26–36]
,
illustrating the effective SA performance of GNRs similar
to 2D materials in the generation of a pulsed laser.
Among these, a few results have been reported on the
COL 16(2), 020011(2018) CHINESE OPTICS LETTERS February 10, 2018
1671-7694/2018/020011(5) 020011-1 © 2018 Chinese Optics Letters