COL 11(12), 121404(2013) CHINESE OPTICS LETTERS December 10, 2013
Fluorescence spectrum, thermal properties, and
continuous-wave laser performance of the mixed crystal
Nd:Lu
0.99
La
0.01
VO
4
Yunzheng Wang
(
)
1
,
Bin Zhao
(
ëëë
RRR
)
2
,
Zhuang Zhuo
(
RRR FFF
)
1∗
,
Jingxuan Wang
(
···
ZZZ
)
1
,
Liqiang Zhang
(
ÜÜÜ
www
rrr
)
1
,
Huabing Qin
(
uuu
WWW
)
3
,
and Jianzhong Chen
(
ïïï
¥¥¥
)
2
1
College of Information Science and Engineering, Shandong University, Jinan 250100, China
2
College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350108, China
3
Shandong Inspur Huaguang Optoelectronics Co., Ltd., Weifang, 261061, China
∗
Corresponding author: zhuozhuang@sdu.edu.cn
Received September 25, 2013; accepted November 12, 2013; posted online December 9, 2013
The fluorescence spectrum and thermal properties of the mixed crystal Nd:Lu
0.99
La
0.01
VO
4
are determined.
The strongest emission peak located at 1065.6 nm had a full width at half maximum (FWHM) of 2.1 nm.
Continuous-wave (CW) laser performance is demonstrated by a compact planar–planar cavity that is end-
pumped by a diode laser. The laser output characteristics are investigated by using output couplers with
different transmissions. A maximum CW output power of 8.09 W was obtained at an incident pump power
of 19.4 W, which corresponds to an optical-to-optical conversion efficiency of 41.7% and a slope efficiency
of 54.6%. The dependence of optimum transmission on pump power is calculated theoretically and is found
to be consistent with experimental results.
OCIS codes: 140.3380, 350.6830, 140.3480, 140.3580.
doi: 10.3788/COL201311.121404.
Presently, diode-pumped solid-state lasers have been
widely used in numerous application fields, including ma-
terial processing, medical devices, and scientific instru-
ments. In such applications, laser crystals serve a key
function in determining laser performance. Compared
with Nd:YAG, Nd-doped single vanadate crystals, such
as Nd:YVO
[1−3]
4
, Nd:GdVO
[4−6]
4
, and Nd:LuVO
[7−9]
4
,
have been proven to be excellent gain mediums for diode-
pumped solid-state laser operations at modest output
power levels because of their broad absorption band-
width, large emission cross sections, and polarized emis-
sion. However, large emission cross sections and short
upper-level lifetimes result in small energy storage ca-
pacities in the
Q-switching operation regime. In ad-
dition, a narrow fluorescence width leads to difficulty
in obtaining sub-picosecond pulses during mode-locking
operation. The inhomogeneous broadening of the spec-
tra enables Nd-doped mixed vanadate crystals to reduce
emission cross sections and to increase fluorescence life-
time while retaining the advantages of single vanadate
crystals. A large number of mixed vanadate crystals,
such as Nd:La
x
Gd
1−x
VO
[10]
4
, Nd:La
x
Y
1−x
VO
4
[11,12]
,
Nd:Lu
x
Y
1−x
VO
4
[13,14]
, Nd:Gd
x
Lu
1−x
VO
4
[15]
, Nd:Y
x
Gd
1−x
VO
4
[16]
, and Nd:Gd
0.33
Lu
0.33
Y
0.33
VO
4
[17]
, have
been grown and demonstrated to be excellent gain candi-
dates in high peak power Q-switching and mode-locking
laser operations. In 2012, Huang et al. reported on
the continuous-wave (CW) and actively Q-switching laser
performance of Nd:Lu
0.99
La
0.01
VO
4
at 1.06 µm; they ob-
tained an output power of 6.26 W for CW operation
and an average output power of 6.06 W for Q-switching
operation
[18]
.
In this letter, we report on the fluorescent spectral
properties of the mixed crystal Nd:Lu
0.99
La
0.01
VO
4
. We
measured its thermal focal length based on incident pump
power. The laser behavior of Nd:Lu
0.99
La
0.01
VO
4
was in-
vestigated sufficiently by using a compact planar–planar
resonant cavity at different output couplers. A maxi-
mum CW output power of 8.09 W was obtained at an
incident pump power of 19.4 W, which corresponds to
an optical-to-optical conversion efficiency of 41.7% and
a slope efficiency of 54.6%. Finally, optimum trans-
mission was theoretically investigated at different pump
powers. The results exhibit fair agreement with experi-
mental data.
The mixed crystal Nd:Lu
0.99
La
0.01
VO
4
, which is an iso-
morphism of Nd:LuVO
4
, was grown via the Czochralski
method with a Nd doping concentration of 0.25%. La
ions replaced a fraction of Lu ions, and the crystal re-
tained its tetragonal symmetry. The fluorescence spec-
trum was obtained by an Edinburgh FLS920 fluorescence
spectrophotometer (Edinburgh Instruments Ltd., UK) at
room temperature. Figure 1 shows the fluorescence spec-
trum ranging from 960 to 1450 nm with a resolution of
0.15 nm.
Fig. 1. Fluorescence spectrum of the mixed crystal
Nd:Lu
0.99
La
0.01
VO
4
.
1671-7694/2013/121404(4) 121404-1
c
2013 Chinese Optics Letters