Generation of sub-100-fs pulses from a diode-pumped
Yb:Y
3
ScAl
4
O
12
ceramic laser
Jie Ma (马 杰)
1,2
, Jun Wang (王 俊)
2
, Deyuan Shen (沈德元)
1
, Akio Ikesue
3
,
and Dingyuan Tang (唐定远)
2,
*
1
Jiangsu Key Laboratory of Advanced Laser Materials and Devices, School of Physic and Electronic Engineering,
Jiangsu Normal University, Xuzhou 221116, China
2
School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore
3
World Lab Co. Ltd, Nagoya 4560023, Japan
*Corresponding author: EDYTang@ntu.edu.sg
Received September 16, 2017; accepted October 27, 2017; posted online November 20, 2017
We experimentally demonstrate the generation of sub-100-fs pulses from a diode-pumped passively mode-locked
Yb:Y
3
ScAl
4
O
12
(Yb:YSAG) ceramic laser. Stable mode-locked pulses as short as 96 fs at the central wavelength
of 1052 nm with a repetition rate of ∼102 MHz are obtained. The laser has a maximum average output power of
51 mW. To the best of our knowledge, these are so far the shortest pulses and the first demonstration of sub-100-
fs pulses obtained from the mode-locked Yb:YSAG ceramic lasers.
OCIS codes: 140.4050, 140.7090, 140.3380, 140.3580.
doi: 10.3788/COL201715.121403.
Since the first demonstration of high-efficiency laser oscil-
lation of the Nd:YAG ceramics in 1995, studies on ceramic
laser materials and ceramic lasers have attracted consid -
erable attention
[1–16]
. In comparison with single crystals
and glasses, ceramic laser materials not only have good
thermal, mechanical, and spectral properties, but also
can be made in a large size, composite structures, and con-
trolled dopant distributions. These advantages make the
rare-earth-doped transparent ceramics promising gain me-
dia for different lasers. So far, many rare-earth-doped
ceramic lasers have been reported with the same or even
higher continuous-wave (CW) laser operatio n efficiency
than that of the single crystals
[2–11]
. In the mode-locking
regime, ultrashort pulse ceramic lasers have also attracted
considerable interest. Mode-locking of a ceramic laser was
first demonstrated by Shirakawa et al. in 2003
[12]
. They
achieved stable mode-locked pulses with a 615 fs pulse
width and 420 mW average power in a diode-pumped
Yb:Y
2
O
3
ceramic laser. Subsequently, they further demon-
strated Kerr-lens mode-locking of diode-pumped Yb:Sc
2
O
3
and Yb:Lu
2
O
3
ceramic lasers
[13,14]
and achieved sub-100-fs
mode-locked pulses among the ceramic lasers. In the mean-
time, mode-locking of the Yb
3þ
-doped garnet ceramic lasers
has also been intensively investigated. Saikawa et al. first,
to the best of our knowledge, demonstrated the passive
mode-locking of a 15 at.% Yb:Y
3
ScAl
4
O
12
(Yb:YSAG)
ceramic chip in 2004, which generated 280 fs pulses with
an maximum average output power of 62 mW
[15]
.After-
ward, mode-locking of the Yb:YAG and Yb:LuAG ceramic
lasers was demonstrated in 2009 and 2012, generating
ultrashort pulses of 233 and 541 fs with average output
powers of 20 and 53 mW, respectively
[16,17]
.However,due
to the relatively sharp and narrow gain bandwidth
at around 1030 nm, it is challenging to obtain sub-100-fs
ultrashort pulses for the Yb
3þ
-doped garnet materials.
Only employing the Kerr-lens mode-locking technique
mode-locked pulses with less than 100 fs were obtained
in the Yb
3þ
-doped garnets
[18–20]
.
A technique to broaden the gain bandwidth of rare-
earth-doped garnets is to engineer the crystal properties
through crystal mixing or disordering. Using the crystal en-
gineering technique, even sub-50-fs pulses have been suc-
cessfully achieved in Yb:CaYAlO
4
[21]
, Yb:CaGdAlO
4
[22]
,
Yb:YCa
4
OðBO
3
Þ
3
[23]
, and Yb:NaYðWO
4
Þ
2
[24]
discorded
crystal lasers. It is therefore to be expected that, based
on the rare-earth-doped disordered ceramics, ultrashort
mode-locked pulses could also be achieved in the
Yb
3þ
-doped garnet ceramic lasers. The first, to the best
of our knowledge, demonstration of Yb
3þ
-doped disordered
transparent ceramic material was the Yb:YSAG ceramic
fabricated by Saikawa et al. in 2004
[25]
. Also, previous stud-
ies on the Yb:YSAG ceramic have shown that it has a
broader gain bandwidth than that of the Yb:YAG ceram-
ics
[15,25]
, implying it could be a good candidate to generate
ultrashort pulses among the family of Yb
3þ
-doped garnet
materials.
In this Letter, we report on the sub-100-fs mode-locked
pulse emission of a diode-pumped Yb:YSAG disordered
garnet ceramic laser. The absorption and emission spectra,
as well as the wavelength tuning characteristic of a
Yb:YSAG disordered ceramic laser, were investigated.
The CW operation wavelength of the laser had a tunable
range from 1029 to 1073 nm. Using a semiconductor satu-
rable absorber mirror (SESAM) as the mode locker, stable
CW mode-locked pulses with pulse duration of 96 fs and
pulse repetition rate of ∼102 MHz at the center wave-
length around 1052 nm were obtained. To the best of
our knowledge, these are so far the shortest pulses and,
also, the first demonstration of sub-100-fs pulses obtained
from the mode-locked Yb:YSAG ceramic lasers.
COL 15(12), 121403(2017) CHINESE OPTICS LETTERS December 10, 2017
1671-7694/2017/121403(4) 121403-1 © 2017 Chinese Optics Letters