CsPbBr
3
perovskite quantum dots: saturable
absorption properties and passively
Q-switched visible lasers
JINGZHOU LI,
1,2
HONGXING DONG,
1,5
BIN XU,
3
SAIFENG ZHANG,
1
ZHIPING CAI,
3
JUN WANG,
1
AND LONG ZHANG
1,4,
*
1
Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science,
Shanghai 201800, China
2
University of Chinese Academy of Sciences, Beijing 100049, China
3
Department of Electronic Engineering, Xiamen University, Xiamen 361005, China
4
IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240, China
5
e-mail: hongxingd@siom.ac.cn
*Corresponding author: lzhang@siom.ac.cn
Received 19 June 2017; revised 20 July 2017; accepted 24 July 2017; posted 25 July 2017 (Doc. ID 298302); published 6 September 2017
This work presents the saturable absorption (SA) properties of CsPbBr
3
perovskite quantum dots (QDs). The
perovskite QDs show excellent SA performance with a nonlinear absorption coefficient of −35 × 10
−2
cm∕GW
and a figure of merit of 3.7×10
−14
esu cm. Further, their use as saturable absorbers in a passively Q-switched
visible solid-state laser for the generation of soliton pulses is demonstrated. These results demonstrate the
potential for the perovskite QDs to act as saturable absorbers.
© 2017 Chinese Laser Press
OCIS codes: (190.4400) Nonlinear optics, materials; (160.4670) Optical materials; (160.4760) Optical properties.
https://doi.org/10.1364/PRJ.5.000457
1. INTRODUCTION
Materials crystallizing with a perovskite structure (a ternary
compound of the form AMX
3
) have received considerable at-
tention owing to their excellent ferroelectric, paraelectric, and
optoelectronic properties [1,2]. Studies on these materials have
been ongoing since the beginning of the last century, but have
mainly concentrated upon the structural and electromagnetic
properties of the compounds. Recently, lead halide perovskite
semiconductors (where A CH
3
NH
3
, Cs, etc.; M Pb, Ge;
X Cl, Br, I) have returned to the focus of researchers because
of their remarkable performance in photo-electronic fields
[3–6]. These ternary compounds not only possess low densities
for mid-gap trap states and excellent band-gap tunability, but
also exhibit high photoluminescence (PL) efficiency (>90%)
and narrow PL bandwidths (12–40 nm). Among them, all-
inorganic CsPbX
3
perovskite quantum dots (QDs) have shown
the potential for application in next-generation optoelectronic
materials [7–9].
To date, most research on perovskite QDs has concentrated
on the linear optical region. Studies on the nonlinear properties
have been relatively rare, and few have focused on two-photon
or multiphoton absorption and emission [10–12]. In fact, their
unique quantized discrete energy structure and direct band gap
imply lower saturation intensity compared to that of traditional
saturable absorption (SA) materials such GaAs and two-
dimensional nanomaterials (MoS
2
and graphene). Further,
compared to metal chalcogenide QDs, perovskite QDs exhibit
faster carrier dynamics [13]. Perovskite semiconductors also
have a relatively low defect concentration, which reduces the
scattering centers for non-radiative charge carrier recombina-
tion [14]. This is conductive to form the SA response. This
means that perovskite QDs are promising candidate materials
for saturable absorbers [15].
In this work, we focus on the SA properties of perovskite
QDs using an open-aperture Z-scan technique. The perovskite
QDs exhibit significant SA for femtosecond pulses at
515 nm, resulting in a nonlinear absorption coefficient of
α
NL
∼ −35 8 × 10
−2
cm∕GW. Based on the perovskite QDs
acting as saturable absorbers, superior passive Q-switching
behavior was observed.
2. EXPERIMENT
The CsPbBr
3
QDs were synthesized via a chemical solution
route similar to a previously reported method [16]. First, a
CsOA
2
solution was obtained by dissolving CsCO
3
(2.394 mmol, 99.9%) in dried oleic acid (OA, 1.25 mL, 90%)
and dried octadecene (ODE, 20 mL, 90%) at 150°C under N
2
.
Then, ODE (10 mL, 90%) and PbBr
2
(0.375 mmol,
Research Article
Vol. 5, No. 5 / October 2017 / Photonics Research 457
2327-9125/17/050457-04 Journal © 2017 Chinese Laser Press
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