All-optical PtSe
2
silicon photonic modulator with
ultra-high stability
KANGKANG WEI,
1,†
DELONG LI,
2,†
ZHITAO LIN,
2
ZHAO CHENG,
1
YUHAN YAO,
1
JIA GUO,
2
YUNZHENG WANG,
2
YUPENG ZHANG,
2
JIANJI DONG,
1,3
HAN ZHANG,
2,4
AND XINLIANG ZHANG
1
1
Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
2
Institute of Microscale Optoelectronics, Collaborative Innovation Centre for Optoelectronic Science & Technology, Key Laboratory of
Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering,
Shenzhen Key Laboratory of Micro-Nano Photonic Information Technology, Guangdong Laboratory of Artificial Intelligence and
Digital Economy (SZ), Shenzhen University, Shenzhen 518060, China
3
e-mail: jjdong@mail.hust.edu.cn
4
e-mail: hzhang@szu.edu.cn
Received 12 March 2020; revised 14 May 2020; accepted 21 May 2020; posted 21 May 2020 (Doc. ID 392512); published 23 June 2020
All-optical modulation based on the photothermal effect of two-dimensional (2D) materials shows great promise
for all-optical signal processing and communication. In this work, an all-optical modulator with a 2D PtSe
2
-on-
silicon struc ture based on a microring resonator is proposed and demonstrated utilizing the photothermal effect
of PtSe
2
. A tuning efficiency of 0.0040 nm · mW
−1
is achieved, and the 10%–90% rise and decay times are 304 μs
and 284 μs, respectively. The fabricated device exhibits a long-term air stability of more than 3 months.
The experimental results prove that 2D PtSe
2
has great potential for optical modulation on a silicon photonic
platform.
© 2020 Chinese Laser Press
https://doi.org/10.1364/PRJ.392512
1. INTRODUCTION
All-optical modulation has received extensive attention since
it avoids the conversion of electrical signals to optical signals
[1]. Although electrically driven modulators using such as
charge carrier injecting effect [2], thermo-optic effect [3],
and Pockels effect [4] have achieved great success on silicon
and lithium niobate platforms, all-optical modulation still
plays an irreplac eable role due to its simple structural design
and easy manufacturing process. Meanwhile, novel two-
dimensional (2D) materials emerging in recent years, such
as graphene [5], black phosp horus (BP) [6], and transition
metal dichalcogenides (TMDs) [7], provide more opportunities
to implement all-optical signal processing, with respect to their
distinct merits, such as intrinsic lattice matching with silicon,
complementary metal oxide semiconductor integrability, as
well as excellent electrical, optical, and thermal properties
[8,9]. Li et al. demonstrate all-optical intensity modulation
in a graphene-clad microfiber by using Pauli blocking in gra-
phene; an ultra-fast decay time of 2.2 ps and a modulation
depth of 38% are achieved [5]. Thermo-optic effect [10] is also
used to achieve all-optical phase modulation in the microfiber
assisted by graphene [11], BP [6], MXene [12], or tungsten
disulfide (WS
2
)[7], but the response time is of the order of
milliseconds. The integrated photonic platform offers higher
compactness and potential for manufacturing large-scale pho-
tonic integrated circuits [13,14]. All-optical modulation based
on an integrated platform has been intensively studied using
photo-excited free-carrier concentrations [15], electromagnetic
induced transparency [16], reverse saturable absorption [17], or
photothermal effect (assisted by metal–insulator–metal absorb-
ers) [18–20], etc. However, 2D material-based all-optical
modulation on an integrated photonic platform has been rarely
reported [21–24]. It is essential to explore the potential of 2D
materials to achieve all-optical modulation on an integrated
photonic platform.
As a group of representative 2D materials, TMDs are com-
posed of two chalcogen (X) atomic layers and a transition metal
(M) atomic layer sandwiched between them [25]. Compared
with the zero bandgap and weak optical absorption (2.3%)
of monolayer graphene [26], TMDs have bandgaps that change
with the number of layers and strong resonant absorption at
specific wavelengths [27]. In addition, TMDs can be prepared
by the chemical vapor deposition (CVD) method and other
bottom-up growth techniques, which reveal the advantages
of excellent uniformity, controllable number of layers, strong
reliability, high repeatability, and large area preparation [28,29].
Platinum selenide (PtSe
2
), a new type of layered TMD, has
been intensively studied due to its special properties since it was
first epitaxially grown by direct selenization of Pt on a substrate
[30]. Its crystal structure can be regarded as being composed
of hexagonal closely arranged Se atoms with Pt atoms occupy-
ing octahedral sites in alternate Se layers [25]. Different from
Research Article
Vol. 8, No. 7 / July 2020 / Photonics Research 1189
2327-9125/20/071189-08 Journal © 2020 Chinese Laser Press