“Periodic” soliton explosions in a dual-wavelength
mode-locked Yb-doped fiber laser
MENG LIU,
1
TI-JIAN LI,
1
AI-PING LUO,
1
WEN-CHENG XU,
1,2
AND ZHI-CHAO LUO
1,3
1
Guangzhou Key Laboratory for Special Fiber Photonic Devices and Applications & Guangdong Provincial Key Laboratory of Nanophotonic
Functional Materials and Devices, South China Normal University, Guangzhou 510006, China
2
e-mail: xuwch@scnu.edu.cn
3
e-mail: zcluo@scnu.edu.cn
Received 16 September 2019; revised 28 November 2019; accepted 16 December 2019; posted 24 December 2019 (Doc. ID 377966);
published 6 February 2020
We report the “periodic” soliton explosions induced by intracavit y soliton collisions in a dual-wavelength mode-
locked Yb-doped fiber laser. Owing to the different group velocities of the two wavelengths, the mode-locked
solitons centered at different wavelengths would periodically collide with each other. By using the dispersive
Fourier transformation technique, it was found that each collision would induce soliton explosions, but none
of them would be identical. Therefore, this phenomenon was termed as “periodic” soliton explosions. In addition,
the dissipative rogue waves were detected in the dual-wavelength mode-locked state. The experimental results
would be fruit ful to the communities interested in soliton dynamics and dual-comb lasers.
© 2020 Chinese
Laser Press
https://doi.org/10.1364/PRJ.377966
1. INTRODUCTION
As efficient pulse sources, ultrafast fiber lasers have been applied
to many fields such as laser processing and optical communica-
tion [1,2]. In addition, due to the dissipative feature of ultrafast
fiber lasers and they have been regarded as great platforms to
investigate nonlinear phenomena and soliton dynamics. So
far, by selecting cavity parameters, various types of soliton dy-
namics have been observed in ultrafast fiber lasers, such as
dissipative soliton resonance [3–6], harmonic mode-locked
solitons [7,8], and vector solitons [9–13]. Most of these soliton
dynamics in ultrafast fiber lasers are stationary or quasi-stationary
states. Besides that, the fiber laser could also operate in the
transient states with some certain cavity parameters. Since the
dispersive Fourier transformation (DFT) technique was intro-
duced into soliton dynamic research as a real-time spectroscopy
technique, soliton transient dynamics have gained more and
more attention because of their fruitful nonlinear phenomena
and potential practical applications. Indeed, by using the
DFT technique, versatile soliton transient dynamics have been
observed in fiber lasers, such as soliton buildup [14–18], evolving
soliton molecules [19,20], rogue waves [21,22], soliton explo-
sions [23–25], and pulsating solitons [26,27].
Among them, soliton explosions could be regarded as one of
the most fantastic phenomen a, in which solitons intermittently
suffer explosive instabilities and then recover to their original
status after each explosion [28–31]. Until now, many efforts
have been devoted to investigation of the soliton explosions.
The earlier numerical results have demonstrated that the
higher-order effects play important roles in the generation
and characteristics of soliton explosions [30,32]. In 2015 the
real-time dynamics of soliton explosions were first observed
in a fiber laser by using the DFT technique [23], and the ex-
perimental investigations on soliton explosions were greatly
stimulated. Soliton explosio ns have been demonstrated to exist
in different operation wavebands with different mode-locking
techniques [23–25,33–37]. In general, the phenomenon of sol-
iton explosion in fiber lasers is related to the cavity nonlinear
effect, which could be regarded as a transition state between
a stable state and a noise-like state. The typical characteristic
of soliton explosion is the abrupt collapse of the soliton spec-
trum and the recovery of the stable state soon after that. In
some cases, the temporal shift of pulse, Raman components,
and dissipative rogue waves (DRWs) would occur accompany-
ing the soliton explosion [23,24]. The duration of soliton ex-
plosion could vary from several to thousands of round-trips
with certain cavity parameters. Up to now, most of the reports
have been focused on the explosion of single soliton. As for the
explosion of multi-solitons, Yu et al. found that explosion
of one soliton could be ignited by another one through the
soliton interactions mediated by the transient gain response
of an erbium-doped fiber [36].
So far, all the soliton explosions mentioned above appeared
randomly and were observed in single-wavelength mode-locked
fiber lasers. As we know, dual-wavelength mode-locked solitons
would periodically collide with each other due to the different
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Vol. 8, No. 3 / March 2020 / Photonics Research
Research Article
2327-9125/20/030246-06 Journal © 2020 Chinese Laser Press