Stimulated Brillouin scattering evolution and
suppression in an integrated stimulated thermal
Rayleigh scattering-based fiber laser
JIWEN CUI,
1,
*
,†
HONG DANG,
1,†
KUNPENG FENG,
1,†
WENLEI YANG,
2,†
TAO GENG,
2
YANG HU,
1,3
YUANHANG ZHANG,
1
DONG JIANG,
1
XUDONG CHEN,
2
AND JIUBIN TAN
1
1
Center of Ultra-precision Optoelectronic Instrument, Harbin Institute of Technology, Harbin 150080, China
2
Key Laboratory of In-Fiber Integrated Optics, Ministry of Education, Harbin Engineering University, Harbin 150001, China
3
VI Service Network Co., Ltd., Shanghai 201203, China
*Corresponding author: cuijiwen@hit.edu.cn
Received 11 January 2017; revised 22 March 2017; accepted 22 March 2017; posted 12 April 2017 (Doc. ID 284418); published 16 May 2017
The spectral purity of fiber lasers has become a critical issue in both optical sensing and communication fields.
As a result of ultra-narrow intrinsic linewidth, stimulated thermal Rayleigh scattering (STRS) has presented spe-
cial potential to compress the linewidth of fiber lasers. To suppress stimulated Brillouin scattering (SBS), the most
dominant disturbanc e for STRS in optical fibers, a semi-quantitative estimation has been established to illuminate
the mechanism of suppressing SBS in a periodic tapered fiber, and it agrees with experimental results. Finally, a
linewidth compression device based on STRS is integrated into a single-longitudinal-mode ring-cavity fiber laser
with secondary cavities, and its linewidth is verified to be 200 Hz through a self-heterodyne detecting and Voigt
fitting method.
© 2017 Chinese Laser Press
OCIS codes: (190.0190) Nonlinear optics; (190.2640) Stimulated scattering, modulation, etc.; (140.3460) Lasers.
https://doi.org/10.1364/PRJ.5.000233
1. INTRODUCTION
Fiber lasers have been widely used in the field s of optical fiber
communication, distributed optical fiber sensing, and optical
spectrum analysis [1–3], where spectral purity is particularly
important since it directly influences the resolution and accu-
racy of these applications. Mostly, spectral purity includes
single-longitudinal-mode (SLM) selection and linewidth com-
pression, and both of them have attracted more and more in-
terest in recent research.
In order to realize SLM output, several approaches have
been reported and demonstrated, such as short cavity [4,5],
saturable absorber [6], twisted-mode element [7], and passive
multiple ring cavities [8]. However, those conventional meth-
ods are usually influenced by the self-pulsation effect induced
by interactions between doped ions in short-cavity configura-
tions, dependence of modulation depth of the equivalent gra-
ting on pump power, and other negative factors, which leads
to a linewidth broadening. Therefore, effective methods to
compress linewidth are still needed. Recently, spontaneous/
stimulated scattering effects in optical fibers offered an alterna-
tive method to compress the linewidth, in which the compres-
sion results were strongly dependent on the intrinsic linewidth
of scattered light. Considering the intrinsic linewidth of stimu-
lated thermal Rayleigh scattering (STRS) is on the order of
kilohertz [9], STRS-based lasers have special potential in the
area of ultranarrow fiber lasers. However, in optical fibers,
the gain of stimulated Brillouin scattering (SBS) could be
∼1000 times larger than that of STRS, and increasing the
power of the pump source would lead STRS to be entirely
drowned in SBS, whose intrinsic linewidth is ∼10 MHz.
Up to now, the main methods to suppress SBS include particu-
lar structure designs of fibers [10], phase modulation [11], and
distributed parameters modulation [12–14] (such as strain,
temperature, and core radius along the fiber length). Among
parameter modulation methods, periodic tapered fiber is an
efficient way to suppress SBS to achieve STRS-based lasers.
In this paper, an SLM fiber laser with ultranarrow linewidth
is demonstrated in detail, wherein passive multiple cavities are
utilized to select SLM, and periodic structures of tapered fiber
are employed to suppress the SBS effect in single mode fiber
(SMF). To design and optimize the tapered structures, a semi-
quantitative estimation has been built to illuminate the mecha-
nism of SBS suppression with the periodic tapered fiber.
2. PRINCIPLE OF SBS SUPPRESSION METHOD
As detailed in Section 1, SBS is one of the most dominant dis-
turbances for STRS in optical fibers, and the suppression of
SBS has therefore become a major issue for STRS-based fiber
Research Article
Vol. 5, No. 3 / June 2017 / Photonics Research 233
2327-9125/17/030233-06 Journal © 2017 Chinese Laser Press
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