High-efficiency DBA-BOTDA with optimized SNR by
multiple bandwidths pump modulation
Huiliang Ma (马辉亮), Xinhong Jia (贾新鸿)*, Kai Lin (林 凯), and Cong Xu (徐 聪)
College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610101, China
*Corresponding author: jiaxh_0@126.com
Received September 18, 2018; accepted November 12, 2018; posted online December 20, 2018
For Brillouin optical time-domain analysis (BOTDA) based on distributed Brillouin amplification (DBA), con-
stant Brillouin response achieved by the exponentially variable bandwidth/intensity pump modulation suffers
from the much lower pumping efficiency for long-range sensing, which counterbalances the merit of DBA. In this
Letter, pump modulation by multiple constant bandwidths was proposed and demonstrated. The ∼98.9 km
sensing with ∼5 m spatial resolution and no use of optical pulse coding (OPC) was achieved by ∼8 dBm Brillouin
pump, which is lower by ∼9 dB in theory by comparison with exponentially increased bandwidth modulation.
Compared with traditional DBA-BOTDA, signal-to-noise ratio (SNR) enhancement with >4.6 dB was ob-
tained. The flattened standard deviation (STD) of Brillouin frequency shift (BFS) (less than ∼2 MHz) along
the whole fiber was demonstrated.
OCIS codes: 060.4370, 290.5900.
doi: 10.3788/COL201917.010603.
Brillouin optical time-domain analysis (BOTDA) sensors
based on stimulated Brillouin scattering (SBS) have been
paid much attention in the past two decades, due to their
ability to monitor temperature and strain distributions
along the sensing fiber
[1,2]
. In practice, it can be applied
in several fields, including structure health monitoring,
fire alarming, oil pipeline leaking, power establishment
security monitoring, etc.
For standard BOTDA, in order to compensate for
the reduction of the signal-to-noise ratio (SNR) caused
by intrinsic attenuation, the peak power of pulse and
Stokes power injected into the fiber under test (FUT)
must be higher. However, the practical pulse peak power
is limited to ∼20 dBm due to the pulse peak decrease
caused by mod ulati on instability (MI)
[3]
and spectral
expansion caused by self-phase modulation (SPM)
[4]
.
The Stokes power is also limited to ∼−10 dBm in
dual-sideband BOTDA, due to the high -order non-local
effect
[5]
.
Several first- or second-order pumping configurations
based on distributed Raman amplification (DRA)
[6–12]
and distributed Brillouin amplification (DBA)
[13–24]
have
been proposed for enhancing the SNR of distributed sen-
sors. By comparison, DBA is more superior in terms
of much higher pumping efficiency (pump power at the
milliwatt level) and reduced pump-to-pulse relative inten-
sity noise (RIN) transfer.
In traditional DBA-BOTDA, a widened bandwidth
(a few hundreds of megahertz) based on uniform frequency
modulation (FM)
[14,16,18]
or optical frequency comb
(OFC)
[13,15,17]
was often utilized to avoid the pulse distor-
tion. However, there exists a wide region with lower SNR
due to the intrinsic loss, resulting in the larger standard
deviation (STD) of Brillouin frequency shift (BFS) in this
range
[13–17]
.
Recently, a tailored pump compensation scheme was
proposed in DBA-BOTDA sensors to achieve the flat-
tened Brillouin response and SNR over FUT
[18]
. In this
scheme, unlike uniform bandwidth modulation, a laser di-
ode with exponentially increased bandwidth (through FM
induced by current change) from 200 MHz to 2 GHz was
used to control its spectral density, and thus the Brillouin
gain coefficient was decreased exponentially along the fi-
ber to compensate for the loss, making the Brillouin re-
sponse approach a constant. A sensing distance of
51.2 km using ∼11 dBm Brillouin pump has been real-
ized
[18]
. A similar sensing distance of 50 km with flattened
Brillouin response was reported by the authors using ex-
ponentially decreased intensity modulation (IM) for the
pump (∼8 dBm)
[19]
.
However, for DBA-BOTDA with constant Brillouin re-
sponse, further extension of sensing distance far beyond
50 km requires the significantly intensified pump power,
as it is increased exponentially with the length of the
FUT (see the analysis below). For example, 10 dB incre-
ments are required for 100 km sensing. This greatly coun-
terbalances the high-efficiency advantage of DBA.
Moreover, for exponential bandwidth modulation, its
dynamic range should also be increased to 20 dB (for ex-
ample, from 100 MHz to 10 GHz). It is technically difficult
to be realized due to the detrimental parasitical amplitude
change of the laser diode
[18]
. Similarly, exponential IM of
the Brillouin pump
[19]
up to 20 dB dynamic range is also
challenged technically.
In this Letter, a new design of pump modulation
by multiple constant bandwidths is proposed and pre-
sented. The simultaneously enhanced pumping efficiency
by ∼9 dB in theory (compared with the exponential
bandwidth/IM) and enhanced SNR with >4.6 dB (com-
pared with the standard DBA-BOTDA) are achieved.
COL 17(1), 010603(2019) CHINESE OPTICS LETTERS January 10, 2019
1671-7694/2019/010603(6) 010603-1 © 2019 Chinese Optics Letters
资源评论
weixin_38629130
- 粉丝: 4
- 资源: 949
最新资源
- 课程设计项目：python+QT实现的小型编译器.zip
- (源码)基于AVR ATmega644的智能卡AES解密系统.zip
- (源码)基于C++插件框架的计算与打印系统.zip
- (源码)基于Spring Boot和Vue的苍穹外卖管理系统.zip
- (源码)基于wxWidgets库的QMiniIDE游戏开发环境管理系统.zip
- 通过C++实现原型模式（Prototype Pattern）.rar
- 学习记录111111111111111111111111
- 通过java实现原型模式（Prototype Pattern）.rar
- 通过python实现原型模式（Prototype Pattern）.rar
- xiefrnsdklmkds
资源上传下载、课程学习等过程中有任何疑问或建议，欢迎提出宝贵意见哦~我们会及时处理！
点击此处反馈
