Method to measure the second-order birefringence
vector distribution along optical fibers based
on high-speed polarization optical time domain
reflectometry
Chao Shang,
1,
* Chongqing Wu,
1,4
Zhi Wang,
1
Yongjun Wang,
2
Jian Wang,
1
Zhengyong Li,
1
and Shuangshou Yang
3
1
Institute of Optical Information, Beijing Jiaotong University, Beijing 100044, China
2
School of Electronic Engineering, Beijing University of Posts and Telecommunications,
Beijing 100876, China
3
Beijing Glass Research Institute, Beijing 101111, China
4
cqwu@bjtu.edu.cn
*Corresponding author: ioicshang@gmail.com
Received 23 January 2012; revised 19 February 2012; accepted 2 March 2012;
posted 8 March 2012 (Doc. ID 161061); published 4 May 2012
Based on a high-speed polarization optical domain reflectometry, an innovative method to measure the
second-order birefringence vector distribution along optical fibers was proposed and implemented in this
paper. Some interesting data were obtained along a 1 km long single mode fiber by only one detection.
The second-order birefringence magnitude distribution curve can reflect both magnitude and direction
change information of the first-order birefringence, and it was more stable (except the catastrophe points)
than that of the first-order. The larger variable range of the second-order birefringence magnitude may
provide a higher sensitivity than the first-order for birefringence-based distributed sensors. © 2012
Optical Society of America
OCIS codes: 060.2300, 120.4825.
1. Introduction
Recently, distributed optical fiber sensors have at-
tracted more and more attention because of the abil-
ity to detect a variety of physical parameters
nondestructively with high sensitivity, such as mag-
netic field, electric field, pressure, strain, tempera-
ture, and so on. When an optical fiber is bent or
pressed by an external stress, the birefringence vec-
tors along the fiber will change [
1]. Polarization op-
tical time domain reflectometry (P-OTDR) is a
typical birefringence-related nondestructive distrib-
uted optical fiber sensing technology, which was first
proposed in 1981 by A. J. Rogers [
2]. In a P-OTDR
system, the change of birefringence along an optical
fiber can be regarded as the essenti al embodiment
of the environmental physical parameter changes.
Therefore, optical fiber bending or the external stress
can be monitored by detecting the change of the
birefringence distribution.
Research on the measurement technique of the
birefringence vectors distribution along an optical
fiber is one of the important foundations for distrib-
uted sensors, and some birefringence-based stress
detection techniques have been proposed [
3,4]. If
the change of the first-order birefringence magnitude
is used to detect the external stress change for an
1559-128X/12/142548-06$15.00/0
© 2012 Optical Society of America
2548 APPLIED OPTICS / Vol. 51, No. 14 / 10 May 2012