New specialty optical fibers for fiber sensing
As an important means of information acquisition, sensing technology, together with communication technology and computer technology, constitutes the three pillars of information technology. From the perspective of the Internet of things, sensing technology is an important indicator of the degree of informatization of a country. Traditional sensing techniques mainly utilize the particular properties of materials such as semiconductors, dielectrics, magnetic materials to make sensors and thereby detect the variations of structural parameters. For instance, the thermoelectric effect, Hall Effect, and the photosensitivity effect are utilized to make the thermocouple sensor, Hall sensor, photosensitivity sensor, respectively. This type of sensor has the defects such as the facts that, the complexity of the device is significantly affected by the number of detected structural parameters, unstable in the special environment, and the monitoring has breakpoints. Since the advent of the world's first optical fiber in the 1960s and 1970s, optical fiber communications and manufacturing technology have developed rapidly. Due to its large dynamic range, wide frequency range, low transmission loss, and easy acceptance of the loading of the measured field under certain conditions, the optical fiber is an excellent sensitive component. In addition, because the optical fiber is uncharged, flexible, resistant to electromagnetic interference and radiation, it is especially suitable for the use in harsh environments such as flammable, explosive, highly space-constraint and strong electromagnetic interfering environments. Therefore, optical fiber sensing technology has attracted a great attention since its invention, and has received extensive concern in various fields.
The joint team of Dr. Tong Weijun from Yangtze Optical Fibre and Cable Joint Stock Limited Company (also known as ‘YOFC’) and Professor Tang Ming from the School of Optics and Electronic Information of Huazhong University of Science and Technology reviewed the progress and applications of a variety of special optical fibers developed by YOFC in the field of optical fiber sensing. In addition to a comprehensive introduction to the related special fiber manufacturing technology and its advantages and disadvantages, the review also introduces the polarization-maintaining fiber based on the Sagnac effect applied to the optical fiber gyroscope; the rotating fiber based on the Faraday effect applied to the optical fiber current transformer; the erbium-doped fiber, the ytterbium-doped fiber and the erbium-ytterbium co-doped fiber based on photoelectric effect applied to energy gain; the bending-insensitive fiber based on optical coherence technology applied to hydro-sensing; the multi-mode and few-mode fiber based on Raman effect and multi-core fiber based on Brillouin effect applied to temperature sensing. In addition, there are energy-transmission optical fibers and ultraviolet optical fibers used in high-energy transmission environments; radiation-resistant optical fibers used in high-radiation environments; high-temperature-resistant optical fibers used in high temperature environments, and other special optical fibers for special environments. The fibers have fabulous performance indices and high environmental reliability. Compared with the sensing systems utilizing conventional communication fiber, the fiber optic sensors based on specialty fibers show evident advances in performance. Additionally, the development of specialty fibers facilitates the advent of novel sensing mechanisms.
Fig. 1 YOFC’s spun fiber: ratio error vs temperature linearity
Fig. 2 (a) YOFC’s few-mode optical fiber for temperature measurement: temperature resolution curve;
(b) YOFC’s few-mode optical fiber for temperature measurement: space resolution curve
Fig. 3 Brillouin frequency shift shows strong bending-sensitive property in the eccentric fiber core of the multi-core optical fiber
About Joint Team of Dr. Tong Weijun from Yangtze Optical Fibre and Cable Joint Stock Limited Company and Professor Tang Ming from Huazhong University of Science and Technology
The research team in YOFC led by Dr. Tong Weijun, is mainly engaged in research on special optical fibers and devices, including: special optical fiber and optical fiber sensing systems for optical fiber sensing, special optical fibers and related devices for fiber lasers, special fiber and related devices for electric power, basic materials and fiber testing equipments. The team members mainly include Dr. Yang Chen, Dr. Liu Tongqing, Dr. Zhang Xinben, and Senior Engineer Yang Kun. In recent years, team members have undertaken or participated in nearly 20 government projects including National 863 Program, National 973 Program, National Key Research and Development Program, National Major Scientific Instrument Project, National Natural Science Foundation and Provincial Science and Technology Research Projects; have more than 50 papers published in domestic and international journals, have been authorized more than 20 invention patents and have participated in the projects winning 1 Second Prize of National Science and Technology Progress Award, 3 First Prizes of Provincial and Ministerial Science and Technology Awards, 3 Second Prizes, and 2 Third Prizes.
The optical fiber sensing team led by Professor Tang Ming from Huazhong University of Science and Technology is mainly engaged in the field of distributed optical fiber sensing technique, covering advanced modulation coding/decoding, signal processing techniques in optical fiber sensing. The achievements include multi-core optical fiber multiplexing/de-multiplexing devices, and distributed fiber sensing techniques based on specialty fibers, such as three-dimensional shape and multi-parameter distributed sensing based on multi-core fiber, curves and long-distance distributed sensing based on few mode fiber and dynamic Brillouin sensing technique based on channel estimation. In recent years, team members have undertaken or participated in the National 863 Program, the National Natural Science Foundation, and various provincial and municipal fund projects, and published dozens of papers in international authoritative optical academic journals and international academic conferences such as Optics Letters, Optics Express, and IEEE Journal of Lightwave Technology. The team stands for the leading level of international optical fiber sensing community.
Tong Weijun, Yang Chen, Liu Tongqing, et al. Progress and prospect of novel specialty fibers for fiber optic sensing[J]. Opto-Electronic Engineering, 2018, 45(9): 180243.