Chao Zuo

Bio: Chao Zuo is an academic researcher. The author has contributed to research in topics: Optical fiber & Optical fiber cable. The author has an hindex of 3, co-authored 5 publications receiving 107 citations.

Dual Michelson interferometers for distributed vibration detection.

Abstract: A distributed fiber optic vibration sensor is described, in which two Michelson interferometers are used as phase detectors and two 3×3 couplers are deployed to demodulate the time-varying phase change caused by vibration. The two interferometers are separated by four wavelength division multiplexers. The position of the vibration is obtained by signal correlation, which can be used as a perimeter security sensor to locate the intruder. The experimental results with a 4012 m fiber sensor are discussed.

Perimeter protection sensing positioning system based on coherent light time domain reflection

Abstract: The invention provides a perimeter protection sensing positioning system based on coherent light time domain reflection technology, which includes a light pulse emitter, a light receiver, a light amplifier, a non-balance Mach-Zehnder interferometer and sensing optical fiber (or optical cable); wherein, light pulse signal generates backward rayleigh scattered light in the sensing optical fiber (or optical cable), according to the light time domain reflection principle, the rayleigh scattered light carries information of each point distributed along the sensing optical fiber (or optical cable), the information includes intensity information caused by loss and phase information caused by external disturbance, and the non-balance Mach-Zehnder interferometer which can demodulate the phase information can realize protection alarm and positioning. The invention can be applied for safety detection and positioning of communication line, transfer cable and oil gas pipeline, incursion safety protection for important area and fields of strain, pressure and vibration detection.

Optical fiber sensing system structure based on wavelength division multiplexing

Abstract: The invention provides a fiber sensing system structure based on wavelength division multiplexing which includes: a transmitting and receiving part of light signal, a module for wavelength division multiplexing, a guide fiber (or cable), a coupling module and a sensing fiber (or cable); wherein, the transmitting and receiving part of light signal transmits two channels light signal with various wavelength, and separates transmitting light signal and receiving light signal through the wavelength division multiplexing module, at the same time, the wavelength division multiplexing module can filter back scattering rayleigh noise and brillouin scattering noise. The wavelength division multiplexing module, the guide fiber (or cable) and the coupling module can be independent or become one whole, the guide fiber (or cable) and the sensing fiber (or cable) can be independent or be in same cable.

Double interference ring perimeter safety protecting and positioning system

Abstract: The invention provides a perimeter security protection sensing and positioning system based on double interference rings, comprising a laser, three fiber optic couplers, sensing optic fiber and two receivers, wherein, two interference rings are composed of single sensing optic fiber and three couplers, the two receivers respectively receive interference signals of the two interference rings, and the position of a disturbance source is determined by analyzing the signals received by the two receivers so as to realize the protection alarm and positioning. The system can be applied to the safety detection and positioning of communication lines, power-transmission cables, oil gas pipelines and the like, and also can be used in important areas for invasion safety protection and fields of strain, stress, vibration detection and the like.

Optical fibre sensing system based on balancing detection

Abstract: The invention provides an optical fiber sensing system based on balanced detection, comprising an optical signal receiving-transmitting part, a coupling module 1, guiding optical fiber (or optical cable), a coupling module 2 and sensing optical fiber (or optical cable), wherein the coupling module 1 adopts an optical circulator to separate transmitted optical signals and received optical signals; the optical signal receiving-transmitting part is based on the photoelectric balanced detection principle; the coupling module 1, the guiding optical fiber (or optical cable) and the coupling module 2 can be mutually independent or become a whole; the guiding optical fiber (or optical cable) and the sensing optical fiber (or optical cable) can be mutually independent or in the same optical cable.

Distributed Fiber-Optic Sensors for Vibration Detection

Abstract: Distributed fiber-optic vibration sensors receive extensive investigation and play a significant role in the sensor panorama. Optical parameters such as light intensity, phase, polarization state, or light frequency will change when external vibration is applied on the sensing fiber. In this paper, various technologies of distributed fiber-optic vibration sensing are reviewed, from interferometric sensing technology, such as Sagnac, Mach-Zehnder, and Michelson, to backscattering-based sensing technology, such as phase-sensitive optical time domain reflectometer, polarization-optical time domain reflectometer, optical frequency domain reflectometer, as well as some combinations of interferometric and backscattering-based techniques. Their operation principles are presented and recent research efforts are also included. Finally, the applications of distributed fiber-optic vibration sensors are summarized, which mainly include structural health monitoring and perimeter security, etc. Overall, distributed fiber-optic vibration sensors possess the advantages of large-scale monitoring, good concealment, excellent flexibility, and immunity to electromagnetic interference, and thus show considerable potential for a variety of practical applications.

Modulated pulses based distributed vibration sensing with high frequency response and spatial resolution.

Abstract: A distributed optical fiber sensing system merged Mach-Zehnder interferometer and phase sensitive optical time domain reflectometer (φ-OTDR) system for vibration measurement with high-frequency response and high spatial resolution is demonstrated, where modulated pulses are proposed to be used as sensing source. Frequency response and location information are obtained by Mach-Zehnder interferometer and φ-OTDR technology, respectively. In order to simulate high-frequency vibration of crack of cable and civil structure, experiments on detection of piezoelectric transducer and pencil-break are carried out. Spatial resolution of 5 m and the maximum frequency response of ~3 MHz are achieved in 1064 m fiber link when the narrow pulse width is 50 ns.

Advanced fiber-optic acoustic sensors

Abstract: Acoustic sensing is nowadays a very demanding field which plays an important role in modern society, with applications spanning from structural health monitoring to medical imaging. Fiber-optics can bring many advantages to this field, and fiber-optic acoustic sensors show already performance levels capable of competing with the standard sensors based on piezoelectric transducers. This review presents the recent advances in the field of fiber-optic dynamic strain sensing, particularly for acoustic detection. Three dominant technologies are identified — fiber Bragg gratings, interferometric Mach-Zehnder, and Fabry-Perot configurations — and their recent developments are summarized.

A Comprehensive Study of Optical Fiber Acoustic Sensing

Abstract: The optical fiber acoustic sensing system is suitable for long-distance monitoring of the acoustic signals generated by the external disturbances. According to the continuity of sensing units, quasi-distributed and distributed optical fiber acoustic sensing technologies are differentiated to meet different application requirements. On the one hand, the recent progress of Fabry-Perot interferometer (FPI) focusing on the diaphragm material, and the research hotspots in the field of the continuous Fiber Bragg grating (FBG) array are firstly reviewed. On the other hand, Mach-Zehnder interferometry (MZI), Michelson interferometry (MI), and Sagnac interferometry (SI) have rapidly developed in the aspect of the demodulation algorithm optimization with the purpose of the sensing performance improvement. Moreover, the current primary research works of the phase-sensitive optical time-domain reflectometer ( $\varphi $ -OTDR) are the signal-to-noise ratio improvement and the mixed optical structure design. Finally, this paper presents an overview of the recent advances of optical fiber acoustic sensing system in the application domains of military defense, structural health monitoring, petroleum exploration, and development.