Wuhan University

Yangtze Optical Fibre and Cable Joint Stock Limited Company

Honghai Wang

Zhengying Li

Jiaqi Wang

Ruichun Wang

Jun Wu

Runhan Wang

Rong Huang

Wufeng Xiao

Desheng Jiang

Haiying Wang

Lixin Wang

Minlang Fan

Huiyong Guo

An interferometric demodulation system for a large capacity fiber grating sensing network is provided by the present disclosure, comprising: a continuous light output end of the nanoscale wide-spectrum light source is connected to an input end of the pulse optical modulator, an output end of the reference grating is connected to an input end of the grating array sensing network, and a third communication end of the optical circulator is connected to an input end of the optical amplifier, an output end of the optical amplifier is connected to an input end of the Mach-Zehnder interferometer, three-channel signal output ends of the Mach-Zehnder interferometer are respectively connected to signal input ends corresponding to the embedded signal processor through the photoelectric converter, and the embedded signal processor controls the heating device to control a temperature of an any one of interference arms of the Mach-Zehnder interferometer.

Interferometric demodulation system and method for large capacity fiber grating sensing network

A high-bandwidth bend-insensitive multimode fiber includes a core laver and a cladding including an inner cladding, a depressed cladding, and an outer cladding arranged sequentially from inside to outside. The core layer is a silicon dioxide glass layer co-doped with germanium, phosphorus (P), and fluorine (F) and has a refractive index profile in a shape of a parabola, a distribution index in a range of 2.0-2.3, a radius in a range of 23-27 &#x3bc;m, and a maximum relative refractive index difference in a range of 0.9-1.2% at its center. A contribution amount of P at the center is in a range of 0.01-0.30%. A doping amount of F increases from the center to the edge of the core layer. A contribution amount of F at the center and edge of the core layer is in range of 0.0% to &#x2212;0.1%, and &#x2212;0.40% to &#x2212;0.20%, respectively.

High-bandwidth bend-insensitive multimode fiber

An optical fiber grating sensing method applied to small-scale fire source monitoring are provided, distinguishing two concepts of a spatial resolution and a perception resolution, under the premise of ensuring the spatial resolution of a traditional fiber Bragg grating sensing system, only increase the number of fiber Bragg gratings covered by a single pulsed optical signal without changing a pulse width of a pulsed optical signal, so as to improve the perception resolution of the system without increasing the requirements for a hardware circuit, and truly shorten an interval between adjacent fiber Bragg gratings. Improving the perception resolution of the system, which not only ensures the spatial resolution of the system, but also realizes the monitoring of small-scale fire sources; by adopting a simple feature extraction algorithm to obtain fire temperature information in different areas, the temperature detection speed of the system is fast.

Optical fiber grating sensing method applied to small-size fire source monitoring

A method for correcting a phase jump caused by polarization-induced fading in optical fiber phase demodulation, including the steps of: 1, selecting a demodulated phase in the case of non-depolarization as historical sample data; 2, determining an autoregressive coefficient and a moving average coefficient of the autoregressive moving average model for the demodulated phase; 3, establishing a Kalman prediction model for the demodulated phase, and deriving recursive equations of the Kalman prediction model for the demodulated phase; and 4, judging whether a jump point exists in the actual demodulated phase, determining polarization states of lights if the jump point exists, and correcting the jump point when the polarization states of the lights are in polarization orthogonality by replacing the actual demodulated phase with a predicted phase value. The disclosure ensures the correctness of subsequent vibration-based signal processing.

Method for correcting phase jump caused by polarization-induced fading in optical fiber phase demodulation

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Wuhan, China

Honghai Wang