With the development of optical fiber sensing networking technology, it has become one of the hot spots in optical fiber sensing technology to build a large-capacity, long-distance and high-precision optical fiber sensing network. In recent years, time division multiplexing, wavelength division multiplexing, frequency division multiplexing and hybrid multiplexing technology in the quasi-distributed optical fiber sensing networking technology has been very widely used. Time-division multiplexing in traditional sensing networks often requires various types of modulators to generate signal light pulses, which greatly increases the cost of sensing networking. At the same time, the existing sensing network needs more manpower and material resources to carry out real-time fault monitoring of the network, which undoubtedly hinder the survivability of the fiber sensing network in practical engineering.
Wuhan Research Institute of Optics and Electronics, Associate Professor of Xia Li, led by Wuhan Optoelectronics National Laboratory, designed a large-capacity quasi-distributed optical fiber sensing network based on optical chaos and hybrid time division multiplexing (Figure 1). The design of the probe light is no longer pulsed light, but by the SOA ring cavity produced a kind of noise-like continuous wide-spectrum optical signal, that is, broad-spectrum chaotic light. Through the use of hybrid time-division multiplexing technology, the multiplexed amount of chirped fiber Bragg grating in the sensor network is greatly improved. The theoretical analysis can support the simultaneous access capability of 512 sensor nodes. Combining the intensity demodulation technique of chirp Bragg grating and the cross-correlation algorithm of chaotic light, the quasi-distributed optical fiber sensing parameters can be measured, and each sensing unit can be accurately located. At the same time, the sensor network itself has a real-time fiber fault monitoring function, the fault point measurement space resolution up to 2.8 cm (Figure 2), this unique advantage greatly enhances its survivability and reliability in engineering applications.
On February 9, 2015, the research result "Optical Chaos and Hybrid WDM / TDM-based large-capacity Quasi-distributed Optical Sensing Network with Real-time Fault Monitoring" (Optical Chaos and Hybrid Time Division Wavelength Division Multiplexing Technology) Optics Express (Vol. 23, No. 3, 2015).
This work has been funded by the National Natural Science Foundation of China (Grant No.).
Figure 1 large-capacity quasi-distributed sensing network diagram
Fig. 2 (a) Correlation spectrum without stress and stress; (b) Full width at half maximum of auto-correlation peak
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