Interference type optical fiber sensor and its digital closed-loop method for controlling working point

Abstract

The invention discloses an interferometric optical fiber sensor and the digital closed-loop method of controlling action spots of the interferometric optical fiber sensor. A square wave phase modulation signal is introduced between two beams of interference light waves of an interferometer so as to enable the output signal of the interferometer to be changed into a square wave error signal from a cosine response signal; the square wave error signal is demodulated by adopting digital correlation detection technology, and the size of low frequency phase drift is obtained; the demodulated low frequency phase drift generates compensating phase shift and sends the compensating phase shift back to a light path for counteracting the low frequency phase drift, and after the process is repeated many times, the interferometer is caused to be at an orthogonal action spot. The invention has the advantages that the low frequency phase drift generated from environmental disturbance is compensated and the orthogonal action spot of the interferometer is stabilized so that a system can work in a most sensitive area always and the stability of the system is enhanced.

Description

technical field [0001] The invention relates to an optical fiber sensor and an active homodyne detection technology, in particular to an interferometric optical fiber sensor and a digital closed-loop method for controlling an operating point. Background technique [0002] Optical fiber sensors have the advantages of high sensitivity, good electrical insulation properties, anti-electromagnetic interference, large dynamic range, wide detection frequency band, small size, light weight, etc., and have broad application prospects in national defense and civil industrial production, etc. attention. Interferometric optical fiber sensor is an important research direction of optical fiber sensor. It has the characteristics of high sensitivity, easy multiplexing, easy networking and formation, and remote sensing and monitoring. It is widely used in the measurement of physical quantities such as sound waves, magnetic fields, and temperatures. [0003] However, interferometric fiber op...

AI Technical Summary

Problems solved by technology

[0019] In the traditional phase tracking feedback link, the integrator is susceptible to integration saturation due to environmental factors, causing the system operating point to drift, and even more likely to cause the system to lose lock, and it is necessary to judge whether the interferometer operating point is π / 2 or 3π / 2

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