Quadrature Demodulation Device of Heterodyne Phase Interference Optical Fiber Sensor

Abstract

The invention discloses a quadrature demodulation device of a heterodyne phase interference optical fiber sensor. Two output ends of the heterodyne phase interference optical fiber sensor are respectively connected with a first photoelectric detector and an adjustable optical fiber delay line; The first photodetector, the first mixer, the first low-pass filter, the first differentiator, and the first multiplier are sequentially connected; the adjustable fiber delay line, the second photodetector, the second mixer, the first Two low-pass filters, the second differentiator, and the second multiplier are connected in sequence; the first low-pass filter is connected with the second multiplier, and the second low-pass filter is connected with the first multiplier; the heterodyne modulation signal sources are respectively It is connected with the heterodyne modulator, the first mixer and the second mixer of the heterodyne phase interference optical fiber sensor; the first multiplier and the second multiplier are respectively connected with the subtractor; the subtractor, the integrator, the high-pass The filters are connected sequentially. The invention realizes the adjustable phase delay and avoids the drift of the phase delay.

Description

technical field [0001] The invention relates to the field of optical fiber sensing, in particular to a quadrature demodulation device of a heterodyne phase interference optical fiber sensor. Background technique [0002] Fiber optic sensor is a new technology developed in the mid-1970s. Various types of sensors such as fiber optic acceleration sensors, fiber optic hydrophones, and fiber optic gyroscopes have become research hotspots. Compared with other sensors, fiber optic sensors have unique advantages such as anti-electromagnetic interference, high sensitivity, large dynamic range, and long detection distance, so they have great application potential in sensing technology. [0003] Now the signal demodulation technology of interferometric optical fiber sensor mainly includes homodyne demodulation method and heterodyne demodulation method. Among the homodyne demodulation methods, the method based on PGC (Phase Generated Carrier) is one of the most studied and widely used ...

AI Technical Summary

Problems solved by technology

The advantage of the heterodyne demodulation method is to avoid the associated AM interference. The disadvantage is that it needs to use a precise phase shift circuit of the heterodyne modulation signal. Once the phase is fixed, it cannot be adjusted with the change of the heterodyne modulation signal, and there is an inherent electronic phase drift. and serious noise interference

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