Optical fiber fabry-perot acoustic-vibration sensing device and demodulation method based on double tunable light sources

Abstract

The invention discloses an optical fiber fabry-perot acoustic-vibration sensing device and a demodulation method based on double tunable light sources, the device comprises a first narrow-linewidth laser, a second narrow-linewidth laser, a first wavelength division multiplexer, an optical fiber coupler, an optical fiber fabry-perot acoustic-vibration sensor, a second wavelength division multiplexer, a first photoelectric detector, a second photoelectric detector and a data acquisition card; wherein two lasers with different wave lengths are coupled by the first wavelength division multiplexer into the same optical fiber and are transmitted to the optical fiber fabry-perot acoustic-vibration sensor through the optical fiber coupler; a modulated signal light reflects to the coupler and is transmitted to the second wavelength division multiplexer, the two lasers with different wave lengths in one optical fiber are divided and separately transmitted into two optical fibers, and the two lasers are separately transmitted into the first photoelectric detector and the second photoelectric detector; the two lasers are converted into electrical signals and are acquired, phase information is extracted from the electrical signals, and an acoustic-vibration signal is demodulated to obtain a measuring result. According to the invention, the signal strength can be effectively ensured, the sensing demodulation of the initial cavity length and cavity length variation of the optical fiber fabry-perot cavity in wide range can be performed.

Description

technical field [0001] The invention relates to the field of optical fiber sensing, in particular to an optical fiber Faroese acoustic vibration sensing device and a demodulation method based on dual tunable lasers. Background technique [0002] Compared with the acoustic vibration sensor in the traditional electrical field, the fiber optic Faber acoustic vibration sensor has the advantages of small size, light weight, high sensitivity, strong anti-electromagnetic interference ability, and convenient long-distance telemetry. For rapidly changing acoustic and vibration signals, researchers have proposed a variety of demodulation methods, including optical loss-based intensity demodulation, interference-based intensity demodulation, and interference-based quadrature-phase demodulation. Among them: the optical loss type intensity demodulation uses the optical loss transformation caused by the change of the distance between the optical fiber and the reflective film to perceive t...

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Problems solved by technology

However, the input optical signal in the above method is obtained by filtering out a wide-spectrum light source through an optical filter, and the reflectivity of the fiber optic sensor is low, and a large amount of optical power is wasted, so the optical power received by the detector is very low. Low, it is difficult to meet the occasions of long distance or large optical fiber transmission loss

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