Multi-frequency carrier polarization modulation and demodulation system and method based on PGC scheme

A polarization modulation and multi-frequency carrier technology, which is applied in the direction of converting sensor output, measuring devices, instruments, etc., to achieve the effect of ensuring performance indicators and solving the problem of polarization-induced signal fading

Active Publication Date: 2019-04-16
NAT UNIV OF DEFENSE TECH
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Problems solved by technology

[0008] The present invention proposes a multi-frequency carrier polarization modulation and demodulation system based on a PGC scheme, aiming to solve the 1 / 4 down-sampling problem caused by the polarization switching method, and to improve the detection frequency band of the matching interference fiber Bragg grating sensor system, expand Provide support for multiplexing capacity and reducing system noise floor

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  • Multi-frequency carrier polarization modulation and demodulation system and method based on PGC scheme
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  • Multi-frequency carrier polarization modulation and demodulation system and method based on PGC scheme

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[0043] The present invention will be further described below in conjunction with accompanying drawing.

[0044] see image 3 , the output of the narrow-linewidth low-noise laser 1 is connected to the acousto-optic modulator 2, and the output is modulated into a pulsed laser; after passing through the 1×4 fiber coupler 3, it is divided into 4 beams, which are respectively incident on the first matching interferometer 401 and the second In the No. 4 matched interferometer 402, No. 3 matched interferometer 403 and No. 4 matched interferometer 404, four pairs of pulses are formed, wherein the first pulse of each pair in the four pairs of pulses introduces the modulated phase signal C cos(ω XX t), C cos(ω XY t), C cos(ω YX t) and C cos(ω YY t), C is the modulation amplitude, ω XX , ω XY , ω YY and ω YX are respectively the phase modulation frequencies introduced into the four matching interferometers, and the required modulation signals are provided by the modulation and dem...

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Abstract

The invention relates to the technical field of optical fiber sensing, in particular to a multi-frequency carrier polarization modulation and demodulation system and method based on a PGC scheme. Thesystem comprises a narrow-line-width low-noise laser, an acousto-optic modulator, a 1*4 optical fiber coupler, a first matching interferometer, a second matching interferometer, a third matching interferometer, a fourth matching interferometer, a first polarization modulator, a second polarization modulator, a third polarization modulator, a fourth polarization modulator, a 4*1 optical fiber coupler, an optical fiber circulator, a modulation and demodulation module, a data acquisition module and a matching interference type fiber grating sensor system; through the adoption of the system and the modulation and demodulation method of the invention, interference results of four paths of polarization channels are obtained at the same time, a key data entry is provided for polarization synthesis, and meanwhile, a problem of 1 / 4 sampling problem is reduced, so that a problem of polarization inducing signal fading is solved without reducing the sampling rate and the modulation frequency of the system, and the performance indexes of the matching interference type fiber grating sensor system are guaranteed.

Description

technical field [0001] The present invention relates to the technical field of optical fiber sensing, and relates to a multi-frequency carrier polarization modulation and demodulation system and method based on a PGC (PGC, Phase Generated Carrier, phase-carrier modulation and demodulation) scheme. Background technique [0002] The Fabry-Perot cavity (FBG-FP) sensor composed of a pair of fiber gratings with the same central wavelength has the advantages of simple structure, high sensitivity, small size, light weight, etc. It is widely used in the fields of underwater acoustic signal detection and seismic wave detection. important application. With the continuous improvement of fiber grating manufacturing technology, integrating a large number of (FBG-FP) sensors on one optical fiber becomes the best guarantee for reducing the volume and weight of the array and improving the reliability of the array, especially suitable for harsh environments such as underwater and downhole F...

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Application Information

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IPC IPC(8): G01D5/34
CPCG01D5/344
Inventor 马丽娜王俊陈羽胡正良熊水东徐志明胡永明
Owner NAT UNIV OF DEFENSE TECH
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