Large-scale fiber bragg grating sensor flexible multiplexing device based on OFDR

Abstract

The invention discloses a large-scale fiber grating sensor flexible multiplexing device based on OFDR. The device comprises a tunable light source, a main interferometer, an auxiliary interferometer,photoelectric detectors PD1 and PD2, a data acquisition unit and a control processing unit, wherein the tunable light source provides periodic scanning light with linearly changing wavelengths for themain interferometer and the auxiliary interferometer, the main interferometer comprises a reference arm and a measuring arm, wherein the reference arm is composed of a single-mode optical fiber and aFaraday rotator mirror connected to the tail end of the single-mode optical fiber, the measuring arm is composed of a plurality of identical weak reflection fiber grating sensors, the auxiliary interferometer comprises two paths of single-mode optical fibers with different lengths and Faraday rotator mirrors connected with the tail ends of the single-mode optical fibers, the data acquisition unittakes an auxiliary interferometer beat frequency signal acquired by the photoelectric detector PD1 as an external sampling clock and performs equal optical frequency interval sampling on a main interferometer beat frequency signal acquired by the photoelectric detector PD2, and the sweep frequency nonlinearity of the tunable light source is compensated. According to the scheme, on the premise that devices such as an optical divider and a photoelectric detector are not additionally arranged, flexible multiplexing of the single-channel multi-channel fiber grating sensor is achieved, and the device can be widely applied to multiple fields.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensing, in particular to an OFDR-based flexible multiplexing device for large-scale optical fiber grating sensors. Background technique [0002] Fiber optic sensing technology is a new type of sensing technology developed with fiber optic communication technology. Fiber Bragg Grating (FBG) is one of the most widely used fiber optic sensors, with high sensitivity, small size, light weight, With the advantages of anti-electromagnetic interference and high density of measuring points, it has important applications in condition monitoring in aerospace, transportation, water conservancy, construction and other fields. [0003] In most applications, it is usually necessary to monitor multiple physical parameters with different spatial distributions at the same time, and multiple fiber grating sensors need to be deployed to achieve quasi-distributed measurement. In order to improve the sensing ab...

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Problems solved by technology

[0005] However, in the current OFDR sensing system, most of the large-scale identical weak emission FBG sensors are serially multiplexed on one optical fiber, which has extremely strict requirements on the reflectivity of the FBG sensor, which increases the difficulty of fabrication; at the same time, once the sensing fiber If some sensors are damaged, all subsequent sensors will fail; in addition, the series multiplexing of fiber grating sensors limits the flexibility of measurement in different areas

In order to solve the above problems, the number of sensing channels can be increased in the system to realize the multi-channel parallel multiplexing of fiber grating sensors. sex

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