CN103808341A - Distributed microstructure optical fiber sensor - Google Patents

Abstract

The invention provides a distributed microstructure optical fiber sensor and mainly aims at solving the problems that the existing optical fiber environment is only capable of supporting one sensing probe, only one outside variable can be measured, and the like. The distributed microstructure optical fiber sensor is composed of an ASE (Amplified Spontaneous Emission) broad band optical source, a spectrum analyzer, an incident optical fiber, a receiving optical fiber, a 50: 50 2*2 optical fiber coupler A, a 50: 50 2*2 optical fiber coupler B, an interference arm A, an interference arm B, an emergent optical fiber A, an emergent optical fiber B, an index-matching fluid, an optical switch, a plurality of segments of polarization-maintaining pohotonic crystal fibers and silver reflector systems as many as the polarization-maintaining pohotonic crystal fibers. The distributed microstructure optical fiber sensor realizes that the sensing probes of different channels are chosen in different time slices and different sensing probes are capable of measuring different physical parameters with the pohotonic crystal fibers, and therefore, a multiple-parameter measurement function is realized.

Description

A Distributed Microstructure Optical Fiber Sensor

technical field

The invention relates to a distributed microstructure optical fiber sensor, which belongs to the technical field of optical fiber sensing.

Background technique

Due to its simple structure, small size and high sensitivity, the fiber optic loop mirror has been widely studied as a sensing structure in recent years. In the initial design of the ordinary single-mode fiber optic loop mirror, a single-mode fiber is used to connect the two output ports of the 2×2 single-mode fiber coupler to form a fiber optic ring. The birefringence effect of single-mode fiber can be neglected under the condition of non-squeezing, bending and twisting. Therefore, if the birefringence effect of the single-mode fiber is not considered, and the effects such as the external Faraday effect or the gyro rotation effect are ignored, when a 3dB single-mode fiber coupler with a splitting ratio of K=0.5 is used, this ideal fiber optic loop mirror To the role of "total reflection mirror", it is called "fiber optic loop mirror". However, any single-mode fiber cannot be perfectly circularly symmetric, that is, it is impossible to have no birefringence effect. Later, people fused a section of high birefringence fiber in the single-mode fiber loop mirror, and began to use the birefringence effect to detect external physical quantities based on the phenomenon of spectral interference. The advantages of this structure are becoming more and more prominent. Sensors based on this structure And more and more. However, flaws still exist, that is, the output results of pure fiber optic loop mirrors are severely affected by external conditions such as extrusion, bending, and torsion, and even lead to incorrect input results. Therefore, the practicability of this structure is far from enough.

Long-tailed fiber optic loop mirror is a new type of fiber optic loop mirror structure based on single-mode fiber optic ring-long-tailed high birefringence. Because it can separate the sensor probe from the fiber optic loop mirror, the sensor structure of the fiber optic loop mirror It is more convenient in actual use, especially suitable for long-distance parameter measurement.

The advantages of the long-tail fiber optic loop mirror are very obvious, and it has been developed rapidly after it was proposed, but at present, this structure can only support one sensing probe.

Contents of the invention

The purpose of the present invention is to realize that a sensing ring mirror unit can simultaneously measure multiple external variables, and a distributed microstructure optical fiber sensor is provided, and its optical switch can realize time-sharing switching of multiple sensing probes on the right side, In order to achieve the purpose of measuring several sensing quantities at the same time.

The purpose of the present invention is achieved through the following technical solutions:

A distributed microstructure fiber optic sensor, including ASE wide-spectrum light source, spectrum analyzer, incident fiber, receiving fiber, 50:50 2×2 fiber coupler A, 50:50 2×2 fiber coupler B, interference arm A, interference arm B, outgoing fiber A, outgoing fiber B, refractive index matching liquid, optical switch, several sections of polarization-maintaining photonic crystal fiber and corresponding number of silver mirror systems.

The ASE wide-spectrum light source is connected to the incident fiber, the spectrum analyzer is connected to the receiving fiber, the two ports at one end of the 50:50 2×2 fiber coupler A are respectively connected to the incident fiber and the receiving fiber, and the two ports at the other end Connect to interference arm A and interference arm B respectively, the two ports at one end of 50:50 2×2 fiber coupler B are respectively connected to interference arm A and interference arm B, and the two ports at the other end are respectively connected to outgoing fiber A, The outgoing fiber B is connected, the outgoing optical fiber A is inserted into the refractive index matching liquid, and the outgoing optical fiber B is connected to the optical switch. All the above connection methods adopt flange connection.

One end of the plurality of polarization-maintaining photonic crystal fibers is connected to the optical switch through a single-mode fiber, and the other end is connected to a corresponding number of silver mirror systems, and the silver mirror system is directly pasted to the end face of the polarization-maintaining photonic crystal fiber .

The incident fiber, receiving fiber, 50:50 2×2 fiber coupler A, 50:50 2×2 fiber coupler B, interference arm A, interference arm B, outgoing fiber A and outgoing fiber B are all single Mode fiber, G.652, G.653 or G.655 single-mode fiber can be used; the length of incident fiber and receiving fiber is 20-40cm; interference arm A and interference arm B form a fiber optic loop mirror, the length is 10- 20cm, the length of outgoing fiber A and outgoing fiber B is 20-40cm.

The light emitted by the ASE wide-spectrum light source passes through the 50:50 2×2 fiber coupler A and enters the interference arm A for clockwise transmission and the interference arm B for counterclockwise transmission, that is, the optical paths are 7→10→8 and 8→ 10→7.

The working bands of the 50:50 2×2 fiber coupler A and the 50:50 2×2 fiber coupler B depend on the output spectral range of the ASE broadband light source, and the birefringence index of the polarization-maintaining photonic crystal fiber is 3.0 ×10 ^-3 -5.0×10 ^-4 .

The working principle of the present invention is: the light emitted by the ASE wide-spectrum light source passes through the 3dB coupler A and enters the interference arm A for clockwise transmission and the interference arm B for counterclockwise transmission, and when it reaches the 50:50 2×2 optical fiber coupler B, it will Enter the output fiber A and the output fiber B respectively, the output fiber A extends into the refractive index matching liquid, the light is completely absorbed by the matching liquid, and there will be no return of light intensity, and the single-mode fiber of the output fiber B is connected to an optical switch. Several sections of polarization-maintaining photonic crystal fiber are welded behind the switch, and a silver reflector system is glued to the end of the polarization-maintaining photonic crystal fiber, which can return the light to the original path. The 2×2 fiber coupler B will be divided into two paths again to extend the interference arm A and the interference arm B for transmission. Finally, the light of all optical paths will interfere at the 50:50 2×2 fiber coupler A. Among the light waves reaching the spectrum analyzer, only the two beams of light waves that travel around the fiber optic loop mirror, that is, the two beams of light waves whose optical path paths are 7→10→8 and 8→10→7 respectively, can be due to the effect of high birefringence fiber The interference output spectrum with periodic distribution is generated, and the corresponding interference output spectrum of the other two light waves cannot be displayed on the spectrum analyzer due to the large optical path difference, and only the average light intensity can be displayed. Since only half of the light produces a periodically distributed output spectrum, and because of the average light intensity, the minimum value of the output spectrum output rate is not 0, so the maximum intensity and intensity range of the output spectrum are reduced, but the overall output spectrum The periodic distribution remains largely unchanged.

The beneficial effect of the invention is that the distributed microstructure optical fiber sensor is used as a distributed microstructure parameter measurement structure. As a time-division multiplexing switch device, the optical switch realizes the selection of sensing probes of different channels in different time slices, so that the system can collect the sensory quantities of the probes in the corresponding time period, and different sensing probes can use photonic crystal fibers to measure different Physical parameters, such as pressure, displacement, temperature, frequency, etc., realize the function of multi-parameter measurement.

Description of drawings

Fig. 1 is a schematic structural view of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Referring to accompanying drawing 1, a kind of distributed microstructure optical fiber sensor, comprises ASE broad-spectrum light source 1, spectrum analyzer 2, incident optical fiber 3, receiving optical fiber 4, 50:50 2 * 2 fiber coupler A5, 50:50 2 ×2 fiber coupler B6, interference arm A7, interference arm B8, outgoing fiber A9, outgoing fiber B10, refractive index matching liquid 11, optical switch 12, several sections of polarization-maintaining photonic crystal fiber 13 and the corresponding number of silver mirror system 14 .

The ASE wide-spectrum light source 1 is connected to the incident optical fiber 3, the spectrum analyzer 2 is connected to the receiving optical fiber 4, and the two ports at one end of the 2×2 fiber coupler A5 of 50:50 are respectively connected to the incident optical fiber 3 and the receiving optical fiber 4, The two ports at the other end are respectively connected to the interference arm A7 and the interference arm B8, and the two ports at one end of the 50:50 2×2 fiber optic coupler B6 are respectively connected to the interference arm A7 and the interference arm B8, and the two ports at the other end They are respectively connected to the outgoing optical fiber A9 and the outgoing optical fiber B10, the outgoing optical fiber A9 extends into the refractive index matching liquid 11, the outgoing optical fiber B10 is connected to the optical switch 12, and all the above connection methods adopt flange connection.

One end of the plurality of polarization-maintaining photonic crystal fibers 13 is connected to the optical switch 12 through a single-mode optical fiber, and the other end is connected to a corresponding number of silver mirror systems 14, and the silver mirror systems 14 are directly pasted to the polarization-maintaining light The end face of the sub-crystal fiber 13.

The incident optical fiber 3, the receiving optical fiber 4, the 50:50 2×2 fiber coupler A5, the 50:50 2×2 fiber coupler B6, the interference arm A7, the interference arm B8, the outgoing optical fiber A9 and the outgoing optical fiber B10 are all It is a single-mode fiber, and G.652, G.653 or G.655 single-mode fiber can be used; the length of the incident fiber 1 and the receiving fiber 2 is 20-40cm; the interference arm A7 and the interference arm B8 form a fiber optic loop mirror, The length is 10-20cm, and the length of the outgoing optical fiber A9 and the outgoing optical fiber B10 is 20-40cm.

The light emitted by the ASE wide-spectrum light source 1 passes through the 50:50 2×2 fiber coupler A5 and enters the interference arm A7 for clockwise transmission and the interference arm B8 for counterclockwise transmission, that is, the optical paths are 7→10→8 and 8 respectively. →10→7.

The working bands of the 50:50 2×2 fiber coupler A5 and the 50:50 2×2 fiber coupler B6 depend on the output spectral range of the ASE wide-spectrum light source 1, and the birefringence coefficient of the polarization-maintaining photonic crystal fiber 13 3.0×10 ^-3 -5.0×10 ^-4 .

Claims (3)

1. A distributed microstructure optical fiber sensor, comprising ASE wide-spectrum light source, spectrum analyzer, incident optical fiber, receiving optical fiber, 2 × 2 fiber optic coupler A of 50:50, it is characterized in that: above-mentioned a kind of distributed microstructure optical fiber sensor It also includes 50:50 2×2 fiber coupler B, interference arm A, interference arm B, outgoing fiber A, outgoing fiber B, refractive index matching liquid, optical switch, several sections of polarization-maintaining photonic crystal fiber and corresponding silver reflector system; the ASE wide-spectrum light source is connected to the incident optical fiber, the spectrum analyzer is connected to the receiving optical fiber, and the two interfaces at one end of the 2×2 fiber coupler A of 50:50 are respectively connected to the incident optical fiber and the receiving optical fiber The two interfaces at the other end are respectively connected to the interference arm A and the interference arm B, the two interfaces at one end of the 50:50 2×2 fiber optic coupler B are respectively connected to the interference arm A and the interference arm B, and the two interfaces at the other end The two interfaces are respectively connected to the outgoing optical fiber A and the outgoing optical fiber B, the outgoing optical fiber A extends into the refractive index matching liquid, the outgoing optical fiber B is connected to the optical switch, and all the above connection methods adopt flange connection; One end of the plurality of polarization-maintaining photonic crystal fibers is connected to the optical switch through a single-mode fiber, and the other end is connected to a corresponding number of silver mirror systems, and the silver mirror system is directly pasted to the end face of the polarization-maintaining photonic crystal fiber . 2. A kind of distributed microstructure optical fiber sensor as claimed in claim 1, it is characterized in that: the 2×2 fiber coupler A of 50:50, the 2×2 fiber coupling of described incident fiber, receiving fiber, 50:50 Device B, interference arm A, interference arm B, outgoing fiber A and outgoing fiber B are all single-mode fibers, and G.652, G.653 or G.655 single-mode fibers can be used; the length of the incident fiber and receiving fiber is 20 -40cm; interference arm A and interference arm B form a fiber optic loop mirror, the lengths of which are 10-20cm respectively, and the lengths of outgoing fiber A and outgoing fiber B are 20-40cm. The light emitted by the ASE wide-spectrum light source passes through the 50:50 2×2 fiber coupler A and enters the interference arm A for clockwise transmission and the interference arm B for counterclockwise transmission, that is, the optical paths are 7→10→8 and 8→ 10→7. 3. A kind of distributed microstructure optical fiber sensor as claimed in claim 1, it is characterized in that: the working band of the 2×2 fiber coupler A of 50:50 and the 2×2 fiber coupler B of 50:50 depends on Based on the output spectrum range of the ASE broadband light source, the birefringence coefficient of the polarization-maintaining photonic crystal fiber is 3.0×10 ^-3 -5.0×10 ^-4 .

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