Method and apparatus for judging symmetry of optical fiber link

Abstract

A method for judging symmetry of an optical fiber link, comprising: obtaining polarization state fluctuation information of the optical fiber link to be tested at a master station and a slave station respectively; performing correlation analysis on the information obtained at the master station and the slave station; and comparing the correlation analysis result with a set threshold to confirm symmetry of the optical fiber link to be tested. The method can test symmetry of the optical fiber link to ensure reliable operation of an application related to the symmetry of the optical fiber link. A device for judging symmetry of an optical fiber link, comprising: a master station, a slave station and a signal processing unit connected by an optical fiber to be tested. The master station comprises: a master light source, a polarization information detection unit, a signal acquisition unit, an optical coupler and a polarizer. The slave station comprises: a slave light source, a polarization information detection unit, a signal acquisition unit, an optical coupler and a polarizer. The signal processing unit comprises: a correlation analysis unit and a symmetry judgment unit. The device can measure symmetry of the optical fiber link connecting the master station and the slave station.

Description

Technical Field

[0001] This invention relates to the measurement of symmetry in optical fiber links, and more particularly to a method and apparatus for measuring the symmetry of optical fiber links. Background Technology

[0002] Optical fiber is short for optical waveguide fiber. Common optical fibers are made of glass or plastic. Because they transmit information using the principle of total internal reflection within a plastic sheath, which is achieved through the transmission of light through a fine fiber, their loss is relatively low. Typically, a laser or light-emitting diode (LED) is used as the light source at the transmitting end, and a photodetector completes the photoelectric conversion of the information.

[0003] Thanks to its advantages such as low loss, high bandwidth, and resistance to electromagnetic interference, optical fiber is widely used in communication, sensing, and time synchronization. However, some applications rely on the symmetry of bidirectional transmission in optical fibers, making symmetry detection of optical fiber links a key research area. Summary of the Invention

[0004] The present invention aims to solve the above-mentioned technical problems. The first aspect of the present invention proposes a method for measuring the symmetry of an optical fiber link, comprising: step a, acquiring polarization state fluctuation information of the optical fiber link under test at a master station and a slave station respectively; step b, performing correlation analysis on the polarization state fluctuation information acquired by the master station and the slave station: sending the polarization state fluctuation information of the optical fiber link under test acquired by the master station and the slave station to a signal processing unit, and performing correlation analysis on the two pieces of information; step c, comparing the correlation analysis result with a set threshold to confirm the symmetry of the optical fiber link under test.

[0005] When the master station and slave station acquire the polarization state fluctuation information of the fiber optic link under test in step a, a polarizer should be used to ensure that the polarization state of the light injected into the fiber optic link under test is the same.

[0006] The acquisition of polarization state fluctuation information of the fiber optic link under test at the master station and the acquisition of polarization state fluctuation information of the fiber optic link under test at the slave station, as described in step a, should be performed within the same time period.

[0007] The polarization state fluctuation information of the optical fiber link under test obtained by the master station and slave station in step a can be optical intensity fluctuation or normalized Stokes parameters.

[0008] The threshold mentioned in step c is related to application requirements and system noise floor, and therefore is not a fixed value.

[0009] A second aspect of the present invention provides an apparatus for measuring the symmetry of an optical fiber link, comprising: a master station and a slave station connected by the optical fiber under test, and a signal processing unit.

[0010] The main site includes: a main light source, a first polarization information detection unit, a first signal acquisition unit, a first optical connection device, and a first polarizer; the first interface of the main light source is connected to the first port of the first polarizer; the first port of the first polarization information detection unit is connected to the third port of the first optical connection device, and the second port is connected to the first port of the first signal acquisition unit; the second port of the first signal acquisition unit is connected to the first port of the first correlation analysis unit; the first port of the first optical connection device is connected to one end of the optical fiber under test, and the second port is connected to the second port of the first polarizer.

[0011] The site includes: a light source, a second polarization information detection unit, a second signal acquisition unit, a second optical connection device, and a second polarizer; the first interface of the light source is connected to the first port of the second polarizer; the first port of the second polarization information detection unit is connected to the third port of the second optical connection device, and the second port is connected to the first port of the second signal acquisition unit; the second port of the second signal acquisition unit is connected to the second port of the second correlation analysis unit; the first port of the second optical connection device is connected to one end of the optical fiber under test, and the second port is connected to the second port of the second polarizer.

[0012] The signal processing unit includes: a first correlation analysis unit and a first symmetry judgment unit; the first port of the first correlation analysis unit is connected to the second port of the first signal acquisition unit, the second port is connected to the second port of the second signal acquisition unit, and the third port is connected to the first port of the first symmetry judgment unit.

[0013] The output wavelength difference between the main light source and the secondary light source should be less than 6 nm, and both should be continuous light.

[0014] The first polarization information detection unit and the second polarization information detection unit can output the light intensity channel or the normalized Stokes matrix.

[0015] The optical transmission between the first optical connector and the second optical connector is as follows:

[0016] Light input from the first port can be output from the second and third ports;

[0017] Light input from the second port can be output from the first port.

[0018] Light input from the third port can be output from the first port.

[0019] The polarization states output by the first polarizer and the second polarizer should be the same.

[0020] The first correlation analysis unit can perform correlation analysis on data from the main site and the slave site and obtain the correlation peak.

[0021] The positions and functions of the primary and secondary sites are relative, their functions are equivalent, and they can be interchanged.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] This technology does not require the acquisition of past link latency fluctuation information, thus it can combat slowly changing latency attacks, and does not require the system to work for a period of time under symmetrical link conditions. Attached Figure Description

[0024] Figure 1 This is a flowchart of a method for measuring the symmetry of an optical fiber link according to the present invention.

[0025] Figure 2 This is a structural diagram of a device for measuring the symmetry of an optical fiber link according to the present invention.

[0026] Figure 3 This is a schematic diagram of an embodiment of a device system for measuring the symmetry of an optical fiber link according to the present invention. Detailed Implementation

[0027] The present invention will be further described below with reference to embodiments and accompanying drawings, but this should not be construed as limiting the scope of protection of the present invention.

[0028] In the description of this invention, it should be understood that the terms 'master station' and 'slave station' are used to describe different stations only and do not refer to any specific station.

[0029] The following description, in conjunction with the accompanying drawings, illustrates a method and apparatus for measuring the symmetry of an optical fiber link according to the present invention.

[0030] Please refer to Figure 1 , Figure 1 This is a flowchart of a method for measuring the symmetry of an optical fiber link according to the present invention. As shown in the figure, the method for measuring the symmetry of an optical fiber link according to the present invention includes the following steps:

[0031] Step s101: Obtain polarization state fluctuation information of the fiber optic link under test at the master station and slave station respectively;

[0032] Step s102: Perform correlation analysis on the information obtained from the master station and the slave station: send the polarization fluctuation information of the fiber optic link under test obtained from the master station and the slave station to the signal processing unit, and perform correlation analysis on the two pieces of information.

[0033] Step s103: Compare the correlation analysis results with the set threshold to confirm the symmetry of the fiber optic link under test.

[0034] When the master station and slave station acquire the polarization state fluctuation information of the optical fiber link under test in step s101, a polarizer should be used to ensure that the polarization state of the light injected into the optical fiber link under test is the same.

[0035] The acquisition of polarization state fluctuation information of the optical fiber link under test at the master station and the acquisition of polarization state fluctuation information of the optical fiber link under test at the slave station, as described in step s101, should be performed within the same time period.

[0036] The polarization state fluctuation information of the optical fiber link under test obtained by the master station and slave station in step s101 can be optical intensity fluctuation or normalized Stokes parameters.

[0037] The correlation analysis described in step s102 is used to obtain the correlation peak value between the polarization fluctuation information from the master station and the slave station.

[0038] The threshold mentioned in step s103 is related to application requirements and system noise floor, and therefore is not a fixed value.

[0039] like Figure 2 As shown, Figure 2 This invention relates to a device for measuring the symmetry of an optical fiber link, comprising: a master station and a slave station connected by the optical fiber under test, and a signal processing unit.

[0040] The main station includes: a main light source a1, a first polarization information detection unit a2, a first signal acquisition unit a3, a first optical connection device a4, and a first polarizer a5; the first interface a1-1 of the main light source a1 is connected to the first port a5-1 of the first polarizer a5; the first port a2-1 of the first polarization information detection unit a2 is connected to the third port a4-3 of the first optical connection device a4, and the second port a2-2 is connected to the first port a3-1 of the first signal acquisition unit a3; the second port a3-2 of the first signal acquisition unit a3 is connected to the first port c1-1 of the first correlation analysis unit c1; the first port a4-1 of the first optical connection device a4 is connected to one end of the optical fiber under test, and the second port a4-2 is connected to the second port a5-2 of the first polarizer a5.

[0041] The site includes: a light source b1, a second polarization information detection unit b2, a second signal acquisition unit b3, a second optical connection device b4, and a second polarizer b5; the first interface b1-1 of the light source b1 is connected to the first port b5-1 of the second polarizer b5; the first port b2-1 of the second polarization information detection unit b2 is connected to the third port b4-3 of the second optical connection device b4, and the second port b2-2 is connected to the first port b3-1 of the second signal acquisition unit b3; the second port b3-2 of the second signal acquisition unit b3 is connected to the second port c1-2 of the second correlation analysis unit c1; the first port b4-1 of the second optical connection device b4 is connected to one end of the optical fiber under test, and the second port b4-2 is connected to the second port b5-2 of the second polarizer b5.

[0042] The signal processing unit includes: a first correlation analysis unit c1 and a first symmetry judgment unit c2; the first port c1-1 of the first correlation analysis unit c1 is connected to the second port a3-2 of the first signal acquisition unit a3, the second port c1-2 is connected to the second port b3-2 of the second signal acquisition unit b3, and the third port c1-3 is connected to the first port c2-1 of the first symmetry judgment unit c2.

[0043] The optical transmission between the first optical connector a4 and the second optical connector b4 is as follows:

[0044] The light input from the first port a4-1, b4-1 can be output from the second port a4-2, b4-2 and the third port a4-3, b4-3;

[0045] Light input from the second ports a4-2 and b4-2 can be output from the first ports a4-1 and b4-1.

[0046] Light input from the third port a4-3, b4-3 can be output from the first port a4-1, b4-1.

[0047] The output wavelength difference between the main light source a1 and the secondary light source b1 should be less than 6nm, and both should be continuous light.

[0048] The first polarization information detection unit a2 and the second polarization information detection unit b2 can output the light intensity channel or the normalized Stokes matrix.

[0049] The polarization states output by the first polarizer a5 and the second polarizer b5 should be the same.

[0050] The positions and functions of the primary and secondary sites are relative, their functions are equivalent, and they can be interchanged.

[0051] The working principle of this invention is as follows:

[0052] The link polarization state fluctuation information acquired from the master station and slave station is sent to the master station, slave station, or a third-party station. When performing cross-correlation on the link polarization state fluctuation information acquired from the master station and slave station, the data is slid-wise, and the maximum cross-correlation value under the current data sequence is obtained as the result of the correlation analysis. A threshold is set according to application requirements and system noise floor. The obtained correlation analysis result is compared with the set threshold. If the correlation analysis result between the two stations is greater than the set threshold, the link under test is considered symmetrical; if it is smaller than the set threshold, the link under test is considered asymmetrical.

[0053] A schematic diagram of an embodiment of a device system for measuring the symmetry of an optical fiber link according to the present invention is shown below. Figure 3 As shown. Both the main and secondary light sources use single-wavelength lasers. The first and second polarization information detection units are polarization analyzers capable of outputting the Stokes matrix of the polarization state. At the secondary site, the acquisition card transmits information related to link polarization fluctuations to the signal processing unit via a data transmission module. Correlation analysis is performed in the correlation analysis unit, and the correlation of the fiber optic link under test is determined in the symmetry judgment unit.

Claims

1. A method for determining the symmetry of an optical fiber link, characterized in that, Including the following steps: Step a: Obtain the polarization state fluctuation information of the master station of the fiber optic link under test, and at the same time, obtain the polarization state fluctuation information of the slave station of the fiber optic link under test. Step b: Perform correlation analysis on the polarization state fluctuation information of the master station and the polarization state fluctuation information of the slave station to obtain the correlation analysis results; Step c: Compare the correlation analysis results with the set threshold to identify the symmetry of the fiber optic link under test; The correlation analysis in step b specifically involves: Step b.1 Send the link polarization state fluctuation information obtained by the master station and slave station in step a to the master station, slave station or third-party station; Step b.2 Perform cross-correlation operation on the link polarization state fluctuation information obtained from the master station and slave station, slide the data, and obtain the maximum value of cross-correlation under the current data sequence as the result of correlation analysis; The symmetry determination in step c specifically involves: Step c.1 Set the threshold according to application requirements and system noise floor. Step c.2 Compare the correlation analysis results obtained in step b.2 with the set threshold; Step c.3 If the correlation analysis result between two sites is greater than the set threshold, the link under test is considered symmetrical; if it is less than the set threshold, the link under test is considered asymmetrical.

2. The method for determining the symmetry of an optical fiber link according to claim 1, characterized in that, The polarization state fluctuation information of the master station and the polarization state fluctuation information of the slave station are the same, which is the light intensity fluctuation or the normalized Stokes parameter.

3. A symmetry determination device for an optical fiber link, comprising a master station and a slave station connected by the optical fiber under test, characterized in that, It also includes a signal processing unit; The main station includes: a main light source (a1), a first polarization information detection unit (a2), a first signal acquisition unit (a3), a first optical connection device (a4), and a first polarizer (a5). The slave station includes: a slave light source (b1), a second polarization information detection unit (b2), a second signal acquisition unit (b3), a second optical connection device (b4), and a second polarizer (b5). The signal processing unit includes a first correlation analysis unit (c1) and a first symmetry judgment unit (c2). The first interface (a1-1) of the main light source (a1) is connected to the first port (a5-1) of the first polarizer (a5), the first port (a2-1) of the first polarization information detection unit (a2) is connected to the third port (a4-3) of the first optical connection device (a4), the second port (a2-2) of the first polarization information detection unit (a2) is connected to the first port (a3-1) of the first signal acquisition unit (a3), the second port (a3-2) of the first signal acquisition unit (a3) ​​is connected to the first port (c1-1) of the first correlation analysis unit (c1), the first port (a4-1) of the first optical connection device (a4) is connected to one end of the optical fiber under test, and the second port (a4-2) of the first optical connection device (a4) is connected to the second port (a5-2) of the first polarizer (a5). The first interface (b1-1) of the light source (b1) is connected to the first port (b5-1) of the second polarizer (b5); the first port (b2-1) of the second polarization information detection unit (b2) is connected to the third port (b4-3) of the second optical connector (b4); the second port (b2-2) of the second polarization information detection unit (b2) is connected to the first port (b3-1) of the second signal acquisition unit (b3); the second port (b3-2) of the second signal acquisition unit (b3) is connected to the second port (c1-2) of the first correlation analysis unit (c1); the first port (b4-1) of the second optical connector (b4) is connected to one end of the optical fiber under test; the second port (b4-2) of the second optical connector (b4) is connected to the second port (b5-2) of the second polarizer (b5). The third port (c1-3) of the first correlation analysis unit (c1) is connected to the first port (c2-1) of the first symmetry judgment unit (c2).

4. The symmetry determination device for an optical fiber link according to claim 3, characterized in that, The output wavelength difference between the main light source (a1) and the secondary light source (b1) is less than 6 nm, and both are continuous light.

5. The symmetry determination device for an optical fiber link according to claim 3, characterized in that, The first polarization information detection unit (a2) and the second polarization information detection unit (b2) output the intensity channel or normalized Stokes matrix of the light.

6. The symmetry determination device for an optical fiber link according to claim 3, characterized in that, The optical transmission between the first optical connector (a4) and the second optical connector (b4) is as follows: Light input from the first port (a4-1, b4-1) is output from the second port (a4-2, b4-2) and the third port (a4-3, b4-3); Light input from the second port (a4-2, b4-2) is output from the first port (a4-1, b4-1); Light input from the third port (a4-3, b4-3) is output from the first port (a4-1, b4-1).

7. The symmetry determination device for an optical fiber link according to claim 3, characterized in that, The polarization states output by the first polarizer (a5) and the second polarizer (b5) should be the same.

8. The symmetry determination device for an optical fiber link according to claim 3, characterized in that, The first correlation analysis unit (c1) performs correlation analysis on the data from the main site and the slave site and obtains the correlation peak.

9. The symmetry determination device for an optical fiber link according to claim 3, characterized in that, The positions and functions of the primary and secondary sites are relative, but their functions are equivalent.

10. The symmetry determination device for an optical fiber link according to claim 3, characterized in that, The first correlation analysis unit (c1) is located at the master end, slave end, or other locations.

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