Preparation method of two-input and two-output optical fiber ring and two-input and two-output optical fiber ring

Abstract

The present invention relates to the technical field of fiber optic gyroscopes, and in particular to a method for preparing a two-input and two-output fiber optic ring, comprising the following steps: measuring two optical fibers of required lengths and reserving fiber pigtails of sufficient length; marking the end points and midpoints; using a quadrupole symmetrical winding method to alternately wind the two optical fibers on a fiber optic ring skeleton; changing the winding sequence of the two optical fibers; leading the four fiber pigtails out of the fiber optic ring skeleton and fixing them; and fixing the wound fiber optic ring. According to the method for preparing a two-input and two-output fiber optic ring of the present invention, firstly, the two optical fibers are alternately wound on the fiber optic ring skeleton, and the two optical fibers maintain physical consistency in space, thereby ensuring a strong correlation between the two optical fibers. Secondly, the two optical fibers are alternately wound on the fiber optic ring skeleton, achieving the equivalent effect of the correlation between the two channels of dual polarization while eliminating the polarization residual coherent phase error of the dual polarization in a single optical fiber.

Description

Technical Field

[0001] The invention relates to the technical field of fiber optic gyroscopes, and in particular to a preparation method of a two-input and two-output fiber optic ring and a two-input and two-output fiber optic ring. Background Art

[0002] The fiber ring is the core component of the interferometric fiber optic gyroscope and the sensing unit for detecting rotation signals, which has a significant impact on the accuracy of the fiber optic gyroscope. The traditional fiber ring is wound with a single optical fiber and includes two ports.

[0003] The main parameters that affect the interferometric fiber gyroscope are zero bias instability and angle random walk. In the dual-polarization fiber gyroscope, the errors that affect zero bias instability mainly include polarization nonreciprocity error and residual coherent phase error unique to the dual-polarization fiber gyroscope. For polarization nonreciprocity error, the polarization nonreciprocity error contained in the two orthogonal polarization states is equal in magnitude and opposite in sign, and is compensated by superposition in the optical or electrical domain; for residual coherent phase error, it is caused by interference between the main wave and the dual-polarization coupling wave, and can be suppressed by adding a delay line to reduce the coherence of the dual-polarization light. The main noise source that affects the angle random walk is the relative intensity noise of the light source. The dual-polarization fiber gyroscope uses the strong correlation of the two orthogonal polarization lights to suppress it by jointly processing the two orthogonal polarization lights.

[0004] Bias instability and angle random walk affect the long-term and short-term performance of the fiber optic gyroscope respectively. Generally, different application scenarios have different requirements for the above two performance parameters of the fiber optic gyroscope. For example, inertial navigation pays more attention to bias instability, while seismic monitoring pays more attention to angle random walk. However, in some special applications, it is necessary to ensure both performance parameters at the same time, because the elimination of residual coherent phase error requires low coherence of dual polarized light, while the relative intensity noise suppression of the light source requires strong correlation between two orthogonal polarized lights. Therefore, it is difficult for dual-polarization fiber optic gyroscopes using traditional fiber rings to meet these special requirements at the same time, which has become a difficulty in the development of fiber optic gyroscopes. Summary of the invention

[0005] The purpose of the present invention is to at least solve the problem that a dual-polarization fiber optic gyroscope using a conventional fiber ring cannot maintain strong correlation while eliminating the residual coherent phase error of two orthogonal polarized lights. This purpose is achieved by the following technical solutions:

[0006] The first aspect of the present invention provides a method for preparing a two-input and two-output optical fiber ring, comprising the following steps:

[0007] Step a: Measure two optical fibers of required length and reserve sufficient length of optical fiber pigtails at both ends of the two optical fibers;

[0008] Step b: Mark the endpoints and midpoints of the two optical fibers respectively;

[0009] Step c: Calculate the winding sequence change points according to the optical fiber length and the size of the optical fiber ring skeleton and mark them on the two optical fibers respectively;

[0010] Step d: Using a quadrupole symmetrical winding method to alternately wind the two optical fibers on the optical fiber ring skeleton until the winding sequence changes;

[0011] Step e: changing the winding order of the two optical fibers, and continuing to use the quadrupole symmetrical winding method to alternately wind the two optical fibers on the optical fiber ring skeleton until the end point marks at both ends of the optical fibers are reached;

[0012] Step f: Lead four optical fiber pigtails out of the optical fiber ring frame and fix them;

[0013] Step g: Fix the wound optical fiber ring.

[0014] According to the preparation method of the two-input and two-output optical fiber ring of the present invention, firstly, the two optical fibers are alternately wound on the optical fiber ring skeleton, and the two optical fibers maintain physical consistency in space, thereby ensuring a strong correlation between the two optical fibers. Secondly, the two optical fibers are alternately wound on the optical fiber ring skeleton, achieving the equivalent effect of the correlation between the two channels of dual polarization while eliminating the polarization residual coherence phase error of the dual polarization in a single optical fiber.

[0015] In addition, the method for preparing the two-input and two-output optical fiber ring according to the present invention may also have the following additional technical features:

[0016] In some embodiments of the present invention, the quadrupole symmetrical winding method in step d and step e comprises the following steps:

[0017] Step 1: Take the midpoint of the optical fiber and attach it to the initial edge tooling on one side of the optical fiber ring skeleton, and wind the optical fiber on one side of the optical fiber midpoint to the final edge tooling on the other side of the optical fiber ring skeleton in a clockwise or counterclockwise direction to form the first optical fiber layer;

[0018] Step 2: The optical fiber on the other side of the optical fiber midpoint is wound along the direction opposite to step 1 to the end edge tooling of the optical fiber ring skeleton to form a second optical fiber layer;

[0019] Step 3: Winding the optical fiber of the second optical fiber layer from the end edge tooling to the initial edge tooling in the opposite direction to step 1 to form a third optical fiber layer;

[0020] Step 4: Winding the optical fiber of the first optical fiber layer from the end edge tooling to the initial edge tooling along the same direction as step 1 to form a fourth optical fiber layer, completing a quadrupole symmetrical periodic winding;

[0021] Step 5: Repeat the quadrupole symmetric periodic winding.

[0022] In some embodiments of the present invention, the alternating winding in step d and step e is layer-by-layer alternating winding or four-layer alternating winding.

[0023] In some embodiments of the present invention, the layer-by-layer alternating winding comprises the following steps:

[0024] Step 1: Wind two optical fibers on the optical fiber ring frame at the same starting position according to step 1 of the quadrupole symmetrical winding method to form a first optical fiber layer and a second optical fiber layer;

[0025] Step 2: Winding the two optical fibers on the optical fiber ring skeleton according to step 2 of the quadrupole symmetrical winding method to form a third optical fiber layer and a fourth optical fiber layer;

[0026] Step 3: Winding the two optical fibers on the optical fiber ring skeleton according to step 3 of the quadrupole symmetrical winding method to form a fifth optical fiber layer and a sixth optical fiber layer;

[0027] Step 4: Winding the two optical fibers on the optical fiber ring skeleton according to step 4 of the quadrupole symmetrical winding method to form a seventh optical fiber layer and an eighth optical fiber layer;

[0028] Step 5: Repeat steps 1 to 4.

[0029] In some embodiments of the present invention, four-layer-alternating winding comprises the following steps:

[0030] Step 1: Winding one of the two optical fibers on the optical fiber ring frame according to the quadrupole symmetrical winding method to form the first optical fiber layer to the fourth optical fiber layer;

[0031] Step 2: Winding the other optical fiber of the two optical fibers on the optical fiber ring skeleton according to the quadrupole symmetrical winding method from the same winding starting point in step 1 to form the fifth optical fiber layer to the eighth optical fiber layer;

[0032] Step 3: Repeat steps 1 to 2.

[0033] In some embodiments of the present invention, optical fiber curing glue is coated between the layers of the wound optical fiber.

[0034] In some embodiments of the present invention, the fixing method in step g is dipping.

[0035] A second aspect of the present invention proposes a two-in-two-out fiber optic ring, which is prepared by the above-mentioned two-in-two-out fiber optic ring preparation method. The two-in-two-out fiber optic ring includes two optical fibers, wherein a fiber layer formed by one of the optical fibers being wound around a fiber optic ring skeleton and a fiber layer formed by another optical fiber being wound around the fiber optic ring skeleton are alternately superimposed on each other.

[0036] According to the two-input and two-output optical fiber ring of the present invention, the two-input and two-output optical fiber ring is obtained by winding two optical fibers, and there is a strong correlation between the two optical fibers, which achieves the equivalent effect of the correlation of the two polarization channels of dual polarization while eliminating the polarization residual coherent phase error in a single optical fiber ring. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference numerals are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0038] Figure 1 The schematic diagram of the structure of layer-by-layer alternating winding of the preparation method according to the embodiment of the present invention is schematically shown;

[0039] Figure 2 A schematic diagram of a four-layer alternating winding structure of a preparation method according to an embodiment of the present invention is schematically shown;

[0040] Figure 3 Shows a comparison diagram of Allan variance analysis according to an embodiment of the present invention;

[0041] Figure 4 A self-noise comparison diagram according to an embodiment of the present invention is shown.

[0042] Reference numerals:

[0043] 10 is a fiber ring skeleton;

[0044] 20 is an optical fiber, 21 is a first optical fiber, 22 is a second optical fiber, and 23 is a midpoint of the optical fiber. DETAILED DESCRIPTION

[0045] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0046] It should be understood that the terms used herein are only for the purpose of describing specific example embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "include", "comprise", "contain", and "have" are inclusive, and therefore specify the existence of stated features, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not interpreted as necessarily requiring them to be performed in the specific order described or illustrated, unless the execution order is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0047] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.

[0048] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature as shown in the figure, such as "inside", "outside", "inner side", "outer side", "below", "below", "above", "above", etc. Such spatial relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figure. For example, if the device in the figure is turned over, the element described as "below other elements or features" or "below other elements or features" will be subsequently oriented to "above other elements or features" or "above other elements or features". Therefore, the example term "below..." may include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions) and the spatial relative descriptors used in the text are interpreted accordingly.

[0049] like Figure 1 and Figure 2As shown, according to an embodiment of the present invention, a two-input and two-output fiber optic ring is proposed, which includes two optical fibers 20, wherein the fiber layer formed by the first optical fiber 21 wound on the fiber optic ring skeleton 10 and the fiber layer formed by the second optical fiber 22 wound on the fiber optic ring skeleton 10 are alternately superimposed on each other.

[0050] According to the two-input and two-output fiber optic ring of the present invention, the two-input and two-output fiber optic ring is obtained by winding two optical fibers 20, and there is a strong correlation between the two optical fibers 20, which can achieve the equivalent effect of the correlation of the two polarization channels of dual polarization while eliminating the polarization residual coherent phase error in a single fiber optic ring, and can simultaneously improve the long-term and short-term performance of the fiber optic gyroscope.

[0051] like Figure 1 and Figure 2 As shown, according to an embodiment of the present invention, a method for preparing the above-mentioned two-input and two-output optical fiber ring is proposed, comprising the following steps:

[0052] Step a: Measure two optical fibers 20 of required length and reserve optical fiber pigtails of sufficient length at both ends of the two optical fibers 20;

[0053] Step b: Mark the end points and midpoints of the two optical fibers 20 respectively;

[0054] Step c: Calculate the winding sequence change points according to the length of the optical fiber 20 and the size of the optical fiber ring skeleton 10 and mark them on the two optical fibers 20 respectively;

[0055] Step d: using a quadrupole symmetrical winding method to alternately wind the two optical fibers 20 on the optical fiber ring skeleton 10 until the winding sequence changes;

[0056] Step e: changing the winding order of the two optical fibers 20, and continuing to use the quadrupole symmetrical winding method to alternately wind the two optical fibers 20 on the optical fiber ring skeleton 10 until the end point marks at both ends of the optical fibers;

[0057] Step f: Leading four optical fiber pigtails out of the optical fiber ring frame 10 and fixing them;

[0058] Step g: Fix the wound two-input and two-output optical fiber ring.

[0059] According to the preparation method of the two-input and two-output optical fiber ring of the present invention, first, two optical fibers 20 are alternately wound on the optical fiber ring skeleton 10, and the two optical fibers maintain physical consistency in space, thereby ensuring that there is a strong correlation between the two optical fibers 20. Secondly, the two optical fibers 20 are alternately wound on the optical fiber ring skeleton 10, achieving the equivalent effect of the correlation between the two channels of dual polarization while eliminating the polarization residual coherent phase error of the dual polarization in a single optical fiber. It should be understood that when dual polarization uses two orthogonal polarization channels of an optical fiber 20 at the same time, the residual coherent phase error is the phase error caused by the optical coupling of one channel to another channel and interference with the main wave of the channel. In the present invention, it is equivalent to letting the two channels of dual polarization each go through an optical fiber 20, eliminating the residual coherent phase error. In addition, the present invention will change the winding order of the two optical fibers after the winding order change point, so that the winding lengths of the two optical fibers 20 can be kept consistent.

[0060] Specifically, the quadrupole symmetrical winding method in step d and step e comprises the following steps:

[0061] Step 1: Take the optical fiber midpoint 23 and attach it to the initial edge tooling on one side of the optical fiber ring skeleton 10, and wind the optical fiber 20 on one side of the optical fiber midpoint 23 to the final edge tooling on the other side of the optical fiber ring skeleton 10 in a clockwise or counterclockwise direction to form a first optical fiber layer;

[0062] Step 2: The optical fiber 20 on the other side of the optical fiber midpoint 23 is wound along the direction opposite to step 1 to the end edge tooling of the optical fiber ring skeleton 10 to form a second optical fiber layer;

[0063] Step 3: Winding the optical fiber of the second optical fiber layer from the end edge tooling to the initial edge tooling in the opposite direction to step 1 to form a third optical fiber layer;

[0064] Step 4: Winding the optical fiber of the first optical fiber layer from the end edge tooling to the initial edge tooling along the same direction as step 1 to form a fourth optical fiber layer, completing a quadrupole symmetrical periodic winding;

[0065] Step 5: Repeat the quadrupole symmetric periodic winding.

[0066] In addition, the alternating winding in step d and step e is layer-by-layer alternating winding or four-layer alternating winding.

[0067] It is understandable that in some embodiments, the winding method of alternating winding layer by layer is adopted, including the following steps:

[0068] Step 1: Winding two optical fibers 20 on the optical fiber ring skeleton 10 at the same starting position according to step 1 of the quadrupole symmetrical winding method to form a first optical fiber layer and a second optical fiber layer;

[0069] Step 2: Winding the two optical fibers 20 on the optical fiber ring skeleton 10 according to step 2 of the quadrupole symmetrical winding method to form a third optical fiber layer and a fourth optical fiber layer;

[0070] Step 3: Winding the two optical fibers 20 on the optical fiber ring skeleton 10 according to step 3 of the quadrupole symmetrical winding method to form a fifth optical fiber layer and a sixth optical fiber layer;

[0071] Step 4: Winding the two optical fibers 20 on the optical fiber ring skeleton 10 according to step 4 of the quadrupole symmetrical winding method to form a seventh optical fiber layer and an eighth optical fiber layer;

[0072] Step 5: Repeat steps 1 to 4.

[0073] It is understood that in some embodiments, a four-layer-one-alternating winding method is adopted, including the following steps:

[0074] Step 1: Winding the first optical fiber 21 of the two optical fibers 20 on the optical fiber ring skeleton 10 according to the quadrupole symmetrical winding method to form the first optical fiber layer to the fourth optical fiber layer;

[0075] Step 2: Winding the second optical fiber 22 of the two optical fibers on the optical fiber ring skeleton 10 according to the quadrupole symmetrical winding method from the same winding starting point in step 1 to form the fifth optical fiber layer to the eighth optical fiber layer;

[0076] Step 3: Repeat steps 1 to 2.

[0077] It should be understood that the spatial physical consistency of layer-by-layer alternating winding is better than that of four-layer-one alternating winding, but the implementation difficulty of four-layer-one alternating winding is less than that of layer-by-layer alternating winding.

[0078] It should be noted that Figure 1 and Figure 2 The solid dot in the center of the optical fiber indicates the winding direction, the hollow dot indicates another winding direction, and the direction of the arrow indicates the order in which the optical fibers are arranged.

[0079] In addition, optical fiber curing glue is coated between the layers of the wound optical fiber to bond the layers of the optical fiber 20 together.

[0080] Specifically, the method for fixing the optical fiber ring in the above step g is to dip in glue to improve the bonding force between the optical fiber 20 and the glue.

[0081] The following data were measured by using the two-input and two-output optical fiber ring of the present invention to access the dual-polarization optical path:

[0082] The two-input and two-output fiber ring is made by alternate winding layer by layer, and the length of the two-input and two-output fiber ring is 2Km, the diameter is 148mm, the modulation frequency is 50KHz, and the modulation depth is 1.84. The light source used in the experiment is an ASE light source with a wavelength of 1550nm and a spectrum width of 40nm.

[0083] Read the output angular velocity data for one hour, perform Allan variance analysis and compare it with the result after relative intensity noise suppression (such as Figure 3 ) and compared with self-noise (as shown in Figure 4 As shown in Table 1, the comparison of Allan variance parameters is shown in Table 1.

[0084] Table 1

[0085]

[0086] in Figure 3 and Figure 4 PD1 is the parameter measured at port 1, PD2 is the parameter measured at port 2, and SUM is the parameter combined with RIN.

[0087] According to the parameters measured in the above embodiment, it can be seen that there is a strong correlation between port 1 and port 2, and when the fiber optic ring of this embodiment is adopted, the short-time and long-time performance of the fiber optic gyroscope are significantly improved. Therefore, it can be proved that the two optical fibers 20 are alternately wound on the fiber optic ring skeleton, and the two optical fibers 20 maintain physical consistency in space, thereby ensuring a strong correlation between the two optical fibers 20. The two optical fibers 20 are alternately wound on the fiber optic ring skeleton, which achieves the equivalent effect of the correlation between the two channels of dual polarization while eliminating the polarization residual coherence phase error of the dual polarization in a single optical fiber. While ensuring strong correlation, both short-time and long-time performance are significantly improved.

[0088] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for preparing a two-input and two-output optical fiber ring, characterized in that: The steps include: Step a: Measure two optical fibers of required length and reserve sufficient length of optical fiber pigtails at both ends of the two optical fibers; Step b: Mark the endpoints and midpoints of the two optical fibers respectively; Step c: Calculate the winding sequence change points according to the optical fiber length and the size of the optical fiber ring skeleton and mark them on the two optical fibers respectively; Step d: using a quadrupole symmetrical winding method to alternately wind the two optical fibers on the optical fiber ring skeleton until the winding sequence changes; Step e: changing the winding order of the two optical fibers, and continuing to use the quadrupole symmetrical winding method to alternately wind the two optical fibers on the optical fiber ring skeleton until the end point marks at both ends of the optical fibers are reached; Step f: Lead four optical fiber pigtails out of the optical fiber ring frame and fix them; Step g: Fix the wound two-input and two-output optical fiber ring; The quadrupole symmetrical winding method in step d and step e comprises the following steps: Step 1: Take the midpoint of the optical fiber and attach it to the initial edge tooling on one side of the optical fiber ring skeleton, and wind the optical fiber on one side of the optical fiber midpoint to the final edge tooling on the other side of the optical fiber ring skeleton in a clockwise or counterclockwise direction to form the first optical fiber layer; Step 2: The optical fiber on the other side of the optical fiber midpoint is wound along the direction opposite to step 1 to the end edge tooling of the optical fiber ring skeleton to form a second optical fiber layer; Step 3: Winding the optical fiber of the second optical fiber layer from the end edge tooling to the initial edge tooling in the opposite direction to step 1 to form a third optical fiber layer; Step 4: Winding the optical fiber of the first optical fiber layer from the end edge tooling to the initial edge tooling along the same direction as step 1 to form a fourth optical fiber layer, completing a quadrupole symmetrical periodic winding; Step 5: Repeat the quadrupole symmetric periodic winding; The alternating winding in step d and step e is layer-by-layer alternating winding or four-layer-one alternating winding; Further, The layer-by-layer alternating winding process includes the following steps: Step 1: Winding two optical fibers on the optical fiber ring frame at the same starting position according to step 1 of the quadrupole symmetrical winding method to form a first optical fiber layer and a second optical fiber layer; Step 2: Winding the two optical fibers on the optical fiber ring skeleton according to step 2 of the quadrupole symmetrical winding method to form a third optical fiber layer and a fourth optical fiber layer; Step 3: Winding the two optical fibers on the optical fiber ring skeleton according to step 3 of the quadrupole symmetrical winding method to form a fifth optical fiber layer and a sixth optical fiber layer; Step 4: Winding the two optical fibers on the optical fiber ring skeleton according to step 4 of the quadrupole symmetrical winding method to form a seventh optical fiber layer and an eighth optical fiber layer; Step 5: Repeat steps 1 to 4; Further, Four-layer alternating winding includes the following steps: Step 1: Winding one of the two optical fibers on the optical fiber ring frame according to the quadrupole symmetrical winding method to form the first optical fiber layer to the fourth optical fiber layer; Step 2: Winding the other optical fiber of the two optical fibers on the optical fiber ring skeleton according to the quadrupole symmetrical winding method from the same winding starting point in step 1 to form the fifth optical fiber layer to the eighth optical fiber layer; Step 3: Repeat steps 1 to 2.

2. The method for preparing a two-input and two-output optical fiber ring according to claim 1, characterized in that: Fiber optic curing glue is applied between the layers of the fiber optic winding.

3. The method for preparing a two-input and two-output optical fiber ring according to claim 1, characterized in that: The fixing method in step g is dipping.

4. A two-input and two-output optical fiber ring, wherein the two-input and two-output optical fiber ring is prepared by the preparation method of the two-input and two-output optical fiber ring according to any one of claims 1 to 3, characterized in that: It comprises two optical fibers, wherein an optical fiber layer formed by winding one optical fiber on an optical fiber ring frame and an optical fiber layer formed by winding another optical fiber on the optical fiber ring frame are alternately superimposed on each other.

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