CN114295114B - Method and system for measuring parameters of optical fiber depolarizer in depolarization type optical fiber gyroscope optical fiber sensitive loop - Google Patents
Method and system for measuring parameters of optical fiber depolarizer in depolarization type optical fiber gyroscope optical fiber sensitive loop Download PDFInfo
- Publication number
- CN114295114B CN114295114B CN202210001199.4A CN202210001199A CN114295114B CN 114295114 B CN114295114 B CN 114295114B CN 202210001199 A CN202210001199 A CN 202210001199A CN 114295114 B CN114295114 B CN 114295114B
- Authority
- CN
- China
- Prior art keywords
- optical fiber
- δnl
- sin2θ
- fiber
- cos
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Landscapes
- Gyroscopes (AREA)
Abstract
The invention belongs to the field of fiber optic gyroscopes, in particular relates to a method, a system and equipment for measuring parameters of a fiber depolarizer in a depolarized fiber optic gyroscope fiber sensitive loop, and aims to solve the problem that the performance of a depolarized fiber optic gyroscope is degraded because the parameters of the fiber depolarizer in the depolarized fiber optic gyroscope fiber sensitive loop cannot be accurately measured in the prior art. The method comprises the following steps: measuring an output spectrum of the optical fiber sensing loop of the depolarization type optical fiber gyroscope as an actual measurement modulation spectrum; carrying out normalized autocorrelation calculation on the actually measured modulation spectrum to obtain a normalized autocorrelation curve, and extracting characteristic peak information; constructing a parameter measurement equation set of the optical fiber depolarizer; and solving a parameter measurement equation set of the optical fiber depolarizer to obtain the lengths of polarization maintaining fibers in the two optical fiber depolarizers and the included angle of a polarization main shaft at the welding point of the Y waveguide polarization maintaining tail fiber and the polarization maintaining fiber. The method realizes accurate measurement of the parameters of the optical fiber depolarizer in the optical fiber sensitive loop of the depolarized optical fiber gyroscope, and improves the quality of the optical fiber depolarizer.
Description
Technical Field
The invention belongs to the field of fiber optic gyroscopes, and particularly relates to a method, a system and equipment for measuring parameters of a fiber depolarizer in a depolarized fiber optic gyroscope fiber sensitive loop.
Background
The depolarization type fiber optic gyroscope is an interference type fiber optic gyroscope adopting a single-mode fiber optic ring, has the characteristics of high sensitivity, low cost and low magnetic field sensitivity, and has stronger application value and competitiveness in the field of high-precision fiber optic gyroscopes with obvious fiber optic ring cost ratio. The optical fiber depolarizer is a key optical device of a depolarizing optical fiber gyroscope, and can depolarize wide-spectrum light entering a single-mode optical fiber ring, improve the stability of interference signals, and inhibit most of noise and drift caused by unstable polarization state, so that the quality of the optical fiber depolarizer determines the performance of the depolarizing optical fiber gyroscope. The optical fiber depolarizer is generally formed by welding two polarization maintaining optical fibers with the length ratio of 1 to 2 at an angle of 45 degrees, in order to ensure the depolarization effect, the length of the shorter polarization maintaining optical fiber needs to be far longer than that of the optical fiber corresponding to the light source decoherence, and meanwhile, the error of the 45-degree welding angle needs to be as small as possible. The parameters of the length of the polarization maintaining optical fiber and the welding angle between the two polarization maintaining optical fibers determine the quality of the optical fiber depolarizer, so that it is very important to accurately evaluate the parameters of the optical fiber depolarizer.
The fiber-optic sensitive loop of the depolarization fiber-optic gyroscope consists of a Y waveguide modulator chip, two polarization-maintaining tail fibers, two polarization-maintaining fibers with set lengths and a single-mode fiber loop, wherein the two polarization-maintaining tail fibers and the two polarization-maintaining fibers are respectively welded, and the included angle of a polarization main shaft between the polarization-maintaining tail fibers and the polarization-maintaining fibers at the welding point is required to be 45 degrees, so that two fiber-optic depolarizers consisting of four sections of polarization-maintaining fibers are formed, and the length ratio of the four sections of polarization-maintaining fibers should satisfy the relationship of 1. The output light of the polarization-maintaining tail fiber of the Y waveguide modulator chip is linearly polarized light, the linearly polarized light enters the second section of polarization-maintaining fiber at an angle of 45 degrees to realize uniform light splitting, the polarization randomization and decoherence effects are mainly ensured by the length of the second section of polarization-maintaining fiber, and therefore the included angle of the polarization main shafts of the fusion point of the polarization-maintaining fiber in the depolarizer and the length of the second section of polarization-maintaining fiber are important parameters. To date, the optical fiber depolarizer used in the depolarizing optical fiber gyroscope generally needs to be manufactured separately and then connected into the optical fiber loop. Due to the problems of welding angle error and uncertain optical fiber interception and cutting length in the access process, parameters of the optical fiber depolarizer are greatly changed after an optical fiber loop is accessed, and the conventional method cannot realize the measurement of the parameters of the optical fiber depolarizer under the condition, so that the performance of the depolarized optical fiber gyroscope has numerous uncertain factors.
Research shows that the output spectrum of the fiber-optic sensitive loop of the depolarization fiber-optic gyroscope is in an interference comb-shaped modulation spectrum shape and is mainly formed by polarization interference introduced by a second section of polarization-maintaining fiber in a fiber-optic depolarizer. Based on the theory, the invention provides an online measurement method for the length of a second section of polarization maintaining optical fiber forming an optical fiber depolarizer in an optical fiber sensitive loop of a depolarization type optical fiber gyroscope and the included angle of a polarization main shaft at the fusion point of the polarization maintaining optical fiber, which is abbreviated as follows: a method for measuring parameters of an optical fiber depolarizer in an optical fiber sensitive loop of a depolarizing optical fiber gyroscope.
Disclosure of Invention
In order to solve the problems in the prior art, namely to solve the problem that the prior art can not accurately measure the parameters of an optical fiber depolarizer in an optical fiber sensitive loop of a depolarizing optical fiber gyroscope, so that the performance of the depolarizing optical fiber gyroscope is degraded, the invention provides a method for measuring the parameters of the optical fiber depolarizer in the optical fiber sensitive loop of the depolarizing optical fiber gyroscope, which is applied to an optical path of the depolarizing optical fiber gyroscope, wherein the optical path comprises a wide-spectrum light source, a coupler, the optical fiber sensitive loop and an optical fiber spectrometer; the optical fiber spectrometer is connected with the computer; the optical fiber sensitive loop consists of a Y waveguide modulator chip, a first optical fiber depolarizer, a second optical fiber depolarizer and a single-mode optical fiber loop; the optical fiber depolarizer consists of Y waveguide polarization maintaining tail fiber and polarization maintaining fiber; the parameter measuring method comprises the following steps:
step S100, measuring an output spectrum of an optical fiber sensitive loop of the depolarization type optical fiber gyroscope through the optical fiber spectrometer as an actually measured modulation spectrum;
step S200, carrying out normalized autocorrelation calculation on the actually measured modulation spectrum to obtain a normalized autocorrelation curve, and extracting characteristic peak information from the normalized autocorrelation curve; the characteristic peak information comprises peak point positions and intensities of characteristic peaks;
step S300, combining the characteristic peak information to construct an optical fiber depolarizer parameter measurement equation set;
and S400, solving a parameter measurement equation set of the optical fiber depolarizer to obtain the lengths of polarization maintaining optical fibers in the two optical fiber depolarizers and the included angle of polarization main shafts at the welding points of the Y waveguide polarization maintaining tail fiber and the polarization maintaining optical fiber.
In some preferred embodiments, the output spectrum of the depolarized fiber optic gyroscope fiber optic sensing loop is modeled by:
wherein, I out (v) Representing the output spectrum, v the optical frequency, iin (v) the spectrum of a broad spectrum light source,
for Sagnac phase shift, F (v) is the spectral transfer function.
In some preferred embodiments, the spectral transfer function is:
F(v)＝F 0 +F 1 (v)+F 2 (v)+F 3 (v)
F 0 ＝1/2+1/2cos2θ 12 cos2θ 34 cos2θ 2s cos2θ 4s
F 1 (v)＝-1/2sin2θ 12 cos2θ 34 sin2θ 2s cos2θ 4s cos(2πvτ 2 ) -1/2cos2θ 12 sin2θ 34 cos2θ 2s sin2θ 4s cos(2πvτ 4 ) -1/2cos2θ 12 cos2θ 34 sin2θ 2s sin2θ 4s cos(2πvτ s )
F 2 (v)＝-1/2sin2θ 12 cos2θ 34 cos 2 θ 2s sin2θ 4s cos(2πv(τ 2 +τ s )) +1/2sin2θ 12 cos2θ 34 sin 2 θ 2s sin2θ 4s cos(2πv(τ 2 -τ s )) -1/2cos2θ 12 sin2θ 34 sin2θ 2s cos 2 θ 4s cos(2πv(τ 4 +τ s )) +1/2cos2θ 12 sin2θ 34 sin2θ 2s sin 2 θ 4s cos(2πv(τ 4 -τ s )) +1/4sin2θ 12 sin2θ 34 sin2θ 2s sin2θ 4s cos(2πv(τ 2 +τ 4 )) +1/4sin2θ 12 sin2θ 34 sin2θ 2s sin2θ 4s cos(2πv(τ 2 -τ 4 ))
F 3 (v)＝-1/2sin2θ 12 sin2θ 34 cos 2 θ 2s cos 2 θ 4s cos(2πv(τ 2 +τ 4 +τ s )) -1/2sin2θ 12 sin2θ 34 sin 2 θ 2s sin 2 θ 4s cos(2πv(τ 2 +τ 4 -τ s )) +1/2sin2θ 12 sin2θ 34 cos 2 θ 2s sin 2 θ 4s cos(2πv(τ 2 -τ 4 +τ s )) +1/2sin2θ 12 sin2θ 34 sin 2 θ 2s cos 2 θ 4s cos(2πv(τ 2 -τ 4 -τ s ))
the first optical fiber depolarizer consists of a Y-waveguide first polarization-maintaining tail fiber and a second polarization-maintaining optical fiber, the second optical fiber depolarizer consists of a Y-waveguide third polarization-maintaining tail fiber and a fourth polarization-maintaining optical fiber, and theta is 12 、θ 34 The included angle of the polarization main shafts at the welding points of a first polarization-maintaining pigtail and a second polarization-maintaining pigtail of a Y waveguide in a first optical fiber depolarizer, the included angle of the polarization main shafts at the welding points of a third polarization-maintaining pigtail and a fourth polarization-maintaining pigtail of the Y waveguide in the second optical fiber depolarizer, theta 2s is the included angle of the polarization main shafts at the welding points of the second polarization-maintaining pigtail and a single-mode optical fiber ring, theta 4s is the included angle of the polarization main shafts at the welding points of the fourth polarization-maintaining fiber and the single-mode optical fiber ring, tau 2= delta nL2/c, tau 4= delta nL4/c, tau s = delta nsLs/c, delta n is polarization-maintaining optical fiber birefringence, delta ns is single-mode optical fiber ring average birefringence, ls is single-mode optical fiber ring length, L2 and L4 are the length of the second polarization-maintaining fiber and the length of the fourth polarization-maintaining fiber respectively, and c is the speed of light in the air.
In some preferred embodiments, the model of the characteristic peak in the normalized autocorrelation curve is:
P 1 ＝A 1 ·γ in (l-ΔnL 2 )
A 1 ＝|[-1/2×sin2θ 12 cos2θ 34 sin2θ 2s cos2θ 4s cos(2πv 0 ΔnL 2 /c) -1/2×sin2θ 12 cos2θ 34 cos 2 θ 2s sin2θ 4s cos(2πv 0 (ΔnL 2 +Δn s L s )/c) +1/2×sin2θ 12 cos2θ 34 sin 2 θ 2s sin2θ 4s cos(2πv 0 (ΔnL 2 -Δn s L s )/c)]|
P 2 ＝A 2 ·γ in (l-ΔnL 4 +ΔnL 2 )
A 2 ＝|[-1/4×sin2θ 12 sin2θ 34 sin2θ 2s sin2θ 4s cos(2πv 0 (ΔnL 4 -ΔnL 2 )/c) +1/2×sin2θ 12 sin2θ 34 cos 2 θ 2s sin 2 θ 4s cos(2πv 0 (ΔnL 4 +ΔnL 2 -Δn s L s )/c) +1/2×sin2θ 12 sin2θ 34 sin 2 θ 2s cos 2 θ 4s cos(2πv 0 (ΔnL 4 -ΔnL 2 +Δn s L s )/c)]|
P 3 ＝A 3 ·γ in (l-ΔnL 4 )
A 3 ＝|[-1/2×cos2θ 12 sin2θ 34 cos2θ 2s sin2θ 4s cos(2πv 0 ΔnL 4 /c) -1/2×cos2θ 12 sin2θ 34 sin2θ 2s cos 2 θ 4s cos(2πv 0 (ΔnL 4 +Δn s L s )/c) +1/2×cos2θ 12 sin2θ 34 sin2θ 2s sin 2 θ 4s cos(2πv 0 (ΔnL 4 -Δn s L s )/c)]|
P 4 ＝A 4 ·γ in (l-ΔnL 4 -ΔnL 2 )
A 4 ＝|[1/4×sin2θ 12 sin2θ 34 sin2θ 2s sin2θ 4s cos(2πv 0 (ΔnL 4 +ΔnL 2 )/c) -1/2×sin2θ 12 sin2θ 34 cos 2 θ 2s cos 2 θ 4s cos(2πv 0 (ΔnL 4 +ΔnL 2 +Δn s L s )/c) -1/2×sin2θ 12 sin2θ 34 sin 2 θ 2s sin 2 θ 4s cos(2πv 0 (ΔnL 4 +ΔnL 2 -Δn s L s )/c)]|
wherein, A 1 、A 2 、A 3 、A 4 Amplitude, P, representing the peak point of the characteristic peak 1 、P 2 、 P 3 、P 4 Indicates that the optical path differences l are respectively equal to delta nL 2 ，ΔnL 4 -ΔnL 2 ，ΔnL 4 ，ΔnL 4 +ΔnL 2 The corresponding characteristic peak is obtained by the method,
normalized auto-coherence function for wide spectrum light source, where l is optical path difference, l d Decoherence length, v, for a wide spectrum light source 0 The center frequency of a broad spectrum light source.
In some preferred embodiments, the optical fiber depolarizer parameter measurement equation set is constructed by:
in the model of characteristic peak in normalized autocorrelation curve, when the optical path difference l is equal to Δ nL respectively 2 ，ΔnL 4 -ΔnL 2 ，ΔnL 4 ，ΔnL 4 +ΔnL 2 When, gamma in (l-ΔnL 2 )，γ in (l-ΔnL 4 +ΔnL 2 )，γ in (l-ΔnL 4 )，γ in (l-ΔnL 4 -ΔnL 2 ) Are each equal to 1, in which case P 1 、P 2 、P 3 、P 4 Taking the maximum value equal to the amplitude A of the respective corresponding characteristic peak point 1 、A 2 、A 3 、A 4 So the optical path difference is Δ nL 2 ，ΔnL 4 -ΔnL 2 ，ΔnL 4 ，ΔnL 4 +ΔnL 2 Sequentially corresponds to the peak point positions l of four characteristic peaks p1 、l p2 、 l p3 、l p4 Amplitude A 1 、A 2 、A 3 、A 4 Sequentially corresponds to the intensities I of four characteristic peaks p1 、I p2 、I p3 、 I p4 ；
Therefore, the constructed parameter measurement equation set of the optical fiber depolarizer is as follows:
ΔnL i+1 ＝l pi (i＝1,3)
A i ＝I pi (i＝1,2,3,4)
wherein, Δ nL i+1 Represents an optical path difference of l pi Position of peak point representing characteristic peak, A i Representing the corresponding amplitude, I, of the peak point of the characteristic peak pi Indicating the intensity of the characteristic peak.
In some preferred embodiments, a in the optical path of the depolarized fiber-optic gyroscope 1 、 A 2 、A 3 、A 4 Is a constant value.
In a second aspect of the present invention, a system for measuring parameters of an optical fiber depolarizer in an optical fiber sensitive loop of a depolarized optical fiber gyroscope is provided, the system comprising: the system comprises a spectrum measurement module, a characteristic peak extraction module, an equation construction module and a parameter solving module;
the spectrum measurement module is configured to measure an output spectrum of the optical fiber sensitive loop of the depolarization type optical fiber gyroscope through the optical fiber spectrometer as an actually measured modulation spectrum;
the characteristic peak extraction module is configured to perform normalized autocorrelation calculation on the measured modulation spectrum to obtain a normalized autocorrelation curve, and extract characteristic peak information from the normalized autocorrelation curve; the characteristic peak information comprises the peak point position and the intensity of the characteristic peak;
the equation building module is configured to build an optical fiber depolarizer parameter measurement equation set by combining the characteristic peak information;
and the parameter solving module is configured to solve a parameter measurement equation set of the optical fiber depolarizer to obtain the lengths of polarization maintaining optical fibers in the two optical fiber depolarizers and the included angle of the polarization main shaft at the welding point of the Y waveguide polarization maintaining tail fiber and the polarization maintaining optical fiber.
In a third aspect of the present invention, an electronic device is provided, including: at least one processor; and a memory communicatively coupled to at least one of the processors; the storage stores instructions executable by the processor, and the instructions are used for being executed by the processor to implement the method for measuring parameters of the optical fiber depolarizer in the depolarizing optical fiber gyroscope optical fiber sensitive loop.
In a fourth aspect of the present invention, a computer-readable storage medium is provided, where the computer-readable storage medium stores computer instructions for being executed by the computer to implement the method for measuring parameters of the optical fiber depolarizer in the fiber-optic sensitive loop of the depolarizing fiber-optic gyroscope.
The invention has the beneficial effects that:
the method realizes accurate measurement of the parameters of the optical fiber depolarizer in the optical fiber sensitive loop of the depolarized optical fiber gyroscope, and improves the quality of the optical fiber depolarizer.
1) Firstly, measuring an output spectrum of an optical fiber sensitive loop, then carrying out normalized autocorrelation calculation on the spectrum to obtain a normalized autocorrelation curve, extracting position and intensity information of a characteristic peak point from the curve, and establishing a measurement equation set based on a peak model and peak information of the normalized autocorrelation curve; and finally solving an equation set to obtain the length of the second section of polarization maintaining optical fiber in the two optical fiber depolarizers and the included angle of the polarization main shaft at the fusion splicing point of the polarization maintaining optical fiber. The invention discloses the relation between the output spectrum of the depolarization type optical fiber gyroscope sensitive loop and the lengths of the second section of polarization maintaining optical fiber in the optical fiber depolarizer and the included angle of the polarization main shaft at the fusion splicing point of the polarization maintaining optical fiber, and provides a novel, effective and high-sensitivity method for the online measurement of the parameters of the optical fiber depolarizer in the depolarization type optical fiber gyroscope sensitive loop.
2) The method is easy to implement, can realize the online measurement of the parameters of the optical fiber depolarizer in the depolarizing gyroscope optical fiber sensitive loop, and improves the quality of the depolarizing gyroscope optical fiber sensitive loop.
Drawings
Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings.
FIG. 1 is a schematic flow chart of a method for measuring parameters of an optical fiber depolarizer in an optical fiber sensitive loop of a depolarizing optical fiber gyroscope according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of an optical path structure of a typical depolarizing fiber-optic gyroscope according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of an apparatus for online measurement of depolarizer parameters in a depolarizing fiber optic gyroscope sensor loop according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a measured output modulation spectrum of a sensing loop of a depolarized fiber optic gyroscope according to an embodiment of the present invention;
FIG. 5 is a graphical illustration of a normalized autocorrelation curve calculated for a measured modulation spectrum in accordance with one embodiment of the present invention;
FIG. 6 is an amplitude A of a characteristic peak of an embodiment of the present invention 3 An included angle theta between the Y waveguide polarization-maintaining tail fiber and the polarization-maintaining fiber in the first optical fiber depolarizer and the polarization main shaft at the welding point of the polarization-maintaining fiber 12 Compared with a simulation relation curve diagram of 45-degree angle deviation;
FIG. 7 is an amplitude A of a characteristic peak of an embodiment of the present invention 1 The included angle theta between the Y waveguide polarization-maintaining tail fiber and the polarization main shaft at the welding point of the polarization-maintaining fiber in the second optical fiber depolarizer 34 Compared with a simulation relation curve diagram of 45-degree angle deviation;
FIG. 8 is an exemplary plot of a normalized autocorrelation curve of a measured modulation spectrum and a normalized autocorrelation curve characteristic peak of a solution parameter simulation based on the measured curve in accordance with one embodiment of the present invention;
FIG. 9 is a block diagram of a computer system suitable for use with an electronic device embodying embodiments of the present application, in accordance with an embodiment of the present invention;
FIG. 10 is a schematic diagram of a frame of a fiber depolarizer parameter measurement system in a fiber-optic sensing loop of a depolarized fiber-optic gyroscope according to an embodiment of the present invention;
the reference numbers in the figures mean: the system comprises a wide-spectrum light source 1, a coupler 2, an optical fiber sensitive loop 3, a detector assembly 4, a Y waveguide modulator chip 5, a first optical fiber depolarizer 6, a second optical fiber depolarizer 7, a single-mode optical fiber ring 8, a first polarization-preserving tail fiber of the Y waveguide modulator chip in the first optical fiber depolarizer 9, a second polarization-preserving fiber in the first optical fiber depolarizer 10, a third polarization-preserving tail fiber of the Y waveguide modulator chip in the second optical fiber depolarizer 11, a fourth polarization-preserving fiber in the second optical fiber depolarizer 12, an optical fiber spectrometer 13 and a computer 14.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
The present application will be described in further detail with reference to the following drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not restrictive of the invention. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.
The method for measuring the parameters of the optical fiber depolarizer in the depolarization type optical fiber gyroscope optical fiber sensitive loop is applied to a depolarization type optical fiber gyroscope optical path, wherein the optical path comprises a wide-spectrum light source, a coupler, an optical fiber sensitive loop and an optical fiber spectrometer; the optical fiber spectrometer is connected with the computer; the optical fiber sensitive loop consists of a Y waveguide modulator chip, a first optical fiber depolarizer, a second optical fiber depolarizer and a single-mode optical fiber loop; the optical fiber depolarizer consists of a Y waveguide polarization-maintaining tail fiber and a polarization-maintaining optical fiber; as shown in fig. 1, the parameter measuring method includes:
step S100, measuring an output spectrum of an optical fiber sensitive loop of the depolarization type optical fiber gyroscope through the optical fiber spectrometer as an actually measured modulation spectrum;
step S200, carrying out normalized autocorrelation calculation on the actually measured modulation spectrum to obtain a normalized autocorrelation curve, and extracting characteristic peak information from the normalized autocorrelation curve; the characteristic peak information comprises peak point positions and intensities of characteristic peaks;
step S300, combining the characteristic peak information to construct an optical fiber depolarizer parameter measurement equation set;
and S400, solving a parameter measurement equation set of the optical fiber depolarizer to obtain the lengths of polarization maintaining optical fibers in the two optical fiber depolarizers and the included angles of polarization main shafts at the welding points of the Y waveguide polarization maintaining tail fibers and the polarization maintaining optical fibers.
In order to more clearly describe the parameter measurement method of the optical fiber depolarizer in the optical fiber sensitive loop of the depolarizing optical fiber gyroscope of the present invention, the following describes in detail the steps in an embodiment of the method of the present invention with reference to the accompanying drawings.
The invention discloses a method for measuring parameters of an optical fiber depolarizer in an optical fiber sensitive loop of a depolarizing optical fiber gyroscope, which is applied to an optical path of the depolarizing optical fiber gyroscope. The depolarization type optical fiber gyro path, as shown in FIG. 2, includes a center frequency v 0 A broad spectrum light source 1, a coupler 2, a fiber optic sensitive loop 3, and a detector assembly 4. The optical fiber sensitive loop consists of a Y waveguide modulator chip 5, a first optical fiber depolarizer 6, a second optical fiber depolarizer 7 and a single-mode optical fiber loop 8, wherein the first optical fiber depolarizer consists of a Y waveguide first polarization-preserving tail fiber 9 and a second polarization-preserving optical fiber 10, and the parameters of the optical fiber depolarizer comprise the length L of the Y waveguide first polarization-preserving tail fiber 1 Length L of the second polarization maintaining fiber 2 And the included angle theta of the polarization main shaft at the welding point of the Y waveguide polarization-maintaining tail fiber and the polarization-maintaining fiber 12 (ii) a The second optical fiber depolarizer consists of a Y-waveguide third polarization-maintaining tail fiber 11 and a fourth polarization-maintaining fiber 12, and the parameters of the optical fiber depolarizer comprise the length L of the third polarization-maintaining tail fiber 3 Length L of the fourth polarization maintaining fiber 4 And the included angle theta of the polarization main shaft at the welding point of the Y waveguide polarization-maintaining tail fiber and the polarization-maintaining fiber 34 . In order to realize online measurement of parameters of an optical fiber depolarizer of a depolarizing optical fiber gyroscope, a fiber spectrometer 13 is used to replace a detector component in an optical path of the depolarizing optical fiber gyroscope, and the fiber spectrometer is connected to a data processing computer (or called computer) 14 for calculation, so as to form an online measurement device shown in fig. 3, and a typical output spectrum measured by the fiber spectrometer is shown in fig. 4. The specific process of measuring the parameters of the optical fiber depolarizer in the optical fiber sensitive loop of the depolarizing type optical fiber gyroscope by the online measuring device is as follows:
step S100, measuring an output spectrum of an optical fiber sensitive loop of the depolarization type optical fiber gyroscope through the optical fiber spectrometer as an actually measured modulation spectrum;
in this embodiment, a single-mode fiber ring is simplified and equivalent to a single birefringent unit, and a model of an output spectrum of the fiber-optic sensing ring is obtained by using jones matrix calculation, where the expression is:
wherein, I out (v) Representing the output spectrum, v the optical frequency, I in (v) Representing the spectrum of a broad-spectrum light source,
for Sagnac phase shift, F (v) is the spectral transfer function.
The spectral transfer function may be represented by the following equation:
F(v)＝F 0 +F 1 (v)+F 2 (v)+F 3 (v) (2)
F 0 ＝1/2+1/2cos2θ 12 cos2θ 34 cos2θ 2s cos2θ 4s (3)
the first optical fiber depolarizer consists of a Y-waveguide first polarization-maintaining tail fiber and a second polarization-maintaining optical fiber, the second optical fiber depolarizer consists of a Y-waveguide third polarization-maintaining tail fiber and a fourth polarization-maintaining optical fiber, and theta is 12 、θ 34 Respectively the included angle of the polarization main shaft at the welding point of the first polarization-maintaining tail fiber and the second polarization-maintaining fiber of the Y waveguide in the first optical fiber depolarizer, and the included angle of the polarization main shaft at the welding point of the third polarization-maintaining tail fiber and the third polarization-maintaining tail fiber of the Y waveguide in the second optical fiber depolarizerAngle of principal axis of polarization at the fusion splice of four polarization maintaining fibers, θ 2s Is the angle of the polarization main axis at the fusion splicing point of the second polarization maintaining fiber and the single mode fiber ring 4s Is the angle of the polarization main axis at the ring fusion point of the fourth polarization-maintaining fiber and the single-mode fiber 2 ＝ΔnL 2 /c，τ 4 ＝ΔnL 4 /c，τ s ＝Δn s L s C, Δ n is the birefringence of the polarization maintaining fiber, Δ n s Is the average birefringence, L, of a single-mode fiber ring s Is a single mode fiber loop length, L 2 、L 4 The length of the second polarization maintaining fiber and the length of the fourth polarization maintaining fiber are respectively, and c is the light speed in vacuum.
Step S200, carrying out normalized autocorrelation calculation on the actually measured modulation spectrum to obtain a normalized autocorrelation curve, and extracting characteristic peak information from the normalized autocorrelation curve; the characteristic peak information comprises peak point positions and intensities of characteristic peaks;
in this embodiment, the modulation of the output spectrum is actually caused by polarization interference introduced by the polarization maintaining optical fiber in the two fiber depolarizers in the depolarizing fiber optic gyroscope sensing loop. A normalized autocorrelation operation is performed on the output spectrum shown in fig. 4 to obtain a typical normalized autocorrelation curve, as shown in fig. 5.
Based on the output spectrum model of the fiber optic sensor ring, the model of the characteristic peak in the normalized autocorrelation curve can be expressed as:
wherein, A 1 、A 2 、A 3 、A 4 Amplitude, P, representing the peak point of the characteristic peak 1 、P 2 、P 3 、 P 4 Indicates that the optical path differences l are respectively equal to delta nL 2 ，ΔnL 4 -ΔnL 2 ，ΔnL 4 ，ΔnL 4 +ΔnL 2 The corresponding characteristic peak, as shown in figure 5,
normalized auto-coherence function for wide spectrum light source, where l is optical path difference, l d Decoherence length for a broad spectrum light source.
Step S300, combining the characteristic peak information to construct an optical fiber depolarizer parameter measurement equation set;
in this embodiment, in the normalized autocorrelation curve characteristic peak model expressions (7) - (10), when the optical path difference l is equal to Δ nL respectively 2 ，ΔnL 4 -ΔnL 2 ，ΔnL 4 ，ΔnL 4 +ΔnL 2 When, gamma in (l-ΔnL 2 )，γ in (l-ΔnL 4 +ΔnL 2 )，γ in (l-ΔnL 4 )，γ in (l-ΔnL 4 -ΔnL 2 ) Are each equal to 1, in which case P 1 、P 2 、P 3 、P 4 Taking the maximum value equal to the amplitude A of the respective corresponding characteristic peak point 1 、A 2 、A 3 、A 4 So the optical path difference is Δ nL 2 ，ΔnL 4 -ΔnL 2 ，ΔnL 4 ，ΔnL 4 +ΔnL 2 Sequentially corresponding to the peak point positions l of the four characteristic peaks p1 、l p2 、l p3 、 l p4 Amplitude A 1 、A 2 、A 3 、A 4 Sequentially corresponds to the intensities I of four characteristic peaks p1 、I p2 、I p3 、I p4 ；
Therefore, the constructed parameter measurement equation set of the optical fiber depolarizer is as follows:
ΔnL i+1 ＝l pi (i＝1,3) (11)
A i ＝I pi (i＝1,2,3,4) (12)
wherein, Δ nL i+1 Represents an optical path difference of l pi The peak point position of the characteristic peak, A i Representing the amplitude, I, of the corresponding characteristic peak-to-peak point pi Indicating the intensity of the characteristic peak.
As shown in FIG. 5, four characteristic peak point positions l are extracted from the curve pi And strength I pi The coordinates of the characteristic peak point are sequentially recorded as (l) p1 ,I p1 )，(l p2 ,I p2 )，(l p3 ,I p3 )，(l p4 ,I p4 )。
And S400, solving a parameter measurement equation set of the optical fiber depolarizer to obtain the lengths of polarization maintaining optical fibers in the two optical fiber depolarizers and the included angles of polarization main shafts at the welding points of the Y waveguide polarization maintaining tail fibers and the polarization maintaining optical fibers.
In this embodiment, the length L of the second polarization maintaining fiber 10 in the first fiber depolarizer can be obtained by solving the equation set forth in equation (11) 2 And the length L of the fourth polarization maintaining fiber 12 in the second fiber depolarizer 4 Solving the equation set in equation (12) can obtain the included angle θ of the polarization main axis at the fusion splice of the polarization maintaining fiber in the first fiber depolarizer 12 And the included angle theta of the polarization main axis at the welding point of the polarization maintaining fiber in the second fiber depolarizer 34 。
L 2 And L 4 The sum and difference combination of the lengths of the polarization maintaining fiber and the optical fiber is far greater than the length of the polarization maintaining fiber corresponding to the incoherent light source, and theta 12 And theta 34 The quality of the optical fiber depolarizer can be guaranteed only if the angular deviation is small compared with 45 degrees. Wherein theta is 12 And theta 34 The welding angle deviation is the main factor causing noise and drift of the depolarization gyro, and the invention can realize high sensitivity theta 12 And theta 34 The weld angle is measured on-line, Δ nL in the normalized autocorrelation curve 4 Characteristic peak amplitude A at optical path difference 3 To theta 12 Compared with the angle deviation of 45 degrees, the change is sensitive, the change curve of the simulation is shown in figure 6, and the change curve of delta nL 2 Characteristic peak amplitude A corresponding to optical path difference 1 To theta 34 Angular deviation variation compared to 45 °The more sensitive, simulated variation curve is shown in fig. 7. Theta.theta. 12 And theta 34 The amplitude of the corresponding sensitive characteristic peak changes sharply when the angular deviation is close to 0 degrees, and the high sensitivity of the measurement algorithm is reflected.
In addition, in order to verify the effectiveness of the technical scheme, the invention is verified through experiments, and the verification process is as follows:
the main parameters of the typical depolarization type optical fiber gyroscope are shown in table 1. The light source is a typical Gaussian wide-spectrum light source, the lengths of four sections of polarization maintaining fibers in the two fiber depolarizers are set values, the length ratio is close to 1.
TABLE 1
In table 1, the first polarization maintaining fiber of the first fiber depolarizer, i.e., the first fiber depolarizer, is made of a Y-waveguide polarization maintaining pigtail, and the first polarization maintaining fiber of the second fiber depolarizer, i.e., the second fiber depolarizer, is made of a Y-waveguide polarization maintaining pigtail.
Electrifying an online measuring device, preheating for a period of time, testing a sensitive loop output spectrum by using an optical fiber spectrometer, performing normalized autocorrelation calculation on the measured spectrum by using a data processing computer as shown in fig. 4 to obtain a normalized autocorrelation curve, wherein as shown in fig. 5, besides a main peak with zero optical path difference, four obvious characteristic peaks exist, the rest are background noise, and the positions of four characteristic peak points respectively correspond to four optical path difference combinations in polarized light interference introduced by polarization maintaining fibers 10 and 12 in two optical fiber depolarizers: Δ nL 2 ，ΔnL 4 -ΔnL 2 ，ΔnL 4 ，ΔnL 4 +ΔnL 2 。
Extracting peak point positions and intensity information of four characteristic peaks in the normalized autocorrelation curve of FIG. 5 by a data processing computer according to an algorithm flow, converting the intensity numerical value into a linear dimensionless numerical value, and converting the characteristic peak point information from left to right in a coordinate modeThe secondary representation is: (1.732 mm, 0.008057), (5.091mm, 0.08717), (6.823mm, 0.02418), (8.555 mm, 0.09581). It can be seen that the peak point positions of the four characteristic peaks satisfy Δ nL 2 ，ΔnL 4 -ΔnL 2 ，ΔnL 4 ，ΔnL 4 +ΔnL 2 Based on equations (11) and (12), the following equation set can be established:
the length parameter of the second polarization maintaining fiber section forming the two fiber depolarizers can be calculated by solving the equation set in equation (13), as shown in table 2:
TABLE 2
The results shown in Table 2 indicate that the length of the second polarization maintaining fiber in the optical fiber depolarizer actually has errors due to the uncertainty of the intercepting and cutting lengths, L 4 Has a difference from the design length shown in table 1.
Solving the equation set in equation (14) can obtain the angle parameter of the polarization main axis at the fusion point of the polarization maintaining optical fibers in the two optical fiber depolarizers, as shown in table 3:
the included angles of the polarization main shafts at the fusion splicing points of the polarization maintaining fibers in the two fiber depolarizers in the solved result are respectively theta 12 ＝-43.07°，θ 34 The numerical values for converting them into the first quadrant are 43.07 ° and 43.14 °, which indicates that the polarization principal axis angle at the fusion point in the actual fiber depolarizer is also deviated from 45 °.
From the above process, the parameters of the two optical fiber depolarizers obtained by analyzing and solving the normalized autocorrelation curve of the actually measured modulation spectrum are as follows: the length of a second section of polarization-maintaining optical fiber of the first optical fiber depolarizer is 2.80m, and the included angle of a polarization main shaft at the fusion splice of the polarization-maintaining optical fibers is 43.07 degrees; the length of the second section of polarization maintaining optical fiber of the second optical fiber depolarizer is 11.04m, and the included angle of the polarization main shaft at the fusion point of the polarization maintaining optical fiber is 43.14 degrees. The characteristic peak of the normalized autocorrelation curve based on the simulation of the solving parameters is shown by the dotted line in fig. 8, the solid line in fig. 8 is the normalized autocorrelation curve in fig. 5, and the simulation result based on the solving parameters is highly consistent with the position and the amplitude of the four characteristic peak values corresponding to the experimental result, which shows that the online measurement algorithm is accurate and reliable.
A parameter measurement system of an optical fiber depolarizer in an optical fiber sensitive loop of a depolarized optical fiber gyroscope according to a second embodiment of the present invention, as shown in fig. 10, includes: the system comprises a spectrum measurement module 100, a characteristic peak extraction module 200, an equation construction module 300 and a parameter solving module 400;
the spectrum measurement module 100 is configured to measure an output spectrum of the optical fiber sensing loop of the depolarizing fiber optic gyroscope through the fiber optic spectrometer as an actually measured modulation spectrum;
the characteristic peak extracting module 200 is configured to perform normalized autocorrelation calculation on the actually measured modulation spectrum to obtain a normalized autocorrelation curve, and extract characteristic peak information from the normalized autocorrelation curve; the characteristic peak information comprises peak point positions and intensities of characteristic peaks;
the equation building module 300 is configured to build a parameter measurement equation set of the optical fiber depolarizer by combining the characteristic peak information;
the parameter solving module 400 is configured to solve a parameter measurement equation set of the optical fiber depolarizer to obtain the lengths of polarization maintaining optical fibers in the two optical fiber depolarizers and the included angle of the polarization main axis at the fusion splicing point of the polarization maintaining pigtail and the polarization maintaining optical fiber.
It can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working process and related description of the system described above may refer to the corresponding process in the foregoing method embodiment, and details are not described herein again.
It should be noted that, the fiber depolarizer parameter measurement system in the depolarizing fiber-optic gyroscope fiber-optic sensitive loop provided in the foregoing embodiment is only illustrated by dividing the functional modules, and in practical applications, the functions may be distributed by different functional modules according to needs, that is, the modules or steps in the embodiment of the present invention are further decomposed or combined, for example, the modules in the foregoing embodiment may be combined into one module, or may be further split into a plurality of sub-modules, so as to complete all or part of the functions described above. Names of the modules and steps related in the embodiments of the present invention are only for distinguishing the modules or steps, and are not to be construed as unduly limiting the present invention.
An electronic device according to a third embodiment of the present invention includes at least one processor; and a memory communicatively coupled to at least one of the processors; wherein the memory stores instructions executable by the processor for implementing the method for measuring parameters of the optical fiber depolarizer in the depolarizing type optical fiber gyroscope optical fiber sensitive loop.
A computer readable storage medium of a fourth embodiment of the present invention stores computer instructions for being executed by the computer to implement the method for measuring parameters of the optical fiber depolarizer in the depolarizing optical fiber gyroscope optical fiber sensitive loop.
It can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes and related descriptions of the electronic device and the computer-readable storage medium described above may refer to corresponding processes in the foregoing method examples, and are not described herein again.
Referring now to FIG. 9, there is illustrated a block diagram of a computer system suitable for use as a server in implementing embodiments of the subject systems, methods, and devices. The server shown in fig. 9 is only an example, and should not bring any limitation to the functions and the scope of use of the embodiments of the present application.
As shown in fig. 9, the computer system includes a Central Processing Unit (CPU) 901 that can perform various appropriate actions and processes in accordance with a program stored in a Read Only Memory (ROM) 902 or a program loaded from a storage section 908 into a Random Access Memory (RAM) 903. In the RAM903, various programs and data necessary for system operation are also stored. The CPU901, ROM 902, and RAM903 are connected to each other via a bus 904. An Input/Output (I/O) interface 905 is also connected to bus 904.
The following components are connected to the I/O interface 905: an input portion 906 including a keyboard, a mouse, and the like; an output portion 907 including components such as a cathode ray tube, a liquid crystal display, and the like, and a speaker; a storage portion 908 including a hard disk and the like; and a communication section 909 including a network interface card such as a local area network card, a modem, or the like. The communication section 909 performs communication processing via a network such as the internet. The drive 910 is also connected to the I/O interface 905 as necessary. A removable medium 911 such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, or the like is mounted on the drive 910 as necessary so that a computer program read out therefrom is mounted into the storage section 908 as necessary.
In particular, according to an embodiment of the present disclosure, the processes described above with reference to the flowcharts may be implemented as computer software programs. For example, embodiments of the present disclosure include a computer program product comprising a computer program embodied on a computer-readable medium, the computer program comprising program code for performing the method illustrated by the flow chart. In such an embodiment, the computer program may be downloaded and installed from a network via the communication section 909, and/or installed from the removable medium 911. The computer program, when executed by the CPU901, performs the above-described functions defined in the method of the present application. It should be noted that the computer readable medium mentioned above in the present application may be a computer readable signal medium or a computer readable storage medium or any combination of the two. The computer-readable storage medium may be, for example but not limited to: an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of the computer readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a RAM, a ROM, an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the present application, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. In this application, however, a computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated data signal may take many forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to: wireless, wire, fiber optic cable, etc., or any suitable combination of the foregoing.
Computer program code for carrying out operations for aspects of the present application may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, smalltalk, C + +, and conventional procedural programming languages, such as the C language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network or a wide area network, or the connection may be made to an external computer (for example, through the Internet using an Internet service provider).
The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present application. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
The terms "first," "second," and the like are used for distinguishing between similar elements and not necessarily for describing or implying a particular order or sequence.
The terms "comprises," "comprising," or any other similar term are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
So far, the technical solutions of the present invention have been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of the present invention is obviously not limited to these specific embodiments. Equivalent changes or substitutions of related technical features can be made by those skilled in the art without departing from the principle of the invention, and the technical scheme after the changes or substitutions can fall into the protection scope of the invention.
Claims (9)
1. A method for measuring parameters of an optical fiber depolarizer in a depolarized optical fiber gyroscope optical fiber sensitive loop is applied to a depolarized optical fiber gyroscope optical path, wherein the optical path comprises a wide-spectrum light source, a coupler, an optical fiber sensitive loop and an optical fiber spectrometer; the optical fiber spectrometer is connected with the computer; the optical fiber sensitive loop consists of a Y waveguide modulator chip, a first optical fiber depolarizer, a second optical fiber depolarizer and a single-mode optical fiber loop; the optical fiber depolarizer consists of Y waveguide polarization maintaining tail fiber and polarization maintaining fiber; the parameter measuring method is characterized by comprising the following steps:
step S100, measuring an output spectrum of an optical fiber sensitive loop of the depolarization type optical fiber gyroscope through the optical fiber spectrometer as an actually measured modulation spectrum;
step S200, carrying out normalized autocorrelation calculation on the actually measured modulation spectrum to obtain a normalized autocorrelation curve, and extracting characteristic peak information from the normalized autocorrelation curve; the characteristic peak information comprises peak point positions and intensities of characteristic peaks;
step S300, combining the characteristic peak information to construct an optical fiber depolarizer parameter measurement equation set;
and S400, solving a parameter measurement equation set of the optical fiber depolarizer to obtain the lengths of polarization maintaining optical fibers in the two optical fiber depolarizers and the included angle of polarization main shafts at the welding points of the Y waveguide polarization maintaining tail fiber and the polarization maintaining optical fiber.
2. The method for measuring the parameters of the optical fiber depolarizer in the depolarizing optical fiber gyroscope optical fiber sensitive loop according to claim 1, wherein the expression of the model of the output spectrum of the depolarizing optical fiber gyroscope optical fiber sensitive loop is as follows:
wherein, I out (v) denotes the output spectrum, v denotes the optical frequency, I in (v) represents the spectrum of the broad spectrum light source,
for Sagnac phase shift, F (v) is the spectral transfer function.
3. The method for measuring the parameters of the optical fiber depolarizer in the optical fiber sensitive loop of the depolarizing optical fiber gyroscope according to claim 2, wherein the spectral transfer function is:
F(ν)＝F 0 +F 1 (ν)+F 2 (ν)+F 3 (ν)
F 0 ＝1/2+1/2cos2θ 12 cos2θ 34 cos2θ 2s cos2θ 4s
F 1 (ν)＝-1/2sin2θ 12 cos2θ 34 sin2θ 2s cos2θ 4s cos(2πντ 2 )-1/2cos2θ 12 sin2θ 34 cos2θ 2s sin2θ 4s cos(2πντ 4 )-1/2cos2θ 12 cos2θ 34 sin2θ 2s sin2θ 4s cos(2πντ s )
F 2 (ν)＝-1/2sin2θ 12 cos2θ 34 cos 2 θ 2s sin2θ 4s cos(2πν(τ 2 +τ s ))+1/2sin2θ 12 cos2θ 34 sin 2 θ 2s sin2θ 4s cos(2πν(τ 2 -τ s ))-1/2cos2θ 12 sin2θ 34 sin2θ 2s cos 2 θ 4s cos(2πν(τ 4 +τ s ))+1/2cos2θ 12 sin2θ 34 sin2θ 2s sin 2 θ 4s cos(2πν(τ 4 -τ s ))+1/4sin2θ 12 sin2θ 34 sin2θ 2s sin2θ 4s cos(2πν(τ 2 +τ 4 ))+1/4sin2θ 12 sin2θ 34 sin2θ 2s sin2θ 4s cos(2πν(τ 2 -τ 4 ))
F 3 (ν)＝-1/2sin2θ 12 sin2θ 34 cos 2 θ 2s cos 2 θ 4s cos(2πν(τ 2 +τ 4 +τ s ))-1/2sin2θ 12 sin2θ 34 sin 2 θ 2s sin 2 θ 4s cos(2πν(τ 2 +τ 4 -τ s ))+1/2sin2θ 12 sin2θ 34 cos 2 θ 2s sin 2 θ 4s cos(2πν(τ 2 -τ 4 +τ s ))+1/2sin2θ 12 sin2θ 34 sin 2 θ 2s cos 2 θ 4s cos(2πν(τ 2 -τ 4 -τ s ))
the first optical fiber depolarizer consists of a Y-waveguide first polarization-maintaining tail fiber and a second polarization-maintaining optical fiber, the second optical fiber depolarizer consists of a Y-waveguide third polarization-maintaining tail fiber and a fourth polarization-maintaining optical fiber, and theta is 12 、θ 34 The included angle of the polarization main shaft at the fusion point of a Y waveguide first polarization-maintaining tail fiber and a second polarization-maintaining fiber in the first optical fiber depolarizer, the included angle of the polarization main shaft at the fusion point of a Y waveguide third polarization-maintaining tail fiber and a fourth polarization-maintaining fiber in the second optical fiber depolarizer, and theta 2s Is the angle of the polarization main axis at the fusion splicing point of the second polarization maintaining fiber and the single mode fiber ring 4s Is the angle of the polarization main axis at the ring fusion point of the fourth polarization-maintaining fiber and the single-mode fiber 2 ＝ΔnL 2 /c，τ 4 ＝ΔnL 4 /c，τ s ＝Δn s L s C, Δ n is the birefringence of the polarization maintaining fiber, Δ n s Is the average birefringence, L, of a single-mode fiber ring s Is the ring length, L, of a single mode optical fiber 2 、L 4 The length of the second polarization maintaining fiber and the length of the fourth polarization maintaining fiber are respectively, and c is the light speed in vacuum.
4. The method for measuring the parameters of the optical fiber depolarizer in the optical fiber sensitive loop of the depolarizing optical fiber gyroscope according to claim 3, wherein the model of the characteristic peak in the normalized autocorrelation curve is as follows:
P 1 ＝A 1 ·γ in (l-ΔnL 2 )
A 1 ＝|[-1/2×sin2θ 12 cos2θ 34 sin2θ 2s cos2θ 4s cos(2πν 0 ΔnL 2 /c)-1/2×sin2θ 12 cos2θ 34 cos 2 θ 2s sin2θ 4s cos(2πν 0 (ΔnL 2 +Δn s L s )/c)+1/2×sin2θ 12 cos2θ 34 sin 2 θ 2s sin2θ 4s cos(2πν 0 (ΔnL 2 -Δn s L s )/c)]|
P 2 ＝A 2 ·γ in (l-ΔnL 4 +ΔnL 2 )
A 2 ＝|[1/4×sin2θ 12 sin2θ 34 sin2θ 2s sin2θ 4s cos(2πν 0 (ΔnL 4 -ΔnL 2 )/c)+1/2×sin2θ 12 sin2θ 34 cos 2 θ 2s sin 2 θ 4s cos(2πν 0 (ΔnL 4 -ΔnL 2 -Δn s L s )/c)+1/2×sin2θ 12 sin2θ 34 sin 2 θ 2s cos 2 θ 4s cos(2πν 0 (ΔnL 4 -ΔnL 2 +Δn s L s )/c)]|
P 3 ＝A 3 ·γ in (l-ΔnL 4 )
A 3 ＝|[-1/2×cos2θ 12 sin2θ 34 cos2θ 2s sin2θ 4s cos(2πν 0 ΔnL 4 /c)-1/2×cos2θ 12 sin2θ 34 sin2θ 2s cos 2 θ 4s cos(2πν 0 (ΔnL 4 +Δn s L s )/c)+1/2×cos2θ 12 sin2θ 34 sin2θ 2s sin 2 θ 4s cos(2πν 0 (ΔnL 4 -Δn s L s )/c)]|
P 4 ＝A 4 ·γ in (l-ΔnL 4 -ΔnL 2 )
A 4 ＝|[1/4×sin2θ 12 sin2θ 34 sin2θ 2s sin2θ 4s cos(2πν 0 (ΔnL 4 +ΔnL 2 )/c)-1/2×sin2θ 12 sin2θ 34 cos 2 θ 2s cos 2 θ 4s cos(2πν 0 (ΔnL 4 +ΔnL 2 +Δn s L s )/c)-1/2×sin2θ 12 sin2θ 34 sin 2 θ 2s sin 2 θ 4s cos(2πν 0 (ΔnL 4 +ΔnL 2 -Δn s L s )/c)]|
wherein A is 1 、A 2 、A 3 、A 4 Amplitude, P, representing the peak point of the characteristic peak 1 、P 2 、P 3 、P 4 Indicates that the optical path differences l are respectively equal to delta nL 2 ，ΔnL 4 -ΔnL 2 ，ΔnL 4 ，ΔnL 4 +ΔnL 2 The corresponding characteristic peak is obtained by the method,
normalization of the autocorrelation function for a wide-spectrum light source, l is the optical path difference, l d Decoherence length, v, for a wide-spectrum light source 0 The center frequency of a broad spectrum light source.
5. The method for measuring the parameters of the optical fiber depolarizer in the optical fiber sensitive loop of the depolarizing optical fiber gyroscope according to claim 4, wherein the method for constructing the system of equations for measuring the parameters of the optical fiber depolarizer comprises the following steps:
in the model of characteristic peak in normalized autocorrelation curve, when the optical path difference l is equal to Δ nL respectively 2 ，ΔnL 4 -ΔnL 2 ，ΔnL 4 ，ΔnL 4 +ΔnL 2 When, gamma is in (l-ΔnL 2 )，γ in (l-ΔnL 4 +ΔnL 2 )，γ in (l-ΔnL 4 )，γ in (l-ΔnL 4 -ΔnL 2 ) Are respectively equal to 1, when P 1 、P 2 、P 3 、P 4 Taking the maximum value equal to the amplitude A of the respective corresponding characteristic peak point 1 、A 2 、A 3 、A 4 So the optical path difference is Δ nL 2 ，ΔnL 4 -ΔnL 2 ，ΔnL 4 ，ΔnL 4 +ΔnL 2 Sequentially corresponds to the peak point positions l of four characteristic peaks p1 、l p2 、l p3 、l p4 Amplitude A 1 、A 2 、A 3 、A 4 Sequentially corresponds to the intensities I of four characteristic peaks p1 、I p2 、I p3 、I p4 ；
Therefore, the constructed parameter measurement equation set of the optical fiber depolarizer is as follows:
ΔnL i+1 ＝l pi (i＝1,3)
A i ＝I pi (i＝1,2,3,4)
wherein, Δ nL i+1 Denotes the optical path difference, < i > l > pi Position of peak point representing characteristic peak, A i Representing the corresponding amplitude, I, of the peak point of the characteristic peak pi Indicating the intensity of the characteristic peak.
6. The method for measuring the parameters of the optical fiber depolarizer in the optical fiber sensitive loop of the depolarizing optical fiber gyroscope of claim 4, wherein A in the optical path of the depolarizing optical fiber gyroscope 1 、A 2 、A 3 、A 4 Is a constant value.
7. A parameter measuring system of an optical fiber depolarizer in a depolarized optical fiber gyroscope optical fiber sensitive loop is applied to a depolarized optical fiber gyroscope optical path, and the optical path comprises a wide-spectrum light source, a coupler, an optical fiber sensitive loop and an optical fiber spectrometer; the optical fiber spectrometer is connected with the computer; the optical fiber sensitive loop consists of a Y waveguide modulator chip, a first optical fiber depolarizer, a second optical fiber depolarizer and a single-mode optical fiber loop; the optical fiber depolarizer consists of Y waveguide polarization maintaining tail fiber and polarization maintaining fiber; characterized in that the system comprises: the system comprises a spectrum measurement module, a characteristic peak extraction module, an equation construction module and a parameter solving module;
the spectrum measurement module is configured to measure an output spectrum of the optical fiber sensitive loop of the depolarization type optical fiber gyroscope through the optical fiber spectrometer as an actually measured modulation spectrum;
the characteristic peak extraction module is configured to perform normalized autocorrelation calculation on the actually measured modulation spectrum to obtain a normalized autocorrelation curve, and extract characteristic peak information from the normalized autocorrelation curve; the characteristic peak information comprises peak point positions and intensities of characteristic peaks;
the equation building module is configured to build an optical fiber depolarizer parameter measurement equation set by combining the characteristic peak information;
and the parameter solving module is configured to solve a parameter measurement equation set of the optical fiber depolarizer to obtain the lengths of polarization maintaining optical fibers in the two optical fiber depolarizers and the included angle of the polarization main shaft at the welding point of the Y waveguide polarization maintaining tail fiber and the polarization maintaining optical fiber.
8. An electronic device, comprising:
at least one processor; and a memory communicatively coupled to at least one of the processors;
wherein the memory stores instructions executable by the processor for implementing the method for measuring parameters of the optical fiber depolarizer in the depolarizing fiber optic gyroscope fiber-sensitive loop of any of claims 1-6.
9. A computer-readable storage medium storing computer instructions for execution by the computer to implement the method for measuring parameters of the optical fiber depolarizer in the depolarizing fiber optic gyroscope fiber-sensitive loop of any of claims 1-6.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210001199.4A CN114295114B (en) | 2022-01-04 | 2022-01-04 | Method and system for measuring parameters of optical fiber depolarizer in depolarization type optical fiber gyroscope optical fiber sensitive loop |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210001199.4A CN114295114B (en) | 2022-01-04 | 2022-01-04 | Method and system for measuring parameters of optical fiber depolarizer in depolarization type optical fiber gyroscope optical fiber sensitive loop |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114295114A CN114295114A (en) | 2022-04-08 |
| CN114295114B true CN114295114B (en) | 2022-10-25 |
Family
ID=80974781
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210001199.4A Active CN114295114B (en) | 2022-01-04 | 2022-01-04 | Method and system for measuring parameters of optical fiber depolarizer in depolarization type optical fiber gyroscope optical fiber sensitive loop |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114295114B (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101881627A (en) * | 2010-06-08 | 2010-11-10 | 北京航空航天大学 | Depolarization performance test device and method of Lyot depolarizer and gyro system |
| CN103674007A (en) * | 2012-09-07 | 2014-03-26 | 中国航空工业第六一八研究所 | Fiber gyroscope depolarization light path design method and fiber gyroscope depolarization light path design system |
| CN104359471A (en) * | 2014-11-26 | 2015-02-18 | 湖北三江航天红峰控制有限公司 | Mixed polarized fiber-optic gyroscope light path and preparation method of depolarizer |
| CN109946042A (en) * | 2019-03-06 | 2019-06-28 | 湖北三江航天红峰控制有限公司 | A kind of measurement method and device of Y type waveguide coupling accuracy |
| CN111238772A (en) * | 2019-12-31 | 2020-06-05 | 中国航空工业集团公司西安飞机设计研究所 | Optical fiber ring detection device and detection method based on polarization crosstalk principle |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6801319B2 (en) * | 2002-01-03 | 2004-10-05 | Honeywell International, Inc. | Symmetrical depolarized fiber optic gyroscope |
-
2022
- 2022-01-04 CN CN202210001199.4A patent/CN114295114B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101881627A (en) * | 2010-06-08 | 2010-11-10 | 北京航空航天大学 | Depolarization performance test device and method of Lyot depolarizer and gyro system |
| CN103674007A (en) * | 2012-09-07 | 2014-03-26 | 中国航空工业第六一八研究所 | Fiber gyroscope depolarization light path design method and fiber gyroscope depolarization light path design system |
| CN104359471A (en) * | 2014-11-26 | 2015-02-18 | 湖北三江航天红峰控制有限公司 | Mixed polarized fiber-optic gyroscope light path and preparation method of depolarizer |
| CN109946042A (en) * | 2019-03-06 | 2019-06-28 | 湖北三江航天红峰控制有限公司 | A kind of measurement method and device of Y type waveguide coupling accuracy |
| CN111238772A (en) * | 2019-12-31 | 2020-06-05 | 中国航空工业集团公司西安飞机设计研究所 | Optical fiber ring detection device and detection method based on polarization crosstalk principle |
Non-Patent Citations (3)
| Title |
|---|
| 光纤陀螺消偏结构与偏振度关系的研究;柳建春等;《光子学报》;20050625;第34卷(第6期);第948-951页 * |
| 消偏光纤陀螺的偏振态研究;王淑敏;《中国优秀博硕士学位论文全文数据库 (硕士) 信息科技辑》;20030315(第01期);全文 * |
| 消偏光纤陀螺的非互易性相位误差的研究;王淑敏等;《激光与红外》;20021025;第32卷(第05期);第336-338页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114295114A (en) | 2022-04-08 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8085407B2 (en) | Resonator optical gyroscope having input beam modulation optimized for high sensitivity and low bias | |
| US7777889B2 (en) | Bias-instability reduction in fiber optic gyroscopes | |
| Li et al. | A novel method for determining and improving the quality of a quadrupolar fiber gyro coil under temperature variations | |
| CN107702730A (en) | Method of testing, device, storage medium and the computer equipment of optical fibre gyro | |
| CN101886925A (en) | Multi-wavelength interference type optical fiber gyro based on carrier modulation | |
| CN106441353B (en) | A kind of symmetry assessment device of optical fibre gyro ring polarization coupled | |
| CN106768867B (en) | LiNbO 3 Performance detection system for phase modulator | |
| EP4343291A1 (en) | Global phase quadrature demodulation method and apparatus for optical fiber sensing data | |
| CN103674007A (en) | Fiber gyroscope depolarization light path design method and fiber gyroscope depolarization light path design system | |
| CN114295114B (en) | Method and system for measuring parameters of optical fiber depolarizer in depolarization type optical fiber gyroscope optical fiber sensitive loop | |
| CN112082651B (en) | Polarization characteristic measurement method for assembling full polarization-maintaining Sagnac closed light path | |
| Ovchinnikov et al. | A prototype for a passive resonant interferometric fiber optic gyroscope with a 3× 3 directional coupler | |
| Kurzych et al. | The laboratory investigation of the innovative sensor for torsional effects in engineering structures’ monitoring | |
| Fang et al. | Distributed optical fiber vibration sensing implemented with delayed feedback reservoir computing | |
| CN206556842U (en) | LiNbO3 phase-modulator performance detecting systems | |
| Zuoming et al. | Analysis of bias thermal stability of interferometer fiber-optic gyroscope using a solid-core polarization-maintaining photonic crystal fiber | |
| CN105466887A (en) | Detection system of thin-walled closed glass chamber's optical parameters and method thereof | |
| CN116046023B (en) | Optical fiber gyroscope precision analysis method and system based on photon lantern | |
| CN113654766B (en) | Single-mode fiber coupler phase shift measuring device, method and storage medium | |
| Sandoval-Romero et al. | A Simple Theoretical Comparison between Two Basic Schemes in Function of the Earth′ s North Pole Detection: The Static Method | |
| Lei et al. | Test for scale factor of resonant micro optical gyro based on equivalent input | |
| Mikhailov et al. | In-line high-speed all-fiber polarimeter with true real-time acquisition for sensor systems based on fast polarization rotation | |
| Temkina et al. | Digital twin-based research on fiber optic current sensor behavior and stability | |
| Li et al. | Online evaluation technology for fiber-optic coil assembly in depolarized fiber-optic gyroscope | |
| Xie et al. | A low‐complexity scheme for enlarging the dynamic range of the open‐loop I‐FOG |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |