Sensing system and method based on geometric phase change in optical fiber Segner ring

Abstract

This invention provides a sensing system based on geometric phase transitions in optical fiber Segner rings. The system comprises the following modules: an optical module that generates split signal light; a sensing module that processes the split signal light to sense the physical parameter to be measured; a detection module that obtains measurement data based on the processed signal light; and a data processing module that processes the measurement data to calculate the physical parameter to be measured. This system exploits the phenomenon of sudden geometric phase transitions in optical fiber rings under specific forces to achieve extremely high sensitivity sensing of physical parameters such as external pressure, providing a new technical approach for optical fiber sensing.

Description

Technical Field

[0001] The present invention relates to the technical field of geometric phase change sensing systems, and more particularly, to a sensing system and method based on geometric phase change in an optical fiber Segner ring. In particular, it preferably relates to a highly sensitive sensing method utilizing geometric phase change in an optical fiber Segner ring. Background Art

[0002] Since the fiber optic Sagnac interferometer was first demonstrated, it has been used in various scenarios due to its high reliability, overall fixed structure, and relatively low manufacturing precision requirements. For example, the optical navigation gyroscope based on the fiber optic Sagnac interferometer in the document B. Culshaw. The optical fiber Sagnac interferometer: an overview of its principles and applications [J], 2005 Meas. Sci. Technol. is based on the principle that when the fiber ring rotates, the forward-transmitting light needs to catch up with the beam splitter, while the reverse-transmitting light and the beam splitter move in opposite directions, resulting in a difference in the paths of the forward and reverse-transmitting light. By detecting this difference, the angular velocity of the fiber ring's rotation can be sensed. Similarly, in the document Xinyong Dong, HY Tam, P. Shum. Temperature-insensitive strain sensor with polarization-maintaining photonic crystal fiber based Sagnac interferometer [J], Appl. Phys. Lett. 90, 151113 (2007)., it is used that the refractive index of a photonic crystal fiber changes differently in different axes when it is stretched, and the polarization directions of two light beams can be modulated into orthogonal directions and pass through the photonic crystal fiber in opposite directions. Because of the different refractive indices, there will also be an optical path difference between the two light beams.

[0003] The Chinese invention patent document with publication number CN103344608A discloses a high-sensitivity MZ interferometer based on a dual-ring structure, including a laser, an isolator, an attenuator, a polarization controller and a first coupler. The first coupler is connected to a phase modulator via an optical fiber, the phase modulator is connected to a second coupler via an optical fiber, the first coupler is connected to a first micro-nano optical fiber ring via an optical fiber and a first coupling region, the second micro-nano optical fiber ring is connected to the first micro-nano optical fiber ring via a second coupling region, the first micro-nano optical fiber ring and the second micro-nano optical fiber ring form a dual optical fiber ring, the dual optical fiber ring is connected to the second coupler via an optical fiber, and the second coupler is connected to a detector via an optical fiber.

[0004] Regarding the above-mentioned related technologies, the inventors believe that in the past application research on optical fiber Segner interferometers, the Segner effect was mainly used to generate an optical path difference of light transmitted in the forward and reverse directions, thereby introducing a non-reciprocal phase, and the corresponding physical parameters were analyzed by detecting the non-reciprocal phase generated by this optical path difference. Summary of the Invention

[0005] In view of the defects in the prior art, the object of the present invention is to provide a sensing system and method based on geometric phase change in an optical fiber Segner ring.

[0006] According to the present invention, a sensing system based on geometric phase change in an optical fiber Segner ring is provided, comprising the following modules:

[0007] Optical module: generates split signal light;

[0008] Sensing module: processes the split signal light and senses the physical parameters to be measured;

[0009] Detection module: obtains measurement data based on the processed signal light;

[0010] Data processing module: processes the measured data and calculates the physical parameters to be measured.

[0011] Preferably, the optical module includes a light source, a beam splitter, a polarizer and an optical fiber ring;

[0012] The light emitted by the light source is split by a beam splitter. The split light is converted into linearly polarized light by polarizers. The linearly polarized light passes through the optical fiber ring, and one beam of linearly polarized light is aligned with the polarization-dependent attenuation axis in the optical fiber.

[0013] Preferably, in the sensing module, polarization-dependent attenuation and birefringence of different axes are introduced into the optical fiber by physical means, and the polarization-dependent attenuation intensity of the optical fiber is changed by external physical quantities acting on the optical fiber.

[0014] Preferably, the detection module includes a detector, which converts the processed signal light into an electrical signal and obtains measurement data based on the electrical signal.

[0015] According to the present invention, a sensing method based on geometric phase change in an optical fiber Segner ring is provided, comprising the following steps:

[0016] Step S1: generating split signal light;

[0017] Step S2: Process the split signal light to sense the physical parameter to be measured;

[0018] Step S3: obtaining measurement data based on the processed signal light;

[0019] Step S4: Process the measured data to calculate the physical parameters to be measured.

[0020] Preferably, in step S1, the light emitted by the light source is split into two beams, and the two beams are converted into linearly polarized light, so that the two beams of linearly polarized light pass through the optical fiber ring, wherein one beam of linearly polarized light is required to be aligned with the polarization-dependent attenuation passing axis in the optical fiber.

[0021] Preferably, in step S1, one beam of linearly polarized light is transmitted along the clockwise direction of the optical fiber ring of the Segner interferometer, and the other beam of linearly polarized light is transmitted along the counterclockwise direction.

[0022] Preferably, in step S2, polarization-dependent attenuation and birefringence of different axes are introduced into the optical fiber by physical means, and the polarization-dependent attenuation intensity of the optical fiber is changed by external physical quantities acting on the optical fiber.

[0023] Preferably, step S2 includes the following steps:

[0024] Step S201: presetting the polarization-dependent attenuation and birefringence of the optical fiber ring physically;

[0025] Step S202: coupling the effect of the external physical parameter on the optical fiber with the polarization-dependent attenuation of the optical fiber to generate signal light whose polarization state contains information about the external physical parameter;

[0026] Step S203: The signal light whose polarization state contains external physical quantity information obtained in step S202 is re-injected into the beam splitter through the fiber-spatial optical coupler.

[0027] Preferably, in step S3, the processed signal light is converted into an electrical signal, and measurement data is obtained according to the electrical signal.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention has the effect of improving the sensitivity of the non-reciprocal phase to the change of the measured parameter;

[0030] 2. This invention utilizes the phenomenon of geometric phase mutation in optical fiber rings under special force conditions to achieve extremely high sensitivity in sensing physical parameters such as external pressure, providing a new technical approach for optical fiber sensing.

[0031] 3. The data results in the present invention are only related to birefringence and polarization-related attenuation, and have low requirements on light source stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0033] Figure 1 This is a schematic diagram of the sensor design scheme for generating geometric phase based on continuous weak coupling according to the present invention;

[0034] Figure 2 This is a physical model diagram of the optical fiber element established based on the transmission matrix model of the present invention;

[0035] Figure 3 This is a simulation curve diagram of the geometric phase changing with polarization-dependent attenuation and birefringence in the present invention;

[0036] Figure 4 A slice diagram of a simulation curve diagram of geometric phase changing with polarization-dependent attenuation and birefringence in the present invention when θ is a specific value;

[0037] Figure 5 This is a schematic diagram used to explain the evolution of the polarization state on the Bloch sphere caused by the phase change in the present invention.

[0038] Reference numerals:

[0039] Light source 1 Additional pressure applied and physical influence introduced by the measured parameter Module 5

[0040] Beam splitter 2 Fiber ring 6

[0041] Polarizer 3 Detector 7

[0042] Fiber-space optical coupler 4 DETAILED DESCRIPTION

[0043] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0044] The embodiment of the present invention discloses a sensing system based on geometric phase change in optical fiber Segner ring, such as Figure 1 As shown, the system includes an optical module, a sensor module, a detection module, and a data processing module. The optical module generates the split signal light. The optical module includes a light source, a beam splitter, a polarizer, and a fiber optic loop. The light from the light source is split by the beam splitter. The split light passes through the polarizer to become linearly polarized light. The linearly polarized light then passes through the fiber optic loop, with one beam of linearly polarized light aligned with the polarization-dependent attenuation axis in the optical fiber.

[0045] The optical module is used to generate signal light. It generates two identical linearly polarized beams. The light emitted by the light source is split into two identical beams. Both beams are linearly polarized, with one beam transmitted clockwise through the Segner interferometer fiber loop, and the other transmitted counterclockwise.

[0046] Two linearly polarized beams with identical polarization directions are passed through a fiber loop, one of which is required to align with the axis of polarization-dependent attenuation in the fiber. Light from a light source is split into two identical beams, one of which travels clockwise and the other counterclockwise through the fiber loop. A polarizer is then used to polarize the two beams, aligning the polarization directions of one of them. The fiber loop is wound around a pillar of a specific radius.

[0047] The light source is split into two identical light paths after passing through a 50 / 50 beam splitter, and the two beams of light are polarized using polarizers. It is required that, under the premise that the birefringence axis of the optical fiber incident end is the two coordinate axes of the local coordinate system, the pass axes of the two polarizers form the same angle with the local coordinate axis, that is, the two beams of linearly polarized light are required to be incident at the same angle.

[0048] The light emitted by the light source is split into two identical beams after passing through a 50 / 50 beam splitter. Using polarizers to polarize the two beams requires that, under the premise that the birefringence axis of the optical fiber incident end is the two coordinate axes of the local coordinate system, the pass axes of the two polarizers and the local coordinate axis form the same angle, that is, the two linearly polarized beams are required to be incident at the same angle. In particular, the polarization state of the incident light can be expressed in the form of a Jones matrix, that is, where θ is as close to 45° as possible.

[0049] Sensing module: processes the split signal light and senses the physical parameter to be measured. Polarization-dependent attenuation and birefringence of different axes are introduced into the optical fiber by physical means, and the polarization-dependent attenuation intensity of the optical fiber is changed by the external physical quantity (physical parameter to be measured) acting on the optical fiber. The acquisition of the physical parameter to be measured is determined by the specific application scenario. For example, in a pressure sensing system, the physical quantity to be measured can be obtained by directly applying the pressure to be measured to the optical fiber. Alternatively, in a voltage sensing system, piezoelectric ceramics can be used to make columns for winding optical fibers. At this time, the external voltage acting on the piezoelectric ceramics will cause the radius of the piezoelectric ceramic column to change, thereby changing the winding radius of the optical fiber ring, and further changing the polarization-dependent attenuation of the optical fiber and changing the geometric phase difference of the forward and reverse transmitted light. In this way, the physical parameter to be measured is obtained.

[0050] The sensing module is used to sense the physical parameter to be measured. This sensor module converts changes in the measured physical quantity into changes in the nonreciprocal phase of the forward and reverse propagating light, achieving sensing. Specifically, by designing and adjusting the sensing module, the sensitivity of this nonreciprocal phase to changes in the physical parameter can be increased, thereby improving measurement sensitivity. Inverse birefringence and polarization-dependent attenuation are generated in the optical fiber. Two beams of light are then passed through the optical fiber loop in the forward and reverse directions, coupling the measured parameter with the polarization-dependent attenuation of the optical fiber to achieve sensing.

[0051] Polarization-dependent attenuation and birefringence are introduced into the optical fiber through physical means, and the polarization-dependent attenuation intensity of the optical fiber is altered when an external physical variable acts on the optical fiber. Polarization-dependent attenuation and birefringence are simultaneously introduced into the optical fiber through appropriate physical methods, and they must be non-coaxial. The polarization-dependent attenuation and birefringence introduced through appropriate physical methods should ensure that the inherent geometric phase change difference between the forward and reverse propagating light approaches the phase transition point when no external measured variable is acting. This ensures that the magnitude of the geometric phase change relative to the physical variable is sufficiently large when the external variable acts on the sensing module. The magnitude of the geometric phase change refers to the magnitude of the geometric phase change for the same magnitude of polarization-dependent attenuation change, or for the same magnitude of the measured variable, and describes a type of sensitivity. This large magnitude ensures sufficient system sensitivity when the measured variable is acting.

[0052] By winding the optical fiber on the pillar, the optical fiber is bent with a sufficiently small curvature radius to obtain polarization-dependent attenuation; by applying pressure to the optical fiber, the optical fiber produces birefringence that is not in the same axis as the polarization-dependent attenuation. The microelement model when polarization-dependent attenuation and birefringence exist simultaneously in a specific optical fiber is as follows: Figure 1 As shown, the infinitesimal element can be represented by the Jones matrix as follows:

[0053]

[0054] Where θ / 2 represents the angle between the birefringence axis and the polarization-dependent attenuation axis, and the equivalent non-ideality in the microelement, η represents the attenuation degree of the attenuation axis of the non-ideal polarizer in the microelement, φ represents the phase difference produced by the birefringence wave plate, and e refers to the mathematical constant, which is also the base of the natural logarithm function, sometimes called the Euler number, an important constant in mathematics. Here i is the imaginary unit. Here e -iφ represents a phase delay of φ.

[0055] At the same time, the evolution process of the light transmitted in the clockwise direction and the evolution process of the light transmitted in the counterclockwise direction in the optical fiber ring can be expressed as:

[0056] |ψ out+ >=∏R-1 (θ)M η R(θ)C(φ)|ψ in >

[0057] |ψ out >=∏C(φ)M η R(θ)M η R -1 (θ)|ψ in >

[0058] Among them, |ψ out+ > is the symbolic representation of the polarization state of the clockwise transmitted light. |ψ out- > is the symbolic representation of the polarization state of the counterclockwise transmitted light. is the inverse matrix of the rotation matrix of the equivalent non-ideal polarizer, and Together they represent the rotation of the non-ideal polarizer by an angle of θ. Represents an equivalent non-ideal polarizer, where η has the same meaning as above. The same meaning as above indicates the phase retardation effect of the birefringent wave plate. ∏ is the multiplication symbol, indicating the cumulative effect of multiple elements acting continuously. θ is the angle between the polarization-dependent attenuation axis and the birefringence axis.

[0059] Detection module: Obtains measurement data based on the processed signal light. The detection module includes a detector that converts the processed signal light into an electrical signal and obtains measurement data based on the electrical signal.

[0060] The detection module is used to convert the optical signal into an electrical signal, obtain the measurement data and save it. The detection module is used to detect the spectrum of the two coherent beams and convert it into an electrical signal to obtain data records.

[0061] After the clockwise and counterclockwise light in the fiber ring exit the corresponding ports, they are projected onto the same linear polarization state through the polarizer and then pass through the 50 / 50 beam splitter. The refracted and reflected light of the two beams in the beam splitter are combined into one beam and become coherent, and finally measured by the detector. The phase difference of the forward light generated by the coupling process can be expressed as: <ψ in |ψ ou >, the phase difference of the reverse transmission light caused by the coupling process can be expressed as: <ψ in |ψ out- >.

[0062] like Figure 2 As shown, the optical fiber is decomposed into Figure 2Each of the microelements shown is composed of an equivalent non-ideal polarizer and an equivalent birefringent wave plate. The cylinder marked with a double-arrow axis is the equivalent non-ideal polarizer, and the θ / 2 indicates the angle of its axis deflection. The adjacent cylinder is the equivalent birefringent wave plate, and l represents the length, which must be much smaller than the beat length of the fiber. "One element" in Chinese means "single microelement," meaning that an equivalent non-ideal polarizer and an equivalent birefringent wave plate are used to represent a microelement. The l represents the length of the equivalent wave plate, which must be much smaller than the beat length of the fiber.

[0063] Figure 3 The figure shows the trend of the non-reciprocal phase generated by this coupling process as θ and η in the sensing module change. Here we assume that the optical fiber consists of 200 microelements, and the birefringence of each microelement is expressed by the Jones matrix: θ (π) refers to the angle between the birefringence axis and the polarization-dependent attenuation axis, which is the same as θ mentioned above. π is the unit of θ, which is also the mathematical constant pi. The overall meaning is: This axis represents the difference between the birefringence axis and the polarization-dependent attenuation axis θ, and the unit is π. Figure 4 This figure shows that the sensitivity of the geometric phase transition to changes in polarization-dependent attenuation increases when the angle between the birefringence axis and the polarization-dependent attenuation axis approaches 45°. Dashed line: Nonreciprocal phase versus η for θ = π / 4; dotted line: Nonreciprocal phase versus η for θ = 3π / 8; dash-dotted line: Nonreciprocal phase versus η for θ = 7π / 16.

[0064] observe Figure 3 , Figure 4 It can be seen that when θ approaches 45°, the nonreciprocal phase changes significantly with η around η = 0.96. In particular, if θ = 45°, a complete phase jump occurs. In this case, the polarization-dependent attenuation of the entire fiber loop must reach 42 dB. In the literature Q. Wang, G. Rajan, P. Wang, and G. Farrell, Polarization dependence of bend loss for a standard single-mode fiber, Opt. Exp. 15, 4909 (2007), 2 dB of polarization-dependent attenuation can be achieved by winding the fiber 10 times with a 9 mm radius. Therefore, 42 dB of polarization-dependent attenuation can be achieved by winding the fiber 210 times with a 9 mm radius.

[0065] The receiving process specifically involves receiving the coherent light from the two beams by a detection device capable of spectral analysis. After the two beams are combined, the phase difference between the two beams is detected by a detector capable of spectral detection. This detector can be a spectrometer, for example, with sufficient resolution and measurement range.

[0066] like Figure 5 As shown, Figure 5 Figure (a) shows the evolution trajectory of the polarization state of light on the Bloch sphere when the polarization-dependent attenuation intensity is low and the polarization-dependent attenuation axis and the birefringence axis are at different angles. It can be seen that when the polarization-dependent attenuation intensity is low, this series of evolution curves ultimately cannot cross the hemisphere, which makes the final geometric phase change smaller. The line segments on the sphere indicate that all the evolution trajectories here are generated when the polarization-dependent attenuation intensity is low, so they cannot cross the hemisphere. Figure 5 In (b), the series of curves depict the evolution of the polarization state of light on the Bloch sphere when the polarization-dependent attenuation axis and the birefringence axis are at different angles, under conditions of high polarization-dependent attenuation. It can be seen that when polarization-dependent attenuation is high, the series of curves crosses the hemisphere, resulting in a large geometric phase transition. The line segments on the sphere indicate that all of the evolutionary trajectories here occur when the polarization-dependent attenuation is high, and therefore cross the hemisphere.

[0067] Data processing module: Processes the measured data and calculates the physical parameters to be measured. The data processing module is used to process the measured data and calculate the physical parameters to be measured. The data processing module is used to analyze the phase difference based on the obtained data and, in combination with the prefabricated state of the geometric fiber optic ring and the analysis of the geometric phase, calculate the size and change of the parameter to be measured. During the data analysis process, the phase difference between the clockwise and counterclockwise transmitted light can be obtained by traditional analysis of the post-interference spectrum. Combined with the pre-set polarization-dependent attenuation and the size and axis of the birefringence, the corresponding relationship between this phase difference and the physical quantity to be measured can be analyzed, thereby realizing the sensing of the measurement to be measured. The phase difference is analyzed by the data processing module to calculate the size of the physical parameter to be measured. In the data processing module, a series of abstract processing procedures are performed after obtaining the measurement data under the preset polarization-dependent attenuation intensity and the angle between the polarization-dependent attenuation and the birefringence axis. For example, the phase difference between the forward and reverse transmitted light is obtained through spectrum analysis. The correspondence between the polarization-dependent attenuation change and the geometric phase change at this time is obtained according to the preset polarization-dependent attenuation and birefringence. At this time, general analysis tools such as computers and mathematical processing software such as Matlab can be used for analysis.

[0068] This embodiment comprises an optical module, a sensing module, a detection module, and a data processing module. This invention combines fiber-optic Segner interferometer technology with the theory of geometric phase generation through continuous weak coupling. The sensitivity of the sensing scheme is enhanced by utilizing the phase-shift characteristics of the geometric phase under specific circumstances. By adjusting the birefringence intensity, polarization-dependent attenuation intensity, and the angle between the two, the system's geometric phase can be adjusted to approach the phase-shift point. Furthermore, the sensitivity of the geometric phase to changes in physical parameters near the phase-shift point can be adjusted. This sensitivity corresponds to the slope of the geometric phase's change with polarization-dependent attenuation. As the slope increases, the measurement range decreases accordingly, requiring optimal adjustment based on actual needs.

[0069] A sensor design method for generating geometric phase based on continuous weak coupling in an optical fiber Segner interferometer includes: utilizing the physical properties of the optical fiber to generate an adjustable geometric phase portion between forward and reverse transmitted light. This portion uses bending and stressing methods to introduce polarization-dependent attenuation and birefringence in different axes in the optical fiber, thereby achieving continuous weak coupling of the incident light, introducing and adjusting the geometric phase between forward and reverse transmitted light, and ultimately improving the sensitivity of the phase to changes in the measured parameter.

[0070] The specific process for generating an adjustable geometric phase between forward and reverse propagating light using the physical properties of optical fiber is as follows: The light emitted by a light source is split into two beams, one transmitted clockwise through the fiber loop, and the other transmitted counterclockwise. The two beams are then polarized and coupled into the two ports of the fiber loop. Polarization-dependent attenuation is introduced into the fiber by bending the fiber. The direction and magnitude of the applied pressure are adjusted to adjust the magnitude and axial direction of the introduced birefringence. The light from the two ports of the fiber loop is then combined into a single beam and allowed to interfere with each other. The resulting interference is then received by a detector, which detects the phase difference between the two beams. After the adjustment is complete, the physical parameter to be measured is coupled to the polarization-dependent attenuation of the fiber. Finally, the data processing module combines the polarization-dependent attenuation and birefringence values ​​pre-set during the adjustment process to determine the corresponding relationship between the geometric phase change and the measured parameter change.

[0071] The present invention utilizes a new type of nonreciprocal phase. Unlike the traditional nonreciprocal phase introduced by the Segner effect, this new nonreciprocal phase is independent of the optical path difference between forward and reverse propagating light, but rather depends solely on the intensity of polarization-dependent attenuation and the angle between the polarization-dependent attenuation axis and the birefringence axis. This nonreciprocal phase also exhibits the properties of a geometric phase: the vertex angle of the curve enclosed by the evolution trajectory of the polarization state on the Bloch sphere can characterize the phase difference generated by the evolution process. This property gives this new type of nonreciprocal phase the following characteristics: its magnitude is related to the evolution trajectory of the polarization state on the Bloch sphere. During the final projection measurement, the enclosing curve consists of two parts: the evolution trajectory introduced by the continuous weak measurement and the shortest path from the end point of the evolution trajectory to the starting point of the evolution trajectory introduced by the projection measurement. When the end point of the evolution trajectory approaches a meridian on the sphere 180° from the starting point, a phase abrupt change occurs due to the change in the shortest projected path. In particular, when the evolution trajectory is on the equator of the Bloch sphere, the nonreciprocal phase exhibits a phase abrupt change from 0 to π. Based on the characteristics of this new type of non-reciprocal phase, a new type of sensor can be manufactured. The present invention uses a special method to introduce a geometric phase change related to the physical quantity to be measured in the optical fiber loop, and then obtains the physical parameter information through interferometric detection.

[0072] The present invention is based on a new sensing method of geometric phase change in an optical fiber Segner ring, and utilizes the characteristics of this new non-reciprocal phase to achieve parameter estimation with higher sensitivity. The present invention includes an optical module, a sensing module, a detection module, and a data processing module. The optical module is used to generate signal light. The sensing module is used to sense the physical parameter to be measured. The detection module is used to convert the optical signal into an electrical signal, obtain and save the measurement data. The data processing module is used to process the measured data and calculate the physical parameter to be measured. The present invention utilizes the phenomenon of geometric phase mutation in the optical fiber ring under special force conditions to achieve extremely high sensitivity perception of physical parameters such as external pressure, providing a new technical approach for optical fiber sensing.

[0073] The present invention also discloses a highly sensitive sensing method utilizing geometric phase transitions in an optical fiber Segner interferometer loop. The method comprises the following steps: Step S1: generating split signal light. Light emitted by a light source is split into two beams, which are then converted into linearly polarized light. The two linearly polarized light beams are passed through the optical fiber loop, with one of the linearly polarized light beams aligned with the polarization-dependent attenuation axis of the optical fiber. One linearly polarized light beam is transmitted in a clockwise direction through the Segner interferometer optical fiber loop, while the other linearly polarized light beam is transmitted in a counterclockwise direction.

[0074] Step S2: Process the split signal light to sense the physical parameter to be measured. Polarization-dependent attenuation and birefringence along different axes are introduced into the optical fiber through physical means, and the intensity of the polarization-dependent attenuation of the optical fiber is changed by the external physical quantity acting on the optical fiber.

[0075] Step S2 includes the following steps: Step S201: Presetting the polarization-dependent attenuation and birefringence of the optical fiber loop physically ensures that the geometric phase of the forward and reverse propagating light in the optical fiber loop is as close as possible to the phase transition point. Step S202: Coupling the effect of an external physical parameter on the optical fiber with the polarization-dependent attenuation of the optical fiber to generate signal light whose polarization state contains information about the external physical quantity. Step S203: Reinjecting the signal light whose polarization state contains information about the external physical quantity, obtained in step S202, into the beam splitter via a fiber-spatial optical coupler, and placing a detector at the right exit of the beam splitter to receive the signal light whose polarization state contains information about the external physical quantity.

[0076] Step S3: Obtain measurement data based on the processed signal light. Convert the signal light obtained in step S203 into an electrical signal, and obtain measurement data based on the electrical signal. Step S4: Process the measurement data to calculate the physical parameter to be measured.

[0077] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0078] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A sensing system based on geometric phase change in optical fiber Segner ring, characterized in that: Includes the following modules: Optical module: generates split signal light; Sensing module: processes the split signal light and senses the physical parameters to be measured; Detection module: obtains measurement data based on the processed signal light; Data processing module: processes the measured data and calculates the physical parameters to be measured; The optical module includes a light source, a beam splitter, a polarizer and an optical fiber ring; The light emitted by the light source is split by a beam splitter. The split light is converted into linearly polarized light by polarizers. The linearly polarized light passes through the optical fiber ring, and one of the linearly polarized lights is aligned with the polarization-dependent attenuation axis in the optical fiber. In the sensing module, polarization-dependent attenuation and birefringence of different axes are introduced into the optical fiber by physical means, and the polarization-dependent attenuation intensity of the optical fiber is changed by the action of external physical quantities on the optical fiber.

2. The sensing system based on geometric phase change in optical fiber Segner ring according to claim 1, characterized in that: The detection module includes a detector, which converts the processed signal light into an electrical signal and obtains measurement data based on the electrical signal.

3. A sensing method based on geometric phase change in optical fiber Segner ring, characterized in that: The sensing system based on geometric phase change in an optical fiber Segner ring according to any one of claims 1 to 2 comprises the following steps: Step S1: generating split signal light; Step S2: Process the split signal light to sense the physical parameter to be measured; Step S3: obtaining measurement data based on the processed signal light; Step S4: Processing the measured data to calculate the physical parameters to be measured; In step S1, the light emitted by the light source is split into two beams, and the two beams are converted into linearly polarized light, so that the two beams of linearly polarized light pass through the optical fiber ring, and one of the linearly polarized light beams is required to be aligned with the polarization-dependent attenuation axis in the optical fiber; In step S1, one linear polarized light beam is transmitted along the clockwise direction of the fiber ring of the Segner interferometer, and the other linear polarized light beam is transmitted along the counterclockwise direction; In step S2, polarization-dependent attenuation and birefringence of different axes are introduced into the optical fiber by physical means, and the polarization-dependent attenuation intensity of the optical fiber is changed by external physical quantities acting on the optical fiber; The step S2 comprises the following steps: Step S201: presetting the polarization-dependent attenuation and birefringence of the optical fiber ring physically; Step S202: coupling the effect of the external physical parameter on the optical fiber with the polarization-dependent attenuation of the optical fiber to generate signal light whose polarization state contains information about the external physical parameter; Step S203: The signal light whose polarization state contains external physical quantity information obtained in step S202 is re-injected into the beam splitter through the fiber-spatial optical coupler.

4. The sensing method based on geometric phase change in optical fiber Segner ring according to claim 3, characterized in that: In step S3, the processed signal light is converted into an electrical signal, and measurement data is obtained according to the electrical signal.

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