Multi-parameter measurement interference device based on all-fiber wedge-shaped-sawtooth double-cavity cooperation

Abstract

The invention provides a multi-parameter measurement interference device based on all-fiber wedge-sawtooth double-cavity cooperation, and relates to the technical field of optical precision measurement, and the device comprises a wedge-shaped cavity, a sawtooth cavity and an all-fiber closed-loop architecture. The wedge-shaped cavity is composed of an AlN ceramic reference reflecting plate and a metasurface wedge-shaped movable plate, the sawtooth cavity is composed of the metasurface wedge-shaped movable plate and a diamond film sawtooth fixing plate, and the wedge-shaped cavity and the sawtooth cavity are connected through an all-fiber closed-loop framework. According to the multi-parameter measurement interference device, an all-fiber framework is adopted, the AlN ceramic reference reflecting plate, the metasurface wedge-shaped movable plate and the diamond film sawtooth fixing plate are integrated, two independent but correlated interference cavities are formed, and high-precision cooperative measurement of multiple physical quantities such as pressure, refractive index, temperature, stress, sound wave vibration and magnetic field intensity can be achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical precision measurement, and particularly relates to a dual-cavity Fabry-Perot (FP) interferometer system with a full-fiber structure, and particularly relates to a multi-parameter measurement interference device based on a full-fiber wedge-sawtooth dual-cavity cooperation. BACKGROUND

[0002] A traditional F-P interferometer is based on a single parallel cavity structure, and has a fundamental defect of single function and poor environmental adaptability. The principle of detecting a single physical quantity through optical path change leads to the inability to distinguish the cross-influence of multiple parameters, and the sensitivity and dynamic range are mutually restricted. In addition, the high thermal expansion coefficient and chemical instability of traditional materials cause the measurement precision to sharply decrease under temperature fluctuation or corrosive environment, and it is difficult to meet the demand for multi-dimensional precision measurement in complex environments in the fields of biomedicine, aerospace, etc. SUMMARY

[0003] In view of the above problems, the present application aims to provide a multi-parameter measurement interference device based on a full-fiber wedge-sawtooth dual-cavity cooperation, which breaks through the performance bottleneck of traditional single-cavity interferometers in multi-dimensional physical quantity measurement through the cooperative optimization of optical structure and signal processing algorithm. The device of the present application adopts a wedge-sawtooth dual-cavity structure, realizes multi-parameter decoupling measurement (such as the wedge cavity focusing on pressure sensitivity and the sawtooth cavity enhancing the refractive index response) through the differential response of two independent interference cavities, and uses the three-plate two-cavity optical path superposition effect to improve the sensitivity by more than 50 times, thereby breaking through the detection limit of traditional interferometers. The use of new materials such as AlN ceramic and diamond film significantly reduces the thermal expansion coefficient (only 1 / 10 of that of traditional materials) and enhances the chemical stability, and the combination of the dual-cavity differential structure effectively suppresses environmental interference (such as a common-mode rejection ratio of 50:1), thereby finally realizing high-precision cooperative measurement of temperature, pressure, refractive index and other multi-dimensional physical quantities in a wide dynamic range (such as pressure 0.1 Pa-10 kPa) (such as measurement error <0.5%). The multi-parameter measurement interference device of the present application adopts a full-fiber architecture, integrates an AlN ceramic reference reflection plate, a super-structured surface wedge movable plate and a diamond film sawtooth fixed plate, forms two independent but interrelated interference cavities, and can realize high-precision cooperative measurement of multiple physical quantities such as pressure, refractive index, temperature, stress, acoustic vibration and magnetic field strength.

[0004] To achieve the above-mentioned purpose, the present application provides the following technical solutions: Based on the above purpose, the present application provides a multi-parameter measurement interference device based on a full-fiber wedge-sawtooth dual-cavity cooperation, which comprises: The wedge cavity is composed of an AlN ceramic reference reflection plate and a super-structured surface wedge movable plate, wherein the wedge movable plate is driven by a piezoelectric displacement table (PZT) to generate a nanoscale inclination change, and responds to pressure and stress changes. Sawtooth cavity: composed of super-structured surface wedge movable plate and diamond thin film sawtooth fixed plate, the surface of the fixed plate is etched with sawtooth grooves to form a light path folding structure; All-fiber closed-loop architecture: the wedge cavity and the sawtooth cavity are connected through an all-fiber closed-loop architecture, which includes a broadband light source with an isolator, a circulator, a fiber coupler, a measured parameter device table, a multimode optical fiber, a spectral analysis unit, a feedback control system, a real-time parameter feedback platform, a photodetector 1 and a photodetector 2, and the light field transmission follows a complex amplitude matrix model.

[0005] The present application uses two photodetectors, the photodetector 1 receives the combined spectrum signal of the double-cavity interference as the original data source for multi-physical quantity (pressure, refractive index, temperature, etc.) measurement. The photodetector 2 receives the independent reflection signal of the single cavity (wedge cavity), which forms a differential comparison with the combined signal of the first detector, and is used to eliminate common-mode interference such as temperature and vibration.

[0006] As a further scheme of the present application, the thickness of the AlN ceramic reference reflection plate is 500 μm, and the reflectivity of the surface evaporated high-reflection film is > 99%.

[0007] As a further scheme of the present application, the super-structured surface wedge movable plate adopts a nano-pillar array structure and generates an inclination change through piezoelectric driving.

[0008] As a further scheme of the present application, when external pressure acts on the wedge movable plate, the cavity length change of the wedge cavity satisfies the time-varying differential equation:

[0009] Wherein, the sound pressure coupling coefficient represents the light field modulation efficiency of the AlN ceramic to pressure; The light path folding structure of the sawtooth cavity makes the light path integral represented as:

[0010] Wherein, N is the light path folding factor, is the transverse refractive index gradient.

[0011] As a further scheme of the present application, the diamond thin film sawtooth fixed plate adopts a 2 μm thick diamond thin film, the surface is etched with sawtooth grooves with a depth of 500 nm and a period of 1 μm, the light path folding factor of the formed light path folding structure is N = 8, the refractive index of the diamond thin film n 2 = 2.4 is uniformly distributed, the effective light path of the light in the cavity is , and the free spectral range of the sawtooth cavity is down to the wedge cavity 1 / 8.

[0012] As a further scheme of the present application, the broadband light source is a light source with built-in isolator protection function covering the 1500-1600 nm spectral range.

[0013] As a further scheme of the present application, the broadband light source, the circulator, the fiber coupler, the device under test platform, the multimode fiber, the spectral analysis unit, the feedback control system, the real-time parameter feedback platform, the photodetector 1 and the photodetector 2 of the all-fiber closed-loop architecture are connected by fiber fusion for low-loss connection. The broadband light source (with built-in isolator to prevent reverse light interference) emits a wide-spectrum stable light signal. The light signal is directed into the fiber coupler through the circulator. The coupler injects the light signal into the wedge-sawtooth double-cavity module. The reflected light of the wedge cavity and the sawtooth cavity interferes in the coupler to form a double-cavity interference combined signal. The signal is transmitted to the photodetector 1 through the circulator, carrying the multi-parameter modulation information of the double-cavity cooperative response. The coupler simultaneously separates the independent reflection signal of the wedge cavity (light reflected only by the wedge cavity without entering the sawtooth cavity). The signal is sent to the spectral analysis unit through the multimode fiber to analyze the single property of the wedge cavity, and is directly transmitted to the photodetector 2. The double-cavity interference combined signal received by the photodetector 1 and the wedge cavity independent reflection signal received by the photodetector 2 are differentially processed by the feedback control system to realize environmental interference suppression and multi-parameter decoupling.

[0014] As a further scheme of the present application, the system incident light emitted by the broadband light source is directed into the fiber coupler through the circulator. After the light signal is injected into the wedge cavity by the coupler, the reflected light and the sawtooth cavity reflected light interfere in the fiber to form a double-cavity interference spectrum. The wedge cavity is composed of an AlN ceramic reference reflection plate and a super-structured wedge movable plate, and the cavity length is the distance between the two plates L 1， free spectral range FSR 1 is defined as the wavelength interval between two adjacent peaks in the interference fringes in the wedge cavity. The sawtooth cavity is composed of a super-structured wedge movable plate and a diamond thin film sawtooth fixed plate. The fixed plate surface is etched with a sawtooth groove with a depth of 500 nm and a period of 1 μm, forming a light path folding structure, and the free spectral range FSR 2 is defined as the wavelength interval between two adjacent peaks in the interference fringes in the sawtooth cavity. By adjusting the difference between the free spectral ranges of the two cavities , the superposition effect generated by the double-cavity light field coupling is used to realize interference signal amplification, and the amplification factor is .

[0015] As a further scheme of the present application, the light field interference cycle system of the all-fiber closed-loop architecture is integrated with a piezoelectric displacement table (PZT) arranged below the wedge-shaped movable plate of the super-structured surface, and the nanoscale displacement adjustment is realized through electrical signal driving, the feedback control system monitors the interference spectrum shift in real time, and the PZT voltage is adjusted based on the PID algorithm to maintain the system working in the optimal sensitivity interval.

[0016] As a further scheme of the present application, the complex amplitude matrix model is:

[0017] wherein, , are the phase differences of the wedge-shaped cavity and the sawtooth cavity, respectively, , is the transmission / reflection coefficient of the wedge-shaped cavity, , is the transmission / reflection coefficient of the sawtooth cavity, corresponding to the optical properties of the AlN ceramic reference plate and the diamond thin film fixed plate.

[0018] As a further scheme of the present application, the multi-parameter measurement interference device is further based on the thermal expansion difference between the AlN ceramic and the diamond thin film to establish a temperature decoupling equation group:

[0019] through differential calculation , the common-mode rejection ratio is 50:1, and the strain error of the double-cavity structure is only 0.2 με when the temperature fluctuation is ±5℃; the magnetic field measurement module complies with the magneto-elastic coupling equation .

[0020] Compared with the prior art, the multi-parameter measurement interference device based on the all-fiber wedge-sawtooth double-cavity cooperation has the following beneficial effects: The present application forms a group delay difference through the difference in the free spectral range of the double cavities, calculates the amplification gain to make the slight physical quantity change produce a significant spectral shift, uses the superposition effect generated by the double-cavity light field coupling to realize interference signal amplification and improve the sensitivity; the double-cavity structure reconstructs the dynamic range model through the group delay difference, breaks through the range limitation of the traditional single cavity, and improves the pressure measurement range coverage; the decoupling equation group is constructed by using the difference in the thermal elastic coefficients of the AlN ceramic and the diamond thin film to realize temperature cross-interference suppression; the machine learning analyzes the frequency domain characteristics of the double-cavity interference spectrum to separate the static pressure and the dynamic acoustic vibration, and the multi-physical quantity synchronous separation measurement is realized through the integration of the magnetostrictive material, and the optical fiber fusion technology is used to connect the broadband light source, the circulator, the interference cavity and other components to avoid the free space optical path calibration problem, solve the cross-interference, environmental sensitivity and range limitation problems in multi-parameter measurement, and provide an irreplaceable solution for precision sensing in the fields of biomedicine, aerospace and the like.

[0021] These or other aspects of this application will become more apparent from the following description of embodiments. It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the application. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the accompanying drawings used in the description of the exemplary embodiments or related technologies will be briefly introduced below. The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the overall structure of a multi-parameter measurement interferometer based on all-fiber wedge-sawtooth dual-cavity coordination according to an embodiment of the present invention.

[0023] Figure 2 This is a detailed diagram of the cavity of the FP interferometer in a multi-parameter measurement interferometer device based on all-fiber wedge-sawtooth dual-cavity collaboration, according to an embodiment of the present invention.

[0024] Figure 3 This is a diagram of the independent interference spectrum of the two cavities in a multi-parameter measurement interferometer based on a fully fiber optic wedge-sawtooth dual-cavity coordinated multi-parameter measurement interferometer according to an embodiment of the present invention.

[0025] Figure 4 This is a sensitivity enhancement curve based on the superposition effect of three-plate two-cavity optical paths in a multi-parameter measurement interferometer device based on all-fiber wedge-sawtooth dual-cavity collaboration, according to an embodiment of the present invention.

[0026] Figure 5 This is a time-domain / cavity length response curve of the interference signal under vibration modulation in a multi-parameter measurement interferometer based on all-fiber wedge-sawtooth dual-cavity coordination according to an embodiment of the present invention.

[0027] Figure 6 This is a comparison curve of resolution improvement in a multi-parameter measurement interferometer based on all-fiber wedge-sawtooth dual-cavity coordination according to an embodiment of the present invention.

[0028] Figure 7 This is a dynamic range expansion curve of a multi-parameter measurement interferometer based on dual-parameter decoupling, according to an embodiment of the present invention, using an all-fiber wedge-sawtooth dual-cavity collaborative device.

[0029] Figure 8 This is a comparison curve of the anti-interference performance of strain measurement under temperature interference for a multi-parameter measurement interferometer based on a fully fiber optic wedge-sawtooth dual-cavity coordinated device according to an embodiment of the present invention. Detailed Implementation

[0030] The application will be further described below in conjunction with the drawings and specific embodiments, and it should be noted that the following described embodiments or technical features can be combined in any manner to form new embodiments without conflict.

[0031] In order to make the objectives, technical solutions and advantages of the present application clearer, the embodiments of the present application are further described in detail below with reference to the drawings and in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0032] It should be noted that all the expressions of "first" and "second" in the embodiments of the present application are used to distinguish two non-identical entities or non-identical parameters with the same name, and it can be seen that "first" and "second" are only used for convenience of description and should not be understood as a limitation on the embodiments of the present application. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, processes, methods, systems, products or devices inherently have other steps or units.

[0033] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0034] The flowchart shown in the drawings is only an example and does not necessarily include all the contents and operations / steps, nor does it necessarily be executed in the described order. For example, some operations / steps can be decomposed, combined or partially combined, so the actual execution order can be changed according to the actual situation.

[0035] Some embodiments of the present application will be described in detail below in conjunction with the drawings. The following embodiments and features in the embodiments can be combined with each other without conflict.

[0036] The traditional F-P interferometer cannot distinguish the cross influence of multiple parameters, the sensitivity and dynamic range are restricted to each other, the high thermal expansion coefficient of traditional materials and chemical instability, and the measurement precision sharply decreases under temperature fluctuation or corrosion environment. The application provides a multi-parameter measurement interferometer based on full optical fiber wedge-sawtooth double cavity cooperation, which breaks through the performance bottleneck of traditional single cavity interferometer in multi-dimensional physical quantity measurement through the cooperation optimization of optical structure and signal processing algorithm. The device adopts wedge-sawtooth double cavity structure, realizes the decoupling measurement of multiple parameters (such as the wedge cavity focuses on pressure sensitivity, and the sawtooth cavity enhances the refractive index response) through the differential response of two independent interference cavities, and uses the three-plate two-cavity light path superposition effect to improve the sensitivity by more than 50 times, thereby breaking through the detection limit of the traditional interferometer. The new materials such as AlN ceramic and diamond film are adopted, the thermal expansion coefficient is significantly reduced (only 1 / 10 of that of traditional materials), and the chemical stability is enhanced, the environmental interference (such as common mode rejection ratio of 50:1) is effectively inhibited by combining the double cavity differential structure, and finally the high-precision cooperative measurement (such as measurement error <0.5%) of temperature, pressure, refractive index and other multi-dimensional physical quantities in a wide dynamic range (such as pressure 0.1 Pa-10 kPa) is realized.

[0037] The multi-parameter measurement interferometer device adopts full optical fiber architecture, integrates AlN ceramic reference reflection plate, superstructure surface wedge movable plate and diamond film sawtooth fixed plate, forms two independent but interrelated interference cavities, and can realize high-precision cooperative measurement of multiple physical quantities such as pressure, refractive index, temperature, stress, acoustic vibration and magnetic field strength.

[0038] Referring to Figure 1 The embodiment of the application provides a multi-parameter measurement interferometer device based on full optical fiber wedge-sawtooth double cavity cooperation, which comprises a wedge cavity, a sawtooth cavity and a full optical fiber closed loop architecture. The wedge cavity is composed of an AlN ceramic reference reflection plate and a superstructure surface wedge movable plate. The wedge movable plate is driven by a piezoelectric displacement table (PZT) to generate a nanoscale inclination change, and responds to pressure and stress changes. The sawtooth cavity is composed of a superstructure surface wedge movable plate and a diamond film sawtooth fixed plate. The surface of the fixed plate is etched with sawtooth grooves to form a light path folding structure. The wedge cavity and the sawtooth cavity are connected through a full optical fiber closed loop architecture. The full optical fiber closed loop architecture comprises a wideband light source with an isolator, a circulator, a fiber coupler, a to-be-measured parameter device table, a multimode optical fiber, a spectrum analysis unit, a feedback control system, a real-time parameter feedback platform, a photodetector 1 and a photodetector 2. The light field transmission follows a complex amplitude matrix model.

[0039] The application is based on a full-fiber wedge-sawtooth double-cavity collaborative multi-parameter measurement interference device. Through the synergy optimization of optical structure and signal processing algorithm, the performance bottleneck of traditional single-cavity interferometer in multi-dimensional physical quantity measurement is broken through. The system adopts a full-fiber architecture, integrates an AlN ceramic reference reflection plate, a super-structure surface wedge movable plate and a diamond thin film sawtooth fixed plate, forms two independent but interrelated interference cavities, and realizes high-precision collaborative measurement of multiple physical quantities such as pressure, refractive index, temperature, stress, acoustic vibration and magnetic field strength. Among them, the double-cavity light field transmission is expressed by a complex amplitude model as follows:

[0040] Among them, is the output complex amplitude of the wedge cavity; is the output complex amplitude of the sawtooth cavity; is the cavity length of the wedge cavity; is the AlN ceramic reflectivity; is the diamond thin film reflectivity; is the phase factor of the wedge cavity light field, wherein is the phase difference of the wedge cavity; is the total phase factor when the double-cavity light field is coupled, wherein is the phase difference of the sawtooth cavity; is the imaginary unit, used to describe the phase delay of the light field; is the complex amplitude incident to the wedge cavity; is the complex amplitude incident to the sawtooth cavity; inter-cavity coupling coefficient mode loss factor determined by super-structure nano-structure design (AlN ceramic plate) and (diamond thin film) reflect the attenuation effect of the material surface roughness on the light field, and the matrix model accurately describes the light field coupling characteristics of the wedge cavity and the sawtooth cavity.

[0041] In this embodiment, the wedge cavity composed of the AlN ceramic reference reflection plate and the super-structure surface wedge movable plate utilizes the low thermal expansion coefficient of the material and the nanoscale displacement control ability of the piezoelectric drive to realize high sensitivity response to pressure and small stress. When external pressure acts on the wedge movable plate, the cavity length change of the wedge cavity satisfies the time-varying differential equation:

[0042] Among them, is a function of the phase change with time; is the time; is the cavity length; is the speed of light; is the refractive index of the medium in the cavity; is the dynamic pressure; acoustic pressure coupling coefficient characterize the light field modulation efficiency of AlN ceramic to pressure; In this embodiment, the thickness of the AlN ceramic reference reflector plate is 500 μm, and the reflectivity of the surface evaporated high reflection film is > 99%. The super-structure wedge-shaped movable plate adopts a nano-pillar array structure, and the inclination angle change is generated by piezoelectric driving.

[0043] In this embodiment, the sawtooth cavity composed of the wedge-shaped movable plate and the diamond thin film sawtooth fixed plate has an optical path folding structure, and the optical path integral is expressed as:

[0044] wherein, is the total optical path difference, N is the optical path folding factor, is the single propagation length, is the refractive index distribution along the optical axis direction, is the transverse coordinate, is the axial coordinate of the light field propagation direction, is the transverse refractive index gradient. The high refractive index and chemical stability of the diamond thin film not only improve the refractive index measurement accuracy, but also provide the possibility for the detection of small refractive index fluctuations in biological cells.

[0045] The above-mentioned sawtooth cavity is composed of the wedge-shaped movable plate and the diamond thin film sawtooth fixed plate, and the unique optical path folding structure makes the light in the cavity experience multiple reflections, significantly enhancing the interaction between light and matter. The high refractive index and chemical stability of the diamond thin film not only improve the refractive index measurement accuracy, but also endow the system with stability in high temperature and strong corrosion environment. When the temperature changes, the difference in thermal expansion between the AlN ceramic and the diamond thin film causes the cavity length to change, and combined with the double-cavity temperature response model, the independent decoupling measurement of temperature can be realized, effectively eliminating the cross interference of temperature on pressure and refractive index measurement.

[0046] In this embodiment, the diamond thin film sawtooth fixed plate adopts a 2 μm thick diamond thin film, and the surface is etched with sawtooth grooves with a depth of 500 nm and a period of 1 μm, and the optical path folding factor of the formed optical path folding structure is N = 8, and the refractive index of the diamond thin film n 2 = 2.4 is uniformly distributed, and the effective optical path of the light in the cavity is , and the free spectral range of the sawtooth cavity is reduced to 1 / 8 of the wedge cavity .

[0047] In the multi-parameter measurement interference device of the application, the sensitivity is also exponentially improved through the three-plate two-cavity optical path superposition effect, and the group delay ​The frequency domain amplification effect caused by the difference can be expressed as: The modal overlap integral Quantify the degree of dual-cavity mode matching. For the group delay of the wedge cavity, For the group delay of the sawtooth cavity, The modal overlap integral modulus squared, For wedge cavity in the frequency domain electric field distribution, The complex conjugate of the electric field distribution in the sawtooth cavity. For frequency domain integral variables. When there is a slight difference in the free spectral range of the two cavities, the superposition of interference fringes amplifies the interference signal through the superposition effect generated by the coupling of the optical fields of the two cavities, making the system's response sensitivity to changes in physical quantities more than 50 times higher than that of the traditional single-cavity structure.

[0048] To achieve synchronous decoupling of multiple physical quantities, the system employs a machine learning-based signal processing algorithm. By extracting deep features from the dual-cavity interferometric spectrum and combining it with a pre-trained physical quantity response model, parameters such as pressure, temperature, refractive index, stress, and acoustic vibration can be simultaneously retrieved. For example, when pressure and acoustic waves are acting simultaneously, the static cavity length change caused by pressure and the dynamic vibration caused by acoustic waves exhibit different characteristics in the frequency domain. The algorithm achieves separate measurement of these two parameters through spectral analysis.

[0049] To achieve independent decoupling of temperature disturbances, a system of differential equations is constructed based on the thermoelastic differences between the two materials:

[0050] In the formula, The change in temperature For integration time variable, The change in refractive index For the time change, The rate of change of refractive index over time is the thermoelastic coefficient of AlN ceramics and diamond films. The difference in temperature sensitivity can be effectively eliminated by combining it with a dual-cavity differential structure. The common-mode rejection ratio reaches 50:1, which reduces interference.

[0051] In magnetic field measurement, magnetostrictive materials (such as Terfenol-D) can be integrated onto the surface of a wedge-shaped movable plate, and their dynamic response can be described by the magnetoelastic coupling tensor equation.

[0052] in, The change in displacement vector. For the time change, is the time derivative of displacement vector, representing the deformation velocity of magnetostrictive material under the action of magnetic field, is the magnetoelastic coupling tensor, is the magnetic field intensity vector, is the Laplacian of displacement vector, is the sound diffusion coefficient, when the external magnetic field changes, the magnetostrictive effect causes the small deformation of the plate, and further causes the change of the interference cavity length. By detecting this change, the system can measure the weak magnetic field, and expand the application of F-P interferometer in the field of magnetism.

[0053] The dynamic range (DR) as the core performance index of the system represents the linear working ability between the maximum measurable signal and the minimum measurable signal. The DR is improved to 80 dB (corresponding to the pressure 0.1 Pa-10 kPa measurement range) by the cooperation optimization of the double-cavity structure and the material characteristics. The statistical model is wherein, NEP is the noise equivalent power, is the maximum signal intensity, is the reflectivity nonlinear coefficient, is the minimum signal intensity. The double-cavity structure expands the range boundary through the three-plate two-cavity optical path superposition effect, while the double cavity makes . .

[0054] In the embodiment, the broadband light source, the circulator, the fiber coupler, the to-be-measured parameter device table, the multi-mode optical fiber, the spectrum analysis unit, the feedback control system, the real-time parameter feedback platform, the photodetector 1 and the photodetector 2 of the all-fiber closed-loop architecture are connected by fiber fusion for low-loss connection. The broadband light source (with an isolator to prevent reverse light interference) emits a wide-spectrum stable light signal, which is introduced into the fiber coupler in a directional manner through the circulator. The coupler injects the light signal into the wedge-sawtooth double-cavity module: the reflected light of the wedge cavity and the sawtooth cavity interferes in the coupler to form a double-cavity interference synthesis signal, which is transmitted to the photodetector 1 through the circulator, carrying the multi-parameter modulation information of the double-cavity cooperative response; the coupler simultaneously separates the independent reflection signal of the wedge cavity (the light reflected only by the wedge cavity without entering the sawtooth cavity), which is sent to the spectrum analysis unit through the multi-mode optical fiber to analyze the single property of the wedge cavity, and directly transmitted to the photodetector 2. The double-cavity interference synthesis signal received by the photodetector 1 and the wedge cavity independent reflection signal received by the photodetector 2 are differentially processed by the feedback control system to realize environmental interference suppression and multi-parameter decoupling.

[0055] Wherein, the light route broadband light source emits after directional introduction coupler by circulator, the coupler injects the light signal into the wedge-sawtooth double cavity interference module, the reflected light is output by the coupler, one way is sent to the spectrum analysis unit by multimode optical fiber, and the spectrum characteristics are analyzed, part of the light is divided to the photodetector 2, and the other way of reflected signal is guided to the photodetector 1 by the circulator. The photodetector 1, 2 converts the optical signal into an electrical signal and transmits it to the feedback control system, the system processes the data and sends it to the real-time parameter feedback platform for visualization, completing the whole process of "light emission-modulation-demodulation-control-display", realizing multi-parameter measurement and feedback.

[0056] Wherein, the broadband light source is a light source with built-in isolator protection function covering the 1500-1600 nm spectral range. The system incident light emitted by the broadband light source is introduced into the fiber coupler by the circulator, and the coupler injects the light signal into the wedge cavity. The reflected light and the sawtooth cavity reflected light interfere in the optical fiber to form a double cavity interference spectrum. The wedge cavity is composed of an AlN ceramic reference plate and a superstructure wedge movable plate, and the cavity length is the distance between the two plates L 1， Free spectral range FSR 1 is defined as the wavelength interval of two adjacent peaks in the interference fringes in the wedge cavity. The sawtooth cavity is composed of a superstructure wedge movable plate and a diamond thin film sawtooth fixed plate. The fixed plate surface is etched with a sawtooth groove with a depth of 500 nm and a period of 1 μm, forming a light path folding structure. The free spectral range is FSR 2 is defined as the wavelength interval of two adjacent peaks in the interference fringes in the sawtooth cavity. By adjusting the difference between the free spectral ranges of the two cavities , the superposition effect generated by the double cavity light field coupling is used to realize interference signal amplification, and the amplification multiple is .

[0057] In this embodiment, the all-fiber closed-loop architecture light field interference cycle system integrates a piezoelectric displacement table (PZT) and is arranged below the superstructure wedge movable plate. Nanoscale displacement adjustment is realized by driving the PZT with an electrical signal. The feedback control system monitors the interference spectrum shift in real time, adjusts the PZT voltage based on the PID algorithm, and maintains the system in the best sensitivity range.

[0058] Wherein, the complex amplitude matrix model is:

[0059] Wherein, , The phase difference of the wedge cavity and the sawtooth cavity is , The transmission / reflection coefficient of the wedge cavity is , The transmission / reflection coefficient of the wedge cavity corresponds to the optical characteristics of the AlN ceramic reference plate and the diamond thin film fixed plate.

[0060] The multi-parameter measurement interference device of the application also establishes a temperature decoupling equation group based on the thermal expansion difference between the AlN ceramic and the diamond thin film:

[0061] The differential calculation is performed through , is the wedge cavity length change amount, is the zigzag cavity length change amount, is the initial cavity length of the wedge cavity, is the initial cavity length of the zigzag cavity, is the thermal expansion coefficient of the AlN ceramic, is the thermal expansion coefficient of the diamond thin film, is the temperature change, is the wedge cavity length change coefficient caused by pressure, is the zigzag cavity length change coefficient caused by pressure, is the pressure, the common mode rejection ratio is 50:1, and the strain error of the double-cavity structure is only 0.2 με when the temperature fluctuation is ±5℃; the magnetic field measurement module complies with the magnetoelastic coupling equation .

[0062] The application is based on a full-fiber wedge-zigzag double-cavity collaborative multi-parameter measurement interference device, adopts a full-fiber closed-loop architecture, and the core components include a broadband light source (covering a 1500-1600 nm spectral range, including an isolator), a circulator, a fiber coupler, an F-P interference cavity, a to-be-measured parameter device table, a multimode optical fiber, a spectrum analysis unit, a photodetector 1, a photodetector 2, a feedback control system, and a real-time parameter feedback platform, and each element is connected through a low-loss fiber fusion technology. For example Figure 1As shown in the system schematic diagram, the broadband light source (with an isolator to prevent reverse light interference) emits a broadband stable light signal, which is directed into the fiber coupler through the circulator. The coupler injects the light signal into the wedge-sawtooth dual-cavity module: the reflected light of the wedge cavity and the sawtooth cavity interferes in the coupler to form a dual-cavity interference synthesis signal, which is transmitted to the photodetector 1 through the circulator, carrying the multi-parameter modulation information of the dual-cavity cooperative response; the coupler simultaneously separates the independent reflection signal of the wedge cavity (light reflected only by the wedge cavity without entering the sawtooth cavity), which is sent to the spectral analysis unit through a multimode optical fiber to analyze the single characteristics of the wedge cavity, and directly transmitted to the photodetector 2. The dual-cavity interference synthesis signal received by the photodetector 1 and the independent reflection signal of the wedge cavity received by the photodetector 2 are differentially processed by the feedback control system to realize environmental interference suppression and multi-parameter decoupling. The photodetectors 1 and 2 convert the optical signal into an electrical signal and transmit it to the feedback control system. After processing, the system sends data to the real-time parameter feedback platform for visualization, completing the whole process of "light emission-modulation-demodulation-control-display" and realizing multi-parameter measurement and feedback. The light field transmission of this architecture follows the complex amplitude matrix model in the invention content:

[0063] wherein, , and are the phase differences of the wedge cavity and the sawtooth cavity, respectively, , is the transmission / reflection coefficient of the wedge cavity, , is the transmission / reflection coefficient of the sawtooth cavity, and Figure 2 the optical properties of the AlN ceramic reference plate and the diamond thin film fixed plate in the cavity detail diagram correspond directly.

[0064] Figure 2 is the light path interference schematic diagram of the three-plate dual-cavity structure, wherein the propagation paths and effects of the six light paths are as follows: the first light path is the incident light and the surface reflected light of the first plate. The incident light emitted by the broadband light source (1500-1600 nm) is transmitted to the first plate (AlN ceramic reference reflection plate) through the optical fiber, which is divided into two parts: one is the light incident to the plate surface, and the other is the reflected light due to the evaporation of the high reflection film (reflectivity > 99%) on the surface of the plate. Among them, the incident light carries the initial light field phase, and the reflected light carries the distance between the first plate and the second plate (wedge movable plate) (the initial cavity length of the wedge cavity LThe phase information of 1) is the reference signal for the dual-cavity interference. The second path of light is the reflected light from the first plate. After the incident light enters the first plate (AlN ceramic reference reflector), it undergoes interface reflection inside the plate (due to the difference in refractive index between the material and air), forming the reflected light inside the plate. When this light propagates inside the plate, it is highly stable due to the characteristics of AlN ceramic material. It is mainly used to counteract the interference of external temperature on the reflected light from the surface of the first plate, ensuring the reliability of the initial phase reference of the wedge cavity. The third path of light is the reflected light from the surface of the second plate. The incident light (transmission component) that passes through the first plate enters the wedge cavity and reaches the surface of the second plate (metasurface wedge-shaped movable plate). Part of the light is reflected by its nanopillar array structure (reflectivity of about 15%-20%), forming the third path of light. The phase of this path of light varies with the length of the wedge cavity. L The dynamic change of 1 (such as the displacement Δ of the second plate driven by pressure) L 1) Modulation, directly carrying the response signal of pressure and stress, is the core of the "dynamic measurement term" in dual-cavity interferometry. The fourth light is the reflected light from the second plate. Of the incident light reaching the second plate, the portion not reflected by the surface enters the interior of the plate (the nanopillar array layer of the metasurface wedge-shaped movable plate), forming the fourth light. As this light propagates within the plate, due to the light field modulation effect of the nanopillar array (such as polarization selection and phase delay), the light field distribution is shaped into a wedge shape, matching the pressure response characteristics of the wedge cavity, enhancing sensitivity to minute displacements. Its propagation path length is related to the plate thickness, and its phase is affected by the plate's own deformation. The fifth light is the folded reflected light from the grooves of the third plate. After the fourth light exits from the second plate, it enters the sawtooth cavity and reaches the third plate (diamond film sawtooth fixing plate). Multiple reflections occur within the sawtooth grooves (500 nm depth, 1 μm period) on its surface, forming the fifth light. Carrying information about changes in external refractive index and temperature, it is a key signal for refractive index measurement. The sixth beam is the light from within the third plate. The portion of the fifth beam that is not reflected by the trenches enters the interior of the third plate (diamond film), forming the sixth beam. Due to the high refractive index and chemical stability of diamond, this beam experiences extremely low light loss as it propagates within the plate. It is primarily used to monitor the physical state of the third plate itself (such as temperature deformation and mechanical stress). Its phase change can serve as an "environmental compensation term" for the sawtooth cavity measurement. By calculating the difference between this beam and the fifth beam, the interference of the plate's own characteristics on the refractive index measurement is eliminated.

[0065] The wedge-shaped cavity consists of an AlN ceramic reference reflector and a metasurface wedge-shaped movable plate. The AlN ceramic reference plate is 500 μm thick and has a high-reflectivity coating (reflectivity >99%) deposited on its surface. Figure 2The cavity details are marked with layered color blocks to indicate the film structure; the metasurface movable plate adopts a nanopillar array structure, which generates tilt angle changes through piezoelectric actuation. The sawtooth cavity fixing plate adopts a 2 μm thick diamond film with sawtooth grooves etched at a depth of 500 nm and a period of 1 μm, forming an optical path folding structure (folding factor). N =8). The effective optical path length of light within the cavity follows an integral model: Due to the refractive index of diamond films n 2 = 2.4 uniform distribution, the above formula simplifies to This structure extends the optical path by eight times compared to a straight optical path, allowing the sawtooth cavity to have a free spectral range. Shrinking to a wedge-shaped cavity FSR 1 / 8 of 1 provides the basis for the superposition effect of the three-plate two-cavity optical path.

[0066] The incident light from the broadband light source is incident into the wedge cavity via an optical fiber coupler. The reflected light interferes with the reflected light from the sawtooth cavity in the optical fiber, forming a dual-cavity interference spectrum, such as... Figure 3 The independent interference spectrum curves of the two cavities show the free spectral range of the two cavities ( FSR ) are respectively FSR 1 and FSR 2. By adjusting the difference in the free spectral range between the two cavities The interference signal is amplified by utilizing the superposition effect generated by the coupling of the two-cavity optical fields, with an amplification factor of [missing value]. ,exist Figure 3 In the dual-cavity independent interference spectrum curve, the wedge cavity serrated cavity ,initial ,correspond The length of the wedge cavity is finely adjusted by the piezoelectric displacement stage. , M Increased to 50 times, such as Figure 4 The sensitivity enhancement comparison curve is shown.

[0067] Figure 6 To improve resolution, a contrast curve was used to compare the wavelength resolution of traditional and novel interferometers. Its performance corresponds to the dynamic range (…). DR Statistical model The dual-cavity structure extends the range boundary through group time delay difference, enabling... DR The phase change curve of the new interferometer is steeper when the wavelength is increased to 80 dB, indicating that it has a stronger ability to resolve small wavelength changes. This is due to the amplification effect of the superposition effect of the three-plate two-cavity optical path.

[0068] Based on the difference in thermal expansion between AlN ceramics and diamond films, a set of temperature decoupling equations is established:

[0069] Difference calculation , common mode rejection ratio 50:1, corresponding Figure 8 The strain error of the double-cavity structure in the temperature fluctuation ±5℃ is only 0.2 με. The magnetic field measurement module complies with the magneto-elastic coupling equation , in Figure 7 It is expressed as 10 μT magnetic field resolution.

[0070] The present application forms a group delay difference through the difference of the free spectral range of the double cavity, calculates the amplification gain to make the slight physical quantity change produce significant spectral shift, uses the superposition effect generated by the double cavity light field coupling to realize the amplification of the interference signal and improve the sensitivity; the double cavity structure reconstructs the dynamic range model through the group delay difference, breaks through the range limitation of the traditional single cavity, improves the coverage of the pressure measurement range; the difference of the thermal elastic coefficients of the AlN ceramic and the diamond film is used to construct a decoupling equation set to realize the temperature cross interference suppression; the machine learning analyzes the frequency domain characteristics of the double cavity interference spectrum, separates the static pressure and the dynamic acoustic vibration, realizes the synchronous separation measurement of multiple physical quantities through the magnetostrictive material integration, simultaneously uses the optical fiber fusion technology to connect the broadband light source, the circulator, the interference cavity and other components, avoids the free space optical path calibration problem, solves the cross interference, the environmental sensitivity and the range limitation problem in the multi-parameter measurement, and provides an irreplaceable solution for the precision sensing in the fields of biomedicine, aerospace and the like.

[0071] The above is the exemplary embodiment disclosed by the present application, but it should be noted that various changes and modifications can be made without departing from the scope of the embodiments disclosed by the present application defined by the claims. The functions, steps and / or acts of the method claims described herein need not be performed in any particular order. Furthermore, although the elements of the embodiments disclosed by the present application can be described or claimed in individual form, they can also be understood as plural, unless explicitly restricted as singular.

[0072] It should be understood that, as used herein, the singular forms "a", "an" and "the" are intended to include plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The embodiment number of the embodiments disclosed by the present application is only for description, and does not represent the advantages and disadvantages of the embodiments.

[0073] Those skilled in the art should understand that the above discussion of any embodiment is only exemplary, and is not intended to mean that the scope of the embodiments disclosed by the present application (including claims) is limited to these examples; under the idea of the embodiments of the present application, the above embodiments or technical features in different embodiments can also be combined, and there are many other changes of different aspects of the embodiments of the present application as above. In order to be brief, they are not provided in details. Therefore, any omission, modification, equivalent replacement, improvement, etc. made in the spirit and principle of the embodiments of the present application shall be included in the protection scope of the embodiments of the present application.

Claims

1. A multi-parameter measurement interference device based on all-fiber wedge-sawtooth dual-cavity cooperation, characterized in that, The device comprises: The wedge-shaped cavity is composed of an AlN ceramic reference reflector plate and a super-structured surface wedge-shaped movable plate, wherein the wedge-shaped movable plate is driven by a piezoelectric displacement stage to generate nanoscale tilt angle changes in response to pressure and stress changes. The sawtooth cavity is composed of a super-structured surface wedge-shaped movable plate and a diamond thin film sawtooth fixed plate, and the surface of the fixed plate is etched with sawtooth grooves to form a light path folding structure. The all-fiber closed-loop architecture connects the wedge-shaped cavity and the sawtooth cavity, and comprises a broadband light source with an isolator, a circulator, a fiber coupler, a measured parameter device table, a multimode optical fiber, a spectral analysis unit, a feedback control system, a real-time parameter feedback platform, a photodetector 1 and a photodetector 2. The light field transmission follows a complex amplitude matrix model.

2. The all-fiber wedge-saw dual-cavity synergic multi-quantity measurement interferometeric device according to claim 1, wherein, The thickness of the AlN ceramic reference reflector plate is 500 μm, and the reflectivity of the surface evaporated high reflection film is >99%.

3. The all-fiber wedge-saw dual-cavity collaborative multi-quantity measurement interferometeric device according to claim 2, wherein, The super-structured surface wedge-shaped movable plate adopts a nano-pillar array structure and generates tilt angle changes through piezoelectric driving.

4. The all-fiber wedge-saw dual-cavity synergic multi-quantity measurement interferometeric device according to claim 3, characterized in that, When external pressure applied to the wedge-shaped movable plate, the cavity length of the wedge-shaped cavity changes to satisfy the time-varying differential equation: wherein the sound pressure coupling coefficient The light field modulation efficiency of AlN ceramic to pressure is characterized. The light path folding structure of the sawtooth cavity makes the light path integral represented as: wherein N is the optical path folding factor, is the transverse refractive index gradient.

5. The all-fiber wedge-saw dual-cavity synergic multi-quantity measurement interferometeric device according to claim 1, wherein, The diamond film sawtooth fixing plate uses a 2 μm thick diamond film with sawtooth grooves etched on its surface to a depth of 500 nm and a period of 1 μm, forming an optical path folding structure with an optical path folding factor. N =8, refractive index of diamond film n 2=2.4 uniform distribution, effective optical path length of light within the cavity The free spectral range of the sawtooth cavity Shrinking to a wedge-shaped cavity 1 / 8 of.

6. The all-fiber wedge-saw dual-cavity synergic multi-quantity measurement interferometeric device according to claim 5, wherein, The broadband light source covers the spectral range of 1500-1600 nm and has a built-in isolator protection function.

7. The all-fiber wedge-saw dual-cavity synergic multi-quantity measurement interferometeric device according to claim 6, characterized in that, The broadband light source, circulator, fiber coupler, measured parameter device table, multimode optical fiber, spectral analysis unit, feedback control system, real-time parameter feedback platform, photodetector 1 and photodetector 2 of the all-fiber closed-loop architecture are connected by fiber fusion for low-loss connection. After the light path is emitted from the broadband light source, it is directed into the fiber coupler through the circulator, and the coupler injects the light signal into the wedge-sawtooth dual-cavity interference module. The reflected light is output through the coupler, one way is sent to the spectral analysis unit for fine analysis of spectral characteristics through the multimode optical fiber, and the other way is reflected to the photodetector 1 through the circulator. The photodetector 1 and the photodetector 2 convert the light signal into an electrical signal and transmit it to the feedback control system. After processing, the data is sent to the real-time parameter feedback platform for visualization.

8. The all-fiber wedge-saw dual-cavity synergic multi-quantity measurement interferometeric device according to claim 7, characterized in that, The system incident light emitted by the broadband light source is directed into the fiber coupler through the circulator, the coupler directs the light signal into the wedge cavity, the reflected light and the sawtooth cavity reflected light interfere in the optical fiber to form a double-cavity interference spectrum, wherein the wedge cavity is composed of an AlN ceramic reference reflection plate and a super-structure surface wedge movable plate, the cavity length of the wedge cavity is the distance between the two plates L 1, free spectral range FSR 1 is defined as the wavelength interval between two adjacent peaks in the interference fringes in the wedge cavity, the sawtooth cavity is composed of a super-structure surface wedge movable plate and a diamond thin film sawtooth fixed plate, the fixed plate surface is etched with sawtooth grooves with a depth of 500 nm and a period of 1 μm to form a light path folding structure, the free spectral range FSR 2 is defined as the wavelength interval between two adjacent peaks in the interference fringes in the sawtooth cavity, by adjusting the difference between the free spectral ranges of the two cavities , using the superposition effect generated by the double-cavity light field coupling, the interference signal is amplified, and the amplification factor is .

9. The all-fiber wedge-saw dual-cavity synergic multi-quantity measurement interferometeric device according to claim 8, wherein, The all-fiber closed-loop architecture's light field interference cycle system integrates a piezoelectric displacement stage and is arranged below the super-structured surface wedge-shaped movable plate. Nanoscale displacement adjustment is achieved through electrical signal driving, and the feedback control system monitors the interference spectrum shift in real time. Based on the PID algorithm, the PZT voltage is adjusted to maintain the system working in the best sensitivity range.

10. The multi-parameter measurement interference device based on the all-fiber wedge-sawtooth dual-cavity cooperation of claim 1, wherein The complex amplitude matrix model is: wherein, , are phase differences of the wedge-shaped cavity and the sawtooth cavity, respectively, , are transmission / reflection coefficients of the wedge-shaped cavity, , are transmission / reflection coefficients of the sawtooth cavity, and correspond to optical characteristics of an AlN ceramic reference plate and a diamond thin film fixing plate.

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