Photonic crystal fiber surface plasmon resonance electric field sensor based on liquid crystal filling and application of photonic crystal fiber surface plasmon resonance electric field sensor

Abstract

The invention discloses a photonic crystal fiber surface plasmon resonance electric field sensor based on liquid crystal filling and application thereof, and relates to the technical field of optical fiber sensors. The sensor comprises: a photonic crystal fiber; a substrate (1) of the photonic crystal fiber comprises a fiber core (2) arranged in the center of the substrate (1) and a wrapping layer distributed around the fiber core (2) from inside to outside. The cladding is provided with a plurality of layers of air holes (3) which are distributed in a regular hexagon shape, and the inner wall of a specific air hole (6) in the plurality of air holes is plated with a gold film (4); the specific air hole (6) is filled with liquid crystal as a liquid crystal core (5). Compared with the prior art, the multi-layer regular hexagonal air hole structure and the liquid crystal filling method are adopted, so that the regulation and control mode of a fundamental mode and an SPP mode and the design of a high-precision electric field sensor are realized. Gold plating treatment outside the liquid crystal hole can more easily excite an SPP mold, so that the limiting loss of a fundamental mode is increased, and a formant is generated. The sensor has the advantages of high precision, low loss, high sensitivity and the like when detecting the electric field intensity. The problems that during optical fiber electric field sensing, loss is large, sensitivity is low, and the sensing sensitivity is not obviously improved by filling an electric field sensitive material are solved.

Description

Technical Field

[0001] This application relates to the field of fiber optic sensor technology, and in particular to a liquid crystal-filled photonic crystal fiber surface plasmon resonance electric field sensor and its application. Background Technology

[0002] Fiber optic sensing technology is a novel sensing technology that utilizes optical fibers as sensing elements. It achieves high-precision monitoring and measurement of target objects by detecting parameter changes (such as intensity, phase, wavelength, and polarization state) caused by external environmental variations (such as temperature, pressure, electric field, and magnetic field) during the transmission of optical signals. This technology boasts advantages such as strong resistance to electromagnetic interference, high sensitivity, low transmission loss, and remote control capabilities. It has already achieved large-scale applications in industrial control, medical diagnostics, environmental monitoring, and aerospace, and shows broad application prospects in emerging fields such as new energy development and intelligent transportation.

[0003] Photonic crystal fiber (PCF), an important branch of fiber optic sensing technology, is a special type of fiber based on a photonic crystal structure. Its light-guiding mechanism can be divided into two categories: refractive index guided and photonic bandgap guided. It possesses unique optical properties such as tunable dispersion characteristics, strong nonlinear effects, cutoff-free single-mode transmission, significant birefringence, and a large effective mode area, providing key technical support for high-precision sensing.

[0004] Liquid crystal materials, as intermediate substances possessing both molecular order and fluidity, can have their refractive index controlled by external electric fields or temperature. In the field of sensing, liquid crystals have been attempted to fill the pores of photonic crystal fibers to measure temperature parameters through changes in refractive index. Surface plasmon resonance (SPR) technology utilizes the interaction between photons and free electrons at the metal-medium interface to detect physical quantities such as electric and magnetic fields through resonance condition matching, offering advantages such as real-time operation, label-free operation, and high sensitivity.

[0005] However, existing technologies still face the following pressing technical challenges. First, the improvement in electric field sensing sensitivity is limited. When filling the air holes in optical fibers with electric field-sensitive materials, traditional designs do not significantly improve the sensitivity, making it difficult to meet the requirements for high-precision electric field detection. Second, the size of the optical fiber restricts application scenarios. The large physical size of existing sensing optical fibers makes it difficult to integrate and deploy magnetic field sensors in confined spaces or complex environments. Third, insufficient sensing performance, with low overall sensing sensitivity and measurement accuracy, limits its application in fields requiring high parameter accuracy, such as precision measurement and medical diagnostics.

[0006] In summary, existing fiber optic sensing technology still faces technical bottlenecks in terms of performance optimization and application expansion, and further improvements are needed to adapt to a wider range of high-precision sensing needs. Summary of the Invention

[0007] Therefore, it is necessary to address the technical problems of large losses, low sensitivity, and insignificant improvement in sensing sensitivity when using fiber optic electric field sensing materials. This necessitates providing a liquid crystal-filled photonic crystal fiber surface plasmon resonance electric field sensor and its applications, which can adjust the electric field mode of the fiber, achieve higher sensor accuracy, lower losses, and higher sensing sensitivity.

[0008] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: In a first aspect, a surface plasmon resonance electric field sensor based on liquid crystal-filled photonic crystal fiber includes: A photonic crystal fiber; wherein, the substrate 1 of the photonic crystal fiber includes, from the inside out, a core 2 disposed at the center of the substrate 1 and a cladding distributed around the core 2; the cladding is provided with multiple air holes 3 distributed in a regular hexagonal pattern, and the inner wall of a specific air hole 6 among the multiple air holes 3 is coated with a gold film 4; the specific air hole 6 is filled with liquid crystal as a liquid crystal core 5.

[0009] Secondly, an electric field detection system includes: In order of optical path direction, it includes: a broadband light source, a polarization controller, a liquid crystal-filled photonic crystal fiber surface plasmon resonance electric field sensor, a single-mode fiber, and a receiving and analysis system; among which... The broadband light source is used to emit a light beam; The polarization controller is used to transmit polarized light after adjusting the polarization of the beam. The sensor is used to receive the polarized light and, after being modulated by the electric field to be detected, form transmitted light carrying electric field information; The single-mode optical fiber is coupled to the sensor and is used to transmit the transmitted light to the receiving and analysis system; The receiving and analysis system is used to determine the resonant wavelength based on the transmitted light, and to determine the real-time intensity of the electric field to be detected based on the resonant wavelength.

[0010] Compared with the prior art, the beneficial effects of the technical solution of the present invention are: This invention proposes a surface plasmon resonance (SPP) electric field sensor based on liquid crystal-filled photonic crystal fiber and its applications. By employing a multi-layered hexagonal air-hole structure and a liquid crystal filling method, the control of the fundamental mode and the SPP mode, as well as the design of a high-precision electric field sensor, are achieved. Gold plating outside the liquid crystal holes facilitates the excitation of the SPP mode, leading to increased confinement loss of the fundamental mode and the generation of a resonance peak. This sensor exhibits advantages such as high precision, low loss, and high sensitivity in detecting electric field intensity. It solves the problems of high loss, low sensitivity, and insignificant sensitivity improvement from filling with electric field-sensitive materials in fiber optic electric field sensing. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of the photonic crystal fiber in Embodiment 1 of this application; Figure 2 This is a schematic diagram of the electric field detection system in Embodiment 2 of this application; Figure 3 This is a schematic diagram of the simulation experiment structure of the electric field detection system in Embodiment 2 of this application; Figure 4 This is a graph showing the relationship between the effective refractive index and confinement loss of the fundamental mode and the effective refractive index of the SPP mode as a function of wavelength in Embodiment 2 of this application. Figure 5 Example 2 of this application =1.28μm and Mode field distribution diagrams of the two modes of PCF at 340V; Figure 6 This is a graph showing the relationship between confinement loss and wavelength in the simulation experiment of the electric field detection system of Embodiment 2 of this application; Figure 7 This is a graph showing the relationship between the resonant wavelength and voltage in the simulation experiment of the electric field detection system in Embodiment 2 of this application; Figure 8 Five examples are shown in Embodiment 3 of this application. Curves showing the variation of limiting loss under different liquid crystal cell diameter parameters; Figure 9 Five examples are shown in Embodiment 3 of this application. Parameter limitation loss as a function of wavelength; Figure 10 Five examples are shown in Embodiment 3 of this application. The relationship between the resonant wavelength of the parameters and voltage; Figure 11 Five examples are shown in Embodiment 3 of this application. The graph shows the relationship between the limiting loss of the parameters and the wavelength, and the relationship between the resonant wavelength and the voltage.

[0012] The labels for each figure are as follows: 1. Substrate of photonic crystal fiber; 2. Core of photonic crystal fiber; 3. Air hole; 4. Gold film; 5. Liquid crystal core; 6. Specific air hole. Detailed Implementation

[0013] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the description of embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of units is not necessarily limited to those units, but may include other units not explicitly listed or inherent to those processes, methods, products, or apparatuses. The term "determine" broadly covers a wide variety of actions, including acquiring, calculating, processing, deriving, investigating, searching (e.g., searching in a table, database, or other data structure), probing, and similar actions; it may also include receiving (e.g., receiving information), accessing (e.g., accessing data in memory), and similar actions; it may also include generating, creating, establishing, and similar actions; and parsing, selecting, choosing, and similar actions, etc. Definitions of other terms will be given in the following description.

[0014] It should be noted that when one element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediary element. Furthermore, in the following embodiments, "connection" should be understood as "electrical connection," "communication connection," etc., if there is transmission of electrical signals or data between the connected objects.

[0015] It should be emphasized that the acquisition, transmission, storage, use, and processing of data in the technical solutions of this application all comply with the relevant provisions of national laws and regulations.

[0016] In the embodiments of this application, certain software, components, models and other existing solutions in the industry may be mentioned. These should be regarded as exemplary and are only intended to illustrate the feasibility of implementing the technical solution of this application. However, they do not mean that the applicant has used or necessarily used the solution.

[0017] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this patent. To better illustrate this embodiment, some parts in the accompanying drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions; It will be understood by those skilled in the art that certain well-known structures and their descriptions may be omitted in the accompanying drawings.

[0018] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Example 1 This embodiment provides a liquid crystal-filled photonic crystal fiber surface plasmon resonance electric field sensor, as shown in Figure 1, including: A photonic crystal fiber; wherein, the substrate 1 of the photonic crystal fiber includes, from the inside out, a core 2 disposed at the center of the substrate 1 and a cladding distributed around the core 2; the cladding is provided with multiple air holes 3 arranged in a regular hexagonal pattern, and the inner wall of a specific air hole 6 among the multiple air holes 3 is coated with a gold film 4. The location of the target hole is identified using a high-resolution microscope or scanning electron microscope, and the non-target area is covered by a mask, exposing only the air hole to be gold-plated; the specific air hole 6 is filled with liquid crystal, serving as a liquid crystal core 5; liquid crystal is a substance between liquid and solid, possessing the characteristics of molecular order and fluidity; the properties of liquid crystal materials can be controlled by external electric fields, temperature, and other factors. Gold plating outside the liquid crystal holes makes it easier to excite the SPP mode, thereby increasing the confinement loss of the fundamental mode and generating a resonance peak.

[0020] In some preferred embodiments, the liquid crystal chip 5 is formed by filling the specific air hole 6 with liquid crystal through capillary action.

[0021] In some preferred embodiments, the liquid crystal is an E7 type nematic liquid crystal, and the diameter of the liquid crystal cell 5 is... The range is from 2.2 μm to 3.0 μm.

[0022] In some preferred embodiments, the diameter of the photonic crystal fiber... It is 33.6 μm.

[0023] In some preferred embodiments, the thickness of the gold film 4 is... The range is from 30nm to 50nm.

[0024] In some preferred embodiments, the diameter of the air hole 3 is... The spacing between adjacent air holes 3 in each layer, ranging from 2.4 μm to 2.8 μm, is in a clockwise direction. The spacing between adjacent air holes 3 in the partition layer is 4 μm. It is 4μm.

[0025] In some preferred embodiments, the substrate 1 of the photonic crystal fiber is made of silicon dioxide.

[0026] Example 2 This embodiment further provides an electric field detection system based on implementation 1, see reference. Figure 2 ,include: In order of optical path direction, it includes: a broadband light source, a polarization controller, a liquid crystal-filled photonic crystal fiber surface plasmon resonance electric field sensor, a single-mode fiber, and a receiving and analysis system; among which... The broadband light source is used to emit a light beam; The polarization controller is used to adjust the polarization of the beam and output polarized light. In this embodiment, the sensor focuses on the optical characteristics of the X-polarization mode, so a polarization controller is used to eliminate light in the Y-polarization direction. The sensor is used to receive the polarized light and, after being modulated by the electric field to be detected, form transmitted light carrying electric field information; The single-mode optical fiber is coupled to the sensor and is used to transmit the transmitted light to the receiving and analysis system; The receiving and analysis system is used to determine the resonant wavelength based on the transmitted light, and to determine the real-time intensity of the electric field to be detected based on the resonant wavelength.

[0027] In some preferred embodiments, the electric field detection system operates in an environment of 300V to 400V, that is, it is suitable for detecting electric field strength of 300V to 400V.

[0028] In some preferred embodiments, the receiving and analysis system includes a spectrometer and an electronic device (such as a computer); wherein the spectrometer is connected to the single-mode optical fiber and is used to obtain spectral data from the transmitted light; the electronic device is connected to the spectrometer and is used to determine the resonant wavelength based on the spectral data, and to determine the real-time intensity of the electric field to be detected based on the resonant wavelength.

[0029] This embodiment further demonstrates simulation experiments conducted on the aforementioned electric field detection system, see reference. Figure 3 In the simulation, the sensor is provided with a test electric field consisting of two conductive glass plates connected to an electric field source, serving as the sensor's operating environment. The conductive glass is ITO conductive glass; ITO is a special transparent conductive material formed by covering a glass surface with an indium oxide thin film; its main characteristics are excellent light transmittance and electrical conductivity, and it is commonly used in optoelectronic devices and antistatic coatings. The simulation experiment includes: The refractive index of the air hole 3 =1. The substrate 1 of the photonic crystal fiber is silicon dioxide, which can be represented by the Sellmeier series equation:

[0030] in, The wavelength is represented by micrometers. The constants of the dispersion equation are shown in Table 1: Table 1. Dispersion equation constants for silicon dioxide

[0031] When an electric field is applied, the molecules of the liquid crystal will rotate. The rotation angle can be expressed as:

[0032] in This is the threshold voltage. When the voltage exceeds the threshold voltage, the molecules begin to rotate. When the voltage reaches its saturation value, the rotation angle approaches 90°.

[0033] Assuming the interval between the two conductive glasses is The calculated threshold voltage is 25V.

[0034] The voltage-dependent refractive index of the liquid crystal can be expressed as:

[0035] In the formula, It is an unusual refractive index. For ordinary light refractive index, Let be the rotation angle of the liquid crystal in the electric field.

[0036] The dielectric constant of gold can be represented by the Drude-Lorentz model:

[0037] In the formula, Where is the dielectric constant of gold. Expressed as the dielectric constant at high frequencies, its value is 5.9673. For plasma frequency, , Damping frequency angular frequency It can be represented as c is the speed of light in a vacuum. =1.09, , , λ is the wavelength.

[0038] Transmission mode limitation loss is one of the most intuitive parameters of sensing performance, and its value is affected by the wavelength of light. and the imaginary part of the effective refractive index The impact is expressed as:

[0039] In the above formula, For wavelength, The imaginary part of the effective refractive index of the mode limits the loss. The unit is dB / m.

[0040] Sensing sensitivity is one of the important parameters for evaluating sensor performance, and can be expressed as:

[0041] The simulation experiment uses the full vector finite element method (FEM) and the above-mentioned sensing sensitivity formula to study the sensing characteristics of the surface plasmon resonance voltage sensor in photonic crystal fiber. Among them, Preferably, the diameter of the liquid crystal chip 5 is... It is 2.6μm.

[0042] Preferably, the diameter of the specific air hole 6 is... It is 2.6μm.

[0043] Preferably, the thickness of the gold film 4 is... It is 40nm.

[0044] Preferably, the operating environment of the electric field detection system is 340V.

[0045] Figure 4 The transmission characteristic diagram shown illustrates the dispersion curves of the X-Pol fundamental mode and the SPP mode, represented by the black and blue curves, respectively. With increasing wavelength, the effective refractive index of the X-Pol fundamental mode gradually decreases; the effective refractive index of the SPP mode also shows a decreasing trend, with the decreasing trend being more pronounced in the SPP mode. When the wavelength... When the wavelength is <1.28 μm, the effective refractive index of the SPP mode is greater than that of the fundamental mode; when the wavelength is <1.28 μm, the effective refractive index of the SPP mode is greater than that of the fundamental mode; When the wavelength is >1.28 μm, the effective refractive index of the SPP mode is less than that of the fundamental mode; when the wavelength is >1.28 μm, the effective refractive index of the SPP mode is less than that of the fundamental mode; At a refractive index of 1.28 μm, the SPP mode and the base film have the same effective refractive index. The mode field distribution diagram of the base mode is shown below. Figure 4 As shown in (2) of the figure, it can be seen that the energy in the optical fiber is concentrated at the fiber core 2, and very little energy is lost in the optical fiber structure.

[0046] See Figure 5 , Figure 5 for =1.28μm and Mode field distribution diagrams of the two modes of PCF at 340V. Figure 5 As can be clearly seen in (a) above, most of the energy is confined to the fiber core at point 2. The confinement loss variation curve of the X-Pol fundamental mode is represented by the solid red line. With increasing wavelength, the energy of the fundamental mode first increases and then decreases. The peak confinement loss of the fundamental mode is at... At approximately 1.28 μm, the fundamental mode experiences the greatest energy loss. The confinement loss of the fundamental mode reaches its maximum at the intersection of the effective refractive index change lines of the SPP mode and the fundamental mode. This indicates that the coupling between the SPP mode and the fundamental mode is at its maximum, with the SPP mode absorbing a significant amount of energy from the fundamental mode. Figure 4 Figure (1) in the diagram describes the mode field diagram of the SPP mode. It can be observed that when the SPR phenomenon occurs near the gold film 4, more energy is coupled into the liquid crystal cell 5, leading to a reduction in the energy of the fundamental mode and increasing the limiting loss of PCF transmission. (See also...) Figure 5 In (b), it can be clearly seen that the SPP mode liquid crystal cell 5 absorbs a large amount of light signal.

[0047] The performance of the PCF-SPR electric field sensor was studied and tested. (See also...) Figure 6 , Figure 6 The relationship between the limiting loss spectrum at various voltages and wavelength was depicted. When the voltage increases from 300V to 400V, the resonance peak undergoes a redshift, and the step size of the shift gradually increases. This means that the higher the detection voltage, the greater the sensitivity of the electric field sensing. (See also...) Figure 7 , Figure 7 It shows that the resonant wavelength varies with voltage. The inserted table shows the linear fitting results of the relationship between the resonant wavelength and the change in electric field intensity, which can be expressed as follows: The slope of the linearly fitted line represents the sensitivity of the electric field sensor. The fitting coefficient indicates the accuracy of the fit to the resonance peak values; the closer the fitting coefficient is to 1, the higher the fitting accuracy. The fitting expression also facilitates the rapid extraction of sensing parameter information. The preset average sensitivity of the electric field sensor is 0.93 nm / V, and it has maximum sensitivity at a voltage of 340V. =1.05nm / V.

[0048] It is understood that the options in Embodiment 1 above also apply to this embodiment, so they will not be described again here.

[0049] Example 3 For the preset structural parameters of the photonic crystal fiber electric field sensor, the simulation experiment in Example 2 has obtained specific limitation loss and sensitivity characteristics. This example further studies the influence of fiber structure parameters on sensor performance based on Example 2, explores the changes in sensor performance caused by different structures, and finally determines the optimal sensor structure to obtain the best sensing sensitivity and the lowest transmission loss.

[0050] First, the diameter of the LCD cell 5 was optimized in detail. (See attached document.) Figure 8 , Figure 8 (a) in the text are respectively The confinement loss variation curves for the liquid crystal cell 5 with diameters of 2.2μm, 2.4μm, 2.6μm, 2.8μm, and 3.0μm are shown. Observation reveals that... Changes in this will lead to changes in the limiting loss value and a shift in the resonant wavelength. The diameter of the liquid crystal chip 5... The larger the diameter, the higher the peak value of the limiting loss. Increasing the diameter of the liquid crystal cell 5 means that there is a larger area of ​​gold film 4 in contact with the liquid crystal molecules, which promotes the generation of the SPP mode and enhances the energy of the SPP mode, thereby reducing the energy of the fundamental mode and increasing the fundamental mode loss. The figure also shows that as the diameter increases... As the wavelength gradually increases, the resonance peak shifts towards longer wavelengths. Figure 8 (b) shows different The variation of the lower resonant wavelength with electric field intensity. When the liquid crystal cell diameters are 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, and 3.0 μm, the average sensitivities of the electric field sensor are 0.79 nm / V, 0.88 nm / V, 0.93 nm / V, 1.03 nm / V, and 1.12 nm / V, respectively, and the maximum sensitivities are 0.95 nm / V, 0.95 nm / V, 1.05 nm / V, 1.05 nm / V, and 1.3 nm / V, respectively. Taking all factors into consideration, the electric field sensing effect based on the SPR effect is found to be optimal when the diameter of the liquid crystal cell 5 is d1 = 3.0 μm.

[0051] See Figure 9 , Figure 9 The description refers to the 3-diameter air vent. The curves show the variation of confinement loss at 2.4μm, 2.5μm, 2.6μm, 2.7μm, and 2.8μm. With... With the increase of , the resonant wavelength did not shift, but the loss peak decreased significantly. This is because The increased aperture size results in a more compact air hole 3, reducing the gaps between them. This enhances the light-binding ability of the fundamental mode, leading to increased energy in the fiber core 2 region and reduced confinement loss. (See also...) Figure 10 , Figure 10 The different air hole diameters are described. The variation of the lower resonant wavelength with electric field intensity, when The air hole diameters are 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, and 2.8 μm, respectively. The average sensitivities of the electric field sensing are 1.18 nm / V, 1.13 nm / V, 1.12 nm / V, 1.14 nm / V, and 1.18 nm / V, respectively, and the maximum sensitivities are 1.55 nm / V, 1.4 nm / V, 1.3 nm / V, 1.35 nm / V, and 1.4 nm / V, respectively. The sensitivities at each air hole diameter are very close. This indicates that changing the air hole diameter... The effect on improving sensitivity was not significant, so a lower loss was selected. =2.8μm is the optimal structural parameter.

[0052] See Figure 11 , Figure 11 (a) shows the thickness of the gold film 4. The data represents the fundamental mode-limited loss curves at 30nm, 35nm, 40nm, 45nm, and 50nm. The loss curves also show the changes in the thickness of the gold film 4. As the wavelength increases, the limiting loss of the resonance peak gradually decreases, and the resonance peak shifts towards longer wavelengths. Figure 10 (b) in the middle shows different The variation of the lower resonant wavelength with electric field intensity At wavelengths of 30nm, 35nm, 40nm, 45nm, and 50nm, the average sensitivities of the electric field sensor are 1.11nm / V, 1.17nm / V, 1.18nm / V, 1.15nm / V, and 1.16nm / V, respectively, while the maximum sensitivities are 1.4nm / V, 1.35nm / V, 1.4nm / V, 1.35nm / V, and 1.35nm / V, respectively. It can be seen that the gold film 4... At a thickness of 40 nm, the sensor exhibits greater sensing sensitivity and lower confinement loss. Therefore, the thickness of the gold film 4 is determined. =40nm is the optimal parameter.

[0053] Referring to Table 2, which shows the sensor sensitivity data for different structural parameters of the PCF-SPR electric field sensor, it can be observed that the average sensitivity of the sensor varies depending on the structural parameters. When the fiber structure parameters are... =3.0μm, =2.4μm, =40nm and =3.0μm, =2.8μm, At a wavelength of 40 nm, both sensors achieved the maximum average sensitivity S = 1.18 nm / V. Furthermore, the fiber optic structure parameters were... =3.0μm, =2.4μm, The maximum sensitivity at 40nm is as high as 1.55nm / V. However, due to limitations in actual simulation studies... The pore size of 2.4 μm is too small, leading to increased gaps between pores and increased sensor wear; furthermore, it caused problems such as unstable spectra and significant interference during data acquisition. Therefore, [the following is missing from the original text: "to..."] =3.0μm, =2.8μm, =40nm is considered the optimal structure. The sensor achieved an optimal average sensitivity of 1.18nm / V and a maximum sensitivity of 1.4nm / V.

[0054] Table 2 Sensitivity corresponding to each structural parameter of the PCF-SPR electric field sensor

[0055] It is understood that the options in Embodiment 2 above also apply to this embodiment, so they will not be described again here.

[0056] The same or similar labels correspond to the same or similar parts; The terms used to describe positional relationships in the accompanying drawings are for illustrative purposes only and should not be construed as limiting this application. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0057] In different specific implementations, the methods or systems described in this application can be implemented in software, hardware, or a combination thereof. Furthermore, the order of the method steps can be changed, and various elements can be added, reordered, combined, omitted, or modified.

[0058] Obviously, the above embodiments of this application are merely examples for clearly illustrating this application, and are not intended to limit the implementation of this application, nor are they intended to limit this application. For those skilled in the art, other variations or modifications can be made based on the above description. The separate structural / functional modules or units can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part. The structure and function of the separate components can be implemented as a combined structure or component. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of the claims of this application.

Claims

1. A surface plasmon resonance electric field sensor based on liquid crystal-filled photonic crystal fiber, characterized in that, The optical fiber includes a photonic crystal fiber; wherein the substrate (1) of the photonic crystal fiber includes, from the inside out, a core (2) disposed at the center of the substrate (1) and a cladding distributed around the core (2); the cladding is provided with multiple air holes (3) distributed in a regular hexagonal pattern, and the inner wall of a specific air hole (6) among the multiple air holes (3) is coated with a gold film (4); the specific air hole (6) is filled with liquid crystal as a liquid crystal core (5).

2. The liquid crystal-filled photonic crystal fiber surface plasmon resonance electric field sensor according to claim 1, characterized in that, The liquid crystal core (5) is formed by filling the specific air hole (6) with liquid crystal through capillary action.

3. The liquid crystal-filled photonic crystal fiber surface plasmon resonance electric field sensor according to claim 2, characterized in that, The liquid crystal is an E7 type nematic liquid crystal, and the diameter of the liquid crystal core (5) is... The range is from 2.2 μm to 3.0 μm.

4. The liquid crystal-filled photonic crystal fiber surface plasmon resonance electric field sensor according to claim 1, characterized in that, The diameter of the photonic crystal fiber It is 33.6 μm.

5. The liquid crystal-filled photonic crystal fiber surface plasmon resonance electric field sensor according to claim 1, characterized in that, The thickness of the gold film (4) ranges from 30 nm to 50 nm.

6. The liquid crystal-filled photonic crystal fiber surface plasmon resonance electric field sensor according to claim 1, characterized in that, The diameter of the air hole (3) The spacing between the air pores (3) in each layer, ranging from 2.4 μm to 2.8 μm, is in a clockwise direction. The spacing between adjacent air pores (3) in the partition layer is 4 μm. It is 4μm.

7. A surface plasmon resonance electric field sensor based on liquid crystal-filled photonic crystal fiber according to claim 1, characterized in that, The substrate (1) of the photonic crystal fiber is made of silicon dioxide.

8. An electric field detection system, characterized in that, The components, arranged sequentially according to the optical path direction, include: a broadband light source, a polarization controller, a sensor as described in any one of claims 1-7, a single-mode optical fiber, and a receiving and analysis system; wherein... The broadband light source is used to emit a light beam; The polarization controller is used to adjust the polarization of the beam and output polarized light; The sensor is used to receive the polarized light and, after being modulated by the electric field to be detected, form transmitted light carrying electric field information; The single-mode optical fiber is coupled to the sensor and is used to transmit the transmitted light to the receiving and analysis system; The receiving and analysis system is used to determine the resonant wavelength based on the transmitted light, and to determine the real-time intensity of the electric field to be detected based on the resonant wavelength.

9. An electric field detection system according to claim 8, characterized in that, The electric field detection system operates in an environment of 300V to 400V.

10. An electric field detection system according to any one of claims 8 to 9, characterized in that, The receiving and analysis system includes a spectrometer and electronic equipment; The spectrometer is connected to the single-mode optical fiber and is used to obtain spectral data from the transmitted light. The electronic device is connected to the spectrometer and is used to determine the resonance wavelength based on the spectral data, and to determine the real-time intensity of the electric field to be detected based on the resonance wavelength.

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