Electro-optic crystal electric field sensing device and method based on dual-wavelength differential measurement

Abstract

The application discloses an electro-optic crystal electric field sensing device and method based on dual-wavelength differential measurement, relates to the technical field of sensing, and utilizes the port isolation characteristic of a polarization maintaining ring to make incident light emitted by a light source enter from a first port, is output to an electro-optic crystal through a second port, and is returned along an original light path after being reflected by a reflecting sheet, passes through the electro-optic crystal, a collimating lens and the polarization maintaining ring again, and is guided to a third port to be output to a spectrometer, so that bidirectional transmission of the input and output of the light signal in the same optical fiber is realized; the complexity of the electric field sensing system is reduced, so that the cost is reduced; and the single-fiber bidirectional transmission reflection structure realized by the polarization maintaining ring integrates the originally separated input / output light paths into a common path, cancels the polarization state drift caused by environmental disturbance, and thus the measurement accuracy is improved. Therefore, the cost is reduced while the measurement accuracy of the electric field sensing device is ensured.

Description

Technical Field

[0001] This application relates to the field of sensing technology, and in particular to an electro-optic crystal electric field sensing device and method based on dual-wavelength differential measurement. Background Technology

[0002] In a typical transmission-type electro-optic field sensor, the transmission optical path structure has a drawback: the optical path is unidirectional, and the light source and the detection system must be arranged on opposite sides of the electro-optic crystal.

[0003] Because of the optical path separation, the optical fiber connection between the light source end and the detection end needs to be laid separately. That is, independent input optical fiber and output optical fiber need to be configured, which increases the number of polarization-maintaining optical fibers used and the difficulty of axial alignment. This further exacerbates the complexity of the electric field sensor, resulting in higher costs. Moreover, long-distance separated optical fiber links are susceptible to environmental temperature changes, mechanical vibrations and other factors, which can cause polarization drift, generate measurement errors and result in low measurement accuracy.

[0004] Therefore, it is impossible to reduce costs while ensuring the measurement accuracy of electric field sensing devices in related technologies. Summary of the Invention

[0005] The main objective of this application is to provide an electro-optic crystal electric field sensing device and method based on dual-wavelength differential measurement, aiming to solve the technical problem of reducing costs while ensuring the measurement accuracy of the electric field sensing device.

[0006] To achieve the above objectives, this application proposes an electro-optic crystal electric field sensing device based on dual-wavelength differential measurement. The electric field sensing device includes a light source, an electro-optic crystal, a polarization-maintaining circulator, a collimating lens, a polarizer, an 1 / 8 wave plate, and a reflector. One port of the polarization-maintaining circulator is optically connected to one end of the light source, the second port is optically connected to one end of the electro-optic crystal, and the third port is optically connected to one end of the spectrometer.

[0007] The light source is used to generate incident light;

[0008] The optical path of the incident light includes: the incident light enters the polarization-maintaining circulator through the first port, exits from the second port and enters the collimating lens, passes through the polarizer and the electro-optic crystal, the polarizer is used to convert the incident light into linearly polarized light, the linear electro-optic effect of the electro-optic crystal causes the applied electric field to be measured to be loaded into the optical path in the form of a phase difference, and converts the linearly polarized light into elliptically polarized light, the elliptically polarized light enters the 1 / 8 wave plate and generates a fixed phase difference through the 1 / 8 wave plate, after being reflected by the reflector, it passes through the 1 / 8 wave plate, the electro-optic crystal and the polarizer again, the polarizer converts the elliptically polarized light into linear light, the linear light enters the collimating lens and exits from the third port into the spectrometer.

[0009] To achieve the above objectives, this application also proposes an electro-optic crystal electric field sensing method based on dual-wavelength differential measurement, applied to the electric field sensing device described above. The electro-optic crystal electric field sensing method based on dual-wavelength differential measurement includes:

[0010] After the incident light generated by the light source enters the electro-optic crystal placed in the electric field to be measured, the first spectrum is obtained by a spectrometer.

[0011] Based on the first spectrum, the target wavelength is determined, wherein the target wavelength is one of two wavelengths corresponding to opposite trends in the transmittance response to light wavelength;

[0012] The first differential signal is calculated based on the transmittance corresponding to the target wavelength;

[0013] The target electric field strength of the electric field to be measured is calculated based on the first differential signal.

[0014] One or more technical solutions proposed in this application have at least the following technical effects:

[0015] This application utilizes the port isolation characteristics of a polarization-maintaining circulator to allow incident light emitted from the light source to enter through the first port, exit through the second port to the electro-optic crystal, and then be reflected by a reflector and return along the original optical path. The light then passes through the electro-optic crystal, polarizer, collimating lens, and polarization-maintaining circulator again, and is guided to the third port for output to the spectrometer. This achieves bidirectional transmission of the optical signal within the same optical fiber, enabling the light source and detection system to be connected to the electro-optic crystal via the same polarization-maintaining fiber. This avoids the need for separate input and output fibers on both sides of the crystal, as required in traditional structures, significantly reducing the number of polarization-maintaining fibers used and lowering material costs and system complexity. Furthermore, the single-fiber bidirectional transmission and reflection structure achieved through the polarization-maintaining circulator integrates the originally separate input / output optical paths into a common path. Utilizing the common-mode suppression effect of the round-trip optical path, it effectively counteracts polarization drift caused by environmental disturbances, thereby significantly improving measurement accuracy.

[0016] Furthermore, the transmissive structure requires precise alignment between the two distal fiber end faces, resulting in a longer free-space optical path and a unidirectional asymmetrical layout, leading to poor stability. In contrast, the reflective structure adopted in this application has a simple optical path, with optical components concentrated at one end of the probe, reducing disturbance-sensitive links in the free-space propagation path. Therefore, it has stronger resistance to environmental interference such as temperature changes and mechanical vibrations. It is particularly suitable for electric field measurement in complex electromagnetic environments such as high-voltage DC and strong electromagnetic pulses. Only a single optical fiber is needed to achieve long-distance connection between the sensing probe and the back-end equipment. The probe end does not require power supply, achieving complete passivity and effectively isolating the impact of high voltage or strong electromagnetic interference on precision instruments such as light sources and detectors. At the same time, it significantly reduces the complexity and material cost of on-site fiber optic cabling, improves safety, and ensures the safety of equipment and personnel.

[0017] Therefore, this application can reduce costs while ensuring the measurement accuracy of the electric field sensing device. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the electric field sensing device provided in Embodiment 1 of the electro-optic crystal electric field sensing method based on dual-wavelength differential measurement of this application;

[0021] Figure 2 This is a flowchart illustrating an embodiment of the electro-optic crystal electric field sensing method based on dual-wavelength differential measurement provided in this application.

[0022] Figure 3 This is a schematic diagram of the first scenario provided in Embodiment 1 of the electro-optic crystal electric field sensing method based on dual-wavelength differential measurement of this application;

[0023] Figure 4 This is a schematic diagram of the second scenario provided in Embodiment 1 of the electro-optic crystal electric field sensing method based on dual-wavelength differential measurement of this application;

[0024] Figure 5 This is a schematic diagram of the third scenario provided in Embodiment 2 of the electro-optic crystal electric field sensing method based on dual-wavelength differential measurement of this application.

[0025] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0026] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0027] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0028] This application provides an embodiment of an electro-optic crystal electric field sensing device based on dual-wavelength differential measurement, referring to... Figure 1 The electric field sensing device includes a light source, an electro-optic crystal, a polarization-maintaining circulator, a collimating lens, a polarizer, an 1 / 8 wave plate, and a reflector. One port of the polarization-maintaining circulator is optically connected to one end of the light source, the second port is optically connected to one end of the electro-optic crystal, and the third port is optically connected to one end of the spectrometer.

[0029] The light source is used to generate incident light. The optical path of the incident light includes: the incident light enters the polarization-maintaining circulator through one port, exits from the second port into the collimating lens, passes through the polarizer and the electro-optic crystal, the polarizer converts the incident light into linearly polarized light, the linear electro-optic effect of the electro-optic crystal loads the applied electric field to be measured into the optical path in the form of a phase difference, and converts the linearly polarized light into elliptically polarized light, the elliptically polarized light enters the 1 / 8 wave plate, generates a fixed phase difference through the 1 / 8 wave plate, is reflected by the reflector, and then passes through the 1 / 8 wave plate, the electro-optic crystal and the polarizer again, the polarizer converts the elliptically polarized light into linear light, the linear light enters the collimating lens and exits from the third port into the spectrometer.

[0030] In the actual measurement process, the incident light enters the polarization-maintaining circulator through port 1 and exits through port 2 into the polarization-maintaining collimating lens, making the incident light converge into parallel light. The polarizer converts the incident light into linearly polarized light. Then, through the electro-optic crystal, the electric field to be measured is applied and loaded into the optical path in the form of a phase difference via the linear electro-optic effect of the crystal, turning the linearly polarized light into elliptically polarized light. A fixed 45° phase difference is generated by passing through an 8 / 10 waveplate (with a 45° angle between the fast axis and the transmission axis of the polarizer). After being reflected back by the reflector, the light passes through the 8 / 10 waveplate again (again generating a fixed 45° phase difference), the electro-optic crystal (the electric field information is loaded into the optical path again), the polarizer (converting the elliptically polarized light into linear light), and the collimating lens before exiting from the three ports of the polarization-maintaining circulator. The spectrometer acquires the first spectrum in real time; that is, the spectrometer records the light intensity distribution of the entire spectrum.

[0031] It is understood that this application employs a reflective electric field sensor, utilizing the port isolation characteristics of a polarization-maintaining circulator. Incident light emitted from the light source enters through the first port, exits through the second port to the electro-optic crystal, and the modulated optical signal is reflected by a reflector and returns along the original optical path. It then passes through the electro-optic crystal, collimating lens, and polarization-maintaining circulator again, and is guided to the third port for output to the spectrometer. This achieves bidirectional transmission of the optical signal within the same optical fiber, enabling the light source and detection system to be connected to the electro-optic crystal via the same polarization-maintaining fiber. This avoids the need for separate input and output fibers on both sides of the crystal, as required in traditional structures, significantly reducing the number of polarization-maintaining fibers used and lowering material costs and system complexity.

[0032] In one feasible implementation, the incident light generated by the light source is broadband light.

[0033] Specifically, light sources used to generate broadband light can be ASE (amplified spontaneous emission) sources, supercontinuum lasers, etc. ASE sources can generate light with broadband characteristics (typical wavelength range of 1528-1561 nm).

[0034] Using broadband light as incident light eliminates the need for multiple lasers: a single broadband light source can cover a wide wavelength range, facilitating wavelength selection during electric field measurement.

[0035] In one feasible implementation, the electro-optic crystal comprises a z-cut lithium niobate crystal.

[0036] It should be noted that, since lithium niobate crystals have the largest electro-optic coefficient along the z-axis, when a z-cut lithium niobate crystal is placed in the electric field to be measured, and the direction of the electric field is consistent with the z-axis direction of the crystal, the electric field will be applied to the lithium niobate crystal along the z-axis, thereby maximizing the utilization of the crystal's r6. 3 The electro-optic coefficient makes the influence of the electric field on the light wave most significant. By making full use of the electro-optic properties of lithium niobate crystal materials, the measurement accuracy of the electric field strength under test can be improved.

[0037] Therefore, in the actual measurement process, the lithium niobate crystal can be placed in the electric field to be measured, and the direction of the electric field to be measured should be consistent with the z-axis direction of the lithium niobate crystal.

[0038] It should be noted that the electro-optic crystal can also be a barium borate crystal. In this embodiment, the preferred electro-optic crystal is a z-cut lithium niobate crystal with a size of 10mm×10mm×12mm. At this size, it can provide a sufficiently long optical path, enhance electro-optic interaction, improve sensitivity, and at the same time ensure sufficient light beam transmission area for easy collimation and coupling.

[0039] In this embodiment, through the collaborative design of the reflective optical path and the polarization-maintaining circulator, while ensuring high sensitivity, the electric field sensing device achieves comprehensive optimization in terms of structural simplification, cost reduction, stability improvement and engineering applicability. It is especially suitable for high-reliability electric field monitoring applications in harsh environments such as high voltage and strong electromagnetic interference, and has outstanding practical value and promotion prospects.

[0040] Based on this, this application provides an electro-optic crystal electric field sensing method based on dual-wavelength differential measurement, applied to the aforementioned electro-optic crystal electric field sensing device based on dual-wavelength differential measurement, with reference to... Figure 2 , Figure 2 This is a flowchart illustrating the first embodiment of the electro-optic crystal electric field sensing method based on dual-wavelength differential measurement according to this application.

[0041] In this embodiment, the electro-optic crystal electric field sensing method based on dual-wavelength differential measurement includes steps S10~S40:

[0042] Step S10: After the incident light generated by the light source enters the electro-optic crystal placed in the electric field to be measured, the first spectrum is obtained by a spectrometer.

[0043] It should be noted that electro-optic sensing technology utilizes the characteristic that the refractive index of an electro-optic crystal changes under the influence of an applied electric field. By detecting changes in the phase, polarization, or intensity of light waves after passing through the crystal, it achieves non-contact, electromagnetic interference-resistant measurement of the applied electric field. However, in actual measurement processes, systematic noises such as fluctuations in light source intensity, detector noise, and optical path loss are coupled with the measured electric field signal in the same light intensity change, leading to inaccurate measured electric field strength.

[0044] To address the aforementioned issues, the electric field sensing device further includes a signal processing unit, which is used to execute an electro-optic crystal electric field sensing method based on dual-wavelength differential measurement.

[0045] Understandably, in the actual measurement process, the electro-optic crystal can be placed in the electric field to be measured. After the incident light generated by the light source enters the electro-optic crystal, the electric field to be measured changes the birefringence of the electro-optic crystal, resulting in a phase difference related to the electric field between the two orthogonal polarization components passing through the electro-optic crystal. The transmittance can be calculated based on the phase difference. The target spectrum is used to describe the distribution of the transmittance of the electro-optic crystal to light at different wavelengths.

[0046] The electric field to be measured changes the birefringence of the electro-optic crystal, resulting in a phase difference between the two orthogonal polarization components passing through the electro-optic crystal that is related to the electric field. The transmittance can be calculated based on the phase difference. The first spectrum is used to describe the distribution of the transmittance of the electro-optic crystal to light at different wavelengths.

[0047] When the electro-optic crystal is a z-cut lithium niobate crystal, the transmittance can be calculated as follows:

[0048]

[0049] Where E is the electric field to be measured, and λ is the wavelength. It is the refractive index of the o-ray. It is the length of the electro-optic crystal. It is a constant.

[0050] Step S20: Based on the first spectrum, determine the target wavelength, wherein the target wavelength is one of two wavelengths corresponding to opposite trends in the transmittance response to light wavelength;

[0051] In this embodiment, the opposite trend in the transmittance response to light wavelength means that the transmittance changes in opposite directions with wavelength. For example, in a certain wavelength range, transmittance increases with increasing wavelength (positive slope), while in another wavelength range, transmittance decreases with increasing wavelength (negative slope). (Refer to...) Figure 3 The blue and red curves represent the two wavelengths corresponding to opposite trends in the transmittance response to light wavelength.

[0052] Specifically, a large number of spectra under different electric fields can be collected and used to train a model (classification model or regression model) to automatically identify the optimal wavelength pair that satisfies the condition that "the response trend of transmittance to light wavelength is opposite"; in actual measurement, the target wavelength can be directly output based on the first spectrum through the trained model.

[0053] Step S30: Calculate the first differential signal based on the transmittance corresponding to the target wavelength;

[0054] Specifically, the transmittance corresponding to the target wavelength is the transmittance of light passing through the electro-optic crystal at the target wavelength. The target wavelength may contain noise interference caused by unstable factors such as light source jitter, detector gain drift, and optical path loss.

[0055] Since light source jitter, detector gain drift, and optical path loss can affect the transmittance of two wavelengths in the same direction (both increase or both decrease), by performing differential calculations on the transmittance corresponding to the target wavelength, these common system noise components will cancel each other out, while the opposite changes caused by the electric field will be retained or even amplified, thereby achieving high-precision and interference-resistant measurements.

[0056] Specifically, the first differential signal can be calculated based on the transmittance corresponding to the target wavelength using a first calculation formula. The first calculation formula can be:

[0057]

[0058] in, and These represent the transmittance corresponding to the target wavelength.

[0059] It is understandable that after differential processing of the transmittance corresponding to the target wavelength, Independent of noise signals, refer to Figure 4 That is, the system noise δ is eliminated in the differential operation, and the differential signal... Because the two valid signals have opposite positive and negative values, they are inversely enhanced. Specifically, this can be expressed as:

[0060] ΔT noise =[T( )+δ]-[T( )+δ]=ΔT;

[0061] Where δ represents the system noise caused by light source jitter, detector gain drift, optical path loss, etc.

[0062] Step S40: Calculate the target electric field strength of the electric field to be measured based on the first differential signal.

[0063] Specifically, the target electric field intensity that maps to the first differential signal can be found using a lookup table method.

[0064] Since the system noise δ is eliminated in the differential operation, and the differential signal... Because the two effective signals have opposite positive and negative values, they are enhanced in the opposite direction, and the target electric field strength calculated based on the first differential signal is also more accurate.

[0065] In this embodiment, the difference in the transmittance response characteristics of an electro-optic crystal to an electric field within a specific wavelength range is utilized. Based on the first spectrum, two wavelengths with opposite transmittance response trends to light wavelength are determined as target wavelengths. Differential measurement is performed on two wavelengths with opposite transmittance response trends to the electric field, so that system noise such as light source intensity fluctuations, detector noise, and optical path loss are mutually canceled in the differential signal, and the measured signal-to-noise ratio reaches more than 40 dB. Based on the first differential signal, the target electric field strength of the electric field to be measured is calculated, thereby improving the accuracy of the measured electric field strength.

[0066] Meanwhile, when the light source is a broadband source, it provides a flexible dual-wavelength selection space. Furthermore, the method of selecting dual wavelengths from a single optical path reduces assembly and adjustment complexity, making it more suitable for industrial use and reducing measurement costs.

[0067] Based on the first embodiment of this application, in the second embodiment of this application, the content that is the same as or similar to that in Embodiment 1 above can be referred to the above description and will not be repeated hereafter. Furthermore, the implementation method for determining the target wavelength based on the first spectrum can also be:

[0068] Based on the first spectrum, determine the rate of change of transmittance with wavelength; take the wavelength corresponding to zero rate of change as the characteristic wavelength; and determine the target wavelength based on the characteristic wavelength.

[0069] Specifically, based on the first spectrum, the rate of change of transmittance with wavelength is determined, that is, the first derivative of the spectrum is calculated, which represents how quickly (slope) the transmittance T changes with wavelength λ. Figure 5 The horizontal axis represents wavelength λ, the vertical axis represents relative transmittance T, and the curve corresponds to the current electric field to be measured.

[0070] The rate of change of transmittance with wavelength can be expressed as dT / dλ. Positive slope: dT / dλ>0, transmittance increases with increasing wavelength; negative slope: dT / dλ<0, transmittance decreases with increasing wavelength; zero slope: dT / dλ=0, extreme point (peak or trough).

[0071] Since a rate of change of zero corresponds to an extreme point (maximum or minimum) in the transmittance curve, wavelengths on either side of a peak or trough exhibit opposite response trends. Therefore, referring to... Figure 5 In this embodiment, the wavelength corresponding to zero rate of change is taken as the characteristic wavelength. Based on the characteristic wavelength, the target wavelength is determined, thereby quickly and accurately selecting the target wavelength whose transmittance response to light wavelength has an opposite trend, which meets the requirements of dual-wavelength differential measurement.

[0072] Specifically, the implementation of determining the target wavelength based on the characteristic wavelength can be as follows: based on the location of the characteristic wavelength, select a first wavelength in a region with a rate of change greater than zero, and select a second wavelength in a region with a rate of change less than zero; use the first wavelength and the second wavelength as the target wavelength.

[0073] It can be understood that when the characteristic wavelength is determined to be the wavelength corresponding to zero rate of change, the location of the characteristic wavelength can be determined. The location of the characteristic wavelength refers to its position in the target projection spectrum. Therefore, based on the location of the characteristic wavelength, a wavelength can be selected on its left and right sides as the target wavelength. That is, based on the location of the characteristic wavelength, a wavelength is randomly selected in the region with a rate of change greater than zero as the first wavelength, and a wavelength is randomly selected in the region with a rate of change less than zero as the second wavelength. The first wavelength and the second wavelength are then used as the target wavelengths.

[0074] In another feasible implementation, the wavelength points with the largest absolute value of the rate of change of transmittance can be found on both sides of the characteristic wavelength, and these wavelengths can be used as target wavelengths; that is, selecting the wavelength that is most sensitive to changes in transmittance can significantly improve the sensitivity of the detection system, enabling the system to capture subtle changes more accurately.

[0075] In this embodiment, by determining the point in the first spectrum where the transmittance changes with wavelength at a rate of zero as the characteristic wavelength, and determining the target wavelength based on this characteristic wavelength, the efficiency of determining the target wavelength can be improved to a certain extent. At the same time, by finding the wavelength points with the largest absolute value of the transmittance change rate on both sides of the characteristic wavelength and using them as the target wavelength, the sensitivity of the detection system can be significantly improved, enabling the system to capture subtle changes more accurately.

[0076] Based on the first embodiment of this application, in the second embodiment of this application, the content that is the same as or similar to that in the first embodiment described above can be referred to the above description and will not be repeated hereafter. Furthermore, the implementation method for calculating the target electric field strength of the electric field to be measured based on the first differential signal can also be:

[0077] The target electric field strength of the electric field to be measured is calculated based on the first differential signal and the preset correlation between the differential signal and the electric field strength.

[0078] It should be noted that the preset correlation between the differential signal and the electric field strength can be determined in advance through calibration. This preset correlation between the differential signal and the electric field strength can be expressed as follows:

[0079]

[0080] Correspondingly, the second calculation formula is obtained: E=( TB) / K;

[0081] Where K is the scaling factor and B is the offset.

[0082] It can be understood that by substituting the first differential signal into the second calculation formula mentioned above, the target electric field strength of the electric field to be measured can be calculated.

[0083] Specifically, before the step of acquiring the first spectrum using a spectrometer, the calibration process may include:

[0084] After the incident light generated by the light source enters the electro-optic crystal placed in the reference electric field, a second spectrum is obtained by a spectrometer; based on the second spectrum, two reference wavelengths with opposite trends in the response of transmittance to light wavelength are determined; based on the transmittance corresponding to the two reference wavelengths, a second differential signal is calculated; based on the second differential signal and the preset electric field strength of the reference electric field, the correlation between the differential signal and the electric field strength is determined.

[0085] Specifically, this can be achieved by applying a reference electric field. After the incident light generated by the light source enters the electro-optic crystal placed in the reference electric field, the second spectrum is obtained by a spectrometer. Based on the second spectrum, the differential transmittance value dT / dλ of each wavelength is calculated, and the wavelength corresponding to dT / dλ being zero is selected as the historical characteristic wavelength. Based on the historical characteristic wavelength, two reference wavelengths with opposite trends in transmittance response to light wavelength are determined (the specific selection method is referred to the above actual measurement process).

[0086] Reference Figure 5 By applying a reference electric field Wavelength calibration was performed using a 1000 kV / m scanning spectrum. The wavelength corresponding to zero dT / dλ was selected as the historical characteristic wavelength, which is 1541.76 nm. In the positive slope linear region of lithium niobate crystals, the transmitted light intensity increases with increasing incident light wavelength; conversely, in the negative slope linear region, the transmitted light intensity decreases with increasing incident light wavelength. Therefore, the wavelength located at the rising edge of the transmittance-wavelength curve (dT / dλ>0 region) can be used as the first reference wavelength, and the wavelength located at the falling edge (dT / dλ<0 region) can be used as the second reference wavelength. The first reference wavelength is located in the positive slope region (…). >0), first reference wavelength = 1530 nm; second reference wavelength is located in the negative slope region ( <0), second reference wavelength = 1560 nm.

[0087] Furthermore, based on the transmittance corresponding to the two reference wavelengths, the second differential signal is calculated; and the electric field strength of the reference electric field is output according to the pre-calibrated linear relationship E = (ΔT - B) / K.

[0088] Calibration curve establishment method: Measurements are performed in the range of 0-2000 kV / m with a step size of 5 kV / m. The differential processing unit calculates ΔT in real time, and the proportional coefficient K and offset B are obtained by fitting using the least squares method. The calibration curve E=(ΔT-B) / K can then be obtained, that is, the correlation between the differential signal and the electric field intensity is calibrated.

[0089] In this embodiment, the correlation between the differential signal and the electric field strength is established through calibration, which standardizes the measurement process, unifies the system response characteristics, ensures the accuracy of measurement results under different times and environments, simplifies the measurement process, and improves measurement efficiency.

[0090] It should be noted that the above examples are only for understanding this application and do not constitute a limitation on the electro-optic crystal electric field sensing method based on dual-wavelength differential measurement of this application. Any simple modifications based on this technical concept are within the protection scope of this application.

[0091] The above descriptions are merely some embodiments of this application and do not limit the scope of protection of this application. Any equivalent structural transformations made based on the technical concept of this application and the content of this specification and drawings, or direct / indirect applications in other related technical fields, are included within the scope of protection of this application. All actions involving the acquisition of signals, information, or data in this application are performed in accordance with the relevant data protection laws and policies of the country where the application is located and with authorization from the owner of the corresponding device.

Claims

1. An electro-optic crystal electric field sensing device based on dual-wavelength differential measurement, the electric field sensing device comprising a light source, an electro-optic crystal, a polarization-maintaining circulator, a collimating lens, a polarizer, an 1 / 8 wave plate, a reflector, and a signal processing unit, wherein one port of the polarization-maintaining circulator is optically connected to one end of the light source, the second port is optically connected to one end of the electro-optic crystal, and the third port is optically connected to one end of the spectrometer; The light source is used to generate incident light with a broad spectrum; The incident light optical path includes: the incident light enters the polarization-maintaining circulator through the first port, exits from the second port and enters the collimating lens, passes through the polarizer and the electro-optic crystal, the polarizer is used to convert the incident light into linearly polarized light, the linear electro-optic effect of the electro-optic crystal causes the applied electric field to be measured to be loaded into the optical path in the form of a phase difference, and converts the linearly polarized light into elliptically polarized light, the elliptically polarized light enters the 1 / 8 wave plate and generates a fixed phase difference through the 1 / 8 wave plate, after being reflected by the reflector, it passes through the 1 / 8 wave plate, the electro-optic crystal and the polarizer again, the polarizer converts the elliptically polarized light into linear light, the linear light enters the collimating lens and exits from the third port into the spectrometer; The signal processing unit is configured to: acquire a first spectrum using a spectrometer after incident light generated by a light source enters an electro-optic crystal placed in the electric field to be measured; determine the rate of change of transmittance with wavelength based on the first spectrum; take the wavelength corresponding to zero rate of change as a characteristic wavelength; determine a target wavelength based on the characteristic wavelength, wherein the target wavelength is one of two wavelengths corresponding to opposite trends in the transmittance response to light wavelength; calculate a first differential signal based on the transmittance corresponding to the target wavelength; and calculate the target electric field strength of the electric field to be measured based on the first differential signal, wherein noise interference in the target wavelength is eliminated in the differential operation.

2. The electro-optic crystal electric field sensing device based on dual-wavelength differential measurement as described in claim 1, characterized in that, The electro-optic crystal includes a z-cut lithium niobate crystal.

3. A method for sensing electric field using an electro-optic crystal based on dual-wavelength differential measurement, characterized in that, Applied to the electric field sensing device as described in any one of claims 1 to 2, the electro-optic crystal electric field sensing method based on dual-wavelength differential measurement includes: After the incident light generated by the light source enters the electro-optic crystal placed in the electric field to be measured, the first spectrum is obtained by a spectrometer. Based on the first spectrum, determine the rate of change of transmittance with wavelength; The wavelength corresponding to zero rate of change is taken as the characteristic wavelength; Based on the characteristic wavelength, the target wavelength is determined, wherein the target wavelength is one of two wavelengths corresponding to opposite trends in the transmittance response to light wavelength; The first differential signal is calculated based on the transmittance corresponding to the target wavelength, wherein noise interference in the target wavelength is eliminated in the differential operation; The target electric field strength of the electric field to be measured is calculated based on the first differential signal.

4. The electro-optic crystal electric field sensing method based on dual-wavelength differential measurement as described in claim 3, characterized in that, The step of determining the target wavelength based on the characteristic wavelength includes: Based on the location of the characteristic wavelength, a first wavelength is selected in the region where the rate of change is greater than zero, and a second wavelength is selected in the region where the rate of change is less than zero. The first wavelength and the second wavelength are used as target wavelengths.

5. The electro-optic crystal electric field sensing method based on dual-wavelength differential measurement as described in claim 3, characterized in that, The step of calculating the target electric field strength of the electric field to be measured based on the first differential signal includes: The target electric field strength of the electric field to be measured is calculated based on the first differential signal and the preset correlation between the differential signal and the electric field strength.

6. The electro-optic crystal electric field sensing method based on dual-wavelength differential measurement as described in claim 5, characterized in that, Before the step of acquiring the first spectrum using a spectrometer, the method further includes: After the incident light generated by the light source enters the electro-optic crystal placed in the reference electric field, the second spectrum is obtained by a spectrometer. Based on the second spectrum, determine the two reference wavelengths corresponding to the opposite trends in the transmittance response to light wavelength; The second differential signal is calculated based on the transmittance corresponding to the two reference wavelengths. The correlation between the differential signal and the electric field strength is determined based on the second differential signal and the preset electric field strength of the reference electric field.

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