Reflection-type high-sensitivity electric field sensor

Abstract

The invention relates to the technical field of optical electric field sensors, in particular to a reflective high-sensitivity electric field sensor which comprises a packaging shell, an input polarization-maintaining optical fiber collimator, a polarizer, a 1 / 4 wave plate, a first lithium niobate crystal, a reflector and an output single-mode optical fiber collimator. A polarizer, a 1 / 4 wave plate, a first lithium niobate crystal and a reflector are arranged at one end of the input polarization-maintaining optical fiber collimator; a second lithium niobate crystal, an analyzer and an output single-mode optical fiber collimator are further arranged in the input end packaging cavity, and the output single-mode optical fiber collimator is arranged in the output end packaging cavity; the main shafts of the first lithium niobate crystal and the second lithium niobate crystal are orthogonal to each other; the vibration transmission directions of the polarizer and the polarization analyzer are perpendicular to each other; according to the invention, the lithium niobate crystal with x-axis light transmission and z-direction electric field application is adopted, and the maximum electro-optic coefficient gamma 33 is utilized, so that the sensitivity is improved.

Description

Technical Field

[0001] The invention relates to the technical field of optical electric field sensors, and in particular to a reflective high-sensitivity electric field sensor. Background Art

[0002] With the rapid development and implementation of new power systems, advanced electric field measurement and sensing technology is of great significance for the realization of intelligent and safe and stable operation of power grids. With the increase of voltage level and capacity of power systems, the measurement and protection requirements are constantly improving, and the shortcomings of traditional electrical electric field sensors are becoming increasingly prominent, mainly manifested as follows: 1. Poor anti-electromagnetic interference ability. Traditional electrical electric field sensors contain a large number of electronic components and are easily affected by electromagnetic interference in complex electromagnetic environments; 2. Difficult insulation, especially above 500kV, due to insulation, the volume, weight and price of the transformer are disproportionately increased; 3. The magnetic saturation, narrow frequency band and slow response speed inherent in the core structure of the transformer. In comparison, optical electric field sensors have the advantages of wide frequency band, large dynamic range, fast response speed, no need for external power supply, and adaptability to large field strength measurement. Optical electric field sensors can directly measure the time domain waveform of the external electric field, providing a better solution for voltage monitoring.

[0003] At present, the measurement of external electric field through the electro-optic effect of optical waveguide or electro-optic crystal has become one of the important ways to measure external electric field. Optical waveguide electric field sensor has the advantages of small size and high sensitivity, but its manufacturing process is relatively complicated. In comparison, block electro-optic crystal type electric field sensor is easy to make and has a full dielectric structure, which is suitable for strong electric field measurement.

[0004] At present, the research on lithium niobate bulk crystal electric field sensors mainly focuses on how to improve the sensitivity of the sensor and realize multi-dimensional electric field measurement. In order to avoid the influence of the natural birefringence of the crystal and improve the temperature stability of the sensor, the sensor usually adopts the z-axis light transmission method. However, due to the use of the crystal z-axis light transmission method, only the minimum electro-optic coefficient γ22 of the lithium niobate crystal can be used, thereby reducing the sensitivity of the sensor. Based on this, a reflective high-sensitivity electric field sensor was developed. By using a lithium niobate crystal with x-axis light transmission and z-direction electric field, and using its maximum electro-optic coefficient γ33, the sensitivity of the sensor was effectively improved. Summary of the invention

[0005] In view of the shortcomings of the existing technology, the present invention proposes a reflective high-sensitivity electric field sensor, which adopts a lithium niobate crystal that transmits light in the x-axis and applies an electric field in the z-axis, and utilizes its maximum electro-optic coefficient γ33 to improve the sensitivity. At the same time, the same crystal orthogonal to the z-axis is cascaded to eliminate the influence of natural birefringence and enhance temperature stability.

[0006] The technical implementation scheme of the present invention is:

[0007] The reflective high-sensitivity electric field sensor comprises a packaging shell, an input polarization-maintaining fiber collimator, a polarizer, a quarter wave plate, a first lithium niobate crystal, a reflector and an output single-mode fiber collimator, wherein the input polarization-maintaining fiber collimator is arranged in an input end packaging cavity, and one end of the input polarization-maintaining fiber collimator is provided with a polarizer, a quarter wave plate, a first lithium niobate crystal and a reflector; a second lithium niobate crystal, a polarizer and an output single-mode fiber collimator are also arranged inside the input end packaging cavity, and the output single-mode fiber collimator is arranged at the input end packaging cavity. Inside the output end packaging cavity; the main axes of the first lithium niobate crystal and the second lithium niobate crystal are arranged orthogonally to each other; the transmission directions of the polarizer and the analyzer are arranged perpendicular to each other; the output end face of the input polarization-maintaining fiber collimator is parallel to the light-transmitting surface of the polarizer, 1 / 4 wave plate, the first lithium niobate crystal, the reflector, the second lithium niobate crystal, and the analyzer, and the input end face of the output single-mode fiber collimator is also parallel to them, so as to ensure the high efficiency of light transmission; the input end packaging cavity and the output end packaging cavity are both fixed in the packaging shell.

[0008] Optionally, the transmission direction of the polarizer forms an angle of 45° with the z-axis of the first lithium niobate crystal.

[0009] Optionally, it also includes a tunable polarization-maintaining light source, a photodetector and an oscilloscope, wherein the tunable polarization-maintaining light source is connected to the sensor via a polarization-maintaining optical fiber; the sensor is connected to the photodetector via a single-mode optical fiber; and the photodetector is connected to the oscilloscope via an oscilloscope probe line.

[0010] Optionally, the polarization-maintaining optical fiber is a panda-type polarization-maintaining optical fiber, and the beat length of the polarization-maintaining optical fiber is 2 mm-4 mm.

[0011] Optionally, the input end packaging cavity is a rectangular structure, and a plurality of grooves are opened inside the input end packaging cavity, in which the input polarization-maintaining fiber collimator, polarizer, 1 / 4 wave plate, first lithium niobate crystal, reflector, second lithium niobate crystal and analyzer are respectively installed.

[0012] Optionally, the input polarization-maintaining fiber collimator is a cylindrical glass collimator, and the output end face of the input polarization-maintaining fiber collimator is a plane; the length of the input polarization-maintaining fiber collimator is 8 mm-12 mm, and the diameter is 2 mm-3 mm.

[0013] Optionally, the polarizer and the analyzer are both cube structures, and the length of the polarizer and the analyzer is 3mm-5mm, the width is 3mm-5mm, and the height is 3mm-5mm; the 1 / 4 wave plate is a circular thin plate, and the upper and lower bottom surface radii of the 1 / 4 wave plate are both 2mm-3mm, and the thickness is 1-1.5mm; the first lithium niobate crystal and the second lithium niobate crystal are both rectangular optical grade crystals, and the length of the first lithium niobate crystal and the second lithium niobate crystal are 30mm-42mm, the width is 4mm-6mm, and the height is 4mm-6mm.

[0014] Optionally, the two reflective structures of the reflector are both triangular prism structures, and the bottom surface of the reflector is an isosceles right triangle, the side length of the reflector is 4mm-6mm, and the height of the reflector is 4mm-6mm.

[0015] Optionally, the input end packaging cavity and the output end packaging cavity are both made of zirconium oxide material, and a groove compatible with the output single-mode fiber collimator is opened inside the input end packaging cavity. The external dimensions of the output end packaging cavity are 14mm-20mm in length, 16mm-20mm in width, and 10mm-14mm in height.

[0016] Optionally, the packaging shell has a rectangular hollow cavity structure, and the outer dimensions of the packaging shell are 74 mm-84 mm in length, 18 mm-22 mm in width, and 14 mm-16 mm in height.

[0017] The working principle of this technical solution is as follows:

[0018] The present invention has the following advantages:

[0019] The present invention introduces a high-sensitivity lithium niobate dual-crystal electric field sensor. In terms of improving sensitivity, a lithium niobate crystal that transmits light in the x-axis and applies an electric field in the z-direction is cleverly selected to give full play to its maximum electro-optic coefficient γ33, making the sensor more sensitive to changes in the electric field; in terms of optimizing stability, another lithium niobate crystal that also transmits light in the x-axis but is orthogonal to the first crystal in the z-axis direction is cascaded to accurately eliminate the interference caused by natural birefringence and ensure the stable performance of the sensor in different temperature environments; at the same time, the innovative use of a reflective structure greatly compresses the volume of the sensor, opening up a new path for the research and development of high-sensitivity lithium niobate crystal electric field sensors and providing a groundbreaking design solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the present invention.

[0021] The meanings of the reference numerals in the figure are: 1-packaging shell, 2-input packaging cavity, 3-input polarization-maintaining fiber collimator, 4-polarizer, 5-1 / 4 wave plate, 6-first lithium niobate crystal, 7-reflector, 8-second lithium niobate crystal, 9-polarizer, 10-output single-mode fiber collimator, 11-output packaging cavity, 12-single-mode optical fiber, 13-photodetector, 14-oscilloscope probe line, 15-oscilloscope, 16-tunable polarization-maintaining light source, 17-polarization-maintaining optical fiber, 18-sensor. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. It is hereby stated that the directional terms such as up, down, left, right, front, back, inside, outside, etc. that appear or will appear in the text of the present invention are only based on the accompanying drawings of the present invention, and are not specific limitations of the present invention.

[0023] like Figure 1 As shown, a reflective high-sensitivity electric field sensor comprises a packaging shell 1, an input polarization-maintaining fiber collimator 3, a polarizer 4, a quarter wave plate 5, a first lithium niobate crystal 6, a reflector 7 and an output single-mode fiber collimator 10, wherein the input polarization-maintaining fiber collimator 3 is arranged in an input end packaging cavity 2, and one end of the input polarization-maintaining fiber collimator 3 is provided with the polarizer 4, the quarter wave plate 5, the first lithium niobate crystal 6 and the reflector 7; a second lithium niobate crystal 8, an analyzer 9 and an output single-mode fiber collimator 10 are also arranged inside the input end packaging cavity 2, and the output single-mode fiber collimator 10 It is arranged inside the output end packaging cavity 11; the main axes of the first lithium niobate crystal 6 and the second lithium niobate crystal 8 are arranged orthogonally to each other; the transmission directions of the polarizer 4 and the analyzer 9 are arranged perpendicular to each other; the output end face of the input polarization-maintaining fiber collimator 3 is parallel to the light-transmitting surface of the polarizer 4, the 1 / 4 wave plate 5, the first lithium niobate crystal 6, the reflector 7, the second lithium niobate crystal 8, and the analyzer 9, and the input end face of the output single-mode fiber collimator 10 is also parallel thereto, so as to ensure the high efficiency of light transmission; the input end packaging cavity 2 and the output end packaging cavity 11 are both fixed in the packaging shell 1.

[0024] It should be noted that the main axes of the first lithium niobate crystal 6 and the second lithium niobate crystal 8 are arranged orthogonally to each other, which means that the main axis directions of the two are perpendicular, which has a significant impact on light propagation. When light propagates between the two crystals, the refractive index and polarization state will change according to the principle of birefringence. In optoelectronic applications, such as electro-optic modulation and nonlinear optical frequency conversion, this orthogonal combination can utilize different main axis characteristics to finely control the phase and polarization of light, improve frequency conversion efficiency, and thus improve the sensitivity of the sensor.

[0025] It needs to be further explained that, on the one hand, a special lithium niobate crystal is cascaded, whose x-axis is transparent and whose z-axis is orthogonal to the z-axis of the first crystal, so as to cleverly eliminate the influence of natural birefringence and effectively improve the temperature stability of the device; on the other hand, a reflective structure is boldly adopted to significantly reduce the volume of the electric field sensor in a breakthrough way, injecting new vitality into the development of related technologies. The advantage of this method is that the other lithium niobate crystal mentioned in the cascade here has the characteristic of "x-axis transparent", which means that light can propagate smoothly in the crystal along its x-axis direction; at the same time, its "z-axis is orthogonal to the z-axis of the first crystal", that is, the z-axis directions of the two crystals are perpendicular to each other. When such two crystals are reasonably cascaded and used, through clever optical principles and the interaction inside the crystal, the influence of the original natural birefringence can be offset or compensated for each other, thereby reducing the adverse effects caused by natural birefringence.

[0026] like Figure 1 As shown, the vibration transmission direction of the polarizer 4 forms an angle of 45° with the z-axis of the first lithium niobate crystal 6; it also includes a tunable polarization-maintaining light source 16, a photodetector 13 and an oscilloscope 15, the tunable polarization-maintaining light source 16 is connected to the sensor 18 through a polarization-maintaining optical fiber 17; the sensor 18 is connected to the photodetector 13 through a single-mode optical fiber 12; the photodetector 13 is connected to the oscilloscope 15 through an oscilloscope probe line 14; the polarization-maintaining optical fiber 17 is a panda-type polarization-maintaining optical fiber, and the beat length of the polarization-maintaining optical fiber 17 is 3 mm; the input end packaging cavity 2 is a rectangular parallelepiped structure, and a plurality of grooves are opened inside the input end packaging cavity 2, and the grooves are respectively installed with an input polarization-maintaining optical fiber collimator 3, a polarizer 4, a 1 / 4 wave plate 5, a first lithium niobate crystal 6, a reflector 7, a second lithium niobate crystal 8 and an analyzer 9.

[0027] It should be noted that when the transmission direction of the polarizer 4 forms an angle of 45° with the z-axis of the first lithium niobate crystal 6, after the linearly polarized light enters the first lithium niobate crystal 6, its electric field vector will be decomposed into two components parallel and perpendicular to the z-axis. The first lithium niobate crystal 6 has an electro-optic effect. When an electric field is applied in the z-direction, these two components will produce a phase difference due to the change in the refractive index of the crystal. This 45° angle setting makes the two components equal in size. In the electro-optic modulation process, the electro-optic coefficient of the crystal can be more effectively used to change the polarization state of the light, thereby improving the response sensitivity to the electric field.

[0028] It should be further explained that the tunable polarization-maintaining light source 16, as the starting end of the optical signal, can generate and adjust light with a specific polarization state, and accurately transmit it to the sensor 18 through the polarization-maintaining optical fiber 17, so as to provide the sensor with high-quality, adaptive input light, and ensure its accurate detection based on electro-optical effects; the photodetector 13 undertakes the key task of converting optical signals into electrical signals, and uses the single-mode optical fiber 12 to receive the light processed by the sensor 18, converts it into electrical signals and can preliminarily process it, to ensure the feasibility of subsequent detection and analysis; the oscilloscope 15 focuses on the visualization and analysis of electrical signals, receives the electrical signals output by the photodetector 13, and presents them in intuitive forms such as waveforms, which is convenient for monitoring the system operation status, troubleshooting, and assisting in evaluating system performance. The three work together to achieve the purpose of optical and electrical signal processing and detection.

[0029] like Figure 1 As shown, the input end packaging cavity 2 is made of zirconium oxide material, and the overall structure is a rectangular parallelepiped. The interior is precisely grooved according to the size of the optical element, and the external dimensions are: length 64mm, width 16mm, height 10mm; the input polarization-maintaining fiber collimator 3 and the polarization-maintaining fiber 17 are connected and solidified by glue injection, and are a cylindrical glass material, and the output end face is a plane, with external dimensions: length 10mm, diameter 2.8mm; the polarizer 4 and the analyzer 9 are both cube structures, made of glass, with a silver-plated reflective film on the surface, and external dimensions: length 5mm, width 5mm, height 5mm; the 1 / 4 wave plate 5 is a quartz crystal cylinder, with the upper and lower bottom radii of 3mm and a height of 1mm; the first lithium niobate crystal 6 and the second lithium niobate crystal 8 are both optical grade crystals, both of which are rectangular parallelepiped structures, with external dimensions: length 40mm, width 4mm, height 4mm; the reflector 7 The two reflective structures contained therein are both in the shape of triangular prisms, and the bottom surfaces of the two reflective structures are isosceles right triangles, with external dimensions: the length of the right-angle side is 6mm, and the height is 6mm; the output single-mode fiber collimator 10 and the polarization-maintaining fiber 12 are connected and solidified by glue injection, and are a cylindrical glass material, and the output end face is a plane, with external dimensions: length 10mm, diameter 2.8mm; the output end packaging cavity 11 is made of acrylic material, and the overall structure is a rectangular parallelepiped, and the interior is precisely grooved according to the size of the output single-mode fiber collimator, with external dimensions: length 14mm, width 16mm, height 10mm; the output single-mode fiber collimator 10 and the input polarization-maintaining fiber collimator 3 are a pair of collimators, and the coupling distance between the two collimators is 65mm; the packaging shell 1 is made of zirconia material, and the packaging shell is a rectangular parallelepiped structure, with external dimensions: length 74mm, width 18mm, height 16mm.

[0030] The installation method of the mechanism of the present invention is as follows:

[0031] Place the first lithium niobate crystal 6 and the second lithium niobate crystal 8 in the input end packaging cavity 2 and fix them by injection of glue. Align the slow axis of the input polarization-maintaining fiber collimator 3 with the x-axis of the first lithium niobate crystal 6, adjust its output end face to be parallel to the light-transmitting surface of the first lithium niobate crystal 6 and fix them by injection of glue; the light-transmitting axis of the polarizer 4 is parallel to the x-axis of the first lithium niobate crystal 6, adjust its output end face to be parallel to the light-transmitting surface of the first lithium niobate crystal 6 and fix them by injection of glue, and the light-transmitting surface of the 1 / 4 wave plate 5 is parallel to the light-transmitting surface of the first lithium niobate crystal 6 and fix them by injection of glue; adjust the reflective surfaces of the two reflective structures of the reflector 7 to form an angle of 45° with the light-transmitting surfaces of the first lithium niobate crystal 6 and the second lithium niobate crystal 8 respectively and fix them by injection of glue; adjust the light-transmitting axis of the analyzer 9 to be perpendicular to the x-axis of the second lithium niobate crystal 8, adjust its output end face to be parallel to the light-transmitting surface of the second lithium niobate crystal 8 The output single-mode optical fiber collimator 10 is fixed in the output end packaging cavity by injection of glue. After the optical glue of each device inside the input end packaging cavity 2 and the output end packaging cavity 11 is completely cured, it is placed in the optical adjustment frame for optical path coupling. When the optical path coupling loss is minimized, the relative positions of the two packaging cavities are fixed by the packaging shell 1, and the production of the sensor 18 is completed. After the linearly polarized light input by the tunable polarization-maintaining light source 16 is aligned with the slow axis of the polarization-maintaining optical fiber 17, it enters the sensor 18. The optical signal output by the sensor 18 enters the photodetector 13 through the single-mode optical fiber 12 for photoelectric conversion, and is finally transmitted to the oscilloscope 15 through the oscilloscope probe line 14 for display output, thereby completing the measurement of the measured electric field.

[0032] The working principle of the present invention is as follows:

[0033] For crystal 1, the external electric field E is along the z-axis of the crystal. According to the electro-optic effect of lithium niobate crystal, the principal axis refractive index of crystal 1 can be expressed as

[0034]

[0035] In formula 1, γ33 and γ13 are the electro-optic coefficients of lithium niobate crystal, no is the refractive index of o light, ne is the refractive index of e light, and κ is the ratio of the external and internal electric fields of lithium niobate crystal. When the light wave is input along the x-axis of crystal 1, it will be decomposed into o light with a vibration direction along the z-axis of the crystal and e light with a vibration direction along the y-axis of the crystal. From formula 1, it can be obtained that the phase difference generated by the light wave passing through crystal 1 in the two polarization directions is:

[0036]

[0037] In formula 2, L1 is the length of crystal 1, and λ is the wavelength of light in vacuum.

[0038] For crystal 2, since the external electric field E is along the y-axis of the crystal, the principal axis refractive index of crystal 2 can be expressed as:

[0039]

[0040] From formula 3, we can get that the phase difference of light waves passing through crystal 2 in two polarization directions is:

[0041]

[0042] In formula 4, L2 is the length of crystal 2. When L1 = L2 = L, formula 2 and formula 4 show that the phase difference in the two polarization directions of the light wave propagating along the x-axis after passing through crystal 1 and crystal 2 is:

[0043]

[0044] Note that for the existing z-transmitted light, the external electric field E is along the x or y axis of the crystal, and the length of the lithium niobate crystal electric field sensor is 2L. The phase difference of the light wave passing through the crystal in both polarization directions is:

[0045]

[0046] It can be seen from Formula 5 and Formula 6 that, since the designed dual crystal structure utilizes the maximum electro-optic coefficient γ33 of the lithium niobate crystal, when the crystal length is the same, the phase change caused by the light wave passing through the dual crystal is significantly increased, thereby improving the sensitivity of the device. In addition, it can be seen from Formula 5 that after the light wave passes through the dual crystal, the phase difference caused by the natural birefringence is offset. It is noted that the natural light birefringence is greatly affected by temperature, so the designed sensor will theoretically have better stability.

[0047] From formula 5, when Dφ=π, the half-wave electric field of the sensor can be obtained as:

[0048]

[0049] Using πE(t) / Eπ to represent the phase change of the light wave, the output optical power Pout of the crystal output light wave after polarization by the analyzer can be expressed as:

[0050]

[0051] In formula 8, a is the optical path loss coefficient, Pin is the input optical power, and φ0 is the static phase difference of the optical wave when no electric field is applied.

[0052] When φ0=90°, πE(t) / Eπ<<1, Formula 8 can be simplified to:

[0053]

[0054] According to formula 9, the output light of the sensor is converted into an electrical signal through photoelectric conversion:

[0055]

[0056] In formula 10, G (V / W) is the photoelectric conversion coefficient of the photodetector. From formula 10, it can be seen that the output electrical signal of the sensing system is proportional to the measured electric field E (t).

[0057] It should be noted that the present invention proposes a high-sensitivity lithium niobate dual-crystal electric field sensor design. On the one hand, a lithium niobate crystal that transmits light along the x-axis and applies an electric field along the z-direction is selected as the core component, and the maximum electro-optic coefficient γ33 of the crystal is fully utilized, so that the sensor's sensitivity to the electric field is greatly improved, and it can accurately capture extremely weak electric field change signals, greatly broadening its application scenarios and detection accuracy range.

[0058] It should be further explained that by cleverly cascading another lithium niobate crystal that also transmits light along the x-axis but is arranged orthogonally to the first crystal along the z-axis, the adverse interference caused by natural birefringence is successfully offset, fundamentally enhancing the temperature adaptability of the device, and ensuring that the sensor can maintain stable and reliable performance under complex and changeable temperature conditions, laying a solid foundation for long-term, high-precision electric field monitoring operations. What is particularly outstanding is that the present invention has introduced a breakthrough reflective structure design. This ingenious conception has greatly compressed the volume of the entire electric field sensor, which not only effectively saves installation space and reduces the difficulty of equipment integration, but also creates the possibility of accurate perception of the electric field in some special fields with strict space requirements, such as microelectronic equipment, precision instrument cabins, etc., and has truly opened up new ideas for the research and development and application of high-sensitivity lithium niobate crystal electric field sensors.

[0059] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of those skilled in the art without departing from the spirit of the present invention.

Claims

1. A reflective high-sensitivity electric field sensor, comprising a packaging shell (1), an input polarization-maintaining optical fiber collimator (3), a polarizer (4), a quarter-wave plate (5), a first lithium niobate crystal (6), a reflector (7) and an output single-mode optical fiber collimator (10), wherein: The input polarization-maintaining optical fiber collimator (3) is arranged in the input end packaging cavity (2), and one end of the input polarization-maintaining optical fiber collimator (3) is provided with a polarizer (4), a quarter wave plate (5), a first lithium niobate crystal (6) and a reflector (7); A second lithium niobate crystal (8), a polarizer (9) and an output single-mode optical fiber collimator (10) are also arranged inside the input end packaging cavity (2), and the output single-mode optical fiber collimator (10) is arranged inside the output end packaging cavity (11); The main axes of the first lithium niobate crystal (6) and the second lithium niobate crystal (8) are arranged to be orthogonal to each other; The polarizer (4) and the analyzer (9) are arranged with their vibration transmission directions perpendicular to each other; The output end face of the input polarization-maintaining optical fiber collimator (3) is parallel to the light-transmitting surfaces of the polarizer (4), the quarter wave plate (5), the first lithium niobate crystal (6), the reflector (7), the second lithium niobate crystal (8), and the analyzer (9), and the input end face of the output single-mode optical fiber collimator (10) is also parallel to them, thereby ensuring the high efficiency of light transmission; The input end packaging cavity (2) and the output end packaging cavity (11) are both fixed in the packaging shell (1).

2. The reflective high-sensitivity electric field sensor according to claim 1, characterized in that: The vibration transmission direction of the polarizer (4) forms an angle of 45° with the z-axis of the first lithium niobate crystal (6).

3. The reflective high-sensitivity electric field sensor according to claim 2, characterized in that: It also includes a tunable polarization-maintaining light source (16), a photodetector (13) and an oscilloscope (15), wherein the tunable polarization-maintaining light source (16) is connected to the sensor (18) via a polarization-maintaining optical fiber (17); The sensor (18) is connected to the photodetector (13) via a single-mode optical fiber (12); The photoelectric detector (13) is connected to an oscilloscope (15) via an oscilloscope probe line (14).

4. The reflective high-sensitivity electric field sensor according to claim 3, characterized in that: The polarization-maintaining optical fiber (17) is a panda-type polarization-maintaining optical fiber, and the beat length of the polarization-maintaining optical fiber (17) is 2 mm to 4 mm.

5. The reflective high-sensitivity electric field sensor according to claim 4, characterized in that: The input end packaging cavity (2) is a rectangular parallelepiped structure, and a plurality of grooves are provided inside the input end packaging cavity (2), and the grooves are respectively equipped with an input polarization-maintaining optical fiber collimator (3), a polarizer (4), a quarter wave plate (5), a first lithium niobate crystal (6), a reflector (7), a second lithium niobate crystal (8) and a polarizer (9).

6. The reflective high-sensitivity electric field sensor according to claim 5, characterized in that: The input polarization-maintaining optical fiber collimator (3) is a cylindrical glass collimator, and the output end face of the input polarization-maintaining optical fiber collimator (3) is a plane; The length of the input polarization-maintaining optical fiber collimator (3) is 8 mm to 12 mm, and the diameter is 2 mm to 3 mm.

7. The reflective high-sensitivity electric field sensor according to claim 6, characterized in that: The polarizer (4) and the analyzer (9) are both cube structures, and the length of the polarizer (4) and the analyzer (9) is 3 mm to 5 mm, the width is 3 mm to 5 mm, and the height is 3 mm to 5 mm; The 1 / 4 wave plate (5) is a circular thin plate, and the upper and lower bottom surfaces of the 1 / 4 wave plate (5) have radii of 2 mm to 3 mm and a thickness of 1 to 1.5 mm; The first lithium niobate crystal (6) and the second lithium niobate crystal (8) are both cuboid optical-grade crystals, and the first lithium niobate crystal (6) and the second lithium niobate crystal (8) have a length of 30 mm to 42 mm, a width of 4 mm to 6 mm, and a height of 4 mm to 6 mm.

8. The reflective high-sensitivity electric field sensor according to claim 1, characterized in that: The two reflective structures of the reflector (7) are both triangular prism structures, and the bottom surface of the reflector (7) is an isosceles right triangle. The side length of the reflector (7) is 4 mm-6 mm, and the height of the reflector (7) is 4 mm-6 mm.

9. The reflective high-sensitivity electric field sensor according to claim 1, characterized in that: The input end packaging cavity (2) and the output end packaging cavity (11) are both made of zirconium oxide material. A groove matching the output single-mode optical fiber collimator (10) is provided inside the input end packaging cavity (11). The external dimensions of the output end packaging cavity (11) are 14 mm to 20 mm in length, 16 mm to 20 mm in width, and 10 mm to 14 mm in height.

10. The reflective high-sensitivity electric field sensor according to claim 1, characterized in that: The packaging shell (1) has a rectangular hollow cavity structure, and the external dimensions of the packaging shell (1) are 74 mm to 84 mm in length, 18 mm to 22 mm in width, and 14 mm to 16 mm in height.

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