Monolithic integrated three-dimensional electric field sensing probe

Abstract

The invention discloses a monolithic integrated three-dimensional electric field sensing probe which comprises an x-path optical waveguide, a y-path optical waveguide, a z-path optical waveguide and three corresponding receiving antennas. Through the combined design of two mutually orthogonal bow-tie type dipole antennas and a microstrip patch antenna, synchronous detection and optical signal modulation of x, y and z three-axis electric field components are realized. In an x-axis electric field and a y-axis electric field in a plane, electric field signals are received by two bow-tie dipole antennas with mutually orthogonal directions, voltage signals are generated between electrodes, and optical phase changes of x-path and y-path optical waveguides are respectively modulated; the z-axis electric field receives a signal through the microstrip patch antenna and generates a voltage signal with the internal metal reference layer, so that the voltage signal is modulated to the optical phase of the z-path optical waveguide. An external system can obtain information such as frequency, intensity and phase of a three-dimensional electric field signal by detecting optical signal phases output by the three paths of optical waveguides. The micro electromagnetic sensing device has the characteristics of high integration level, small size and interference resistance, and is suitable for micro electromagnetic sensing equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic sensing, and particularly relates to a three-dimensional electric field sensing probe based on a z-cut thin film lithium niobate (TFLN) platform, which can simultaneously measure the components of the spatial electric field in the x, y, and z directions. Background Art

[0002] Electric field detection has important applications in electromagnetic environment monitoring, biomedical imaging, wireless communication and other fields. Traditional electric field sensors mostly have single-axis or biaxial detection structures, and three-dimensional measurement needs to be realized by combining multiple discrete probes, which have problems such as large volume, low integration, and complex anisotropic calibration. Although existing optical electric field sensing technologies have advantages such as strong anti-interference ability and high bandwidth, they are limited by a single modulator structure and planar antenna design, and it is difficult to achieve high-precision three-dimensional electric field synchronous detection.

[0003] The main defects of traditional technologies include:

[0004] 1. Dimension limitation: Single-axis or biaxial probes cannot directly obtain three-dimensional electric field information, and complex calibration or mechanical adjustment is required.

[0005] 2. Low integration: Discrete probes have a large volume and are difficult to be applied in miniaturized devices.

[0006] 3. Anisotropic error: The combination of multiple probes is likely to introduce spatial position deviation, resulting in a decrease in measurement accuracy.

[0007] 4. Insufficient frequency band coverage: Traditional antenna designs are difficult to balance the detection requirements of multiple directions and wide frequency bands.

[0008] Therefore, there is an urgent need for a probe with high integration and capable of synchronously measuring three-dimensional electric field components to break through the limitations of existing technologies. Summary of the Invention

[0009] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a monolithic integrated three-dimensional electric field sensing probe that uses a single integrated optical chip to achieve synchronous measurement of three-axis electric field components, can eliminate spatial deviation, and has the characteristics of high integration, small volume and strong anti-interference.

[0010] The purpose of the present invention is achieved through the following technical solutions: A monolithic integrated three-dimensional electric field sensing probe includes three optical waveguides for x, y, and z arranged in parallel, and three receiving antennas for the x, y, and z axes respectively corresponding to the three optical waveguides for x, y, and z;

[0011] The three optical waveguides for x, y, and z are etched on the same thin film lithium niobate layer, a silicon oxynitride layer is provided above the thin film lithium niobate layer, and a SiO 2 layer is used as the first layer of base material below the thin film lithium niobate layer, and SiO 2Below the layer is provided with a bottom substrate lithium niobate;

[0012] The x-axis receiving antenna and the y-axis receiving antenna are located above the silicon oxynitride layer, at positions corresponding to the x optical waveguide and the y optical waveguide; the x-axis receiving antenna and the y-axis receiving antenna have the same structure and both adopt a bowtie dipole structure; the bowtie dipole structure includes two triangular dipole single arms with their apexes symmetrically arranged about the optical waveguide, and each apex of the triangular dipole single arm is connected to an electrode, and the two electrodes are also symmetric about the optical waveguide; the direction of the y-axis bowtie dipole structure is perpendicular to the direction of the x-axis bowtie dipole structure;

[0013] The z-axis receiving antenna includes a microstrip patch antenna and a metal reference layer; the microstrip patch antenna is located above the silicon oxynitride layer and is on the same horizontal plane as the x-axis receiving antenna and the y-axis receiving antenna; on the SiO 2 layer adjacent to the bottom substrate lithium niobate, at a position corresponding to the microstrip patch antenna of the z-axis receiving antenna, a hollowed-out area is provided, and a metal reference layer is grown in this area.

[0014] The thickness of the thin film lithium niobate layer is 400 - 1000 nm, and the etching depth is 300 - 600 nm; the thickness of the silicon oxynitride layer is 1 um; the thickness of the SiO 2 layer is 2 um; the thickness of the bottom substrate lithium niobate is 525 um.

[0015] The x, y-axis receiving antennas and the microstrip patch antenna of the z-axis receiving antenna are all made of gold material with a thickness of 1 um as the metal layer of the monolithic integrated three-dimensional electric field sensing probe; the metal reference layer is made of gold material with a thickness of 100 nm.

[0016] The beneficial effects of the present invention are: The present invention uses a single integrated optical chip to realize the synchronous measurement of three-axis electric field components, can eliminate spatial deviation, and has the characteristics of high integration, small volume and strong anti-interference, and is suitable for miniaturized electromagnetic sensing devices. Its advantages are specifically reflected in the following aspects:

[0017] (1) Three-dimensional synchronous detection: A single integrated chip realizes the synchronous measurement of three-axis electric field components, eliminating spatial deviation.

[0018] (2) High integration: The three-dimensional optical waveguides and antennas are monolithically integrated, and the size is less than 25 mm × 30 mm.

[0019] (3) Strong anti-interference: The optical carrier modulation technology avoids electromagnetic crosstalk and can improve the signal-to-noise ratio. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the overall structure of the three-dimensional electric field sensing probe of the present invention.

[0021] Figure 2 It is a cross-sectional structure diagram of a monolithic integrated chip. Specific implementation mode

[0022] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0023] As Figure 1 shown, a monolithic integrated three-dimensional electric field sensing probe of the present invention includes three x, y, and z optical waveguides arranged in parallel, and three receiving antennas on the x, y, and z axes respectively corresponding to the three x, y, and z optical waveguides;

[0024] The three x, y, and z optical waveguides are all used to realize the input of external optical signals, receive the transmission of the electrode-modulated optical signals of the antennas, and output optical signals to the outside; the monolithic integrated three-dimensional electric field sensing probe of the present invention is designed based on a z-cut thin film lithium niobate (TFLN; the crystal material is anisotropic, and z-cut means cutting the thin film lithium niobate material along a plane perpendicular to the z-axis) platform. The three x, y, and z optical waveguides are etched on the same thin film lithium niobate (TFLN) layer, as Figure 2 shown; in this embodiment, the thickness of the TFLN layer is 600 nm, the etching depth is 300 nm, and the waveguide width is 1 μm.

[0025] Above the thin film lithium niobate layer, there is a silicon oxynitride layer for reducing the light absorption of metals. Below the thin film lithium niobate layer, there is a SiO 2 layer as the first layer of base material, and below the SiO 2 layer, there is a bottom substrate lithium niobate (LN);

[0026] The x-axis receiving antenna and the y-axis receiving antenna are located above the silicon oxynitride layer at positions corresponding to the x optical waveguide and the y optical waveguide; the x-axis receiving antenna and the y-axis receiving antenna have the same structure and both adopt a bow-tie dipole structure; the bow-tie dipole structure includes two triangular dipole single arms with their apex angles symmetrically arranged about the optical waveguide, and each apex angle of the triangular dipole single arm is connected to an electrode, and the two electrodes are also symmetric about the optical waveguide;

[0027] The direction of the y-axis bow-tie dipole structure is perpendicular to that of the x-axis bow-tie dipole structure. The y-axis and x-axis bow-tie dipole structures are in the same horizontal plane and perpendicular to each other. The x-axis receiving antenna is used to detect the electric field in the x-axis direction of the horizontal plane, and the y-axis receiving antenna is used to detect the electric field in the y-axis direction of the horizontal plane. Two mutually orthogonal electrodes can ensure the detection of electric fields in two orthogonal directions. In this embodiment, the x, y, and z optical waveguides all adopt a three-section structure connected end to end. The first and third sections of the optical waveguide are parallel, and the second section of the optical waveguide is perpendicular to the other two sections. The x-axis receiving antenna is installed at the second section of the x optical waveguide, the y-axis receiving antenna is installed at the first section of the y optical waveguide, and the z-axis antenna is installed at the third section of the z optical waveguide. Since the first section of the optical waveguide and the second section of the optical waveguide are perpendicular, setting the x-axis receiving antenna and the y-axis receiving antenna in this way can ensure their perpendicularity. There is no position requirement for the z-axis antenna, and its z-axis performance is determined by the antenna type. The structure of the above optical waveguide and the position of the antenna setting are not unique. As long as the structure can make the x-axis receiving antenna and the y-axis receiving antenna perpendicular to each other, it belongs to the protection scope of the present invention.

[0028] The z-axis receiving antenna is used to detect the electric field in the vertical direction and includes a microstrip patch antenna and a metal reference layer; the microstrip patch antenna is located above the silicon oxynitride layer and is in the same horizontal plane as the x-axis receiving antenna and the y-axis receiving antenna; on the SiO 2 layer adjacent to the underlying substrate lithium niobate, at the position corresponding to the microstrip patch antenna of the z-axis receiving antenna, a hollowed-out area is provided, and a metal reference layer is grown in this area.

[0029] The arm lengths, angles, and spacings of the three receiving antennas on the x, y, and z axes are parametrically designed and can be adapted to different frequency bands. The specific arm lengths, angles, and spacings can be designed according to the actually used frequency band. In this embodiment, the arm lengths (i.e., the height of a single arm of the triangular dipole) of the x-axis receiving antenna and the y-axis receiving antenna are 8 mm, the opening angle is 60 degrees (i.e., the apex angle of a single arm of the triangular dipole), the electrode length (i.e., Figure 1 the length of the electrode in Figure 1 is 1 mm, the electrode height (i.e.,

[0030] the width of the electrode in 2The thickness of the layer is 2 um; the thickness of the underlying substrate lithium niobate is 525 um.

[0031] The microstrip patch antennas of the x, y-axis receiving antennas and the z-axis receiving antenna are all made of gold material with a thickness of 1 um as the metal layer of the monolithic integrated three-dimensional electric field sensing probe; the metal reference layer is made of gold material with a thickness of 100 nm. In contrast, there is no metal reference layer in the area below the x and y-axis bowtie antennas.

[0032] In the probe of the present invention, the three x, y, z optical waveguides and the three x, y, z-axis receiving antennas are respectively combined and work together. The x and y optical waveguides respectively pass between the electrodes of the x and y-axis bowtie dipole structures, and convert the received electric field signal into a potential difference and modulate it onto the optical signal passing through the optical waveguide between the electrodes; the z-axis microstrip patch antenna is located on the top metal layer, and a metal reference layer is provided below at the same time. The z optical waveguide passes between the microstrip patch antenna electrodes and the metal reference layer, and modulates the optical signal passing through the z optical waveguide through the potential difference caused by the vertical electric field; the optical signals in the three optical waveguides respectively carry the electric field frequency signals in three dimensions, and the optical signals are coupled and output to a photodetector through an external optical fiber, and the three-axis electric field components are restored through spectrum analysis..

[0033] A monolithic integrated three-dimensional electric field sensing probe, the optical waveguide is based on a z-cut thin film lithium niobate integrated optical platform, and a metal layer is integrated to make a receiving antenna. Through the combined design of two mutually orthogonal bowtie dipole antennas and a microstrip patch antenna, the synchronous detection and optical signal modulation of the x, y, z three-axis electric field components are realized. The x-axis and y-axis electric fields in the plane are received by two mutually orthogonal bowtie dipole antennas to generate voltage signals between the electrodes, and are respectively modulated onto the optical phase changes of the x and y optical waveguides; the z-axis electric field is received by the microstrip patch antenna and generates a voltage signal with the internal metal reference layer, and thus is modulated onto the optical phase of the z optical waveguide.

[0034] Those of ordinary skill in the art will realize that the embodiments described herein are for helping readers understand the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other specific deformations and combinations without departing from the essence of the present invention according to the technical revelations disclosed in the present invention, and these deformations and combinations are still within the protection scope of the present invention.

Claims

1. A monolithic integrated three-dimensional electric field sensor probe, characterized in that: It includes three optical waveguides x, y and z arranged in parallel, and three receiving antennas on the x, y and z axes arranged corresponding to the three optical waveguides x, y and z axes respectively; The three optical waveguides x, y and z are etched on the same thin-film lithium niobate layer, a silicon oxynitride layer is arranged above the thin-film lithium niobate layer, a SiO2 layer is arranged below the thin-film lithium niobate layer as the first layer of base material, and a bottom substrate lithium niobate is arranged below the SiO2 layer; The x-axis receiving antenna and the y-axis receiving antenna are located above the silicon oxynitride layer, at positions corresponding to the x-optical waveguide and the y-optical waveguide; the x-axis receiving antenna and the y-axis receiving antenna have the same structure, both of which adopt a bowtie dipole structure; the bowtie dipole structure comprises two triangular dipole arms whose vertex angles are symmetrically arranged with respect to the optical waveguide, each of the triangular dipole arms is connected to an electrode at its vertex angle, and the two electrodes are also symmetrical with respect to the optical waveguide; The direction of the y-axis bowtie dipole structure is perpendicular to the direction of the x-axis bowtie dipole structure; The z-axis receiving antenna includes a microstrip patch antenna and a metal reference layer; the microstrip patch antenna is located above the silicon oxynitride layer and is at the same level as the x-axis receiving antenna and the y-axis receiving antenna; on the SiO2 layer adjacent to the underlying substrate lithium niobate, a hollowed-out area is provided at a position corresponding to the microstrip patch antenna of the z-axis receiving antenna, and a metal reference layer is grown in the area.

2. The monolithic integrated three-dimensional electric field sensing probe according to claim 1, characterized in that: The thickness of the thin film lithium niobate layer is 400-1000nm, and the etching depth is 300-600nm; the thickness of the silicon oxynitride layer is 1um; the thickness of the SiO2 layer is 2um; and the thickness of the bottom substrate lithium niobate is 525um.

3. The monolithic integrated three-dimensional electric field sensing probe according to claim 1, characterized in that: The microstrip patch antennas of the x-axis and y-axis receiving antennas and the z-axis receiving antenna are all made of gold material with a thickness of 1um, serving as the metal layer of the monolithic integrated three-dimensional electric field sensing probe; the metal reference layer is made of gold material with a thickness of 100nm.

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