Vertical characterization system based on coherent detection technology

Abstract

The invention relates to a vertical characterization system based on a coherent detection technology. The method belongs to the technical field of nonlinear optical characterization. The incident light path assembly is used for performing polarization control and light splitting on a generated incident ray polarization ultra-short laser pulse to obtain a beam splitting laser beam vertical to a sample, vertically focusing the beam splitting laser beam on the sample, and outputting the other beam splitting laser beam to a reference light path assembly; the emergent light path assembly is used for receiving the laser beam vertically reflected by the sample and filtering the laser beam to obtain a detection laser beam; the reference optical path assembly is used for performing frequency multiplication, optical path and phase control and polarization direction control on the input split laser to obtain a reference laser beam carrying second harmonics; and the beam combination detection assembly is used for carrying out coherent detection after carrying out beam combination and focusing on the reference laser beam and the detection laser beam to extract a sample interface signal in the second harmonic. According to the invention, the extraction of the interface signal in the non-centrosymmetric material system is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of nonlinear optical characterization, and in particular relates to a vertical characterization system based on coherent detection technology. Background Art

[0002] Second harmonic generation (SHG) is a nonlinear optical microscopy characterization technique developed in recent years that produces second-order polarization by irradiating materials with high-intensity lasers. Among many characterization methods, second harmonics has demonstrated its ability to characterize the electric field and structural properties of material interfaces due to its non-destructive testing, high stability, and simple operation. For example, second harmonic characterization technology can be used to locate and identify structural defects such as stacking faults and dislocations in SiC wafers, and to characterize non-uniform strain information in materials. At the same time, time-dependent second harmonics can obtain information on interface state density and fixed oxide charge.

[0003] In the field of wafer characterization, the existing second harmonic characterization technology is not applicable to material systems with strong bulk signals, which greatly restricts the development and application of this technology. For non-centrosymmetric materials, the interface signal carrying defect information will be submerged in the strong bulk signal and cannot be accurately measured. Summary of the invention

[0004] In view of the above analysis, the present invention aims to disclose a vertical characterization system based on coherent detection technology. By using coherent detection technology, the second harmonic interface signal and the body signal can be distinguished in the vertical direction, solving the problem of extracting the interface signal.

[0005] The present invention discloses a vertical characterization system based on coherent detection technology, comprising: an incident light path component, an outgoing light path component, a reference light path component and a beam combining detection component;

[0006] The incident optical path component is used to generate an incident light beam; after polarization control and spectral splitting of the generated incident linearly polarized ultrashort laser pulse, a beam of split laser light perpendicular to the sample obtained after spectral splitting is vertically focused on the sample, and a vertical reflected laser beam carrying a second harmonic is generated after reflection; and another beam of split laser light obtained after spectral splitting is output to the reference optical path component;

[0007] The outgoing optical path component is used to receive the vertical reflected laser beam and obtain the detection laser beam after filtering;

[0008] The reference optical path component is used to obtain a reference laser beam carrying a second harmonic after frequency doubling, optical path and phase control, and polarization direction control of the input split laser beam;

[0009] The beam combining and detecting component is used to combine and focus the reference laser beam and the detecting laser beam, and then perform coherent detection to extract the sample interface signal in the second harmonic.

[0010] Furthermore, the incident light path component includes: a laser, a polarization control component, a beam splitter, and a first convex lens;

[0011] The laser is used to generate ultrashort laser pulses with incident linear polarization and output to the polarization control component;

[0012] The polarization control component is used to adjust the polarization direction of the incident laser beam and screen the polarization direction to control the laser power, and after further performing extinction ratio enhancement and polarization direction control on the power-controlled incident laser beam, an incident laser beam that meets the test conditions is obtained and output to the spectrometer;

[0013] The beam splitter is used to split the laser beam output by the polarization control component to output two split laser beams, wherein one split laser beam points to the sample stage and is perpendicular to the sample carried by the sample stage; the other split laser beam points to the reference optical path component and is output to the reference optical path component;

[0014] The first convex lens is used to focus the split laser beam perpendicular to the sample on the sample, and generate a second harmonic carrying the sample defect information after reflection.

[0015] Further, the polarization control assembly includes: a first half-wave plate, a Glan-Taylor polarizer, a first polarizer, and a second half-wave plate;

[0016] The first half-wave plate is used to change the polarization direction of the incident laser beam according to the test requirements and output it to the Glan-Taylor polarizer;

[0017] The Glan-Taylor polarizer is used to screen the polarization direction of the incident laser beam, output a light beam with a set polarization direction to the first polarizer, and cooperate with the half-wave plate to realize the control of the laser power;

[0018] The first polarizer is used to further enhance the extinction ratio of polarized light and enhance the polarization characteristics of the light beam with a set polarization direction emitted by the Glan-Taylor polarizer;

[0019] The second half-wave plate is used to change the polarization direction of the laser beam output by the first polarizer according to the test requirements, and output an incident laser beam that meets the test conditions.

[0020] Further, the reference optical path component includes: a reference beam generating component, an optical path and phase control component and a polarization direction control component;

[0021] The reference beam generating component is used to frequency-double the incident split beam laser to generate a reference laser beam carrying the second harmonic and output it to the optical path and phase control component;

[0022] The optical path and phase control component is used to control the optical path and phase of the reference laser beam carrying the second harmonic, so that the optical path and phase of the reference laser beam match the optical path and phase of the subsequent combined detection laser beam;

[0023] The polarization direction control component is used to perform extinction, light intensity and polarization control to match the light intensity and polarization direction of the reference laser beam with the subsequent combined detection laser beam.

[0024] Further, the reference beam generating assembly comprises: a second convex lens, a frequency doubling crystal, and a third convex lens;

[0025] The second convex lens is used to focus the incident laser beam and then inject it into the frequency doubling crystal;

[0026] The frequency doubling crystal is used to frequency-double the incident laser beam to generate a reference laser beam carrying a second harmonic;

[0027] The third convex lens is used to focus the reference laser beam emitted by the frequency doubling crystal, and output the focused reference laser beam to the optical path and phase control component.

[0028] Further, the polarization direction control component includes a second polarizer, an attenuation plate and a third half-wave plate;

[0029] The second polarizer is used to enhance the extinction ratio of polarized light of the incident laser beam;

[0030] The attenuation plate is used to control the light intensity of the laser beam output by the second polarizer;

[0031] The third half-wave plate is used to control the polarization direction of the laser beam output by the attenuation plate, so that the polarization direction of the reference laser beam matches the polarization direction of the subsequent combined detection laser beam.

[0032] Further, the optical path and phase control assembly includes: a first reflector, a second filter, a second reflector and an electric translation stage;

[0033] The first reflector and the second reflector are arranged at mutually symmetrical angles; the incident laser beam of the first reflector is reflected by the second reflector after being reflected by the first reflector, and the outgoing laser beam after being reflected by the second reflector is parallel to the incident beam of the first reflector;

[0034] Between the first reflector and the second reflector, the incident laser beam passes through the second filter to filter out the fundamental frequency beam;

[0035] The electric translation stage is used to carry the first reflector, the second filter and the second reflector, and to drive the first reflector and the second reflector to translate according to the control information, and simultaneously approach or move away from the incident light beam direction of the first reflector;

[0036] The incident light beam of the first reflector is the reference laser beam focused by the third convex lens, and the outgoing light beam of the second reflector is incident on the second polarizer;

[0037] The optical path and phase of the laser beam emitted from the third convex lens and incident on the second polarizer are controlled by controlling the translation of the electric translation stage.

[0038] Further, the outgoing optical path component includes a first convex lens, a beam splitter, and a first filter multiplexed with the incident optical path component;

[0039] In the outgoing optical path component, the multiplexed first convex lens is used to collimate the vertically reflected laser beam carrying the second harmonic generated on the sample;

[0040] The beam splitter is used to provide an optical path for the collimated reflected laser beam;

[0041] The first filter is used to perform fundamental frequency light filtering on the collimated reflected laser beam, and output the reflected laser beam after fundamental frequency light filtering as a detection laser beam to the beam combining detection component.

[0042] Further, the beam splitter prism includes a first light input end, a second light input end, a first light output end, a second light output end and a third light output end;

[0043] The light beam incident on the first light input end is split, and a beam of split light is emitted from the first light output end and the second light output end respectively; the position of the second light input end coincides with the first light output end, and the light beam incident on the second light input end is not split, and the light beam is directly output from the third light output end.

[0044] Further, the beam combining detection assembly comprises: a beam combiner, a fourth convex lens and a photodetector;

[0045] The beam combiner is used to combine the incident exploration laser beam after filtering the fundamental frequency light and the polarization-matched reference laser beam, and output the combined beam light;

[0046] The fourth convex lens is used to focus the combined light beam onto the photodetector;

[0047] The photoelectric detector is used to use the detection laser beam as signal light and the reference laser beam as local oscillator light to perform coherent detection and extract the interface signal in the second harmonic.

[0048] The present invention can achieve one of the following beneficial effects:

[0049] The vertical characterization system based on coherent detection technology of the present invention can distinguish second harmonic interface signals and body signals in the vertical direction by using coherent detection technology, realize the extraction of interface signals in non-centrosymmetric material systems, and further expand the application scenarios of second harmonic characterization technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The accompanying drawings are only used for the purpose of illustrating specific embodiments and are not to be considered as limiting the present invention. In the entire drawings, the same reference symbols represent the same components;

[0051] Figure 1 A vertical characterization system based on coherent detection technology in an embodiment of the present invention;

[0052] Figure numerals: 1. Laser, 2. First half-wave plate, 3. Glan-Taylor polarizer, 4. Polarizer, 5. Second half-wave plate, 6. Beam splitter, 7. First convex lens, 8. Sample (wafer), 9. Six-dimensional sample stage, 10. First filter, 11. Second convex lens, 12. Frequency doubling crystal, 13. Third convex lens, 14. First reflector, 15. Second filter, 16. Second reflector, 17. Second polarizer, 18. Attenuation plate, 19. Third half-wave plate, 20. Beam combiner, 21. Fourth convex lens, 22. Photodetector; A. Electric translation stage. DETAILED DESCRIPTION

[0053] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used to illustrate the principles of the present invention together with the embodiments of the present invention.

[0054] The embodiment of the present invention discloses a vertical characterization system based on coherent detection technology, such as Figure 1 As shown, it includes: an incident light path component, an output light path component, a reference light path component and a beam combining detection component;

[0055] The incident optical path component is used to generate an incident light beam; after polarization control and spectral splitting of the generated incident linearly polarized ultrashort laser pulse, a beam of split laser light perpendicular to the sample obtained after spectral splitting is vertically focused on the sample, and a vertical reflected laser beam carrying a second harmonic is generated after reflection; and another beam of split laser light obtained after spectral splitting is output to the reference optical path component;

[0056] The outgoing optical path component is used to receive the vertical reflected laser beam and obtain the detection laser beam after filtering;

[0057] The reference optical path component is used to obtain a reference laser beam carrying a second harmonic after frequency doubling, optical path and phase control, and polarization direction control of the input split laser beam;

[0058] The beam combining and detecting component is used to combine and focus the reference laser beam and the detecting laser beam, and then perform coherent detection to extract the sample interface signal in the second harmonic.

[0059] Specifically, the sample is a non-centrosymmetric material system sample including silicon carbide and diamond.

[0060] Specifically, the incident light path component includes: a laser, a polarization control component, a beam splitter, and a first convex lens;

[0061] The laser is used to generate ultrashort laser pulses with incident linear polarization and output to the polarization control component;

[0062] Preferably, the parameters of the linearly polarized ultrashort laser pulse are: wavelength 800 nm; pulse width 100 fs.

[0063] The polarization control component is used to adjust the polarization direction of the incident laser beam and screen the polarization direction to control the laser power, and after further performing extinction ratio enhancement and polarization direction control on the power-controlled incident laser beam, an incident laser beam that meets the test conditions is obtained and output to the spectrometer;

[0064] The beam splitter is used to split the laser beam output by the polarization control component to output two split laser beams, wherein one split laser beam points to the sample stage and is perpendicular to the sample carried by the sample stage; the other split laser beam points to the reference optical path component and is output to the reference optical path component;

[0065] The first convex lens is used to focus the split laser beam perpendicular to the sample on the sample, and generate a second harmonic carrying the sample defect information after reflection.

[0066] Specifically, the polarization control assembly includes: a first half-wave plate, a Glan-Taylor polarizer, a first polarizer, and a second half-wave plate;

[0067] The first half-wave plate is used to change the polarization direction of the incident laser beam according to the test requirements and output it to the Glan-Taylor polarizer;

[0068] The Glan-Taylor polarizer is used to screen the polarization direction of the incident laser beam, output a light beam with a set polarization direction to the first polarizer, and cooperate with the half-wave plate to realize the control of the laser power;

[0069] The first polarizer is used to further enhance the extinction ratio of polarized light and enhance the polarization characteristics of the light beam with a set polarization direction emitted by the Glan-Taylor polarizer;

[0070] The second half-wave plate is used to change the polarization direction of the laser beam output by the first polarizer according to the test requirements, and output an incident laser beam that meets the test conditions.

[0071] Specifically, the reference optical path component includes: a reference beam generating component, an optical path and phase control component and a polarization direction control component;

[0072] The reference beam generating component is used to frequency-double the incident split beam laser to generate a reference laser beam carrying the second harmonic and output it to the optical path and phase control component;

[0073] The optical path and phase control component is used to control the optical path and phase of the reference laser beam carrying the second harmonic, so that the optical path and phase of the reference laser beam match the optical path and phase of the subsequent combined detection laser beam;

[0074] The polarization direction control component is used to perform extinction, light intensity and polarization control to match the light intensity and polarization direction of the reference laser beam with the subsequent combined detection laser beam.

[0075] More specifically, the reference beam generating assembly includes: a second convex lens, a frequency doubling crystal, and a third convex lens;

[0076] The second convex lens is used to focus the incident laser beam and then inject it into the frequency doubling crystal;

[0077] The frequency doubling crystal is used to frequency-double the incident laser beam to generate a reference laser beam carrying a second harmonic;

[0078] The frequency doubling crystal is a frequency doubling crystal including a BBO crystal.

[0079] The third convex lens is used to focus the reference laser beam emitted by the frequency doubling crystal, and output the focused reference laser beam to the optical path and phase control component.

[0080] More specifically, the polarization direction control component includes a second polarizer, an attenuation plate and a third half-wave plate;

[0081] The second polarizer is used to enhance the extinction ratio of polarized light of the incident laser beam;

[0082] The attenuation plate is used to control the light intensity of the laser beam output by the second polarizer;

[0083] The third half-wave plate is used to control the polarization direction of the laser beam output by the attenuation plate, so that the polarization direction of the reference laser beam matches the polarization direction of the subsequent combined detection laser beam.

[0084] More specifically, the optical path and phase control assembly includes: a first reflector, a second filter, a second reflector and an electric translation stage;

[0085] The first reflector and the second reflector are arranged at mutually symmetrical angles; the incident laser beam of the first reflector is reflected by the second reflector after being reflected by the first reflector, and the outgoing laser beam after being reflected by the second reflector is parallel to the incident beam of the first reflector;

[0086] Between the first reflector and the second reflector, the incident laser beam passes through the second filter to filter out the fundamental frequency beam;

[0087] The electric translation stage is used to carry the first reflector, the second filter and the second reflector, and to drive the first reflector and the second reflector to translate according to the control information, and simultaneously approach or move away from the incident light beam direction of the first reflector;

[0088] The incident light beam of the first reflector is the reference laser beam focused by the third convex lens, and the outgoing light beam of the second reflector is incident on the second polarizer;

[0089] The optical path and phase of the laser beam emitted from the third convex lens and incident on the second polarizer are controlled by controlling the translation of the electric translation stage.

[0090] Specifically, the outgoing optical path component includes a first convex lens, a beam splitter, and a first filter multiplexed with the incident optical path component;

[0091] In the outgoing optical path component, the multiplexed first convex lens is used to collimate the vertically reflected laser beam carrying the second harmonic generated on the sample;

[0092] The beam splitter is used to provide an optical path for the collimated reflected laser beam;

[0093] The first filter is used to perform fundamental frequency light filtering on the collimated reflected laser beam, and output the reflected laser beam after fundamental frequency light filtering as a detection laser beam to the beam combining detection component.

[0094] Since the incident laser beam irradiates the sample on the sample stage vertically, the incident light path and the reflected light path overlap. In this way, the first convex lens in the incident light path, which focuses the incident laser beam, has the function of collimating the laser beam reflected from the sample.

[0095] Furthermore, since the beam splitter in the incident light path splits a beam of laser light to point to the sample stage, which is perpendicular to the sample carried by the sample stage, the reflected laser beam must return to the beam splitter along the light path of the split laser beam. The laser needs to provide an optical path for the collimated reflected laser beam.

[0096] Specifically, the beam splitter prism includes a first light input end, a second light input end, a first light output end, a second light output end, and a third light output end;

[0097] The light beam incident on the first light input end is split, and a beam of split light is emitted from the first light output end and the second light output end respectively; the position of the second light input end coincides with the first light output end, and the light beam incident on the second light input end is not split, and the light beam is directly output from the third light output end.

[0098] Specifically, the beam combining detection assembly includes: a beam combiner, a fourth convex lens and a photodetector;

[0099] The beam combiner is used to combine the incident exploration laser beam after filtering the fundamental frequency light and the polarization-matched reference laser beam, and output the combined beam light;

[0100] The fourth convex lens is used to focus the combined light beam onto the photodetector;

[0101] The photoelectric detector is used to use the detection laser beam as signal light and the reference laser beam as local oscillator light to perform coherent detection and extract the interface signal in the second harmonic.

[0102] Since the signal light and the local oscillator light come from the incident linearly polarized ultrashort laser pulse emitted by the same laser, and the optical path and phase of the local oscillator light are adjusted to be consistent with the signal light, and the polarization direction of the local oscillator light is adjusted to be consistent with that of the signal light; after coherent detection, the interface signal in the pure second harmonic can be obtained.

[0103] In a more preferred embodiment, the sample stage is a 6-dimensional sample stage. By controlling the displacement and rotation of the sample stage and adopting a mapping scanning method, the movement of the sample stage is controlled to scan and detect the sample. The interface signal in the detected second harmonic is spliced ​​according to the scanning data points to obtain the interface signal of the entire sample.

[0104] The process of extracting the interface signal from the second harmonic of the sample by the vertical characterization system based on the coherent detection technology includes:

[0105] The laser emits 800nm, 100fs linearly polarized ultrashort laser pulses. The light beam changes the polarization direction of the laser through a half-wave plate, and cooperates with a Glan prism to complete the screening of laser polarization and realize the control of laser power. The laser beam with a specific polarization direction emitted from the Glan prism further strengthens the extinction ratio of polarized light through a polarizer to ensure that it has better polarization characteristics, and then controls the polarization direction of the laser through a half-wave plate. The laser is divided into two beams by a beam splitter. One beam is vertically focused on the sample through a lens to generate a second harmonic. The signal reflected by the second harmonic is collimated by a lens and filtered out through a filter to filter out the fundamental frequency light and enter the beam combiner. The other beam is focused on the frequency doubling crystal through a lens to complete the generation of the second harmonic, and the signal is collimated through a lens. The control of the optical path and phase of the detection path signal is realized through the combination of an electric translation stage and a reflector. The light beam strengthens the extinction ratio of polarized light through a polarizer, and the light intensity is controlled through an attenuator. Then, the polarization direction of the detection light is controlled through a half-wave plate to complete the polarization matching of the signal beam. Finally, two beams of light with the same polarization direction and comparable intensity are combined in a beam combiner and focused on a detector through a lens. Coherent detection is achieved by controlling the phase of the detection beam to extract the interface signal in the second harmonic.

[0106] In summary, the vertical characterization system based on coherent detection technology of this embodiment can distinguish the second harmonic interface signal and the body signal in the vertical direction by utilizing the coherent detection technology, realize the extraction of the interface signal in the non-centrosymmetric material system, and further expand the application scenarios of the second harmonic characterization technology.

[0107] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A vertical characterization system based on coherent detection technology, characterized in that: include: An incident light path component, an output light path component, a reference light path component and a beam combining detection component; The incident optical path component is used to generate an incident light beam; after polarization control and spectral splitting of the generated incident linearly polarized ultrashort laser pulse, a beam of split laser light perpendicular to the sample obtained after spectral splitting is vertically focused on the sample, and a vertical reflected laser beam carrying a second harmonic is generated after reflection; and another beam of split laser light obtained after spectral splitting is output to the reference optical path component; The outgoing optical path component is used to receive the vertical reflected laser beam and obtain the detection laser beam after filtering; The reference optical path component is used to obtain a reference laser beam carrying a second harmonic after frequency doubling, optical path and phase control, and polarization direction control of the input split laser beam; The beam combining and detecting component is used to combine and focus the reference laser beam and the detecting laser beam, and then perform coherent detection to extract the sample interface signal in the second harmonic.

2. The vertical characterization system based on coherent detection technology according to claim 1, characterized in that: The incident light path component includes: a laser, a polarization control component, a beam splitter, and a first convex lens; The laser is used to generate ultrashort laser pulses with incident linear polarization and output to the polarization control component; The polarization control component is used to adjust the polarization direction of the incident laser beam and screen the polarization direction to control the laser power, and after further performing extinction ratio enhancement and polarization direction control on the power-controlled incident laser beam, an incident laser beam that meets the test conditions is obtained and output to the spectrometer; The beam splitter is used to split the laser beam output by the polarization control component to output two split laser beams, wherein one split laser beam points to the sample stage and is perpendicular to the sample carried by the sample stage; the other split laser beam points to the reference optical path component and is output to the reference optical path component; The first convex lens is used to focus the split laser beam perpendicular to the sample on the sample, and generate a second harmonic carrying the sample defect information after reflection.

3. The vertical characterization system based on coherent detection technology according to claim 2, characterized in that: The polarization control assembly includes: a first half-wave plate, a Glan-Taylor polarizer, a first polarizer, and a second half-wave plate; The first half-wave plate is used to change the polarization direction of the incident laser beam according to the test requirements and output it to the Glan-Taylor polarizer; The Glan-Taylor polarizer is used to screen the polarization direction of the incident laser beam, output a light beam with a set polarization direction to the first polarizer, and cooperate with the half-wave plate to realize the control of the laser power; The first polarizer is used to further enhance the extinction ratio of polarized light and enhance the polarization characteristics of the light beam with a set polarization direction emitted by the Glan-Taylor polarizer; The second half-wave plate is used to change the polarization direction of the laser beam output by the first polarizer according to the test requirements, and output an incident laser beam that meets the test conditions.

4. The vertical characterization system based on coherent detection technology according to claim 2, characterized in that: The reference optical path component comprises: a reference beam generating component, an optical path and phase control component and a polarization direction control component; The reference beam generating component is used to frequency-double the incident split beam laser to generate a reference laser beam carrying the second harmonic and output it to the optical path and phase control component; The optical path and phase control component is used to control the optical path and phase of the reference laser beam carrying the second harmonic, so that the optical path and phase of the reference laser beam match the optical path and phase of the subsequent combined detection laser beam; The polarization direction control component is used to perform extinction, light intensity and polarization control to match the light intensity and polarization direction of the reference laser beam with the subsequent combined detection laser beam.

5. The vertical characterization system based on coherent detection technology according to claim 4, characterized in that: The reference beam generating assembly comprises: a second convex lens, a frequency doubling crystal, and a third convex lens; The second convex lens is used to focus the incident laser beam and then inject it into the frequency doubling crystal; The frequency doubling crystal is used to frequency-double the incident laser beam to generate a reference laser beam carrying a second harmonic; The third convex lens is used to focus the reference laser beam emitted by the frequency doubling crystal, and output the focused reference laser beam to the optical path and phase control component.

6. The vertical characterization system based on coherent detection technology according to claim 5, characterized in that: The polarization direction control component includes a second polarizer, an attenuation plate and a third half-wave plate; The second polarizer is used to enhance the extinction ratio of polarized light of the incident laser beam; The attenuation plate is used to control the light intensity of the laser beam output by the second polarizer; The third half-wave plate is used to control the polarization direction of the laser beam output by the attenuation plate, so that the polarization direction of the reference laser beam matches the polarization direction of the subsequent combined detection laser beam.

7. The vertical characterization system based on coherent detection technology according to claim 6, characterized in that: The optical path and phase control assembly comprises: a first reflector, a second filter, a second reflector and an electric translation stage; The first reflector and the second reflector are arranged at mutually symmetrical angles; the incident laser beam of the first reflector is reflected by the second reflector after being reflected by the first reflector, and the outgoing laser beam after being reflected by the second reflector is parallel to the incident beam of the first reflector; Between the first reflector and the second reflector, the incident laser beam passes through the second filter to filter out the fundamental frequency beam; The electric translation stage is used to carry the first reflector, the second filter and the second reflector, and to drive the first reflector and the second reflector to translate according to the control information, and simultaneously approach or move away from the incident light beam direction of the first reflector; The incident light beam of the first reflector is the reference laser beam focused by the third convex lens, and the outgoing light beam of the second reflector is incident on the second polarizer; The optical path and phase of the laser beam emitted from the third convex lens and incident on the second polarizer are controlled by controlling the translation of the electric translation stage.

8. The vertical characterization system based on coherent detection technology according to claim 4, characterized in that: The outgoing optical path component includes a first convex lens, a beam splitter, and a first filter multiplexed with the incident optical path component; In the outgoing optical path component, the multiplexed first convex lens is used to collimate the vertically reflected laser beam carrying the second harmonic generated on the sample; The beam splitter is used to provide an optical path for the collimated reflected laser beam; The first filter is used to perform fundamental frequency light filtering on the collimated reflected laser beam, and output the reflected laser beam after fundamental frequency light filtering as a detection laser beam to the beam combining detection component.

9. The vertical characterization system based on coherent detection technology according to claim 8, characterized in that: The beam splitter prism comprises a first light input end, a second light input end, a first light output end, a second light output end and a third light output end; The light beam incident on the first light input end is split, and a beam of split light is emitted from the first light output end and the second light output end respectively; the position of the second light input end coincides with the first light output end, and the light beam incident on the second light input end is not split, and the light beam is directly output from the third light output end.

10. The vertical characterization system based on coherent detection technology according to claim 8, characterized in that: The beam combining detection assembly comprises: a beam combiner, a fourth convex lens and a photoelectric detector; The beam combiner is used to combine the incident exploration laser beam after filtering the fundamental frequency light and the polarization-matched reference laser beam, and output the combined beam light; The fourth convex lens is used to focus the combined light beam onto the photodetector; The photoelectric detector is used to use the detection laser beam as signal light and the reference laser beam as local oscillator light to perform coherent detection and extract the interface signal in the second harmonic.

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