CN113655018A - A Terahertz Time-Domain Spectroscopy System for Microstructural Characterization of Multiferroic Materials - Google Patents
A Terahertz Time-Domain Spectroscopy System for Microstructural Characterization of Multiferroic Materials Download PDFInfo
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- 238000003384 imaging method Methods 0.000 claims description 5
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- G01N21/3586—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using far infrared light; using Terahertz radiation by Terahertz time domain spectroscopy [THz-TDS]
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Abstract
本发明公开了一种用于多铁性材料微结构表征的太赫兹时域光谱系统，包括飞秒激光器、太赫兹发射器和太赫兹探测器。通过借助LiNbO3晶体太赫兹发射技术，利用强太赫兹脉冲提高了太赫兹时域谱系统中太赫兹源脉冲的能量，产生能量大于1.5微焦，频谱在0.1‑2.0THz范围的太赫兹脉冲，在待测样品前配置两个可旋转的用于调节太赫兹强度和确定所需入射光偏振方向金属线栅太赫兹线偏振器第一WGP和第二WGP，在待测样品后放置两个太赫兹线偏振器第三WGP和第四WGP，确保最大效率探测Ey或Ex太赫兹分量，得到两个相互垂直的太赫兹电场分量，并将太赫兹时域谱技术结合9T超导磁体，可以直接测量太赫兹透射的幅度、相位和偏振，获得强磁场下共振吸收、旋光性等自旋动力学信息。
The invention discloses a terahertz time-domain spectroscopic system for microstructure characterization of multiferroic materials, comprising a femtosecond laser, a terahertz transmitter and a terahertz detector. With the help of LiNbO 3 crystal terahertz emission technology, the energy of the terahertz source pulse in the terahertz time-domain spectrum system is increased by using the strong terahertz pulse, and the energy of the terahertz pulse is greater than 1.5 microjoules and the spectrum is in the range of 0.1-2.0THz. Two rotatable metal wire grid terahertz linear polarizers, the first WGP and the second WGP, are arranged in front of the sample to be tested for adjusting the terahertz intensity and determining the polarization direction of the required incident light. Two terahertz linear polarizers are placed behind the sample to be tested. The third WGP and the fourth WGP of Hertz linear polarizers ensure maximum efficiency to detect E y or Ex terahertz components, obtain two mutually perpendicular terahertz electric field components, and combine terahertz time-domain spectroscopy technology with 9T superconducting magnets, The amplitude, phase and polarization of terahertz transmission can be directly measured, and information on spin dynamics such as resonance absorption and optical rotation under strong magnetic fields can be obtained.
Description
Technical Field
The invention relates to the field of multiferroic materials, in particular to a terahertz time-domain spectroscopy system for microstructural characterization of multiferroic materials.
Background
Multiferroic materials have been widely studied because of their abundant physical properties and broad application prospects. Recently, researches show that the hexaferrite material can generate magnetically induced ferroelectric polarization under high temperature and low magnetic field, so that the application of magnetoelectric coupling effect is a new step, however, the magnetoelectric coupling effect of the material is weak and the dynamic magnetoelectric coupling mechanism is not clear yet. The invention aims to research an element excitation-electromagnetic vibrator of the magnetoelectric coupling effect of a hexagonal ferrite sample in a strong magnetic field environment by using a terahertz time-domain spectroscopy technology so as to explore a microscopic mechanism generated by the electromagnetic vibrator and main factors influencing magnetoelectric coupling.
Therefore, the research on the electromagnetic vibrator is beneficial to researching and researching the micro mechanism of magnetoelectric coupling of the hexagonal ferrite material and regulating the magnetoelectric coupling, the terahertz pulse spinning regulation based on the electromagnetic vibrator is preliminarily realized by deeply researching the characteristics of the electromagnetic vibrator in the material, the excitation mechanism and the selection rule of the electromagnetic vibrator through a terahertz time-domain spectroscopy system, the exploration on the spinning dynamics problems of chirality, resonance absorption, terahertz Faraday rotation and the like of the magneton of the material is simultaneously carried out, the precession mode and the relaxation process of the helical state magnetic moment in a terahertz frequency band are understood, the micro mechanism of magnetoelectric coupling in the multiferroic material is researched and regulated by combining the experimental results, and the experimental foundation is laid for exploring a new characterization method of magnetoelectric coupling in the multiferroic material and discovering new phenomena.
The electromagnetic vibrator is a low-energy magnetic vibrator, which can be excited by an alternating electric field due to the coupling with an optical phonon, and the element excitation has the following two characteristics: first, because it is a magneton that can be directly excited by the electric field component of an electromagnetic wave, it is found that its frequency tends to be in the terahertz band, lower than the frequency of an optical phonon in a sample to be measured. Secondly, the excitation of the electromagnetic vibrator has a selection rule, that is, the electromagnetic vibrator can be excited only by placing an alternating electric field along a certain specific crystal axis. Due to the particularity of the electromagnetic vibrator, a common terahertz time-domain spectroscopy system is difficult to excite and observe the electromagnetic vibrator, and therefore the terahertz time-domain spectroscopy system for microstructure representation of multiferroic materials is provided.
Disclosure of Invention
The invention mainly aims to provide a terahertz time-domain spectroscopy system for microstructure characterization of multiferroic materials by means of LiNbO3The crystal terahertz emission technology utilizes strong terahertz pulses to improve the energy of terahertz source pulses in a terahertz time-domain spectroscopy system, generates terahertz pulses with the energy larger than 1.5 microjoules and the frequency spectrum in the range of 0.1-2.0THz, and is arranged in front of a sample to be detectedTwo rotatable metal wire grid terahertz linear polarizers, namely a first WGP and a second WGP, are configured and used for adjusting terahertz intensity and determining the polarization direction of required incident light, and a third WGP and a fourth WGP are placed behind a sample to be detected so as to ensure the maximum efficiency detection E yOr ExThe terahertz component is obtained to obtain two orthogonal terahertz electric field components, a terahertz time-domain spectroscopy technology is combined with a 9T superconducting magnet, four optical windows of a low-temperature superconducting magnet are utilized, two geometrically configured optical paths with magnetic fields perpendicular to and parallel to the terahertz light propagation direction are designed, the amplitude, the phase and the polarization of terahertz transmission can be directly measured, further, the spin dynamics information such as resonance absorption and optical rotation in a strong magnetic field can be simultaneously obtained, and the problem in the background technology can be effectively solved.
In order to achieve the purpose, the invention adopts the technical scheme that:
a terahertz time-domain spectroscopy system for the representation of a multiferroic material microstructure comprises a femtosecond laser used for emitting femtosecond laser pulses, a terahertz emitter used for generating terahertz waves and a terahertz detector used for detecting terahertz polarization, wherein the femtosecond laser emits the femtosecond laser pulses, a spectroscope used for separating the laser pulses is arranged on a transmission route of the femtosecond laser pulses, the femtosecond laser pulses are divided into a pumping light path and a detection light path by the spectroscope, reflecting plates are arranged on the transmission routes of the pumping light path and the detection light path, the pumping light path enters the terahertz emitter after being reflected by the reflecting plates to generate the terahertz waves, a front-arranged THz terahertz line polarizer used for adjusting terahertz intensity and determining the polarization direction of incident light, a superconducting magnet used for generating a magnetic field and a rear-arranged THz terahertz line polarizer used for obtaining terahertz electric field components are sequentially arranged on the transmission route of the terahertz waves, a sample to be detected is placed on a sample frame of the superconducting magnet, the sample to be detected is installed at the central position of the superconducting magnet, and a detection light path is reflected by a reflecting plate, sequentially penetrates through a first half-wave plate, a polarizing crystal, a first lens and a rear THz terahertz linear polarizer and then enters a terahertz detector.
Further, the femtosecond laser emits femtosecond laser pulses with a wavelength of 800nm and a pulse width of 50 fs.
Further, the terahertz transmitter comprises a grating for pumping optical path wave front inclination, a second lens, a second half-wave plate and LiNbO for imaging3And after a pumping light path enters the terahertz transmitter, the terahertz transmitter sequentially passes through the grating, the second lens and the second half-wave plate, images are formed on the LiNbO crystal, and terahertz pulses are generated through excitation.
Furthermore, the terahertz detector comprises a ZnTe crystal, a lambda/4 wave plate, a third half-wave plate and a phase-locked amplifier.
Furthermore, the front-mounted THz terahertz linear polarizer comprises a first WGP which is arranged on the terahertz wave transmission line and can independently rotate and is used for adjusting terahertz intensity, a second WGP which is used for determining the polarization direction of incident light, and front-mounted gold-plated parabolic mirrors which are symmetrically distributed on the upper side and the lower side of the first WGP and the second WGP and are used for reflecting light paths.
Furthermore, four optical windows are arranged on the outer side of the superconducting magnet, namely two horizontal optical windows parallel to the magnetic field direction and two vertical optical windows perpendicular to the magnetic field direction.
Furthermore, the reflecting plate is symmetrically arranged on the outer side of the vertical optical window.
Furthermore, the rear-mounted THz terahertz linear polarizer comprises a third WGP and a fourth WGP which are arranged on the terahertz wave transmission line and rear-mounted gold-plated parabolic mirrors which are symmetrically distributed on the upper side and the lower side of the third WGP and the fourth WGP, and the terahertz pulses entering the front-mounted THz terahertz linear polarizer sequentially pass through the third WGP and the fourth WGP after being reflected by the rear-mounted gold-plated parabolic mirrors on the upper side.
Furthermore, the terahertz detector detects the electric field component E in a free space electro-optical detection modexAnd EyElectro-optical sampling is performed.
Furthermore, the magnetic field intensity of the superconducting magnet is adjusted within the range of 0-9T, and the temperature is adjusted within the range of 4-300K.
Further, the device comprises the following steps:
step one, flyingThe femtosecond laser device emits femtosecond laser pulse, the femtosecond laser pulse is divided into a pumping light path and a detection light path after passing through the spectroscope, the pumping light path enters the terahertz transmitter after being reflected by the reflecting plate, and the pumping light path sequentially passes through the grating, the second lens and the second half-wave plate after the grating wave front is inclined, and is positioned on the LiNbO3Imaging on the crystal, and exciting to generate terahertz pulses with energy greater than 1.5 microjoules and frequency spectrum in the range of 0.1-2.0 THz;
step two, the terahertz pulse is reflected by a front gold-plating paraboloid mirror positioned on the upper side of a front THz terahertz linear polarizer, then sequentially penetrates through a first WGP and a second WGP which can independently rotate, and is reflected by the front gold-plating paraboloid mirror positioned on the lower side of the front THz terahertz linear polarizer, the reflected terahertz pulse is irradiated on a sample to be detected arranged on a sample rack in the middle of the superconducting magnet through a horizontal optical window of the superconducting magnet, penetrates through the sample to be detected, is reflected by a rear gold-plating paraboloid mirror positioned on the upper side of a rear THz terahertz linear polarizer, then penetrates through a third WGP distributed at positive 45 degrees, and is reflected by a fourth WGP and the rear gold-plating paraboloid mirror positioned on the lower side of the rear THz terahertz linear polarizer to reach a terahertz detector, so that a configured terahertz component E is obtained x；
Adjusting the configuration state of a third WGP, enabling the terahertz pulse to pass through the third WGP distributed at minus 45 degrees after being reflected by a rear gold-plated parabolic mirror positioned on the upper side of the rear THz terahertz linear polarizer, and then to pass through a fourth WGP and a rear gold-plated parabolic mirror positioned on the lower side of the rear THz terahertz linear polarizer to reach a terahertz detector after being reflected by a rear gold-plated parabolic mirror to obtain a configured terahertz component Ey；
The detection light path is reflected by the reflecting plate, then sequentially passes through the first half-wave plate, the polarizing crystal, the first lens and the rear THz terahertz linear polarizer, then enters the terahertz detector, the terahertz pulse entering the terahertz detector and the detection light path pass through the ZnTe nonlinear optical crystal, and the electric field component E is detected in a free space electro-optic detection modexAnd EyElectro-optical sampling is performed, and frequency signals are separated through a phase-locked amplifier to obtain spectral information.
The invention has the following beneficial effects:
compared with the prior art, by means of LiNbO3The crystal terahertz emission technology improves the energy of terahertz source pulses in a terahertz time-domain spectroscopy system by using strong terahertz pulses, can generate terahertz pulses with energy larger than 1.5 microjoules and frequency spectrum in the range of 0.1-2.0 THz, and is favorable for exciting and detecting electromagnetic vibrators;
Compared with the prior art, the method has the advantages that the first WGP and the second WGP of the two rotatable metal wire grid terahertz linear polarizers are arranged in front of a sample to be detected and used for adjusting terahertz intensity and determining the polarization direction of required incident light, and the third WGP and the fourth WGP of the two terahertz linear polarizers are arranged behind the sample to be detected, so that the maximum efficiency detection E can be ensuredyOr ExObtaining two orthogonal terahertz electric field components, namely the terahertz polarization of an xy plane;
compared with the prior art, the terahertz time-domain spectroscopy technology is combined with a 9T superconducting magnet, four optical windows of a low-temperature superconducting magnet are utilized, two geometrically configured optical paths with magnetic fields perpendicular to and parallel to the terahertz light propagation direction are designed, the amplitude, the phase and the polarization of terahertz transmission can be directly measured, further, the spin dynamics information such as resonance absorption and optical rotation under a strong magnetic field can be simultaneously obtained, and analysis is carried out according to the obtained spin dynamics information, so that the dynamic magnetoelectric coupling micro mechanism of the researched multiferroic material can be known.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the technical description of the present invention will be briefly introduced below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive labor.
FIG. 1 is a schematic overall structure diagram of a terahertz time-domain spectroscopy system for microstructural characterization of multiferroic materials according to the present invention;
FIG. 2 is a schematic diagram of an installation structure of a terahertz time-domain spectroscopy system superconducting magnet for microstructure characterization of a multiferroic material according to the present invention;
FIG. 3 is a terahertz wave polarization regulation and control schematic diagram of a terahertz time-domain spectroscopy system for multiferroic material microstructure representation according to the present invention;
FIG. 4 is a schematic diagram of an internal structure of a terahertz transmitter of a terahertz time-domain spectroscopy system for microstructural characterization of multiferroic materials according to the present invention;
FIG. 5 is a schematic diagram of an internal structure of a terahertz detector of a terahertz time-domain spectroscopy system for microstructural characterization of multiferroic materials.
In the figure: 1. a femtosecond laser; 2. a terahertz transmitter; 21. a grating; 22. a second lens; 23. a second half-wave plate; 24. LiNbO3A crystal; 3. a terahertz detector; 31. ZnTe crystal; 32. a lambda/4 wave plate; 33. a third half-wave plate; 34. a phase-locked amplifier; 4. a beam splitter; 5. a reflective plate; 6. a front THz terahertz linear polarizer; 61. a first WGP; 62. a second WGP; 63. a front gold-plated parabolic mirror; 7. a superconducting magnet; 71. a horizontal optical window; 72. a vertical optical window; 8. a rear THz terahertz linear polarizer; 81. a third WGP; 82. a fourth WGP; 83. a rear gold-plated parabolic mirror; 9. a sample to be tested; 10. a first half wave plate; 11. a polarizing crystal; 12. a first lens.
Detailed Description
The present invention will be further described with reference to the following detailed description, wherein the drawings are for illustrative purposes only and are not intended to be limiting, wherein certain elements may be omitted, enlarged or reduced in size, and are not intended to represent the actual dimensions of the product, so as to better illustrate the detailed description of the invention.
Example 1
As shown in fig. 1-5, a terahertz time-domain spectroscopy system for characterizing a multiferroic material microstructure includes a femtosecond laser 1, a terahertz emitter 2 and a terahertz detector 3, the femtosecond laser 1 emits femtosecond laser pulses, a spectroscope 4 is arranged on a propagation path of the femtosecond laser pulses, the femtosecond laser pulses are divided into a pumping light path and a detection light path by the spectroscope 4, reflecting plates 5 are respectively arranged on the propagation paths of the pumping light path and the detection light path, the pumping light path enters the terahertz emitter 2 after being reflected by the reflecting plates 5 to generate terahertz waves, a front THz terahertz wire polarizer 6, a rear THz terahertz wire polarizer 7 and a rear THz terahertz wire polarizer 8 are sequentially arranged on the propagation path of the terahertz waves, a sample 9 to be tested is placed on a sample holder of the superconducting magnet 7, the sample 9 to be tested is installed at a central position of the superconducting magnet 7, the detection light path is reflected by the reflecting plate 5, then sequentially passes through the first half-wave plate 10, the polarization crystal 11, the first lens 12 and the rear THz terahertz linear polarizer 8, and then enters the terahertz detector 3.
The front THz terahertz wire polarizer 6 comprises a first WGP61 and a second WGP62 which are arranged on a terahertz wave transmission line and can rotate independently, and front gold-plated parabolic mirrors 63 which are symmetrically distributed on the upper side and the lower side of the first WGP61 and the second WGP 62.
Four optical windows, namely two horizontal optical windows 71 parallel to the magnetic field direction and two vertical optical windows 72 perpendicular to the magnetic field direction, are formed on the outer side of the superconducting magnet 7.
The reflecting plate 5 is symmetrically arranged at the outer side of the vertical optical window 72.
The rear THz terahertz wire polarizer 8 comprises a third WGP81 and a fourth WGP82 which are arranged on a terahertz wave transmission line, and rear gold-plated parabolic mirrors 83 which are symmetrically distributed on the upper side and the lower side of the third WGP81 and the fourth WGP82, wherein terahertz pulses entering the front THz terahertz wire polarizer 6 sequentially pass through the third WGP81 and the fourth WGP82 after being reflected by the rear gold-plated parabolic mirrors 83 on the upper side.
By adopting the technical scheme: when an optical path of a magnetic field perpendicular to the terahertz light propagation direction needs to be configured, the height of the front THz terahertz linear polarizer 6 is adjusted, so that the center of the reflecting surface of the front gold-plated parabolic mirror 63 located below the second WGP and the center of the reflecting plate 5 located above the superconducting magnet 7 are on the same straight line, the center of the reflecting surface of the rear gold-plated parabolic mirror 83 located above the third WGP81 and the center of the reflecting plate 5 located below the superconducting magnet 7 are on the same straight line, at this time, the terahertz wave reflected by the front gold-plated parabolic mirror 63 located below the second WGP reaches the reflecting plate 5 located above the superconducting magnet 7 along the horizontal direction, the terahertz wave enters from the vertical optical window 72 at the upper end of the superconducting magnet 7 after being reflected by the reflecting plate 5 and irradiates at the sample 9 to be measured, then is emitted from the vertical optical window 72 at the lower end of the superconducting magnet 7, and irradiates at the center of the reflecting surface of the rear gold-plated parabolic mirror 83 located above the third WGP81 after being reflected by the reflecting plate 5, at this time, the propagation direction of the terahertz light is perpendicular to the direction of the magnetic field.
Example 2
As shown in fig. 1-5, a terahertz time-domain spectroscopy system for characterizing a multiferroic material microstructure includes a femtosecond laser 1, a terahertz emitter 2 and a terahertz detector 3, the femtosecond laser 1 emits femtosecond laser pulses, a spectroscope 4 is arranged on a propagation path of the femtosecond laser pulses, the femtosecond laser pulses are divided into a pumping light path and a detection light path by the spectroscope 4, reflecting plates 5 are respectively arranged on the propagation paths of the pumping light path and the detection light path, the pumping light path enters the terahertz emitter 2 after being reflected by the reflecting plates 5 to generate terahertz waves, a front THz terahertz wire polarizer 6, a rear THz terahertz wire polarizer 7 and a rear THz terahertz wire polarizer 8 are sequentially arranged on the propagation path of the terahertz waves, a sample 9 to be tested is placed on a sample holder of the superconducting magnet 7, the sample 9 to be tested is installed at a central position of the superconducting magnet 7, the detection light path is reflected by the reflecting plate 5, then sequentially passes through the first half-wave plate 10, the polarization crystal 11, the first lens 12 and the rear THz terahertz linear polarizer 8, and then enters the terahertz detector 3.
The femtosecond laser 1 emits femtosecond laser pulses with a wavelength of 800 nm and a pulse width of 50 fs.
The terahertz transmitter 2 includes a grating 21, a second lens 22, a second half-wave plate 23, and LiNbO 3After entering the terahertz transmitter 2, the pumping optical path of the crystal 24 sequentially passes through the grating 21, the second lens 22 and the second half-wave plate 23 and is on LiNbO3Imaging is carried out on the crystal 24, and terahertz pulses are generated through excitation.
By adopting the technical scheme: by means of LiNbO3The crystal 24 terahertz emission technology improves the energy of terahertz source pulses in a terahertz time-domain spectroscopy system by using strong terahertz pulses, can generate terahertz pulses with energy larger than 1.5 microjoules and frequency spectrum in the range of 0.1-2.0 THz, and is favorable for exciting and detecting electromagnetic vibrators.
Example 3
As shown in fig. 1-5, a terahertz time-domain spectroscopy system for characterizing a multiferroic material microstructure includes a femtosecond laser 1, a terahertz emitter 2 and a terahertz detector 3, the femtosecond laser 1 emits femtosecond laser pulses, a spectroscope 4 is arranged on a propagation path of the femtosecond laser pulses, the femtosecond laser pulses are divided into a pumping light path and a detection light path by the spectroscope 4, reflecting plates 5 are respectively arranged on the propagation paths of the pumping light path and the detection light path, the pumping light path enters the terahertz emitter 2 after being reflected by the reflecting plates 5 to generate terahertz waves, a front THz terahertz wire polarizer 6, a rear THz terahertz wire polarizer 7 and a rear THz terahertz wire polarizer 8 are sequentially arranged on the propagation path of the terahertz waves, a sample 9 to be tested is placed on a sample holder of the superconducting magnet 7, the sample 9 to be tested is installed at a central position of the superconducting magnet 7, the detection light path is reflected by the reflecting plate 5, then sequentially passes through the first half-wave plate 10, the polarization crystal 11, the first lens 12 and the rear THz terahertz linear polarizer 8, and then enters the terahertz detector 3.
The terahertz detector 3 includes a ZnTe crystal 31, a λ/4 wave plate 32, a third half-wave plate 33, and a lock-in amplifier 34.
Four optical windows, namely two horizontal optical windows 71 parallel to the magnetic field direction and two vertical optical windows 72 perpendicular to the magnetic field direction, are formed on the outer side of the superconducting magnet 7.
The magnetic field intensity of the superconducting magnet 7 is adjusted within the range of 0-9T, and the temperature is adjusted within the range of 4-300K.
By adopting the technical scheme: by combining the terahertz time-domain spectroscopy technology with the 9T superconducting magnet 7 and utilizing four optical windows of the low-temperature superconducting magnet 7, two geometrically configured optical paths with magnetic fields perpendicular to and parallel to the terahertz light propagation direction are designed, the amplitude, the phase and the polarization of terahertz transmission can be directly measured, further, the spin dynamics information such as resonance absorption, optical rotation and the like under a strong magnetic field can be simultaneously obtained, and analysis is carried out according to the obtained spin dynamics information so as to understand the dynamic magnetoelectric coupling micro mechanism of the studied multiferroic material.
When the terahertz time-domain spectroscopy system for the microstructure characterization of the multiferroic material is used, the femtosecond laser 1 emits femtosecond laser pulses, the femtosecond laser pulses are divided into a pumping optical path and a detection optical path after passing through the spectroscope 4, the pumping optical path is reflected by the reflecting plate 5 and enters the terahertz transmitter 2, the wavefront of the grating 21 inclines, the pumping optical path sequentially passes through the grating 21, the second lens 22 and the second half-wave plate 23, and the pumping optical path is subjected to LiNbO 3Imaging on the crystal 24, exciting to generate terahertz pulses with energy larger than 1.5 micro-focus and frequency spectrum within the range of 0.1-2.0THz, wherein the terahertz pulses are reflected by a front gold-plated parabolic mirror 63 positioned on the upper side of a front THz terahertz linear polarizer 6, sequentially pass through a first WGP61 and a second WGP62 which can rotate independently, and are reflected by the front gold-plated parabolic mirror 63 positioned on the lower side of the front THz terahertz linear polarizer 6, the reflected terahertz pulses are irradiated on a sample 9 to be detected which is arranged on a sample rack in the middle of a superconducting magnet 7 through a horizontal optical window 71 of the superconducting magnet 7, penetrate through the sample 9 to be detected, are reflected by a rear gold-plated parabolic mirror 83 positioned on the upper side of a rear THz terahertz linear polarizer 8, pass through a third WGP81 which is distributed at positive 45 degrees, pass through a fourth WGP82 and are reflected by the rear gold-plated parabolic mirror 83 positioned on the lower side of the rear THz terahertz linear polarizer 8, and reach a terahertz detector 3, obtaining a configured terahertz component ExAdjusting the configuration state of the third WGP81, enabling the terahertz pulse to pass through the third WGP81 distributed at negative 45 degrees after being reflected by the rear gold-plated parabolic mirror 83 positioned on the upper side of the rear THz terahertz linear polarizer 8, then pass through the fourth WGP82 and the rear gold-plated parabolic mirror 83 positioned on the lower side of the rear THz terahertz linear polarizer 8, and then reach the terahertz detector 3, and obtaining a configured terahertz component E yThe detection light path is reflected by the reflecting plate 5 and then is orderly arrangedThe terahertz wave passes through the first half-wave plate 10, the polarization crystal 11, the first lens 12 and the rear THz terahertz linear polarizer 8 and then enters the terahertz detector 3, the terahertz pulse entering the terahertz detector 3 and a detection light path pass through the ZnTe nonlinear optical crystal, and the electric field component E is detected in a free space electro-optic detection modexAnd EyElectro-optical sampling is performed and the frequency signal is separated by a lock-in amplifier 34 to obtain spectral information.
The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
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