CN114136915A - System and method for generating broadband terahertz waves with any polarization angle - Google Patents
System and method for generating broadband terahertz waves with any polarization angle Download PDFInfo
- Publication number
- CN114136915A CN114136915A CN202111308190.XA CN202111308190A CN114136915A CN 114136915 A CN114136915 A CN 114136915A CN 202111308190 A CN202111308190 A CN 202111308190A CN 114136915 A CN114136915 A CN 114136915A
- Authority
- CN
- China
- Prior art keywords
- electric field
- generating
- terahertz wave
- light
- polarization angle
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000010287 polarization Effects 0.000 title claims abstract description 97
- 238000000034 method Methods 0.000 title claims abstract description 26
- 230000005684 electric field Effects 0.000 claims abstract description 182
- 238000001514 detection method Methods 0.000 claims abstract description 34
- 238000006243 chemical reaction Methods 0.000 claims abstract description 20
- 239000002131 composite material Substances 0.000 claims abstract description 9
- 230000033228 biological regulation Effects 0.000 claims abstract description 5
- 239000013078 crystal Substances 0.000 claims description 21
- 230000003287 optical effect Effects 0.000 claims description 12
- 239000000523 sample Substances 0.000 claims description 8
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 claims description 3
- 238000005086 pumping Methods 0.000 claims description 2
- 230000000694 effects Effects 0.000 abstract description 4
- 238000010586 diagram Methods 0.000 description 8
- 229910007709 ZnTe Inorganic materials 0.000 description 7
- 238000003384 imaging method Methods 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000003631 expected effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000009659 non-destructive testing Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 238000001328 terahertz time-domain spectroscopy Methods 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3581—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
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/21—Polarisation-affecting properties
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3581—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
- 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]
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
- G01N2021/0106—General arrangement of respective parts
- G01N2021/0112—Apparatus in one mechanical, optical or electronic block
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Analytical Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Toxicology (AREA)
- Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
The invention provides a system and a method for generating broadband terahertz waves with any polarization angle, which comprises a signal generating device and a polarization conversion device, wherein the signal generating device is used for generating pump light, the signal generating device comprises a focusing lens, and the focusing lens is arranged on the light path of the pump light to focus the pump light on the air to excite the air to form air plasma; the polarization conversion device comprises a first electric field generation device for generating a first electric field, a second electric field generation device for generating a second electric field and an electric field regulation device, wherein the first electric field and the second electric field are crossed to form a composite electric field, and the air plasma passes through the composite electric field to form terahertz waves. The intensity of the two crossed electric fields is adjusted, so that the air plasma in the synthetic electric field generates terahertz waves with any polarization angle, the intensity of the terahertz waves can be accurately controlled by adjusting the intensity of the electric field, the loss of the intensity of the terahertz waves is avoided, and the detection effect of the terahertz wave detector is improved.
Description
Technical Field
The invention relates to the technical field of terahertz waves, in particular to a system and a method for generating broadband terahertz waves with any polarization angle.
Background
Due to the particularity of the spectrum position of the terahertz wave, the terahertz wave has the characteristics of high penetrability, low energy, sensitivity to polar molecules, friendliness to non-metallic non-polar materials and the like, and has unique advantages in nondestructive testing and safety monitoring. By utilizing the terahertz time-domain spectroscopy detection system, imaging experiments in different polarization directions are carried out on the sample by changing the polarization directions of incident light and detection light. Because many materials are low in transmittance and large in dispersion, the traditional direct imaging result cannot be distinguished, and the expected effect is difficult to achieve, so that the polarization imaging result needs to be processed to further improve the imaging effect. At present, the mainstream method for obtaining the polarized terahertz wave is to perform polarization tuning on the generated terahertz wave, and generally, the terahertz waves with different polarization angles are obtained by using a wire grid polarizer or other terahertz polarization devices, but such devices cause loss on the intensity of the broadband terahertz wave.
Disclosure of Invention
The invention provides a system and a method for generating broadband terahertz waves with any polarization angle, which are used for solving the defect that terahertz waves with different polarization angles are obtained by utilizing a wire grid polaroid or other terahertz polarization devices in the prior art and loss is caused to the intensity of the broadband terahertz waves.
The invention provides a system for generating broadband terahertz waves with any polarization angle, which comprises:
the signal generating device is used for generating pump light and comprises a focusing lens, wherein the focusing lens is arranged on a light path of the pump light and is used for focusing the pump light in the air to excite the air to form air plasma;
the polarization conversion device comprises a first electric field generation device for generating a first electric field, a second electric field generation device for generating a second electric field, and an electric field adjusting device for adjusting the intensity of the first electric field and/or the second electric field, wherein the first electric field generation device and the second electric field generation device are arranged in a crossed manner, the first electric field and the second electric field are crossed to form a combined electric field, and the polarization conversion device is arranged on a propagation path of the air plasma, so that the air plasma passes through the combined electric field to form terahertz waves.
According to the system for generating the broadband terahertz wave with any polarization angle, which is provided by the invention, the first electric field generation device comprises a pair of first electrode plates and a first power supply which are arranged in parallel, wherein the two first electrode plates are respectively and electrically connected with the anode and the cathode of the first power supply;
the second electric field generating device comprises a pair of second electrode plates and a second power supply which are arranged in parallel, and the two second electrode plates are respectively and electrically connected with the anode and the cathode of the second power supply;
the first power source and/or the second power source is electrically connected with the electric field regulation device.
According to the system for generating the broadband terahertz wave with any polarization angle, provided by the invention, an included angle is formed between the first electrode plate and the second electrode plate.
According to the system for generating the broadband terahertz wave with any polarization angle, provided by the invention, the signal generation device further comprises:
a femtosecond laser for emitting a polarized laser beam;
and the spectroscope is arranged on the light path of the polarized laser beam and is used for dividing the polarized laser beam into the pumping light and the detection light, and the focusing lens is arranged between the spectroscope and the polarization conversion device.
According to the system for generating the broadband terahertz wave with any polarization angle, provided by the invention, the signal generating device further comprises a chopper positioned on the optical path of the pump light, and the chopper is arranged between the spectroscope and the condensing lens.
The system for generating the broadband terahertz wave with any polarization angle further comprises a terahertz wave detection device for detecting the terahertz wave.
According to the system for generating the broadband terahertz wave with any polarization angle, provided by the invention, the terahertz wave detection device comprises:
a first convex lens for focusing the probe light;
the reflector group is used for focusing the terahertz wave and enabling the terahertz wave and the detection light to be located on the same light path;
an electro-optical crystal disposed on an optical path of the probe light and the terahertz wave;
and the photoelectric detector is arranged on a propagation light path of the electro-optical crystal and is used for receiving the terahertz waves and the detection light which pass through the electro-optical crystal.
The invention also provides a method for generating broadband terahertz waves with any polarization angle, and a system for generating broadband terahertz waves with any polarization angle based on any one of the methods comprises the following steps:
controlling a first electric field generating device to generate a first electric field and a second electric field generating device to generate a second electric field, and enabling the first electric field and the second electric field to be crossed to form a composite electric field; the control signal generating device generates pump light, so that the pump light is focused in the air through the focusing lens and excites the air to form air plasma;
passing the air plasma through the resultant electric field;
and adjusting the voltage of the first electric field generating device and/or the second electric field generating device to enable the air plasma to form terahertz waves with any polarization angle.
The method for generating the broadband terahertz wave with any polarization angle further comprises the following steps: and detecting a light intensity signal of the terahertz wave through a photoelectric detector.
According to the method for generating the broadband terahertz wave with any polarization angle, before the photoelectric detector detects the light intensity signal of the terahertz wave, the method further comprises the following steps: the terahertz wave is focused through the reflector group, the detection light generated by the signal generating device is focused through the first convex lens, and the terahertz wave and the detection light are focused on the same optical path and transmitted to the electro-optic crystal.
The system and the method for generating the broadband terahertz wave with any polarization angle comprise a signal generating device and a polarization conversion device. The signal generating device is used for generating pump light and comprises a focusing lens, wherein the focusing lens is arranged on a light path of the pump light and is used for focusing the pump light in air and exciting the air to form air plasma; the polarization conversion device comprises a first electric field generation device, a second electric field generation device and an electric field regulation device, wherein the first electric field generation device is used for generating a first electric field, the second electric field generation device is used for generating a second electric field, and the electric field regulation device is used for regulating the strength of the first electric field and/or the second electric field so as to regulate the polarization angle of the terahertz wave. The first electric field and the second electric field are crossed to form a synthesized electric field, the air plasma forms terahertz waves through the synthesized electric field, and the intensity of the first electric field and/or the second electric field is adjusted through the electric field adjusting device, so that the vector directions of the first electric field and the second electric field are adjusted, and the polarization direction (polarization angle) of the terahertz waves is adjusted.
Compared with the traditional method for generating the terahertz wave, the method provided by the invention has the advantages that the intensity of the two crossed electric fields is adjusted, and the vector directions of the two electric fields are adjusted, so that the air plasma in the combined electric field generates the terahertz wave with any polarization angle, and the intensity of the terahertz wave can be accurately controlled by adjusting the intensity of the electric fields, so that the loss of the intensity of the terahertz wave is avoided, and the detection effect of the terahertz wave detector is improved.
Drawings
In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a system for generating broadband terahertz waves with any polarization angle provided by the invention;
FIG. 2 is a side view of a polarization conversion device provided by the present invention;
FIG. 3 is a side view of a polarization conversion device provided by the present invention;
FIG. 4 is a schematic diagram of a polarization state of a terahertz wave detected by a photodetector provided by the present invention;
FIG. 5 is a second schematic diagram illustrating the polarization state of the terahertz wave detected by the photodetector provided by the present invention;
FIG. 6 is a third schematic diagram of the polarization state of a terahertz wave detected by a photodetector provided by the present invention;
FIG. 7 is a fourth schematic diagram illustrating the polarization state of terahertz waves detected by the photodetector provided by the present invention;
FIG. 8 is a fifth schematic diagram illustrating the polarization state of terahertz waves detected by the photodetector provided by the present invention;
fig. 9 is a sixth schematic diagram of the polarization state of the terahertz wave detected by the photodetector provided by the present invention.
Reference numerals:
1: a signal generating device; 2: a polarization conversion device; 3: a terahertz wave detection device;
11: a femtosecond laser amplifier; 12: a beam splitter; 13: a chopper;
14: first off-axis paraboloids 21: a first electrode plate; 22: a second electrode plate;
a mirror;
31: second off-axis paraboloid 32: a silicon wafer; 33: a first convex lens;
a mirror;
34: third off-axis paraboloid 35: ZnTe crystal; 36: a second convex lens;
a mirror;
37: a photodetector.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The system and method for generating a broadband terahertz wave with an arbitrary polarization angle according to the present invention are described below with reference to fig. 1 to 9.
As shown in fig. 1, the system for generating broadband terahertz waves with any polarization angle provided by the invention comprises a signal generating device 1 and a polarization conversion device 2. The signal generating device 1 is used for generating pump light, and the signal generating device 1 comprises a focusing lens which is arranged on an optical path of the pump light and used for focusing the pump light in air and exciting the air to form air plasma; the polarization conversion device 2 includes a first electric field generation device for generating a first electric field, a second electric field generation device for generating a second electric field, and an electric field adjustment device for adjusting the intensity of the first electric field and/or the second electric field to adjust the polarization angle of the terahertz wave.
Here, the first electric field generating means and the second electric field generating means are surrounded outside the air plasma so that the air plasma passes through the composite electric field.
Specifically, the first electric field generating device and the second electric field generating device may be arranged to intersect such that the first electric field and the second electric field intersect to form a composite electric field, and the polarization conversion device may be arranged on a propagation path of air plasma, the air plasma passes through the composite electric field to form terahertz waves, and the intensity of the first electric field and/or the second electric field is adjusted by the electric field adjusting device to realize adjustment of the vector directions of the first electric field and the second electric field, thereby adjusting the polarization direction (polarization angle) of the terahertz waves.
It should be noted that, by adjusting the strength of the first electric field and the second electric field by the electric field adjusting device, the vector direction of the combined electric field can be adjusted, where the strength of the combined electric field can be calculated by the vector of the first electric field and the second electric field, and the polarization direction of the terahertz wave is parallel to the vector direction of the combined electric field. In this way, by adjusting the intensity of the combined electric field, the polarization angle (polarization direction) of the terahertz wave can be adjusted. As shown in fig. 4-9, they are schematic diagrams of the polarization states of the terahertz waves formed at different synthesized electric field strengths.
The first electric field generated by the first electric field generating device can enable the air plasma to form terahertz waves, the angle between the first electric field and the second electric field can be adjusted by adjusting the vector direction of the second electric field generated by the second electric field generating device, and the intensity of the terahertz waves can be accurately controlled by adjusting the intensity of the first electric field.
Compared with the traditional method for generating the terahertz wave, the method provided by the invention has the advantages that the intensity of the two crossed electric fields is adjusted, and the vector directions of the two electric fields are adjusted, so that the air plasma in the combined electric field generates the terahertz wave with any polarization angle, and the intensity of the terahertz wave can be accurately controlled by adjusting the intensity of the electric fields, so that the loss of the intensity of the terahertz wave is avoided, and the detection effect of the terahertz wave detector is improved.
In an alternative embodiment of the present invention, the first electric field generating device includes a pair of first electrode plates 21 and a first power source, and the second electric field generating device includes a pair of second electrode plates 22 and a second power source, wherein the pair of first electrode plates 21 may be two first electrode plates 21 arranged in parallel, the pair of second electrode plates 22 may be two second electrode plates 22 arranged in parallel, and the two first electrode plates 21 are respectively electrically connected to a positive electrode of the first power source and a negative electrode of the first power source; the two second electrode plates 22 are electrically connected to a positive electrode of the second power source and a negative electrode of the second power source, respectively. By applying current to the first electrode plates 21 and the second electrode plates 22 in this manner, a first electric field is formed between the two first electrode plates 21, and a second electric field is formed between the two second electrode plates 22.
Here, the two first electrode plates 21 are electrically connected to a positive electrode of the first power source and a negative electrode of the first power source through wires, respectively, and the two second electrode plates 22 are electrically connected to a positive electrode of the second power source and a negative electrode of the second power source through wires, respectively. The conductive wire may be a copper conductive wire, and the first electrode plate 21 and the second electrode plate 22 may be made of a conductive material, a metal material, and are not limited to aluminum, copper, and the like. The first power supply and the second power supply may each be a direct current high voltage power supply.
And the first power supply and/or the second power supply are/is electrically connected with the electric field adjusting device so as to adjust the output voltage of the first power supply or the second power supply, thereby realizing the adjustment of the intensity of the first electric field or the second electric field and realizing the adjustment of the polarization angle of the terahertz wave.
It should be noted that two electric field adjusting devices may be provided, and the two electric field adjusting devices may respectively adjust the voltages of the first electric field generating device and the second electric field generating device. Specifically, the electric field adjusting device may be a transformer, or a step switch for adjusting the first power source and the second power source, or a circuit capable of changing the output voltage of the first power source and/or the second power source, and here, the electric field adjusting device is not particularly limited.
In this embodiment, an included angle is formed between the first electrode plate 21 and the second electrode plate 22, so that the formed first electric field and the second electric field intersect with each other, thereby forming a composite electric field.
It should be noted that, by adjusting the included angle between the first electrode plate 21 and the second electrode plate 22, the vector directions of the first electric field and the second electric field can be adjusted, so that the polarization angle of the terahertz wave can be adjusted. Here, it is sufficient to ensure that the directions of the first electric field and the second electric field have a certain included angle. The terahertz wave with any polarization angle can be obtained by adjusting the electric field intensity to obtain the synthetic vector with any intensity in any direction as long as a certain included angle exists.
In this embodiment, the first electric field and the second electric field generated by the first electric field generating device and the second electric field generating device may be orthogonal so as to calculate the strength of the resultant electric field.
In this embodiment, the distance between the two first electrode plates 21 may be 5-10mm, and/or the distance between the two second electrode plates 22 may be 5-10mm, so that a gap for air plasma to pass through is left between the two pairs of electrode plates.
The thickness of the first electrode plate 21 and the second electrode plate 22 can be 1-2mm, the length can be 20mm, and the width can be 10 mm.
The surface roughness Ra of the first electrode plate 21 and the second electrode plate 22 is less than or equal to 0.2 μm. Thus, the charge distribution on the surfaces of the first electrode plate 21 and the second electrode plate 22 is relatively uniform, and the phenomenon of point discharge and breakdown reduction can be reduced.
In an alternative embodiment of the invention, the signal generating device 1 further comprises a femtosecond laser and a beam splitter 12.
The femtosecond laser is used for emitting a polarized laser beam, wherein the polarized laser beam can be a horizontally polarized laser beam.
The beam splitter 12 is disposed on an optical path of the polarized laser beam and is configured to split the polarized laser beam into pump light and probe light.
The condensing lens is disposed between the beam splitter 12 and the polarization conversion device 2, and the condensing lens may be a first off-axis parabolic mirror 14, and the first off-axis parabolic mirror 14 is disposed on a light path of the pump light and is configured to focus the pump light into the polarization conversion device 2, that is, to focus the pump light into the synthetic electric field, so that the air plasma formed by exciting air by the pump light forms terahertz waves in the synthetic electric field. Here, the first off-axis parabolic reflector 14 may be a 1 inch off-axis parabolic reflector.
Further, the signal generating apparatus 1 further includes a chopper 13, the chopper 13 being disposed between the spectroscope 12 and the first off-axis parabolic mirror 14, and the chopper 13 being disposed on the optical path of the pump light to be able to modulate the intensity of the pump light, modulate the continuous pump light into pump light having a fixed frequency and simultaneously output the modulation frequency.
In an alternative embodiment of the present invention, the present system further comprises a terahertz-wave detection device 3 for detecting terahertz waves.
The terahertz wave detection device 3 comprises a first convex lens 33, a reflector group, an electro-optic crystal and a photoelectric detector 37, wherein the first convex lens 33 is used for focusing detection light generated by the signal generation device 1, the reflector group is used for focusing terahertz wave, the terahertz wave and the detection light are located on the same light path, the terahertz wave and the detection light act on the electro-optic crystal at the same time, the photoelectric detector 37 is arranged on a transmission light path of the electro-optic crystal, the polarization state of the detection light is changed after the detection light is modulated by the terahertz wave in the electro-optic crystal, the terahertz wave enters the photoelectric detector 37 after transient birefringence is caused in the electro-optic crystal, and the photoelectric detector 37 is used for detecting the signal intensity, converting the received optical signal into an electric signal and outputting the electric signal. Here, the electro-optical crystal may be a ZnTe crystal 35.
Here, the mirror group includes a second off-axis parabolic mirror 31 and a third off-axis parabolic mirror 34, and the second off-axis parabolic mirror 31 is disposed at the rear end of the polarization conversion device 2, so as to condense the terahertz waves passing through the polarization conversion device 2 into a bundle of parallel light. The third off-axis parabolic mirror 34 is disposed on the propagation light path of the second off-axis parabolic mirror 31, and is configured to focus the parallel light, and to locate the focused terahertz wave and the probe light on the same light path, so as to act on the ZnTe crystal 35.
And, a silicon wafer 32 is disposed between the second off-axis parabolic mirror 31 and the third off-axis parabolic mirror 34 to filter the terahertz wave.
In this embodiment, the terahertz wave detection device 3 further includes a second convex lens 36, and the second convex lens 36 is disposed between the ZnTe crystal 35 and the photodetector 37, so as to focus the light beam projected by the ZnTe crystal 35 on the photodetector 37, and improve the detection efficiency of the photodetector 37.
Here, the photodetector 37 may be a self-balanced photodetector, and the second off-axis parabolic mirror 31 and the third off-axis parabolic mirror 34 may each be a 4-inch focusing off-axis parabolic mirror.
The method for generating terahertz waves with any polarization angle width provided by the invention is described below, and the method for generating terahertz waves with any polarization angle width described below and the system for generating terahertz waves with any polarization angle width described above can be correspondingly referred to each other.
The invention provides a method for generating terahertz waves with any polarization angle width, which comprises the following steps:
controlling the first electric field generating device to generate a first electric field and the second electric field generating device to generate a second electric field, and enabling the first electric field and the second electric field to be crossed to form a composite electric field; the control signal generating device 1 generates pump light, so that the pump light is focused in the air through the focusing lens to excite the air to form air plasma;
passing the air plasma through a resultant electric field;
and adjusting the voltage of the first electric field generating device and/or the second electric field generating device to enable the air plasma to form terahertz waves with any polarization angle.
It should be noted that, by adjusting the voltage of the first electric field generating device and/or the second electric field generating device, the strength of the first electric field and/or the second electric field can be adjusted, that is, the vector direction of the first electric field and/or the second electric field can be adjusted, so as to adjust the included angle between the first electric field and the second electric field, and enable the air plasma passing through the synthesized electric field to form terahertz waves with different polarization angles.
In an alternative embodiment of the present invention, the method for generating terahertz waves with arbitrary polarization angle widths further includes: the light intensity signal of the terahertz wave is detected by the photodetector 37.
Also, the method of generating a terahertz wave of an arbitrary polarization angle width before detecting a light intensity signal of the terahertz wave by the photodetector 37 further includes: the terahertz wave is focused by the reflector group, the detection light generated by the signal generating device 1 is focused by the first convex lens 33, and the terahertz wave and the detection light are focused on the same optical path and transmitted to the ZnTe crystal 35.
Specifically, the method for generating terahertz waves with any polarization angle width comprises the following steps: the femtosecond laser amplifier 11 is controlled to emit a horizontal polarization laser beam, a beam splitter is arranged on a light path of the horizontal polarization laser beam and divides the horizontal polarization laser beam into pump light and probe light, a chopper 13 and a first off-axis parabolic reflector 14 are sequentially arranged on the light path of the pump light, the chopper 13 modulates continuous pump light into light with fixed frequency, the pump light is focused in air through the first off-axis parabolic reflector 14 and excites the air to form air plasma, the air plasma enters a combined electric field formed by a first electric field generating device and a second electric field generating device, and the voltage of the first electric field generating device and/or the second electric field generating device is adjusted through an electric field adjusting device so that the air plasma forms terahertz waves with any polarization angle.
Then, the terahertz waves are converged into a beam of parallel light by the first off-axis parabolic reflector 14, filtered by a silicon wafer 32 and then projected onto a third off-axis parabolic reflector 34, the terahertz waves (parallel light) are focused by the third off-axis parabolic reflector 34, the detection light is focused by the first convex lens 33, the terahertz waves and the detection light are focused on the same light path and spread onto a ZnTe crystal 35, and then the terahertz waves enter the self-balancing photoelectric detector through the second convex lens 36, so that the detection of the terahertz waves is realized.
The chopper 13 can be used together with a lock-in amplifier to improve the signal ratio of the pump light, so that the signal-to-noise ratio of the terahertz wave is improved.
The above-described embodiments of the apparatus are merely illustrative, and some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A system for generating broadband terahertz waves of any polarization angle, comprising:
the signal generating device is used for generating pump light and comprises a focusing lens, wherein the focusing lens is arranged on a light path of the pump light and is used for focusing the pump light in the air to excite the air to form air plasma;
the polarization conversion device comprises a first electric field generation device for generating a first electric field, a second electric field generation device for generating a second electric field, and an electric field adjusting device for adjusting the intensity of the first electric field and/or the second electric field, wherein the first electric field generation device and the second electric field generation device are arranged in a crossed manner, the first electric field and the second electric field are crossed to form a combined electric field, and the polarization conversion device is arranged on a propagation path of the air plasma, so that the air plasma passes through the combined electric field to form terahertz waves.
2. The system for generating a broadband terahertz wave with an arbitrary polarization angle according to claim 1, wherein the first electric field generation device comprises a pair of first electrode plates arranged in parallel and a first power supply, and the two first electrode plates are electrically connected with a positive electrode and a negative electrode of the first power supply respectively;
the second electric field generating device comprises a pair of second electrode plates and a second power supply which are arranged in parallel, and the two second electrode plates are respectively and electrically connected with the anode and the cathode of the second power supply;
the first power source and/or the second power source is electrically connected with the electric field regulation device.
3. The system for generating broadband terahertz waves with any polarization angle according to claim 2, wherein an included angle is arranged between the first electrode plate and the second electrode plate.
4. The system for generating a broadband terahertz wave of an arbitrary polarization angle according to claim 1, wherein the signal generation device further comprises:
a femtosecond laser for emitting a polarized laser beam;
and the spectroscope is arranged on the light path of the polarized laser beam and is used for dividing the polarized laser beam into the pumping light and the detection light, and the focusing lens is arranged between the spectroscope and the polarization conversion device.
5. The system for generating an arbitrary polarization angle broadband terahertz wave according to claim 4, wherein the signal generating device further comprises a chopper located on an optical path of the pump light, the chopper being disposed between the spectroscope and the focusing lens.
6. The system for generating an arbitrary polarization angle broadband terahertz wave according to claim 4, further comprising a terahertz wave detection device for detecting the terahertz wave.
7. The system for generating an arbitrary polarization angle broadband terahertz wave according to claim 6, wherein the terahertz wave detection device comprises:
a first convex lens for focusing the probe light;
the reflector group is used for focusing the terahertz wave and enabling the terahertz wave and the detection light to be located on the same light path;
an electro-optical crystal disposed on an optical path of the probe light and the terahertz wave;
and the photoelectric detector is arranged on a propagation light path of the electro-optical crystal and is used for receiving the terahertz waves and the detection light which pass through the electro-optical crystal.
8. A method for generating broadband terahertz waves with any polarization angle, which is based on the system for generating broadband terahertz waves with any polarization angle in any one of claims 1 to 7, and comprises the following steps:
controlling a first electric field generating device to generate a first electric field and a second electric field generating device to generate a second electric field, and enabling the first electric field and the second electric field to be crossed to form a composite electric field; the control signal generating device generates pump light, so that the pump light is focused in the air through the focusing lens and excites the air to form air plasma;
passing the air plasma through the resultant electric field;
and adjusting the voltage of the first electric field generating device and/or the second electric field generating device to enable the air plasma to form terahertz waves with any polarization angle.
9. The method for generating an arbitrary polarization angle broadband terahertz wave according to claim 8, further comprising: and detecting a light intensity signal of the terahertz wave through a photoelectric detector.
10. The method for generating an arbitrary polarization angle broadband terahertz wave according to claim 9, further comprising, before the photodetector detects an optical intensity signal of the terahertz wave: the terahertz wave is focused through the reflector group, the detection light generated by the signal generating device is focused through the first convex lens, and the terahertz wave and the detection light are focused on the same optical path and transmitted to the electro-optic crystal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111308190.XA CN114136915A (en) | 2021-11-05 | 2021-11-05 | System and method for generating broadband terahertz waves with any polarization angle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111308190.XA CN114136915A (en) | 2021-11-05 | 2021-11-05 | System and method for generating broadband terahertz waves with any polarization angle |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114136915A true CN114136915A (en) | 2022-03-04 |
Family
ID=80392400
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111308190.XA Pending CN114136915A (en) | 2021-11-05 | 2021-11-05 | System and method for generating broadband terahertz waves with any polarization angle |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114136915A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115128823A (en) * | 2022-06-17 | 2022-09-30 | 上海理工大学 | Terahertz polarization state conversion method based on orthogonal parallel plates |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106052873A (en) * | 2016-05-27 | 2016-10-26 | 北京环境特性研究所 | Gas-based terahertz wave coherent detector and terahertz wave polarization detection method |
| CN107421910A (en) * | 2017-06-24 | 2017-12-01 | 天津大学 | The Terahertz high field system of ultrashort pulse pumping based on wave tilt method |
| CN108683059A (en) * | 2018-06-08 | 2018-10-19 | 首都师范大学 | The system and method for generating high-intensity broadband THz wave using liquid column |
| CN109115690A (en) * | 2018-09-07 | 2019-01-01 | 中国人民解放军国防科技大学 | Real-time polarization sensitive terahertz time-domain ellipsometer and optical constant measuring method |
| CN110444888A (en) * | 2019-08-08 | 2019-11-12 | 中国人民解放军军事科学院国防科技创新研究院 | Photoconductive antenna array and the method for improving photoconductive antenna array radiation power |
| CN112114463A (en) * | 2020-08-27 | 2020-12-22 | 中国人民解放军军事科学院国防科技创新研究院 | Device and method for generating tunable terahertz waves |
| US20210018364A1 (en) * | 2018-03-30 | 2021-01-21 | Centre National De La Recherche Scientifique | Generation and detection of terahertz radiation with an arbitrary polarization direction |
| CN113437620A (en) * | 2021-06-25 | 2021-09-24 | 重庆邮电大学 | Terahertz wave frequency adjusting system based on BBO crystal and pump pulse energy |
-
2021
- 2021-11-05 CN CN202111308190.XA patent/CN114136915A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106052873A (en) * | 2016-05-27 | 2016-10-26 | 北京环境特性研究所 | Gas-based terahertz wave coherent detector and terahertz wave polarization detection method |
| CN107421910A (en) * | 2017-06-24 | 2017-12-01 | 天津大学 | The Terahertz high field system of ultrashort pulse pumping based on wave tilt method |
| US20210018364A1 (en) * | 2018-03-30 | 2021-01-21 | Centre National De La Recherche Scientifique | Generation and detection of terahertz radiation with an arbitrary polarization direction |
| CN108683059A (en) * | 2018-06-08 | 2018-10-19 | 首都师范大学 | The system and method for generating high-intensity broadband THz wave using liquid column |
| CN109115690A (en) * | 2018-09-07 | 2019-01-01 | 中国人民解放军国防科技大学 | Real-time polarization sensitive terahertz time-domain ellipsometer and optical constant measuring method |
| CN110444888A (en) * | 2019-08-08 | 2019-11-12 | 中国人民解放军军事科学院国防科技创新研究院 | Photoconductive antenna array and the method for improving photoconductive antenna array radiation power |
| CN112114463A (en) * | 2020-08-27 | 2020-12-22 | 中国人民解放军军事科学院国防科技创新研究院 | Device and method for generating tunable terahertz waves |
| CN113437620A (en) * | 2021-06-25 | 2021-09-24 | 重庆邮电大学 | Terahertz wave frequency adjusting system based on BBO crystal and pump pulse energy |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115128823A (en) * | 2022-06-17 | 2022-09-30 | 上海理工大学 | Terahertz polarization state conversion method based on orthogonal parallel plates |
| CN115128823B (en) * | 2022-06-17 | 2024-03-15 | 上海理工大学 | Terahertz polarization state conversion method based on orthogonal parallel plates |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Tcherbakoff et al. | Time-gated high-order harmonic generation | |
| US20200284722A1 (en) | Terahertz Full-Polarization-State Detection Spectrograph | |
| JP2014530380A (en) | Solid-state laser and inspection system using 193NM laser | |
| CN106546555B (en) | The spectrum modulation method and light path system of air plasma generation THz wave | |
| TW201721266A (en) | Laser with high quality, stable output beam, and long life high conversion efficiency non-linear crystal | |
| CN103557941A (en) | Broadband TeraHertz wave time domain detection and light spot imaging integrated device and adjustment method | |
| CN106099624B (en) | The system and method that laser excitation air plasma generates high intensity THz wave | |
| CN110911947B (en) | Pulse width compression device and method based on electronegative gas plasma | |
| US20230305280A1 (en) | Method and device of phase modulated fluorescence emission difference microscopy based on electro-optic modulation technology | |
| CN104457991A (en) | Method for detecting gas Rybderg state exquisite spectral line through Terahertz waves | |
| CN114136915A (en) | System and method for generating broadband terahertz waves with any polarization angle | |
| CN106483096B (en) | System and method for generating high-intensity terahertz waves by exciting air plasmas through laser | |
| CN113872022B (en) | Terahertz wave generation device and generation method | |
| CN113394647B (en) | Terahertz wave phase adjustment and control system based on line bias position | |
| CN107611755B (en) | System and method for generating high-intensity terahertz waves by double plasmas with adjustable spacing | |
| CN114156723A (en) | Cross polarized wave generating device and method based on vortex rotation | |
| CN113437620A (en) | Terahertz wave frequency adjusting system based on BBO crystal and pump pulse energy | |
| KR20110014849A (en) | Simultaneous generation devices of terahertz wave and supercontinuum, method there of and spectroscopy method using the same | |
| You et al. | Alignment-dependent terahertz radiation in two-color photoionization of molecules | |
| Çınar et al. | Characterization of a glow discharge detector with terahertz time domain spectroscopy | |
| Çınar et al. | THz transmission and detection through glow discharge detectors | |
| CN110068978B (en) | Non-classical optical field generator with self-compensated phase | |
| CN207234145U (en) | The system that double plasma adjustable in pitch produces high intensity THz wave | |
| Nabinger et al. | Efficient Terahertz Generation by Tilted-Pulse-Front Pumping in Lithium Niobate for the Split-Ring Resonator Experiment at FLUTE | |
| US10658155B2 (en) | Phase contrast transmission electron microscope device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |