CN113612102B - Spin terahertz generating device - Google Patents
Spin terahertz generating device Download PDFInfo
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- CN113612102B CN113612102B CN202110872824.8A CN202110872824A CN113612102B CN 113612102 B CN113612102 B CN 113612102B CN 202110872824 A CN202110872824 A CN 202110872824A CN 113612102 B CN113612102 B CN 113612102B
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- terahertz
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S1/00—Masers, i.e. devices using stimulated emission of electromagnetic radiation in the microwave range
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
- G02B27/283—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising used for beam splitting or combining
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S2302/00—Amplification / lasing wavelength
- H01S2302/02—THz - lasers, i.e. lasers with emission in the wavelength range of typically 0.1 mm to 1 mm
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- Optics & Photonics (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
The invention relates to a spin terahertz generating device, which comprises an emitter shell, a pumping light inlet hole, a polarization beam splitter, a quarter wave plate, a focusing lens, a spin terahertz emitter and a detection light outlet hole, wherein the polarization beam splitter is arranged on the emitter shell; the spin terahertz transmitter consists of a permanent magnet, a spin terahertz sample wafer and a silicon lens; the spin terahertz sample wafer is fixed at the focus of the focusing lens in parallel with the pump light incidence hole, and femtosecond laser incident from the pump light incidence hole is converged on the spin terahertz sample wafer by the focusing lens; the femtosecond laser energy is totally acted on the spin terahertz transmitter by introducing the polarization beam splitter and the quarter wave plate, the generated terahertz is detected by using the femtosecond laser reflected by the spin terahertz transmitter, the utilization rate of the femtosecond laser energy is greatly improved, and the generated terahertz signal is enhanced.
Description
Technical Field
The invention relates to the technical field of terahertz, in particular to a spin terahertz generating device.
Background
The spin terahertz generating device is characterized in that a terahertz frequency band is positioned between infrared and microwaves, is a transition frequency band of macroscopic electronics and microscopic photonics, has various advantages of broadband property, low energy property, high permeability, uniqueness and the like, and has great scientific value and wide application prospect in the fields of nondestructive detection, satellite communication, medical diagnosis, satellite communication and the like. The spin terahertz source has the advantages of low cost, high efficiency and the like due to the unique terahertz generation mechanism, and is an important development direction of the terahertz technology in the future.
The terahertz size generated by the spin terahertz transmitter is irrelevant to the polarization state of the femtosecond laser applied to the spin terahertz transmitter, and is closely related to the energy of the femtosecond laser, the spin terahertz system in the prior art needs to divide the femtosecond laser into two beams by adopting a beam splitter, and the two beams are respectively used for generating and detecting the terahertz, so that the utilization rate of the femtosecond laser is low, and the generated terahertz is weaker.
Disclosure of Invention
The spin terahertz generating device provided by the invention can solve the technical problems.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the spin terahertz generating device comprises an emitter shell, a pumping light inlet hole, a polarization beam splitter, a quarter wave plate, a focusing lens, a spin terahertz emitter and a detection light outlet hole;
the spin terahertz transmitter consists of a permanent magnet I, a permanent magnet II, a spin terahertz sample wafer and a silicon lens; the spin terahertz sample piece is tightly attached to the silicon lens, and the permanent magnet I and the permanent magnet II are symmetrically fixed on two sides of the spin terahertz sample piece;
the focusing lens is positioned between the quarter wave plate and the spin terahertz emitter, and the spin terahertz sample plate is fixed at the focus of the focusing lens in parallel with the pump light incident hole. The femtosecond laser with the polarization direction parallel to the transmission direction of the polarization beam splitter is incident from a pump light incidence hole, is converged on a spin terahertz sample wafer through a quarter wave plate by a focusing lens to generate terahertz radiation, and the radiated terahertz radiation is collimated by a silicon lens and then output;
the femtosecond laser reflected by the surface of the spin terahertz sample wafer is called terahertz detection light, and the terahertz detection light sequentially passes through a focusing lens, a quarter wave plate and a polarization beam splitter and then is emitted from a detection light emitting hole.
Furthermore, the included angle between the pump light inlet hole and the detection light outlet hole is 90 degrees, and the two surfaces of the polarization beam splitter are respectively parallel to the pump light inlet hole and the detection light outlet hole.
Further, the fast axis direction of the quarter wave plate forms an angle of 45 degrees with the polarization direction of the light transmitted by the polarization beam splitter; after passing through the quarter wave plate, the linearly polarized light changes its polarization state into circular polarization.
According to the technical scheme, the spin terahertz generating device has the following beneficial effects:
according to the spin terahertz efficient transmitter, the polarization beam splitter is adopted to enable all the femtosecond laser to act on the spin transmitter, the femtosecond laser reflected by the surface of the spin terahertz transmitter is used as detection light to detect the generated terahertz, the quarter wave plate is introduced to enable the polarization state of the terahertz detection light to be orthogonal with that of the femtosecond laser transmitted through the polarization beam splitter, and then the polarization beam splitter is used again to achieve terahertz detection light reflection output, so that the utilization rate of the femtosecond laser energy is greatly improved in the whole process, and the generated terahertz signal is enhanced.
It is apparent that when the polarization direction of the femtosecond laser incident from the pump light incident hole is parallel to the transmission direction of the polarization beam splitter, the energy utilization rate of the femtosecond laser is highest, and the generated terahertz signal is strongest.
Drawings
FIG. 1 is an overall block diagram of the present invention;
in the figure: a 101 transmitter housing; 102 pump light entrance holes; 103 polarization beam splitters; a 104 quarter wave plate; a 105 focus lens; 106 permanent magnets; 107 permanent magnets; 108 spinning the terahertz sample plate; 109 silicon lens; 110 detects the light exit aperture.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention.
As shown in fig. 1, the spin terahertz high-efficiency transmitter in this embodiment includes a transmitter housing 101, a pump light entrance aperture 102, a polarization beam splitter 103, a quarter wave plate 104, a focusing lens 105, a spin terahertz transmitter, and a probe light exit aperture 110; the spin terahertz transmitter consists of a first permanent magnet 106, a second permanent magnet 107, a spin terahertz sample wafer 108 and a silicon lens 109; the arrow direction of the drawing is the magnetic field direction of the permanent magnets 106, 107.
The focusing lens 105 is located between the quarter wave plate 104 and the spin terahertz emitter, and the spin terahertz sample wafer 108 is fixed at the focus of the focusing lens in parallel with the pump light entrance hole 102, and the femtosecond laser incident from the pump light entrance hole 102 is converged onto the spin terahertz sample wafer 108 by the focusing lens 105.
The included angle between the pump light incident hole 102 and the detection light emergent hole 110 is 90 degrees, and the two surfaces of the polarization beam splitter are respectively parallel to the pump light incident hole 102 and the detection light emergent hole 110; the commercial polarizing beamsplitter 103 is a 90 ° polarizing beamsplitter such that the 90 ° design allows light from the polarizing beamsplitter to enter 102 and exit 110.
The fast axis direction of the quarter wave plate 104 forms an angle of 45 degrees with the polarization direction of the light transmitted by the polarization beam splitter 103; after passing through the quarter wave plate 104, the linearly polarized light changes its polarization state into circular polarization; the circularly polarized pump light is focused on the spin sample wafer 108 by the focusing lens 105 to generate terahertz radiation, and the terahertz radiation is collimated by the silicon lens 109 and then output.
The femtosecond laser reflected by the surface of the spin terahertz sample plate 108 is called terahertz detection light, and after passing through the focusing lens 105 and the quarter wave plate 104 in turn, the polarization state of the femtosecond laser is changed from circular polarization into linear polarization orthogonal to the input light of the pump light incidence hole 102, and then the linear polarization is emitted from the detection light emission hole 110 through the polarization beam splitter 103.
The spin terahertz sample sheet 108 is tightly attached to the silicon lens 109 and is used for improving the terahertz emission efficiency, and if a gap exists in the middle, the silicon lens has a reflection effect on the emergent terahertz, so that the final terahertz emission efficiency can be reduced; the first permanent magnet 106 and the second permanent magnet 107 are symmetrically fixed on two sides of the spin terahertz sample wafer 108 and are used for magnetizing a spin sample.
It is assumed that when the polarization direction of the incident femtosecond laser is perpendicular to the paper surface direction, the femtosecond laser will be totally transmitted through the polarization beam splitter 103, and the terahertz efficiency is highest at this time. The polarization direction of the incident femtosecond laser can be manually adjusted, and is not considered to be within the scope of the invention.
The following description will be made with respect to a preferred example in which the polarization direction of the incident femtosecond laser light is perpendicular to the paper surface.
When the linearly polarized femtosecond laser passes through the polarization beam splitter 103 and the quarter wave plate 104, the polarization direction of the linearly polarized femtosecond laser is changed into circularly polarized light, and the circularly polarized light is focused on the spin terahertz sample wafer 108 by the focusing lens 105 to generate terahertz radiation, and the terahertz radiation is collimated by the silicon lens 109 and then output; the femtosecond laser reflected by the surface of the spin terahertz sample plate 108 is called terahertz detection light, and passes through the quarter wave plate 104 in the original path through the focusing lens 105, and the polarization direction of the terahertz detection light is linear polarized light perpendicular to the paper surface, is orthogonal to the polarization direction of the originally incident femtosecond laser, is reflected by the polarization beam splitter 103, and is emitted from the detection light emitting hole 110 for detecting the generated terahertz.
The entire femtosecond laser polarization state evolution process is described mathematically by means of the jones matrix. Assume that the Jones matrix of the polarization direction of the incident femtosecond laser is perpendicular to the paper surface direction
As described above, the fast axis direction of the quarter wave plate 104 forms an angle of 45 ° with the polarization direction of the light transmitted by the polarization beam splitter 103, and when the incident femtosecond laser passes through the quarter wave plate for the first time, its jones matrix is +.>
After that, the femtosecond laser is focused on the spin terahertz sample wafer 108 by a focusing lens 109, wherein part of the femtosecond laser is reflected by the surface of the spin terahertz sample wafer 108 with a reflection matrix of +.>
The reflected femtosecond laser is called terahertz probe light, which sequentially passes through the focusing lens 109 and the quarter wave plate 104, and the transmission direction of the femtosecond laser is opposite to the original direction of the quarter wave plate 104, so that the quarter wave plate Jones matrix is +.>
The probe light that finally passes through the quarter wave plate 104 is
It can be seen that the polarization state is orthogonal to the initial incident femtosecond laser, and finally, the polarized beam splitter 103 outputs the polarized beam from the probe light output hole 110.
From the above, it can be seen that the spin terahertz efficient transmitter according to this embodiment uses the polarization beam splitter to apply all the incident femtosecond laser polarized perpendicular to the paper surface to the spin transmitter, uses the femtosecond laser reflected by the surface of the spin terahertz transmitter as the detection light to detect the generated terahertz, introduces the quarter wave plate to rotate the polarization direction of the terahertz detection light by 90 °, and further uses the polarization beam splitter to realize the reflection output of the terahertz detection light, so that the energy utilization rate of the femtosecond laser is greatly improved in the whole process, and the generated terahertz signal is enhanced.
The above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the 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 scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (2)
1. The utility model provides a spin terahertz produces device, includes spin terahertz transmitter, transmitter shell (101), pump light entry hole (102) and probe light exit hole (110), its characterized in that:
the device also comprises a polarization beam splitter (103), a quarter wave plate (104) and a focusing lens (105);
the spin terahertz transmitter consists of a permanent magnet I (106), a permanent magnet II (107), a spin terahertz sample wafer (108) and a silicon lens (109); the spin terahertz sample sheet (108) is closely attached to the silicon lens (109), and the permanent magnet I (106) and the permanent magnet II (107) are symmetrically fixed on two sides of the spin terahertz sample sheet (108);
the focusing lens (105) is positioned between the quarter wave plate (104) and the spin terahertz transmitter, and the spin terahertz sample wafer (108) is fixed at the focus of the focusing lens in parallel with the pump light inlet hole (102);
femtosecond laser with the polarization direction parallel to the transmission direction of the polarization beam splitter (103) is incident from the pump light incident hole (102), is converged on the spin terahertz sample wafer (108) through the quarter wave plate (104) by the focusing lens (105) to generate terahertz radiation, and the terahertz radiation is output after being collimated by the silicon lens (109);
the femtosecond laser reflected by the surface of the spin terahertz sample wafer (108) is called terahertz detection light, and the terahertz detection light is emitted from a detection light emitting hole (110) after passing through a focusing lens (105), a quarter wave plate (104) and a polarization beam splitter (103) in sequence;
the included angle between the pump light incident hole (102) and the detection light emergent hole (110) is 90 degrees;
the fast axis direction of the quarter wave plate (104) forms an angle of 45 degrees with the polarization direction of the transmitted light of the polarization beam splitter (103); after passing through the quarter wave plate (104), the linearly polarized light changes into circular polarization.
2. The spin terahertz generating apparatus according to claim 1, wherein:
the two surfaces of the polarization beam splitter (103) are respectively parallel to the pump light inlet hole (102) and the detection light outlet hole (110).
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110872824.8A CN113612102B (en) | 2021-07-30 | 2021-07-30 | Spin terahertz generating device |
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| CN202110872824.8A CN113612102B (en) | 2021-07-30 | 2021-07-30 | Spin terahertz generating device |
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| CN113612102A CN113612102A (en) | 2021-11-05 |
| CN113612102B true CN113612102B (en) | 2023-06-23 |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112103756A (en) * | 2020-10-12 | 2020-12-18 | 北京航空航天大学合肥创新研究院 | Spin terahertz transmitter with controllable polarization direction |
| JP2021063704A (en) * | 2019-10-11 | 2021-04-22 | 国立研究開発法人物質・材料研究機構 | Terahertz magneto-optic sensor, high-performance non-destructive inspection device and method using the same, and magneto-optical pickup sensor used in the same |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013114863A1 (en) * | 2012-02-01 | 2013-08-08 | パナソニック株式会社 | Method for polarizing terahertz electromagnetic wave using light polarizer |
| WO2018107142A1 (en) * | 2016-12-09 | 2018-06-14 | Brown University | Polarizing beam splitter for thz radiation |
| CN110556688A (en) * | 2019-09-28 | 2019-12-10 | 北京航空航天大学合肥创新研究院 | terahertz generation device |
| CN112285938B (en) * | 2020-11-10 | 2023-01-31 | 北京工业大学 | Device and method for generating singular hollow beams |
| CN113008369B (en) * | 2021-02-26 | 2022-10-04 | 北京航空航天大学合肥创新研究院(北京航空航天大学合肥研究生院) | Spinning terahertz generation device |
| CN113178766B (en) * | 2021-04-20 | 2022-08-09 | 中国科学院合肥物质科学研究院 | Terahertz generator based on two-dimensional material phonon die |
| CN113178505A (en) * | 2021-04-26 | 2021-07-27 | 中国科学技术大学 | In-situ terahertz spectrum electrochemical device and preparation method thereof |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2021063704A (en) * | 2019-10-11 | 2021-04-22 | 国立研究開発法人物質・材料研究機構 | Terahertz magneto-optic sensor, high-performance non-destructive inspection device and method using the same, and magneto-optical pickup sensor used in the same |
| CN112103756A (en) * | 2020-10-12 | 2020-12-18 | 北京航空航天大学合肥创新研究院 | Spin terahertz transmitter with controllable polarization direction |
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