阅读说明：本技术 硒化镓/二硫化锡异质结膜电控太赫兹强度调制器件 (Gallium selenide/tin disulfide heterojunction film electric control terahertz intensity modulation device ) 是由 柴路 刘伟宁 宋琦 陈骏祺 胡明列 于 2020-04-21 设计创作，主要内容包括：本发明属于太赫兹技术领域领域,为调制器件结构简单,调制度大,灵敏度高。为此,本发明采取的技术方案是,硒化镓/二硫化锡异质结膜电控太赫兹强度调制器件,包括GaSe/SnS<Sub>2</Sub>异质结膜、附加电极、主动控制直流电源、线性偏振的THz源,线性偏振的THz源生成的太赫兹波入射到GaSe/SnS<Sub>2</Sub>异质结薄膜,GaSe/SnS<Sub>2</Sub>异质结膜为在硅酸盐玻璃衬底上采用液相剥离方法或者化学气相沉积CVD方法制备,形成单分子层或者少分子层的结构；主动控制直流电源通过附加电极,以垂直于太赫兹波偏振方向对GaSe/SnS<Sub>2</Sub>异质结薄膜施加调制电压。本发明主要应用于太赫兹强度调制器件设计制造场合。(The invention belongs to the technical field of terahertz, and provides a modulation device which is simple in structure, large in modulation degree and high in sensitivity. Therefore, the technical scheme adopted by the invention is that the gallium selenide/tin disulfide heterojunction film electric control terahertz intensity modulation device comprises GaSe/SnS 2 The terahertz waves generated by the linearly polarized THz source are incident to the GaSe/SnS 2 Heterojunction thin film, GaSe/SnS 2 The heterojunction film is prepared on a silicate glass substrate by adopting a liquid phase stripping method or a Chemical Vapor Deposition (CVD) method to form a monomolecular layer or a small molecular layer structure; actively controlling a direct current power supply to couple GaSe/SnS in a direction vertical to the polarization direction of the terahertz waves through an additional electrode 2 The heterojunction film applies a modulating voltage. The terahertz intensity modulation device is mainly applied to the design and manufacturing occasions of terahertz intensity modulation devices.)

1. An electric control terahertz intensity modulation device of a gallium selenide/tin disulfide heterojunction film is characterized by comprising GaSe/SnS₂The terahertz waves generated by the linearly polarized THz source are incident to the GaSe/SnS₂Heterojunction thin film, GaSe/SnS₂The heterojunction film is prepared on a silicate glass substrate by adopting a liquid phase stripping method or a Chemical Vapor Deposition (CVD) method to form a monomolecular layer or a small molecular layer structure; actively controlling the DC power supply to pass through the additional electrode to plumbDirect terahertz wave polarization direction to GaSe/SnS₂The heterojunction film applies a modulating voltage.

2. The gallium selenide/tin disulfide heterojunction film electric control terahertz intensity modulation device of claim 1, wherein the additional electrode material is tin-doped indium oxide, gold or silver.

3. The gallium selenide/tin disulfide heterojunction film electric control terahertz intensity modulation device as claimed in claim 1, wherein the active control direct current power supply is a programmable direct current power supply, and direct current voltage and arbitrary waveform required by electric control are applied between the additional electrodes.

Technical Field

The invention belongs to the technical field of terahertz, and relates to an electric control terahertz intensity modulation device for a gallium selenide/tin disulfide heterojunction film.

Background

Terahertz wave is an electromagnetic wave with a wavelength between millimeter wave band and near infrared wave band, and the frequency is from 0.1THz-10THz 1. Compared with electromagnetic radiation of other bands, terahertz waves have many excellent properties, such as: the transient property, namely the terahertz pulse width is in the sub-picosecond magnitude, and can be used for transient spectrum research of sub-picosecond and even femtosecond time resolution; the penetrability is high, and the method can be used for security inspection and anti-terrorism; low damage, namely low radiation photon energy, and is mainly used for biological nondestructive detection; the fingerprint spectrum characteristics, namely the vibration and rotation energy levels of most polar molecules are in a terahertz wave band, so that the method can be used for characterization of substances [2-4 ].

In the aspect of research and development of terahertz modulation devices, the terahertz modulation devices are mainly divided into passive devices and active devices at present. The passive device is mainly composed of conventional materials or artificial metamaterials, such as: 5-7 parts of lens, beam splitter, grating and polarizing device; active devices are mainly made of materials with a particularly sensitive response, such as: piezoelectric, electrooptical, acousto-optic, magneto-optic, phase change and other materials, or based on the combination of the controllable materials and artificial metamaterials, and characteristic parameters of transmission or reflection of terahertz waves are actively regulated and controlled by an external electric field, an optical field, a magnetic field and a thermal field [8-10 ].

In recent years, a two-dimensional material is widely regarded and researched as a graphene-like semiconductor material in the application of the photoelectric field, the acting wavelength range of the material can cover a terahertz waveband (0.1-1THz), and the wide-spectrum-range modulation can be realized, so that the development and the application of a terahertz modulator based on the two-dimensional material become possible [11 ].

Van der Waals heterostructures (van der Waals heterostructures) refer to p-n junction structures that intersect two different types (n-type and p-type) of semiconductor two-dimensional materials, thereby forming a new molecular bond linkage. This structure not only combines the respective photoelectric properties of the two materials, but also produces many new physical or chemical properties [12 ]]. If such a heterojunction is a p-n junction layer formed by two simple films joined together in the vertical direction by van der waals force, a heterojunction film is formed. In such a heterojunction film, the electric field due to the heterojunction increasesSensitivity of photoelectric response is improved, and therefore, the photoelectric modulator is particularly suitable for being used as a photoelectric modulation device. The invention is based on gallium selenide/tin disulfide (GaSe/SnS)₂) An electrically controlled terahertz intensity modulation device for a heterojunction membrane.

Reference documents:

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[3]Mickan S,Abbott D,Munch J,et al.Analysis of system trade-offs forterahertz imaging[J].Microelectronics Journal,2000,31(7):503-514.

[4]Kawase K,Ogawa Y,Watanabe Y,et al.Non-destructive terahertzimaging of illicit drugs using spectral fingerprints[J].Optics express,2003,11(20):2549-2554.

[5]Scherger B,Scheller M,Jansen C,et al.Terahertz lenses made bycompression molding of micropowders,Appl.Opt.,2011,50(15):2256-2262.

[6]Berry C.W.and Jarrahi M.,Broadband terahertz polarizing beamsplitter on a Polymer Substrate,J Infrared Milli Terahz Waves,2012,33:127-130.

[7]Gan Qiaoqiang,Fu Zhan,Ding Yujie et al.,Ultrawide-bandwidth slow-light system based on THz plasmonic graded metallic grating structures,Phys.Rev.Lett.,2008,100:256803.

[8]Minah Seo,Jisoo Kyoung,,Hyeongryeol Park et al.,Active terahertznanoantennas based on VO 2phase transition,Nano Lett.,2010,10:2064–2068.

[9]Jianqiang Gu,Ranjan singh,Xiaojun Liu,et al.,Active control ofelectromagnetically induced transparency analogue in terahertz metamaterials,2012,Nat.Commun.3:1151

[10]Oliver Paul,Christian Imhof,Bertet al.,Polarization-independent active metamaterial for high-frequency terahertz modulation,2008,Opt.Express,2008,17(2):819-827.

[11]Liu.L,Park J,Siegel.D.A,McCarty.K.F,et al.Heteroepitaxial Growthof Two-Dimensional Hexagonal Boron Nitride Templated by Graphene Edges[J].Science,2014,343(6167),163-167

[12]Novoselov K S,Mishchenko A,Carvalho A,et al.2D materials and vander Waals heterostructures[J].Science,2016,353(6298):aac9439。

disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a GaSe/SnS₂And an external electric field is added on the heterojunction film to realize the terahertz intensity modulation device for active control. The modulation device has the advantages of simple structure, large modulation degree and high sensitivity. Therefore, the technical scheme adopted by the invention is that the gallium selenide/tin disulfide heterojunction film electric control terahertz intensity modulation device comprises GaSe/SnS₂The terahertz waves generated by the linearly polarized THz source are incident to the GaSe/SnS₂Heterojunction thin film, GaSe/SnS₂The heterojunction film is prepared on a silicate glass substrate by adopting a liquid phase stripping method or a Chemical Vapor Deposition (CVD) method to form a monomolecular layer or a small molecular layer structure; actively controlling a direct current power supply to couple GaSe/SnS in a direction vertical to the polarization direction of the terahertz waves through an additional electrode₂The heterojunction film applies a modulating voltage.

The additional electrode material is tin-doped indium oxide, gold or silver.

The active control direct current power supply is a programmable direct current power supply, and direct current voltage and any waveform required by electric control are applied between the additional electrodes.

The invention has the characteristics and beneficial effects that:

at present, intensity modulation devices for terahertz wave bands are mainly divided into a metal mesh grid, a carbon nano tube and an artificial metamaterial. The first two devices belong to passive devices and cannot be actively regulated, and the artificial metamaterial can be designed in principle at willHowever, in practice, a design is a function and is only feasible for a specific (design) wavelength, and broadband modulation cannot be achieved. In addition, the photoetching and etching processes are required, the process is complex, the cost is high, and particularly, the size after preparation is too small, and the large-area application is not easy. In addition, most metamaterials are metallic materials and dielectric materials, so temperature control, electric control and magnetic control are mainly adopted for active modulation, but the modulation degree and the tuning range are limited. The photoelectric device based on the two-dimensional material is a high-sensitivity device with development prospect, and the invention is based on GaSe/SnS₂The technical characteristics and effects of the electric control terahertz intensity modulation device for the heterojunction membrane are as follows: (1) GaSe/SnS₂The preparation of the heterojunction film adopts a liquid phase stripping method or a Chemical Vapor Deposition (CVD) method, the preparation is relatively simple, and the universality and the popularity are high; (2) GaSe/SnS₂The heteroconjunctiva belongs to a monomolecular layer or a small molecular layer, and the upper layer and the lower layer are bound by weak van der Waals force; (3) the voltage applied to the lateral side of the heterojunction film can not only increase the anisotropy of the molecular film layer, but also regulate and control the additional internal electric field of the heterojunction, thus obviously changing the density and the mobility of photon-generated carriers at the heterojunction, and further increasing the modulation degree of the transmitted light field intensity; (4) the control voltage source adopts a programmable direct current voltage source, can design and program a modulation voltage signal with any waveform and amplitude in forward and reverse directions, and can realize the random control of the intensity signal; (5) the modulation device belongs to a broadband modulator, and can realize modulation effect in visible light to terahertz wave bands.

Description of the drawings:

FIG. 1 is an experimental schematic of the present invention.

The adopted devices comprise 1 femtosecond laser pumping source, 2 terahertz wave generating crystal, 3 parabolic mirror pair and 4 GaSe/SnS₂A heterojunction membrane, 5, a terahertz detector and 6, a programmable direct current power supply.

Fig. 2 is a graph showing the effect of the device of the present invention on the intensity modulation degree of the transmitted terahertz wave after applying a dc voltage.

Detailed Description

The invention provides a method for preparing GaSe/SnS₂HeterojunctionAnd an external electric field is added on the film to realize the active control of the terahertz intensity modulation device. The modulation device has simple structure, and the GaSe/SnS can be increased by applying variable voltage to the lateral electrodes₂Changes in carrier mobility and density in the heterojunction thin film, and anisotropy of the heterojunction film. The active modulation of the intensity of the transmitted polarized terahertz waves is realized by controlling the external voltage, the modulation degree is large, and the sensitivity is high. The technical scheme adopted by the invention is based on GaSe/SnS₂An electronic control terahertz intensity modulation device of a heterojunction film comprises: GaSe/SnS₂The device comprises a heteroconjunctiva, an additional electrode, an active control direct current power supply, a linearly polarized THz source and a terahertz detector.

The GaSe/SnS₂The heterojunction film is prepared on a silicate glass substrate by adopting a liquid phase stripping method or a chemical vapor deposition CVD method to form a monomolecular layer or a small molecular layer structure.

The additional electrode material is tin-doped indium oxide, gold or silver, and the direction of the applied electrode is vertical to the polarization direction of the terahertz wave.

The active control direct current power supply is a programmable direct current power supply, and direct current voltage and any waveform required by electric control are applied between the additional electrodes;

the linear polarization terahertz source is used for outputting any terahertz transmitter through a terahertz polarizer.

The terahertz detector is a terahertz power detector and a terahertz time-domain spectrometer and is used for detecting the passing of GaSe/SnS₂And the terahertz wave intensity, the electric field amplitude and the frequency spectrum after the heterojunction film voltage modulation.

The invention is realized by the following technical scheme that the method is based on GaSe/SnS₂The automatically controlled terahertz of heteroconjunctiva intensity modulation device, this device and experimental apparatus include: the output pulse of the femtosecond laser pumping source 1 passes through the terahertz wave generating crystal 2, then passes through the beam expanding, collimating and focusing of the parabolic mirror pair 3, and then enters GaSe/SnS₂The heterojunction film 4 applies modulation voltage on the heterojunction film 4 through a programmable direct current power supply 6, and the power or electric field intensity of the modulated terahertz wave is measured by a terahertz detector 5Amount of the compound (A). The experimental schematic diagram of the device is shown in figure 1, and the implementation effect of the electric control intensity modulation in the terahertz wave band is shown in figure 2.

GaSe/SnS as described above₂The heterojunction film 4 is prepared by liquid phase stripping method or Chemical Vapor Deposition (CVD) method, has single heterojunction layer or few heterojunction layers (2-10 layers), and is added with electrodes by deposition method or embedding method in the direction perpendicular to the polarization direction of terahertz wave, wherein the electrode size is × mm in length, 5mm in width, × mm in thickness and 0.06mm in thickness, and the electrode spacing is 5 mm.

The programmable direct current power supply 6 is a commercial product or a modularized integrated direct current power supply, can output any required waveform and positive and negative voltages, and meets the requirement of GaSe/SnS₂Active modulation of the heterojunction membrane 4.

The femtosecond laser pumping source 1 is a femtosecond laser generated in the prior art.

The terahertz generation crystal 2 is an existing commercial electro-optic crystal product.

The parabolic mirror pair 3 is formed by a pair of metal off-axis parabolic mirrors.

The terahertz detector 5 is a commercial Golay-cell and a terahertz time-domain spectrometer, and is used for measuring terahertz wave power and electric field intensity (frequency spectrum) respectively.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.