KR102082979B1 - Terahertz Modulator and Manufacturing Method of Producing the same - Google Patents

Abstract

The present invention relates to technology for novel terahertz modulator capable of modulating terahertz with ultrahigh speed and high efficiency by implementing a structure in which plasma resonance frequency is changed by using intrinsic properties of a phase insulator. A terahertz modulator comprises: a substrate; a phase insulator coupled to the substrate and having a structure in which plasmon resonates at predetermined terahertz wave frequency; and a conductivity variable that coupled to the phase insulator and causing the plasmon resonance frequency of the phase insulator to change when the electrical conductivity changes.

Description

Terahertz modulator and manufacturing method of the same

The present invention relates to a terahertz wave modulator and a method of manufacturing the same, and more particularly, by implementing a structure in which the plasmon resonance frequency is changed by using inherent characteristics of the phase insulator, thereby modulating the terahertz wave at a very high speed and high efficiency. Technology for a new terahertz wave modulator.

Terahertz electromagnetic waves are electromagnetic waves whose frequency is in the terahertz region. Terahertz waves, on the order of hundreds of micrometers, are shorter than those in the frequency bands used in communications, but have wavelengths longer than visible and infrared light. The method of generating terahertz waves is greatly limited compared to other microwave and visible light regions, and thus a new technology capable of generating terahertz frequencies is required.

까지 밖에 조절 할 수 없으며, 수 %의 변조율 밖에 달성할 수 없었다.Conventional terahertz wave control technology adjusts the surface charge concentration by controlling the degree of absorption of the terahertz wave signal by adjusting the charge concentration of the material surface to the gate voltage.

It can only be adjusted up to and only a few percent modulation rate can be achieved.

까지 조절하여 100%에 가까운 변조가 가능하다. 그래핀은 테라헤르츠파 흡수 특성이 전영역에서 광범위하게 나타나므로 선택적 주파수 변조가 불가능하며, 수 십 V의 전압이 필요하여 효율성이 현저히 떨어진다.Graphene has constant terahertz wave permeability at all frequencies. In addition, graphene can only change the permeability intensity even by changing the transporter concentration. Graphene has a single graphene plasmon structure once, and the modulation region is fixed. In order to modulate the complex frequency with graphene, a plurality of plasmon structures must be made, but in this case, the modulation efficiency is greatly reduced due to scattering in different structures. Graphene is not suitable for terahertz frequency modulation because it does not change much by frequency. If only graphene is used, the surface charge concentration

Modulation up to 100% is possible. Graphene does not have selective frequency modulation because its terahertz wave absorption characteristics are widespread in the whole range, and it requires a voltage of several tens of volts, which significantly reduces efficiency.

Phase insulators show very high modulation efficiency at certain frequencies due to plasmon-phonon interference, but the efficiency of other frequencies is not high. The point where the frequency modulation efficiency is high is that it appears according to the properties of the material, so no change can be observed even when the gate voltage is applied. In addition, the phase insulator itself has very low electrical gating efficiency. Once the phase insulator plasmon structure is made, the modulation region is limited to a single frequency like graphene.

The plasmon structure for limiting the terahertz wave's broad absorption characteristics to a specific frequency has an effect of increasing absorption characteristics, but has a limitation in that a plurality of plasmonic structures must be manufactured individually and repeatedly because the modulation frequency is fixed.

Terahertz device applications can be broadly divided into terahertz wave generators (THz generators), terahertz wave detectors (THz detectors) and terahertz wave modulators (THz modulators). Dual terahertz wave generators and terahertz wave detectors have been actively researched around the world and have reached the stage of practical use. However, the field of terahertz wave modulators is in the early stages of research worldwide, and new device concepts and implementations are needed to move to commercialization.

Performance indicators of terahertz wave modulators relate to modulation efficiency, which can be quantitatively analyzed using modulation depth. To this quantitative analysis, there exist optical modulation and electrical modulation.

Conventional terahertz wave modulators using electrical control use the surface of the Dirac charge concentration control, this method consumes more than a few tens of volts (V), the efficiency was not good.

On the other hand, the most conventional optical modulation method uses a plasmon structure of the phase insulator and a method of increasing the modulation rate by using the dirac charge and the bulk-dirac charge interaction, and the modulation depth record high of this method (modulation depth record high) ) Was 2,400%.

Korea Patent Publication 10-1727291

Therefore, the present invention has been proposed to solve the conventional problems as described above, an object of the present invention by implementing a structure in which the plasmon resonance frequency is changed by using the intrinsic characteristics of the phase insulator, terahertz at high speed and high efficiency It is to provide a new terahertz wave modulator that can modulate the wave.

In order to achieve the above object, the terahertz wave modulator according to the present invention includes a substrate; A phase insulator coupled to the substrate and having a structure in which plasmons resonate at a predetermined terahertz wave frequency; A conductivity variable coupled to the phase insulator and configured to change the plasmon resonant frequency of the phase insulator when the electrical conductivity changes, and inputted by the plasmon-phonon interaction when the plasmon resonant frequency of the phase insulator changes. The degree of cancellation of the terahertz wave is characterized by a change.

In addition, the substrate; A phase insulator having a structure in which plasmon resonates at a predetermined terahertz wave frequency on the substrate; It is coupled to the phase insulator, characterized in that it comprises a conductivity variable consisting of graphene.

In addition, the phase insulator may be characterized in that the structure of the form in which the plasmon resonates at a predetermined terahertz wave frequency.

In addition, the conductivity variable may be characterized in that the terahertz wave can be transmitted.

In addition, the conductivity variable may be characterized in that the electrical conductivity is changed when receiving an optical pulse.

In addition, the conductivity variable may be characterized in that the graphene.

In addition, the phase insulator may be in the form of a strip.

In addition, the width of the phase insulator may be characterized in proportion to the separation distance from other adjacent phase insulators.

In addition, the phase insulator may be protruded or recessed in a cross shape.

In addition, the width of the portion extending in the vertical direction of the phase insulator may be characterized in proportion to the length of the portion extending in the left or right direction.

In addition, the width of the portion extending in the vertical direction of the phase insulator may be characterized in proportion to the separation distance from other adjacent phase insulators.

In addition, the conductivity variable may be physically coupled to the phase insulator.

The method may further include a gating layer coupled to the conductivity variable and electrically gating the conductivity variable.

In addition, when a voltage is applied through the conductivity variable and the gating layer, the electrical conductivity of the conductivity variable may be changed.

In addition, the gating layer may be characterized in that the ion gel (Ion gel).

On the other hand, in order to achieve the above object, the method of manufacturing a terahertz wave modulator according to the technical idea of the present invention includes the steps of: combining a phase insulator having a structure in which the plasmon resonates at a predetermined terahertz wave frequency; Coupling a conductivity variable to the phase insulator such that the plasmon resonance frequency of the phase insulator changes when electrical conductivity changes.

The method may further include arranging a phase insulator having a structure in which plasmons resonate at a predetermined terahertz wave frequency on a substrate; And coupling the conductivity variable composed of graphene to the phase insulator.

In addition, the phase insulator may be characterized in that a structure in which the plasmon resonates at a predetermined terahertz wave frequency is arranged on the substrate.

In addition, the conductivity variable may be characterized in that the terahertz wave can be transmitted.

In addition, the conductivity variable may be characterized in that the electrical conductivity is changed when receiving an optical pulse.

In addition, the conductivity variable may be characterized in that the graphene.

In addition, the phase insulator may be in the form of a strip.

In addition, the width of the phase insulator may be characterized in proportion to the separation distance from other adjacent phase insulators.

In addition, the phase insulator may be protruded or recessed in a cross shape.

In addition, the width of the portion extending in the vertical direction of the phase insulator may be characterized in proportion to the length of the portion extending in the left or right direction.

In addition, the width of the portion extending in the vertical direction of the phase insulator may be characterized in proportion to the separation distance from other adjacent phase insulators.

In addition, the conductivity variable may be physically coupled to the phase insulator.

In addition, after the coupling of the conductivity variable to the phase insulator, the method may further comprise coupling a gating layer electrically gating the conductivity variable to the conductivity variable.

In addition, the gating layer may be characterized in that the ion gel (Ion gel).

Furthermore, in order to achieve the above object, a method of modulating a terahertz wave by using a terahertz wave modulator according to the technical idea of the present invention is, as a first embodiment, an optical pulse corresponding to a terahertz wave to be modulated. Irradiating with the terahertz wave modulator; Irradiating the terahertz wave modulator of the object to be modulated to the terahertz wave modulator, wherein the terahertz wave modulator is coupled to the substrate and has a structure in which the plasmon resonates at a predetermined terahertz wave frequency. And an conductivity variable coupled to the phase insulator and causing the plasmon resonance frequency of the phase insulator to change when the electrical conductivity changes.

In addition, the light pulse may be characterized in that it is irradiated toward the conductivity variable.

In addition, as a second embodiment, the step of applying a control signal corresponding to the terahertz wave to be modulated to the terahertz wave modulator; Irradiating the terahertz wave modulator of the object to be modulated to the terahertz wave modulator, wherein the control signal is a voltage signal, and the terahertz wave modulator is coupled to the substrate and at a predetermined terahertz wave frequency. A phase insulator having a structure in which a plasmon resonates, a conductivity variable coupled to the phase insulator and configured to change a plasmon resonance frequency of the phase insulator when the electrical conductivity changes, and a conductivity variable coupled to the conductivity variable It characterized in that it comprises a gating layer to electrically gate.

In addition, the voltage signal may be applied to an electrode disposed on the conductivity variable.

In addition, the signal may be characterized in that it further comprises an optical pulse signal.

According to the terahertz wave modulator and the manufacturing method thereof according to the present invention,

First, since the terahertz wave modulator using the phase insulator has been modulated according to the physical size of the structure, a separate device has to be manufactured as many as desired frequency bands. Continuous frequency modulation is possible.

Secondly, the arranged phase insulator of the present invention is very easy to manufacture because it is possible to manufacture a structure resonant to terahertz waves in the form of a single strip.

Third, according to the present invention, the arranged phase insulators are connected to each other through graphene, and the graphene is electrically gated through an ion gel to obtain an effect of controlling the physical size of the phase insulator, thereby adjusting the plasmon natural frequency. A new method of spectral shift is realized.

Fourth, the present invention consumes a few volts (V) of voltage during electrical control, and thus it is possible to modulate terahertz waves with significantly less power than before.

Fifth, when the light pulse irradiation and the voltage application control are simultaneously used in the present invention, a modulation depth significantly improved than the conventional one can be obtained at the frequency of 1.8 THz when calculated using the plasmon-phonon interaction model. appear.

Sixth, the present invention is capable of optical modulation of the picosecond level by using an ultra-fast light pulse.

1 is a perspective view showing a separate configuration of a terahertz wave modulator according to an embodiment of the present invention.
FIG. 2 is a perspective view visually illustrating a situation of modulating a terahertz wave transmitted by applying an optical pulse or a voltage to a terahertz wave modulator according to an embodiment of the present invention; FIG.
3 shows the length relationship of one phase insulator structure unit.
FIG. 4 is a diagram showing an arrangement photograph of a gastric insulator structure actually manufactured using the length relationship of FIG. 3, and a relationship between w (width) of a phase insulator structure unit and a resonance frequency of plasmon. FIG.
5 is a flowchart illustrating a method of manufacturing a terahertz wave modulator according to an embodiment of the present invention.
6 is a view showing an application example of a method of modulating a terahertz wave by using a terahertz wave modulator according to a first embodiment of the present invention.
7 is a view showing an application example of a method of modulating a terahertz wave using a terahertz wave modulator according to a first embodiment of the present invention.

A terahertz wave modulator and a method of manufacturing the same according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific form disclosed, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the drawings, similar reference numerals are used for similar elements.

In addition, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

The phase insulator 120 can derive a very large modulation efficiency at a specific frequency by using the difference between the plasmon off period generated in the plasmon-phonon interference and the charge transfer characteristics of the bulk and surface levels generated during the excitation of the optical pulse. have. In addition, if the charge density on the surface of the phase insulator 120 is changed, it is possible to change the plasmon off period to another frequency, thereby maximizing modulation efficiency at various frequencies. Thus, it is possible to selectively modulate the frequency plasmon using the phase insulator 120.

If the plasmon structure is separately formed on the graphene and the phase insulator 120, the plasmon modulation efficiency is high only at a specific frequency, so that the usability is not good in a real environment requiring the modulation of the frequency. However, the present invention made the junction structure of the phase insulator 120 and graphene to overcome the structural limitations. Specifically, when the phase insulator 120 is etched into a structure having an appropriate size, the plasmon frequency is present in the terahertz region. First, the phase insulator 120 is manufactured to be arranged on the substrate 110. When the width of the phase insulator 120 is w, the graphene is bonded onto the phase insulator 120 and the graphene is selectively gated by using an ion gel to form the phase insulator microribbon structure 120. The effect is as if the width is changed to w, 2w, 3w and so on. When graphene is used as an electrode and gating is performed using an ion gel, electrons are supplied to graphene to modulate the surface plasmon frequency of the phase insulator 120. Since the frequency of the plasmon is inversely proportional to the size of the phase insulator 120, increasing the size of the phase insulator 120 may reduce the plasmon frequency. That is, using the junction structure of the phase insulator array 120 and graphene overcomes the disadvantage that the modulation frequency is fixed, thereby modulating the complex frequency with one physical plasmon resonance structure. In other words, it is not necessary to repeatedly manufacture several elements depending on the frequency. Therefore, by connecting plasmons generated from the phase insulators 120 using graphene, and controlling the gating of graphene, a modulator 100 capable of continuously tuning terahertz waves can be developed.

The optical modulation of the plasmon is possible by irradiating an optical pulse (pulse laser) to supply derac electrons to the phase insulator 120. When the phase insulator 120 is optically excited with a laser, electrons are generated at the bulk level, and the electrons flow into the surface level to supply Dirac electrons. It has been reported that the Dirac electrons supplied by the optical method shift the plasmon frequency and thus increase the modulation efficiency.

The terahertz wave modulator 100 according to the embodiment of the present invention is capable of modulating the terahertz wave by selectively or simultaneously using an electrical modulation method and an optical modulation method. In particular, the use of both electrical and optical modulation can lead to very high terahertz wave modulation efficiency.

A terahertz wave modulator 100 according to an embodiment of the present invention will be described.

1 and 2, a terahertz wave modulator 100 according to an embodiment of the present invention is a structure in which a plasmon resonates at a predetermined terahertz wave frequency in combination with a substrate 110 and a substrate 110. A phase insulator 120 having a phase insulator 120 and a conductivity variable 130 coupled to the phase insulator 120 to change the plasmon resonance frequency of the phase insulator 120 when the electrical conductivity changes. When the plasmon resonant frequency of) is changed, the degree of cancellation of the terahertz wave input by the plasmon-phonon interaction is changed.

As shown in the drawing, the substrate 110, the phase insulator 120, and the conductivity variable 130 may have a layered structure.

The substrate 110 is preferably selected from a material through which terahertz waves are transmitted. For example, the material of the substrate 110 may be Al 2 O 3 sapphire, Si-based, and the like.

Plasmons appear to be proportional to the concentration of the transporter. Since ordinary metals have very high transporter concentrations, many plasmons can be induced. However, ordinary metals are unable to change the concentration of the transporter and thus cannot modulate the size of the plasmon. On the other hand, the general semiconductor has a problem that it is difficult to form plasmon because the concentration of the carrier is relatively very low compared to the general metal. However, general semiconductors can increase the concentration of the transporter through photoexcitation, and as the concentration of the transporter increases, plasmons are formed, and as a result, the size of the plasmon can be modulated. The phase insulator 120 used in this embodiment exhibits the characteristics of the metal at the surface level, and the characteristics of the semiconductor at the bulk level, thereby taking advantage of both the metal and the semiconductor. When photoexcitation is performed on the phase insulator 120, the bulk level serves as an electron supply reservoir to the surface level, thereby greatly increasing the surface charge concentration. In addition, the phase insulator 120 has a specific frequency point at which plasmon is hardly formed by Dirac plasmon-phonon interference. The phase insulator 120 increases the center frequency of the plasmon by Dirac plasmon-phonon interference when the charge concentration is increased at the surface level, which can lead to a very high modulation efficiency at a frequency where no plasmon was previously formed. do.

The material of the phase insulator 120 may be selected and applied from materials having phase insulator characteristics. In the embodiment of the present invention Bi2Se3 is used.

The phase insulator 120 is implemented by arranging structures on the substrate 110 in a shape resonant with the plasmon. That is, the phase insulator 120 having a predetermined shape may be arranged to be uniformly arranged in one direction or in a row direction. By using the arrangement of the phase insulator 120 formed for the purpose of plasmon resonance, a specific frequency is selectively amplified through the plasmon-phonon interaction inherent in the phase insulator 120 and the charge supply from the bulk level to the surface level. It is possible. In addition, when terahertz waves are input to the array of phase insulators 120, the terahertz waves not only absorb the terahertz waves, but also modulate terahertz waves passing through the modulator 100, that is, output terahertz waves.

Referring to FIGS. 3 and 4, the phase insulator 120 may have various shapes. For the purpose of experiment, this embodiment is manufactured in a strip shape and a cross shape.

The phase insulator 120 arranged on the substrate 110 in the shape of a single letter was able to select a plasmon in which the phase insulator 120 resonates by making a proportional distance from the other phase insulator 120 adjacent to the width. In particular, the phase insulator 120 of this embodiment is manufactured to have the same width as the separation distance from other phase insulators 120 adjacent thereto. The relationship between the size of the single-shaped phase insulator 120 and the resonant terahertz wave was confirmed as shown in the following table as a result of actual sample fabrication and testing.

Width of structure (w) Resonant frequency Strip Structure Example 1 6 μm 2.2 THz Strip Structure Example 2 9 μm 1.8 THz Strip Structure Example 3 12 μm 1.5 THz Strip Structure Example 4 20 μm 1.2 THz

As the size of the single-shaped phase insulator 120 increases, the resonant terahertz frequency may decrease.

On the other hand, the phase insulator 120 arranged on the substrate 110 in a + shape has a + shape protruding from the substrate 110, or a + shape in the phase insulator 120 layer is recessed in the direction of the substrate 110. In the same manner as the Babinet's principle, the terahertz wave region in which the phase insulator 120 resonates according to the size of the + -shape is the same regardless of the protruding / interfering shape of the + -shape.

The phase insulator 120 arranged on the substrate 110 in a + shape has a width in proportion to a length of a portion extending in the vertical direction in a widthwise direction. The phase insulator 120 of this embodiment is formed such that the width of the portion extending in the up-down direction or the left-right direction of the + shape is 1/3 larger than the length of the portion extending in the orthogonal direction. In addition, the separation distance between the phase insulators 120 is proportional to the width of the portion extending in the vertical direction or the left and right directions in the + shape. In this embodiment, the width (w) of the portion extending in the vertical direction or the left and right directions and the separation distance from the other phase insulator 120 located on the left or right side are made the same. The relation between the size of the + -shaped phase insulator 120 and the resonant terahertz wave was confirmed as shown in the following table as a result of fabricating and testing an actual sample.

Extension width (w) Resonant frequency + Cross structure Example 1 3 μm 1.8 THz + Cross structure Example 2 4 μm 1.5 THz + Cross structure example 3 8 μm 1.2 THz

In the + -shaped phase insulator 120, the larger the size, the smaller the resonant terahertz frequency.

In this case, the width refers to a region having a relatively small length, and the length refers to a region having a relatively large length in the structure. In the above description, the width and length are perpendicular to each other.

Since the size of the phase insulator 120 is a unit of several micrometers (μm), tens to tens of thousands of phase insulators 120 are arranged on the substrate 110 having a diameter of at least 1 mm or more.

Referring back to FIGS. 1 and 2, in one embodiment of the present invention, the conductivity variable 130 has graphene applied thereto. Graphene is a two-dimensional conductive material having an atomic unit thickness, and has excellent electrical characteristics and high transparency, and transmits terahertz waves. In particular, when the light pulse is irradiated on the graphene, the electrical conductivity of the graphene increases with increasing the temperature of the electrons of the graphene. Irradiation of light pulses on the arrangement 120 of the phase insulator and the graphene-coupled device increases the electrical conductivity of the graphene. At this time, the electrical coupling between the phase insulators 120 is increased to change the plasmon resonance frequency. Induced. In addition, when graphene is gated by supplying a voltage from a device in which the array of phase insulators 120 and graphene are coupled, electrical coupling between the phase insulators 120 also increases, thereby inducing a change in the plasmon resonance frequency. The change in the plasmon resonance frequency of the phase insulator 120 further enhances the cancellation of the terahertz wave due to the plasmon-phonon interaction, thereby modulating the terahertz wave passing through the modulator 100.

 Graphene has a smaller electronic density (DOS) than other materials, and is easily doped by an external gate. Gating in the form of a silicon backgate requires a large voltage of more than a few tens of volts (V), but graphene can be gated with just a few volts (V). Graphene exhibits a broad absorption spectrum in the terahertz wave region because of its semi-metal nature with high charge density.

The conductivity variable 130 is physically coupled with the phase insulators 120. The conductivity variable 130 is physically connected to the phase insulators 120 spaced apart from each other for the arrangement so that the plasmons of the phase insulators 120 may be connected to each other. In order to be connected to all the phase insulators 120, the conductivity variable 130 is preferably configured to have a large area that covers the entire region where the phase insulators 120 are arranged.

를 제어할 수 있다. 이 두 가지 요소의 변조를 이용하면 변조 깊이를 향상 시킬 수 있다(변조 깊이의 정의는 위키피디아, 논문 등에서 기 공지됨. Wagner, M. et al. Ultrafast dynamics of surface plasmons in InAs bytime-resolved infrared nanospectroscopy. Nano Lett. 14, 4529??4534 (2014); Wagner, M. et al. Ultrafast and nanoscale plasmonic phenomena in exfoliatedgraphene revealed by infrared pump-probe nanoscopy. Nano Lett. 14, 894??900 (2014); Rotenberg, N., Caspers, J. N. & van Driel, H. M. Tunable ultrafast control ofplasmonic coupling to gold films. Phys. Rev. B 80, 245420 (2009); Rotenberg, N., Betz, M. & van Driel, H. M. Ultrafast control of grating-assistedlight coupling to surface plasmons. Opt. Lett. 33, 2137??2139 (2008)).In addition, the electronic control enables the Fano dip position modulation. Fano dip creates an asymmetric spectrum when two spectra are coupled between the broad plasmon energy spectrum and the discrete phonon spectrum, meaning a spectrum of this shape. Defined at modulation depth using Fano dip position modulation

Can be controlled. Modulation of these two factors can be used to improve modulation depth (definition of modulation depth is well known in Wikipedia, thesis, etc. Wagner, M. et al. Ultrafast dynamics of surface plasmons in InAs bytime-resolved infrared nanospectroscopy. Nano Lett. 14, 4529 ?? 4534 (2014); Wagner, M. et al. Ultrafast and nanoscale plasmonic phenomena in exfoliated graphene revealed by infrared pump-probe nanoscopy.Nano Lett. 14, 894 ?? 900 (2014); Rotenberg, N., Caspers, JN & van Driel, HM Tunable ultrafast control of plasmonic coupling to gold films.Phys. Rev. B 80, 245420 (2009); Rotenberg, N., Betz, M. & van Driel, HM Ultrafast control of grating -assistedlight coupling to surface plasmons.Opt. Lett. 33, 2137 ?? 2139 (2008)).

The modulation depth, which is a performance index, is calculated as shown in Equation 1.

[Equation 1]

은

이고, 외부 전압 및 광펄스가 조사되지 않았을 때의 상태의 플라즈몬 에너지 레벨을 의미하는

는

이다. 즉, 변조 깊이는 외부 환경변화에 의해 플라즈몬 에너지가 얼마나 변화하였는지 보여주는 성능 지표가 된다.At this time, it means a plasmon energy level changed by the external voltage and the light pulse

silver

, Which means the plasmon energy level of the state when no external voltage and light pulse are irradiated.

Is

to be. That is, the modulation depth is a performance indicator showing how the plasmon energy is changed by the external environment change.

Optical control parameters of the terahertz wave modulator 100 according to an embodiment of the present invention are as shown in [Equation 2].

[Equation 2]

는 표면 전하밀도이다. 본 발명의 실시예는 표면 전하밀도는 광학적 및 전기적 변조로 제어 할 수 있으므로, 광학적 전하밀도인

과 전기적 전하밀도인

의 합으로 나타난다.

Is the surface charge density. In the embodiment of the present invention, since the surface charge density can be controlled by optical and electrical modulation,

And electrical charge density

It appears as the sum of.

In addition, the electrical control parameter of the terahertz wave modulator 100 according to an embodiment of the present invention is as shown in [Equation 3].

[Equation 3]

은 디랙 전하밀도이다.

Is the Dirac charge density.

In addition, the terahertz wave modulator 100 according to an embodiment of the present invention may further include a gating layer 140 coupled to the conductivity variable 130 and electrically gating the conductivity variable 130. . In this embodiment, an ion gel was used as the gating layer 140. Ion gel is a gel-like material used for the gate effect. Gating using ion gel has high-K characteristics, so it is easy to control graphene doping even with a small gate voltage. In addition, ion gels are suitable for modulation elements because of the transmission of terahertz waves. Since the terahertz wave is transmitted through the ion gel, the modulator 100 can be controlled using both an optical pulse irradiation method and a voltage control method.

Between the graphene and the ion gel includes a bonded electrode of graphene, if the voltage is supplied after connecting the voltage supply circuit to the electrode, (-) ions are accumulated on the (+) electrode, and (+) on the (-) electrode Ions will accumulate. When a voltage is applied, the electrical conductivity of the conductivity variable 130 is changed. When the electrical conductivity of the conductivity variable 130 is changed, the plasmon resonance frequency of the phase insulator 120 is changed. At this time, the degree to which the terahertz waves input by the plasmon-phonon interaction are correspondingly canceled is changed. .

Those skilled in the art to understand the properties of the phase insulator 120, graphene and ion gel, the phase insulator in which the substrate 110 and the structure in which the plasmon resonates at a predetermined terahertz wave frequency are arranged on the substrate 110 ( 120 and a terahertz wave is controlled by irradiating a controlled light pulse to the conductivity variable 130 when using a device including a conductivity variable 130 composed of graphene coupled to the phase insulator 120. You will understand the facts.

In addition, when the ion variable coupled to the conductivity variable 130 and electrically gated to the conductivity variable 130 is further included, it is possible to control the terahertz wave even when a voltage is applied to graphene instead of an optical pulse. I can understand.

Next, a method of manufacturing the terahertz wave modulator 100 according to an embodiment of the present invention will be described.

Referring to FIG. 5, the method for manufacturing the terahertz wave modulator 100 according to an embodiment of the present invention includes a phase insulator 120 having a structure in which a plasmon resonates at a predetermined terahertz wave frequency on a substrate 110. Coupling step (S120), and coupling the conductivity variable 130 consisting of graphene to the phase insulator (120) (S130).

The above steps can be implemented by applying a process for manufacturing a semiconductor.

The step S120 is performed by arranging the phase insulator 120 having the form of resonating plasmon on the substrate 110 at a predetermined terahertz wave frequency. Fabrication of the phase insulator array 120 layer on the substrate 110 may be performed through an etching process.

The shape of the phase insulator 120 may be implemented in various ways. In this embodiment, the phase insulator 120 may have a single shape or a + shape.

In operation S130, the graphene is physically coupled to the arranged phase insulators 120. In order for the graphene to be connected to all of the phase insulators 120 arranged on the substrate 110, the graphene preferably has a size wider than the width of the phase insulator 120.

Further, after the step S130, the method may further include a step (S140) of coupling the gating layer 140 electrically gating the conductivity variable 130 to the conductivity variable 130. The gating layer 140 may be an ion gel. First, after placing the electrodes on both sides of the graphene (S135), the ion gel is coupled to cover both the graphene and the electrode.

Next, a method of modulating a terahertz wave using the terahertz wave modulator 100 according to an embodiment of the present invention will be described.

Referring to FIG. 6, the method of modulating terahertz waves using the terahertz wave modulator 100 according to the first embodiment of the present invention is characterized in that the terahertz waves are modulated using an optical pulse.

Referring to FIG. 6, a configuration for irradiating terahertz waves to the modulator 100, a configuration for irradiating light pulses, and a configuration for receiving terahertz waves output from the modulator 100 are also displayed.

First, the terahertz wave modulator 100 is prepared in advance by fixing the terahertz wave and the light pulse to the path to which the light is irradiated. Subsequently, an optical pulse corresponding to a terahertz wave to be modulated is irradiated to the modulator 100. The light pulse is preferably irradiated toward the conductivity variable 130. In addition, the terahertz wave of the object to be modulated is irradiated to the modulator 100. The modulator 100 receiving the optical pulse and the terahertz wave outputs the modulated terahertz wave.

In this case, the terahertz wave modulator 100 includes at least a substrate 110, a phase insulator 120 coupled to the substrate 110 and having a structure in which plasmons resonate at a predetermined terahertz wave frequency, and the phase insulator 120. And a conductivity variable 130 that is coupled to and causes the plasmon resonance frequency of the phase insulator 120 to change when the electrical conductivity changes.

A detailed process in which the terahertz wave is modulated in the modulator 100 according to the first embodiment of the present invention will be described.

After generating an optical pulse corresponding to the terahertz wave to be modulated by using an apparatus or system for generating the optical pulse, the conductivity variable 130 of the modulator 100 is irradiated. In this embodiment, graphene was used as the conductivity variable 130. Graphene increases in electrical conductivity as the temperature of electrons increases as light pulses are received. Graphene functions as a bridge connecting the plasmons of the phase insulators 120. Therefore, if the electrical conductivity of the graphene is increased, the electrical coupling of the phase insulators 120 is increased to induce a change in the plasmon resonance frequency. The change in the plasmon resonance frequency of the phase insulator 120 further enhances the cancellation of terahertz waves by the plasmon-phonon interaction, thereby modulating the input terahertz waves to a desired size.

Optical modulation using such optical pulses, that is, pulse lasers, enables ultra-fast modulation control of several tens of picoseconds.

Referring to FIG. 7, the method of modulating the terahertz wave using the terahertz wave modulator 100 according to the second embodiment of the present invention is characterized in that the terahertz wave is modulated using voltage control.

Referring to FIG. 7, a configuration for irradiating terahertz waves to the modulator 100, a configuration for applying a voltage, and a configuration for receiving terahertz waves output from the modulator 100 are also displayed.

First, a power line capable of applying a voltage to an electrode of the terahertz wave modulator 100 is connected. Next, the modulator 100 is prepared by fixing the terahertz wave to the path to be irradiated. Subsequently, a control signal corresponding to the terahertz wave to be modulated is applied to the modulator 100. In addition, the terahertz wave of the object to be modulated is irradiated to the modulator 100. At this time, the control signal includes a voltage signal. As a voltage signal is applied, the modulator 100 receiving the terahertz wave outputs the modulated terahertz wave.

In this case, the terahertz wave modulator 100 is coupled to the substrate 110, the phase insulator 120 having a structure in which the plasmon resonates at a predetermined terahertz wave frequency, and the phase insulator 120. Coupled to the conductivity variable 130 and coupled to the conductivity variable 130 to cause the plasmon resonance frequency of the phase insulator 120 to change when the electrical conductivity changes, and electrically gates the conductivity variable 130. Gating layer 140 is included. In this embodiment, graphene was used as the conductivity variable 130, and the gating layer 140 used an ion gel.

The voltage signal is applied to the electrode disposed in the conductivity variable 130. In one embodiment, electrodes are formed at both ends of the graphene and the ion gel, and a line capable of applying a voltage to the electrodes may be connected.

A voltage corresponding to a terahertz wave to be modulated is applied to the modulator 100 by using a device or a system that supplies a controlled voltage. The ion gel has a high-K characteristic and can easily control the doping of graphene even with a small gate voltage. Graphene increases in electrical conductivity with the applied voltage. Increasing the electrical conductivity of the graphene increases the electrical coupling of the phase insulators 120 to induce a change in the plasmon resonance frequency. The change in the plasmon resonance frequency of the phase insulator 120 further enhances the cancellation of terahertz waves by the plasmon-phonon interaction, thereby modulating the input terahertz waves to a desired size.

In addition, the method for modulating the terahertz wave by using the terahertz wave modulator 100 according to the second embodiment of the present invention is applied to the gating layer 140 is a material that can transmit the terahertz wave, such as ion gel In this case, the control signal further includes an optical pulse signal. When the optical pulse signal is further irradiated to the modulator 100, the electrical conductivity increases with increasing temperature of the electrons of the graphene, and a control effect such as a method of modulating the terahertz wave according to the first embodiment is obtained. It becomes possible.

The terahertz wave modulator 100 according to an embodiment of the present invention may be applied to a biological image generation system, a non-destructive inspection system, and the like.

The biological image generating system includes a generator for radiating terahertz waves to a human body to which a contrast agent is applied, a detector for generating an electrical signal for imaging based on terahertz waves reflected from the human body, and generating the electrical signals. It includes a configuration such as an image generating unit for generating an image of the outside or inside of the human body by using. In this case, the terahertz wave modulator 100 according to an embodiment of the present invention is applied to the generator.

In addition, the non-destructive inspection system generates a terahertz wave, the power antenna for outputting the generated terahertz wave through the exit port, a transmission antenna including a antenna corresponding to the terahertz wave output from the power distributor, and a transmission antenna And a receiver-like configuration for detecting terahertz waves emitted from and passed through or reflected from the sample. At this time, the terahertz wave modulator 100 according to an embodiment of the present invention is implemented to be included in the power divider.

Although preferred embodiments of the present invention have been described above, the present invention may use various changes, modifications, and equivalents. It is clear that the present invention can be applied in the same manner by appropriately modifying the above embodiments. Therefore, the above description does not limit the scope of the present invention as defined by the limitations of the following claims.

100: terahertz wave modulator
110: substrate
120: phase insulator (arranged phase insulator structure)
130: conductivity variable
140: gating layer

Claims (36)

A substrate;
A phase insulator coupled to the substrate and having a structure in which plasmons resonate at a predetermined terahertz wave frequency;
A conductivity variable coupled to the phase insulator, the conductivity variable causing the plasmon resonance frequency of the phase insulator to change when electrical conductivity changes,
When the plasmon resonance frequency of the phase insulator is changed, the degree of cancellation of the terahertz wave input by the plasmon-phonon interaction is changed,
The phase insulator is a terahertz wave modulator, characterized in that the structure in which the plasmon resonates at a predetermined terahertz wave frequency is arranged. delete The method of claim 1,
The conductivity variable is a terahertz wave modulator, characterized in that the terahertz wave can be transmitted. The method of claim 3,
The conductivity variable terahertz wave modulator, characterized in that the electrical conductivity is changed when receiving a light pulse. The method of claim 4, wherein
The conductivity variable is a terahertz wave modulator, characterized in that the graphene. delete The method of claim 1,
The terahertz wave modulator, characterized in that the phase insulator is in the form of a strip. The method of claim 7, wherein
And a width of the phase insulator is proportional to a distance between adjacent phase insulators. The method of claim 1,
The phase insulator is a terahertz wave modulator, characterized in that protruding or recessed in the form of a cross. The method of claim 9,
The terahertz wave modulator, characterized in that the width of the portion extending in the vertical direction of the phase insulator is proportional to the length of the portion extending in the left or right direction. The method of claim 10,
And a width of a portion extending in the vertical direction of the phase insulator is proportional to a distance between adjacent phase insulators. The method of claim 1,
And said conductivity variable is physically coupled to said phase insulator. The method of claim 1,
A terahertz wave modulator coupled to the conductivity variable, further comprising a gating layer electrically gating the conductivity variable. The method of claim 13,
The terahertz wave modulator, characterized in that the electrical conductivity of the conductivity variable is changed when a voltage is applied through the conductivity variable and the gating layer. The method of claim 14,
The gating layer is a terahertz wave modulator, characterized in that the ion gel (Ion gel). In the method of manufacturing a terahertz wave modulator,
Coupling a phase insulator having a structure in which the plasmon resonates at a predetermined terahertz wave frequency to the substrate;
Coupling a conductivity variable to the phase insulator such that the plasmon resonance frequency of the phase insulator changes when electrical conductivity changes;
The phase insulator is a method of manufacturing a terahertz wave modulator, characterized in that the structure in which the plasmon resonates at a predetermined terahertz wave frequency is arranged on the substrate. delete The method of claim 16,
The conductivity variable is a method of manufacturing a terahertz wave modulator, characterized in that the terahertz wave can be transmitted. The method of claim 18,
The conductivity variable is a method of manufacturing a terahertz wave modulator, characterized in that the electrical conductivity is changed when receiving an optical pulse. The method of claim 19,
The method of manufacturing a terahertz wave modulator, characterized in that the conductivity variable is graphene. delete The method of claim 16,
The phase insulator is a method of manufacturing a terahertz wave modulator, characterized in that the form of a strip (strip). The method of claim 22,
The width of the phase insulator is a method of manufacturing a terahertz wave modulator, characterized in that it is proportional to the separation distance from other adjacent phase insulator. The method of claim 16,
The phase insulator is a method of manufacturing a terahertz wave modulator, characterized in that the protruding or recessed in the form of a cross. The method of claim 24,
The width of the portion extending in the vertical direction of the phase insulator is a method of manufacturing a terahertz wave modulator, characterized in that proportional to the length of the portion extending in the left or right direction. The method of claim 25,
The width of the portion extending in the vertical direction of the phase insulator is a method of manufacturing a terahertz wave modulator, characterized in that proportional to the separation distance from the adjacent phase insulator. The method of claim 16,
And said conductivity variable is physically coupled to said phase insulator. The method of claim 16, wherein after the conductivity variable is coupled to the phase insulator,
And coupling the gating layer electrically gating the conductivity variable to the conductivity variable. The method of claim 28,
The gating layer is a method of manufacturing a terahertz wave modulator, characterized in that the ion gel (Ion gel). delete delete delete delete delete delete delete

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