CN105607297A - Terahertz polarization electro-optical modulation device based on DAST crystals and method - Google Patents
Terahertz polarization electro-optical modulation device based on DAST crystals and method Download PDFInfo
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- CN105607297A CN105607297A CN201610156667.XA CN201610156667A CN105607297A CN 105607297 A CN105607297 A CN 105607297A CN 201610156667 A CN201610156667 A CN 201610156667A CN 105607297 A CN105607297 A CN 105607297A
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/03—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect
- G02F1/0305—Constructional arrangements
- G02F1/0316—Electrodes
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/03—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect
- G02F1/0327—Operation of the cell; Circuit arrangements
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- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
Abstract
The invention discloses a terahertz polarization electro-optical modulation device based on DAST crystals and a modulation method thereof. The modulation device comprises a modulator and an input match circuit. The modulator is formed by the organic electro-optical DAST crystals and a metal electrode. The input match circuit is formed by an input power source and a tunable resistor. The positive electrode and the negative electrode of the input power source are respectively connected with the metal electrode on the modulator. According to the modulation device and the modulation method, the polarization state of terahertz radiation waves is modulated through the electro-optical characteristics of the organic electro-optical DAST crystals, the driving voltage is low, the response speed is high, the output polarization state is stable, and the corresponding linear-polarization-to-linear-polarization polarization direction rotating function and the linear-polarization-to-any-polarization-state converting function of the terahertz waves can be achieved under different voltages. In addition, the modulation device has the advantages that the modulation bandwidth is large, transmission losses and insertion losses are small, driving power is small, and the manufacturing technology is simple, and can be used for the fields of terahertz radiation communication and information processing.
Description
Technical field
The present invention relates to THz wave modulation field, specifically, relate to a kind of based on organic electric light DASTCrystal carries out the apparatus and method of Electro-optical Modulation to transmission terahertz polarization state, utilize DAST crystal crystallographic axisRefractive index can change under different voltage of electric field, thereby affects THz wave at intracrystalline time delay phase difference,Polarization state to transmission THz wave is modulated.
Background technology
THz wave is all experiencing development at full speed in the fields such as Non-Destructive Testing, safe imaging, communication and sensingWith application mode miscellaneous. In recent years, the polarization state control of THz wave can be applied in a lot of fields,Comprise communication code, high-speed optical switch, sensing, detection and imaging etc. and the people closely bound up field of livingIn. These valuable application not only need efficient terahertz sources source and highly sensitive terahertz detector,Also need efficient optics to regulate and control THz wave, as inclined to one side in modulator, prism, wave plate, speed-sensitive switch boxCirculator etc. shakes. But due to the restriction of technology, the mankind study also in comparing vacuum the polarization of terahertz wave bandState, the research of the polarization state regulation device to terahertz wave band is few. Therefore, realize the palm arbitrarilyThe polarization state of control THz wave just becomes urgent and initiative task.
At present, the polarization state regulation device in terahertz wave band is mainly wire grating polarizer, this structureRealize commercialization, but also existed many deficiencies and defect, comprised its expensive, Polarization Modulation sideFormula is single, the fragility of metal structure etc. Terahertz polarization sheet and wave plate are also that the Terahertz of relatively commonly using is inclined to one sideThe element that shakes, the linear polarization that polarizer can be realized THz wave plays partially and analyzing effect, and wave plate plays bit phase delay and inclined to one sideThe function of the state of shaking conversion. Adopt the Terahertz wave plate of two-sided cutting or the super material of split ring resonator also can realize greatlyIn 99% circular polarization, but also can only single frequency operation. The polarization conversion of the super material of isotropism chirality is inclined to one side to incidentThe direction of shaking is insensitive, generally need to realize by three-dimensional structure, and manufacturing process is more complicated. Two anisotropy are superMaterial can be realized its polarization conversion by the oblique incidence of THz wave, but applicable elements and practical operation are more complicated.Except above-mentioned polarizer device, in Terahertz field, there is no again more practical and effective light polarization modulatorPart.
What crystal photoelectric modulator part mainly used is electro-optic crystal, as ktp crystal, lithium niobate ferroelectric crystalAnd DAST crystal etc., under DC Electric Field, produce electrooptic effect and reach the object of modulation. OrganicNonlinear optical crystal 4-(4-dimethylamino styryl) picoline toluenesulfonate (DAST)Crystal, belongs to monoclinic system, space group Cc, point group m, with inorganic nonlinear optical crystal (as KTP,LiNbO3 etc.) to compare, the nonlinear optical coefficients of DAST crystal and electro-optic coefficient are all larger, low JieElectric constant, and all taking advantage aspect coherence length and response time. Therefore, DAST crystal can not onlyEnough utilize beat frequency phase coupling to produce terahertz radiation with this, and can modulate THz wave.Due to the nonlinear polarization effect of DAST crystal, in the time having DC Electric Field on crystal, crystal is exported tooThe phase place of Hertz wave signal can change along with the variation of crystal refractive index, so just makes to export two pointsPhase difference between amount changes along with the variation of extra electric field, thereby realizes Electro-optical Modulation. He can be in differenceRealize the corresponding linear polarization of THz wave under voltage and arrive to polarization direction spinfunction and the linear polarization of linear polarizationThe polarization state transformation function of elliptical polarization. In fact can design corresponding optical rotation according to the demand of applicationChange device, thereby greatly improved the use value of this conversion device.
Summary of the invention
The object of the invention is in order to overcome deficiency of the prior art, provide a kind of based on DAST crystalTerahertz polarization electro-optic modulation arrangement and method, become electrooptic modulator by organic electric light DAST crystal design,The linear polarization THz wave of input can be transformed into the polarization state output of any appointment. This modulator approach is used simultaneouslyDevice have that technique is simple, cheap, the contour technical performance of miniaturization, make it to have more use value andIndustrialization.
The object of the invention is to be achieved through the following technical solutions:
A terahertz polarization electro-optic modulation arrangement based on DAST crystal, comprises modulator and Input matchingCircuit, described modulator is made up of organic electric light DAST crystal and metal electrode, described input matching circuitFormed by input power and tunable resistor, the positive and negative electrode of described input power respectively with described modulator onMetal electrode be connected.
Described organic electric light DAST crystal is of a size of 10mm × 10mm × (1～2mm).
The thickness of described metal electrode is 500nm～1000nm.
Described metal electrode is made up of gold, silver, platinum or aluminum metal.
A modulator approach for terahertz polarization electro-optic modulation arrangement based on DAST crystal, comprises following stepRapid:
Regulate tunable resistor to make the modulation voltage that input power provides be loaded into organic electric light DAST crystalMetal electrode on;
Make THz wave be incident to organic electric light DAST crystal, incide organic electric light DAST crystal tooHertz wave is decomposed into two orthogonal polarized components;
The input voltage that regulates input matching circuit by tunable resistor, changes organic electric light DAST crystalline substanceThe refractive index of two induction main shafts of body, controls THz wave phase place between two oscillating components under electric field actionPoor, realize the modulation to terahertz polarization state.
Compared with prior art, the beneficial effect that technical scheme of the present invention is brought is:
The present invention utilizes the electro-optical characteristic of organic electric light DAST crystal to carry out terahertz emission wave polarization state and adjustsSystem, realize have that driving voltage is low, fast response time, output polarization state be stable, can be under difference obtains voltageRealizing the corresponding linear polarization of THz wave arrives inclined to one side arbitrarily to polarization direction spinfunction and the linear polarization of linear polarizationState transformation function shakes. In addition apparatus of the present invention have that modulation bandwidth is high, loss and insertion loss little, driveKinetic power is little, the simple advantage of manufacture craft, can be used for terahertz emission communication and information processing field.
Brief description of the drawings
Fig. 1 is crystallographic axis and the medium axle schematic diagram of organic electric light DAST crystal.
Fig. 2 is the structural representation of terahertz polarization state electro-optic modulation arrangement.
Fig. 3 is THz wave output intensity modem devices structural representation.
The tunable resistor 4-of the organic electric light DAST of Reference numeral: 1-crystal 2-metal electrode 3-input power5-analyzer
Detailed description of the invention
Below in conjunction with accompanying drawing, the invention will be further described:
The x occurring in following view1Axle, x2Axle and x3Axle is respectively the reference axis that rectangular coordinate system in space is corresponding.
A terahertz polarization electro-optic modulation arrangement based on DAST crystal, comprises modulator and Input matchingCircuit, described modulator is made up of organic electric light DAST crystal 1 and metal electrode 2, input matching circuitFormed by input power 4 and tunable resistor 3, the positive and negative electrode of input power 4 respectively with modulator onMetal electrode 2 is connected.
When organic electric light DAST crystal 1 is used as terahertz polarization Electro-optical Modulation, this crystal need to carry out cCutting, after having cut, identifies crystallographic axis and the medium axle of organic electric light DAST crystal. Crystallographic axis is for having light(in this direction, refractive index is constant, even if non-polarized light incident also for direction in the birefringece crystal of isomeryDo not occur birefringence, and ordinary ray overlaps with extraordinary light), medium axle is ordinary ray and extraordinary lightDepart from minimum direction. As shown in Figure 1, the optical axis of nonlinear optical crystal can be according to the folding of crystalPenetrating rate and crystal structure comes unique definite. Fig. 1 is exemplified with crystallographic axis and the medium axle of organic electric light DAST crystal.For the mark of crystallographic axis and medium axle, can be by the method for measurement refractive index (such as measuring absorption coefficient alsoCalculate the method for Kremers-Krona Buddhist nun (Kramers-Kronig) relation) identify. Can also be by profitDetermine that according to molecularly oriented the method for crystallographic axis and medium axle identifies with crystal structure analysis. These crystallographic axis andMedium axle can also be by shining directly on crystal by electromagnetic field and mark makes characteristic under any conditionThe direction of largeization identifies with experiment method. And, depend on this crystal, existence can by crystal habitDepending on identify the crystal of crystallographic axis and medium axle, so also can carry out visible mark.
Regulate the output voltage of input matching circuit by tunable resistor 3, thereby change organic electric lightThe refractive index of two induction main shafts of DAST crystal, controls THz wave two oscillating component shapes under electric field actionThe phase difference becoming, thus realize the modulation of terahertz polarization state. In the present invention on THz wave optical directionCrystal length is L, and thickness is d (i.e. distance between two metal electrodes), when applied voltage V=E*d,From the phase difference of the two-beam of crystal outgoing beAs long as after crystal and logical light wavelength lambda are determined, phase differenceSize just depend on applied voltage V.
Two sides of what metal electrode 2 was corresponding be plated in organic electric light DAST crystal 1, in order to provide goodGood electric conductivity, the material of metal electrode 2 is selected the metals such as gold, silver, platinum, aluminium, metal electrode thickness oneAs at 500nm-1000nm. The positive and negative electrode of input power 4 is carried in respectively the upper and lower table of DAST crystalOn the electrode of face, provide input voltage to modulator.
The present invention utilizes non-linear electric light principle, the terahertz polarization electro-optic modulation arrangement based on DAST crystalModulator approach have following steps:
The modulation voltage that regulates tunable resistor 3 that input power 4 is provided is loaded into organic electric light DASTOn the metal electrode 2 of crystal 1;
Launch terahertz emission ripple by THz source and be incident to organic electric light DAST crystal 1, work as THz waveDuring by this modulator, its propagation characteristic can be affected and change, and THz wave enters organic electric light DASTAfter crystal, will be decomposed into along two orthogonal polarized components;
Utilize organic electric light DAST crystal 1 electricity that its crystallographic axis refractive index changes under DC Electric FieldLuminous effect, regulates the input voltage of input matching circuit by tunable resistor 3, change organic electric light DASTThe refractive index of crystal induction main shaft, can change two phase differences between component, finally changes outgoing THz wavePolarization state;
Control THz wave phase difference between two oscillating components under electric field action, realize inclined to one side to THz waveThe shake modulation of state.
Apparatus of the present invention structure as shown in Figure 2, at organic electric light DAST crystal 1 along x1Axial upper tableFace and lower surface plate metal level as metal electrode 2, and the Thickness scope of metal electrode exists500nm-1000nm. The input matching circuit being formed by tunable resistor 3 and input power 4, direct currentPress and be connected on metal electrode 2 by tunable resistor 3. Apply after voltage, because extra electric field is along x1AxleDirection, the main shaft x of crystal2、x3Rotate 45 ° to x2' axle and x3' axle. THz wave incident direction and x1Axle hangs downDirectly, from the lateral vertical incident of organic electric light DAST crystal 1, along x3' direction propagation, enter after crystalTo be decomposed into along x2' and x1Two vertical polarization components of direction, due to the refractive index of these two polarized components notIdentical, be respectively nx1And nx2’. So when they are through organic electric light DAST crystal 1 length L, be thicklyD, L=1～2mm in the present embodiment, the distance of two 2 of metal electrodes is d=10mm, applied voltage V=E*d,From the phase difference between two components of organic electric light DAST crystal 1 outgoing be:
Wherein, γ11: with x1The photoelectric coefficient that direction of principal axis is relevant; γ21: with x2' photoelectric coefficient that direction of principal axis is relevant.
(input voltage range is 0v-to regulate tunable resistor 3 to obtain different magnitude of voltage V by change500V), this phase difference will change the polarization state of outgoing beam. When phase difference isTime, output is tooHertz wave light field vector is linearly polarized light;Time, the synthetic light field vector of Terahertz becomes circularly polarized light; WhenTime, the synthetic light field vector of Terahertz is the linearly polarized light after half-twist.In all the other situations, defeatedGoing out the synthetic light field vector of Terahertz is elliptically polarized light.
Use embodiment as shown in Figure 3 at of the present invention another, defeated at organic electric light DAST crystal 1Go out end and place a polarizer vertical with incident THz wave direction as analyzer 5, so when organic electric lightOn DAST crystal 1, added voltage, 0 when changing between half-wave voltage value, is exported too from analyzer 5Hertz wave is an axial component of elliptical polarization, thereby the variation of polarization state can be changed and becomes TerahertzThe variation (intensity modulated) of intensity of wave.
Finally it should be noted that: these are only the preferred embodiments of the present invention, be not limited to the present invention, to the greatest extentPipe has been described in detail the present invention with reference to embodiment, and for a person skilled in the art, it stillThe technical scheme that can record aforementioned each embodiment is modified, or part technical characterictic is wherein carried outBe equal to replacement, but within the spirit and principles in the present invention all, any amendment of making, be equal to replacement, changeEnter etc., within all should being included in protection scope of the present invention.
Claims (5)
1. the terahertz polarization electro-optic modulation arrangement based on DAST crystal, is characterized in that, comprises modulationDevice and input matching circuit, described modulator is made up of organic electric light DAST crystal and metal electrode, described inInput matching circuit is made up of input power and tunable resistor, the positive and negative electrode of described input power respectively withMetal electrode on described modulator is connected.
2. a kind of terahertz polarization electro-optic modulation arrangement based on DAST crystal according to claim 1, itsBe characterised in that, the specification of described organic electric light DAST crystal is 10mm × 10mm × (1～2mm).
3. a kind of terahertz polarization electro-optic modulation arrangement based on DAST crystal according to claim 1, itsBe characterised in that, the thickness of described metal electrode is 500nm～1000nm.
4. according to a kind of terahertz polarization electro-optic modulation arrangement based on DAST crystal described in claim 1 or 3,It is characterized in that, described metal electrode is made up of gold, silver, platinum or aluminum metal.
5. a kind of tune of the terahertz polarization electro-optic modulation arrangement based on DAST crystal according to claim 1Method processed, is characterized in that, comprises the following steps:
Regulate tunable resistor to make the modulation voltage that input power provides be loaded into organic electric light DAST crystalMetal electrode on;
Make THz wave be incident to organic electric light DAST crystal, incide organic electric light DAST crystal tooHertz wave is decomposed into two orthogonal polarized components;
The input voltage that regulates input matching circuit by tunable resistor, changes organic electric light DAST crystalline substanceThe refractive index of two induction main shafts of body, controls THz wave phase place between two oscillating components under electric field actionPoor, realize the modulation to terahertz polarization state.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110297337A (en) * | 2019-06-26 | 2019-10-01 | 天津大学 | Two selenizing rhenium nanometer sheet terahertz polarization modulation devices of regulating and controlling voltage |
| CN110401496A (en) * | 2019-07-11 | 2019-11-01 | 桂林电子科技大学 | A kind of transmission-type THz wave 2bit code devices, method and system |
| CN111142175A (en) * | 2020-01-19 | 2020-05-12 | 电子科技大学 | DAST-based adjustable metamaterial, preparation method and application thereof |
| CN114001821A (en) * | 2021-11-08 | 2022-02-01 | 南开大学 | Room temperature terahertz wave power measuring device and method based on photothermal acoustic mechanism |
-
2016
- 2016-03-18 CN CN201610156667.XA patent/CN105607297A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110297337A (en) * | 2019-06-26 | 2019-10-01 | 天津大学 | Two selenizing rhenium nanometer sheet terahertz polarization modulation devices of regulating and controlling voltage |
| CN110297337B (en) * | 2019-06-26 | 2021-04-06 | 天津大学 | Voltage-controlled terahertz polarization modulation device with rhenium diselenide nanosheets |
| CN110401496A (en) * | 2019-07-11 | 2019-11-01 | 桂林电子科技大学 | A kind of transmission-type THz wave 2bit code devices, method and system |
| CN111142175A (en) * | 2020-01-19 | 2020-05-12 | 电子科技大学 | DAST-based adjustable metamaterial, preparation method and application thereof |
| CN114001821A (en) * | 2021-11-08 | 2022-02-01 | 南开大学 | Room temperature terahertz wave power measuring device and method based on photothermal acoustic mechanism |
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