CN102176521B - Terahertz surface plasma wave temperature control switch and control method thereof - Google Patents

Abstract

The invention discloses a terahertz surface plasma wave temperature control switch and a control method thereof, which relate to a terahertz surface plasma wave temperature control device and the method for modulating terahertz surface plasma waves by utilizing the characteristic that the frequency of semiconductor plasmas is changed along with temperature. The switch comprises an intrinsic semiconductor wafer (2), two blades (3) and a temperature controller (5), wherein the plasma frequency of the intrinsic semiconductor wafer (2) is in a terahertz wave band at normal temperature; the two blades (3) are arranged in parallel, and are vertical to the intrinsic semiconductor wafer (2); a distance between the knife edge of the blade (3) and the upper surface of the intrinsic semiconductor wafer (2) is less than attenuation distances of terahertz surface plasma waves (4) in air; the blades (3) convert terahertz waves into the terahertz surface plasma waves, and convert the terahertz surface plasma waves into the terahertz waves; and the temperature controller (5) controls the temperature of the intrinsic semiconductor wafer (2), thereby changing the carrier concentration of the intrinsic semiconductor wafer.

Description

Terahertz surface plasma wave temp control switch and control method thereof

Technical field

A kind of method that the present invention relates to a kind of Terahertz surface plasma wave temperature control equipment and utilize the temperature variant characteristic of intrinsic semiconductor plasma frequency to modulate the Terahertz surface plasma wave.

Background technology

Terahertz (THz) ripple typically refers to frequency at 0.1～10THz (1THz=10 ¹²Hz) electromagnetic wave, its wavelength is between microwave and near-infrared.On frequency domain, THz wave is in macroscopic view to the microcosmic transitional region, and on radiation mechanism, THz wave is in classical electromagnetic radiation to the quantum leap transitional region.For a long time, owing to lack effective THz wave generation, modulation, detection method, people are very limited for the electromagnetic application of this frequency range, so that this wave band is called as the Terahertz space in the electromagnetic spectrum.Yet because the peculiar property of THz wave, it has a wide range of applications in fields such as communication, spectrum analysis, safety inspections.In order to produce effective Terahertz wave modulation apparatus, people such as J.G ó mez Rivas are converted to the Terahertz surface plasma wave to THz wave, by temp control switch the Terahertz surface plasma wave are carried out switch modulation.If temp control switch is closed, then there is not signal to pass through; If temp control switch is open-minded, again the Terahertz surface plasma wave is coupled as THz wave, or directly transmits with the Terahertz surface plasma wave, thereby realized switch modulation to the Terahertz frequency range.

Yet existing Terahertz surface plasma wave temp control switch need use grating, and is therefore still imperfect on performance.At first, and since the use of grating, the energy of grating meeting scattering Terahertz surface plasma wave itself, thus make signal energy incur loss.Secondly, need produce the grating that can reflect characteristic frequency Terahertz surface plasma wave, this has also increased difficulty and the cost made.The more important thing is that existing Terahertz surface plasma wave temp control switch can only be realized switch control to the characteristic frequency of very narrow wave band, can not regulate and control the Terahertz surface plasma wave of wide range.If there are all multi-wavelength signals far away of being separated by in the THz wave of incident the inside, just can't be simultaneously the signal of several wavelength be carried out switch modulation with conventional device.Therefore, we are necessary to design the Terahertz surface plasma wave temp control switch of a kind of low cost, low-loss, wide spectrum.

The background technology file:

1.J.Gómez?Rivas，M.Kuttge，H.Kurz，P.Haring?Bolivar，and?J.A.Sánchez-Gil，“Low-frequency?active?surface?plasmon?optics?on?semiconductors”Appl.Phys.Lett.88，082106(2006).

2.J.Gómez?Rivas，M.Kuttge，P.Haring?Bolivar，H.Kurz，and?J.A.Sánchez-Gil，“Propagation?of?surface?plasmon?polaritons?on?semiconductor?gratings”Phys.Rev.Lett.93，256804(2004).

3.JoséA.Sánchez-Gil，and?Jaime?Gómez?Rivas，“Thermal?switching?of?the?scattering?coefficients?of?terahertz?surface?plasmon?polaritons?impinging?on?a?finite?array?of?subwavelength?grooves?on?semiconductor?surfaces”Phys.Rev.B?73，205410(2006).

Summary of the invention

Technical problem: the object of the present invention is to provide a kind of Terahertz surface plasma wave temp control switch, solve technical problems such as cost of manufacture is higher in the background technology, energy loss is bigger, tuning frequency bandwidth is narrower.

Technical scheme: the present invention is a kind of Terahertz surface plasma wave temp control switch and control method thereof.Terahertz surface plasma wave temp control switch of the present invention comprises that a plasma frequency is in blade and a temperature control equipment of the intrinsic semiconductor wafer of terahertz wave band, two parallel placements at normal temperatures.Two blades are perpendicular to the intrinsic semiconductor wafer, the edge of a knife of two blades is from the distance of the intrinsic semiconductor upper wafer surface aerial decay distance of Terahertz surface plasma wave less than peak frequency, the distance between two blades less than the Terahertz surface plasma wave of peak frequency in the semiconductor surface propagation distance.The thickness of intrinsic semiconductor wafer is greater than the decay distance of Terahertz surface plasma wave in semiconductor of minimum frequency.Temperature controller is close to the lower surface of intrinsic semiconductor wafer.The temperature regulating range of temperature controller should make semiconductor wafer plasma frequency can along with variations in temperature greater than with less than the surface plasma wave frequency of propagating.

The present invention proposes a kind of Terahertz surface plasma wave temperature-controlled process.Control the intrinsic semiconductor chip temperature by temperature controller, thereby change the carrier concentration of this intrinsic semiconductor.When semi-conductive carrier concentration changed, its plasma frequency also changed, thereby its dielectric constant will change.In general, when the frequency of Terahertz surface plasma wave during greater than the plasma frequency of intrinsic semiconductor wafer, this semiconductor shows as dielectric property, and its real part of permittivity is for just; When the frequency of Terahertz surface plasma wave during less than the plasma frequency of intrinsic semiconductor wafer, this semiconductor shows as metallic character, and its real part of permittivity is for negative.Because the Terahertz surface plasma wave can only be propagated at the opposite two media interface of dielectric constant, so the Terahertz surface plasma wave can be propagated at semiconductor surface when semiconductor shows as metallic character, and the Terahertz surface plasma wave can not be propagated at semiconductor surface when semiconductor shows as dielectric property, thereby has realized the function of switch.Blade is for THz wave being converted into the Terahertz surface plasma wave and the Terahertz surface plasma wave of conducting being converted into THz wave.The knife-edge part that THz wave need be incided at a certain angle one of them blade when THz wave is converted into the Terahertz surface plasma wave could be realized maximum coupling efficiency.Equally, the THz wave of sending in the edge of a knife place of another blade also is the strongest on certain orientation.

Device can place general air, but influence the switch effect for the globule (when reducing temperature with temperature controller) that prevents airborne steam and condense in the intrinsic semiconductor surface absorbs THz wave, device is placed in the environment of vacuum or inflated with nitrogen can reach better effect.

In order to realize the switch control in the broad spectrum scope, need the temperature range of control to increase.Kong Zhi temperature and normal temperature differ bigger if desired, can adopt multistage temperature controller to realize.

Beneficial effect: the present invention has the following advantages:

1, cost of manufacture is low.Need not make grating in the intrinsic semiconductor wafer surface, so the cost of whole device is lower.

2, energy loss is little.Do not have structural scattering energy such as grating, so the energy loss of Terahertz surface plasma wave is less, signal to noise ratio is improved.

3, modulation range is wide.Can carry out switch modulation to wideer terahertz wave band, improve performance and the range of application of device.

Description of drawings

Fig. 1 is structure principle chart of the present invention.Terahertz surface plasma wave temp control switch comprises that a plasma frequency is in blade and a temperature control equipment of the intrinsic semiconductor wafer of terahertz wave band, two parallel placements at normal temperatures.Two blades are perpendicular to the intrinsic semiconductor wafer, the edge of a knife of two blades is from the distance of the intrinsic semiconductor upper wafer surface aerial decay distance of Terahertz surface plasma wave less than peak frequency, the distance between two blades less than the Terahertz surface plasma wave of peak frequency in the semiconductor surface propagation distance.The thickness of intrinsic semiconductor wafer is greater than the decay distance of surface plasma wave in semiconductor.Temperature controller is close to the lower surface of intrinsic semiconductor wafer.When at a certain temperature, the plasma frequency of intrinsic semiconductor wafer is greater than the THz wave frequency of transmitting.At this moment, the THz wave that a part incides the blade knife-edge part is coupled as the Terahertz surface plasma wave earlier, the Terahertz surface plasma wave can be propagated along the surface of intrinsic semiconductor then, when the Terahertz surface plasma wave arrived the knife-edge part of second blade, some Terahertz surface plasma wave was coupled into THz wave at last.

Fig. 2 is the Terahertz surface plasma wave along the electric field strength perpendicular to the intrinsic semiconductor surface direction | E _z| field strength distribution.

Fig. 3 adopts the schematic diagram of multistage temperature controller and water cooling plant control temperature.

Have among the figure: THz wave 1, intrinsic semiconductor 2, blade 3, Terahertz surface plasma wave 4, temperature controller 5, extraneous gas (then not being vacuum as having) 6, copper sheet 7, water cooling plant 8.

Embodiment

The structure of Terahertz surface plasma wave temp control switch of the present invention is: two blades of parallel placement above the intrinsic semiconductor wafer, a temperature control equipment is close in intrinsic semiconductor wafer below.The edge of a knife of two blades of top is from the distance of the intrinsic semiconductor upper wafer surface aerial decay distance of Terahertz surface plasma wave less than peak frequency, distance between two blades is less than the Terahertz surface plasma wave of the peak frequency propagation distance at semiconductor surface, and the thickness of intrinsic semiconductor wafer is greater than the decay distance of Terahertz surface plasma wave in intrinsic semiconductor of minimum frequency.

The intrinsic semiconductor wafer be characterized as at normal temperatures or during near normal temperature its plasma frequency at terahertz wave band.When at a certain temperature, the plasma frequency of intrinsic semiconductor wafer is greater than the THz wave frequency of transmitting.At this moment, the THz wave that a part incides the blade knife-edge part is coupled as the Terahertz surface plasma wave earlier, the Terahertz surface plasma wave can be propagated along the surface of intrinsic semiconductor then, when the Terahertz surface plasma wave arrived the knife-edge part of second blade, some Terahertz surface plasma wave was coupled into THz wave at last.Under this temperature, just realize to all conductings less than the THz wave of the Terahertz frequency range of intrinsic semiconductor plasma frequency, as shown in Figure 1 like this.Yet, by reducing temperature, the intrinsic carrier concentration of intrinsic semiconductor reduces, the plasma frequency of intrinsic semiconductor is along with reducing, at this moment the intrinsic semiconductor plasma frequency is less than the THz wave frequency of transmitting, at this moment the Terahertz surface plasma wave of this frequency range can not be propagated on the intrinsic semiconductor surface, thereby has realized the blocking-up to the THz wave of this frequency range.On the contrary, by improving temperature, can realize the conducting to the THz wave of this frequency range again.

The propagation distance of Terahertz surface plasma wave and externally the decay distance in gas (or vacuum) and the intrinsic semiconductor can try to achieve according to the dispersion equation of surface plasma, the dispersion equation of Terahertz surface plasma is:

$k_x=\frac{\mathrm{\ω}}{c}\sqrt{\frac{{\widetilde{\mathrm{\ϵ}}}_1{\widetilde{\mathrm{\ϵ}}}_2}{{\widetilde{\mathrm{\ϵ}}}_1+{\widetilde{\mathrm{\ϵ}}}_2}}=A+\mathrm{Bi}$

${\mathrm{<figure-callout\; id="1"\; label="k\; z"\; filenames="HSA00000377475400011.png"\; state="\{\{state\}\}">k</figure-callout>}}_z=\frac{\mathrm{\&omega;}}{c}\sqrt{\frac{{{\widetilde{\mathrm{\&epsiv;}}}_1}^2}{{\widetilde{\mathrm{\&epsiv;}}}_1+{\widetilde{\mathrm{\&epsiv;}}}_2}}=C+\mathrm{Di}$

${\mathrm{<figure-callout\; id="2"\; label="k\; z"\; filenames="HSA00000377475400011.png,HSA00000377475400012.png"\; state="\{\{state\}\}">k</figure-callout>}}_z=\frac{\mathrm{\&omega;}}{c}\sqrt{\frac{{{\widetilde{\mathrm{\&epsiv;}}}_2}^2}{{\widetilde{\mathrm{\&epsiv;}}}_1+{\widetilde{\mathrm{\&epsiv;}}}_2}}=E+\mathrm{Fi}$

K in the above formula _xIt is the propagation constant along the Terahertz surface plasma wave of intrinsic semiconductor surface direction (+x direction).k _Z1And k _Z2Be perpendicular to the upward direction (+z direction) on intrinsic semiconductor surface and the propagation constant of downward direction (z direction) respectively.C is the light velocity in the vacuum.ω is the corresponding angular frequency of peak frequency in the THz wave.

Be the complex dielectric permittivity (ε of extraneous gas or vacuum ₁Be the real part of extraneous gas complex dielectric permittivity, ε ₁' be the imaginary part of extraneous gas complex dielectric permittivity). Be the complex dielectric permittivity (ε of intrinsic semiconductor wafer ₂Be the real part of intrinsic semiconductor complex dielectric permittivity, ε ₂' be the imaginary part of intrinsic semiconductor complex dielectric permittivity).A, C and E be respectively this frequency Terahertz surface plasma wave edge+x direction ,+the z direction ,-phase constant of z direction, B, D and F be respectively this frequency Terahertz surface plasma wave edge+x direction ,+the z direction ,-attenuation constant of z direction.

The Terahertz surface plasma wave of this frequency is propagated on the interface of air and intrinsic semiconductor, when its intensity is reduced to original 1/e the Terahertz surface plasma wave the distance of process be propagation distance.Propagation distance δ _SpThe attenuation constant B of (+x direction) calculates and to try to achieve along the direction of propagation for expression, available Terahertz surface plasma wave:

${\mathrm{\&delta;}}_{\mathrm{sp}}=\frac{1}{\left|2B\right|}$

Referring to Fig. 2, the Terahertz surface plasma wave is along the electric field strength perpendicular to the intrinsic semiconductor surface direction | E _z| be exponential damping in this direction (± z direction).Vertical range to the intrinsic semiconductor surface when electric field strength is reduced to the 1/e of intrinsic semiconductor surface field intensity is respectively the decay distance of this frequency Terahertz surface plasma wave in air and intrinsic semiconductor medium, uses δ respectively _dAnd δ _mExpression.Available Terahertz surface plasma wave is along trying to achieve perpendicular to attenuation constant D and the F calculating of intrinsic semiconductor surface direction in air and intrinsic semiconductor:

${\mathrm{\&delta;}}_d=\frac{1}{\left|D\right|}$

${\mathrm{\&delta;}}_m=\frac{1}{\left|F\right|}$

Can this Terahertz temp control switch use, and selects for use suitable intrinsic semiconductor most important.In order to make this Terahertz temp control switch not need very low or very high temperature to regulate, the plasma frequency of this intrinsic semiconductor must be near terahertz wave band.This conclusion can be derived by the Drude model, according to the Drude model

${\widetilde{\mathrm{\&epsiv;}}}_2={\mathrm{\&epsiv;}}_2+i{{\mathrm{\&epsiv;}}_2}^{\&prime;}={\mathrm{\&epsiv;}}_{\mathrm{static}}[1-\frac{{\mathrm{\&omega;}}_{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="HSA00000377475400011.png,HSA00000377475400012.png"\; state="\{\{state\}\}">p</figure-callout>}}^2{\mathrm{\&tau;}}^2}{1+{\mathrm{\&omega;}}^2{\mathrm{\&tau;}}^2}+i\frac{{\mathrm{\&omega;}}_{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="HSA00000377475400011.png,HSA00000377475400012.png"\; state="\{\{state\}\}">p</figure-callout>}}^2\mathrm{\&tau;}}{\mathrm{\&omega;}(1+{\mathrm{\&omega;}}^2{\mathrm{\&tau;}}^2)}]$

In the above-mentioned formula,

Be the complex dielectric permittivity of intrinsic semiconductor, ε ₂Be the real part of intrinsic semiconductor complex dielectric permittivity, ε ₂' be the imaginary part of intrinsic semiconductor complex dielectric permittivity, ε _StaticBe the static dielectric of intrinsic semiconductor, ω _pBe the plasma angular frequency of intrinsic semiconductor, ω is the THz wave angular frequency that transmits, and is the momentum relaxation time, and it can be calculated by the carrier mobility of intrinsic semiconductor

$\mathrm{\&tau;}=\frac{m^{*}\mathrm{\&mu;}}{e}$

In the above-mentioned formula, m ^*Be the effective mass of charge carrier, μ is carrier mobility, and e is a charge carrier institute carried charge.

According to the Drude model, by changing the plasma angular frequency of intrinsic semiconductor _pCan change intrinsic semiconductor complex dielectric permittivity real part ε ₂Sign.If the plasma angular frequency of intrinsic semiconductor at normal temperatures _pMore approaching with the THz wave angular frequency of transmitting, ω so _pNeed the amount of change just smaller.The plasma angular frequency of intrinsic semiconductor _pPlasma frequency f with intrinsic semiconductor _pRelation be:

$f_p=\frac{{\mathrm{\&omega;}}_{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="HSA00000377475400011.png,HSA00000377475400012.png"\; state="\{\{state\}\}">p</figure-callout>}}}{2\mathrm{\&pi;}}$

The plasma angular frequency of intrinsic semiconductor _pCan be calculated by following formula

${\mathrm{\&omega;}}_p=\sqrt{\frac{{\mathrm{ne}}^2}{{\mathrm{\&epsiv;}}_0{\mathrm{\&epsiv;}}_{\mathrm{static}}{m}^{*}}}$

In the above-mentioned formula, n is the free carrier concentration of intrinsic semiconductor, ε ₀Be absolute dielectric constant, ε _StaticBe the static dielectric of intrinsic semiconductor, m ^*It is the effective mass of charge carrier.Because the free carrier concentration of intrinsic semiconductor can change along with variations in temperature, so change the plasma angular frequency that temperature just can change intrinsic semiconductor _pThereby, the sign of change intrinsic semiconductor real part of permittivity.At normal temperatures, the plasma frequency f of intrinsic semiconductor _pNear (ω 1THz _pBe about 2 π * 10 ¹²Rad/s) corresponding carrier concentration can be calculated by following formula

$n=\frac{{\mathrm{\&epsiv;}}_0{\mathrm{\&epsiv;}}_{\mathrm{<figure-callout\; id="2"\; label="static\; m"\; filenames="HSA00000377475400011.png,HSA00000377475400012.png"\; state="\{\{state\}\}">static</figure-callout>}}{m}^{}{}^2{\mathrm{\&omega;}}_p^2}{{\mathrm{<figure-callout\; id="2"\; label="e"\; filenames="HSA00000377475400011.png,HSA00000377475400012.png"\; state="\{\{state\}\}">e</figure-callout>}}^2}\&ap;{10}^{15}c{m}^{-3}$ Or 10 ¹⁶Cm ^-3

Because different semiconductors has different static dielectric and charge carrier effective mass, so as long as the free carrier concentration of this intrinsic semiconductor is near 10 at normal temperatures ¹⁵Cm ^-3Or 10 ¹⁶Cm ^-3, its plasma frequency is all near 1THz.And the intrinsic semiconductor that meets such condition has indium arsenide and indium antimonide.Indium arsenide intrinsic carrier concentration under the temperature of 300K is about 7 * 10 ¹⁴Cm ^-3, indium antimonide intrinsic carrier concentration under the temperature of 300K is about 1 * 10 ¹⁶Cm ^-3

And other a lot of intrinsic semiconductors do not meet such requirement.Be about 2.1 * 10 such as GaAs intrinsic carrier concentration under the temperature of 300K ⁶Cm ^-3If make the intrinsic carrier concentration of gallium arsenide wafer reach 1THz, the amplitude that needs to change temperature at normal temperatures will be greater than 650K, and obviously this is unpractical.Germanium intrinsic carrier concentration under the temperature of 300K is about 2 * 10 for another example ¹³Cm ^-3If make the intrinsic carrier concentration of germanium wafer reach 1THz, need to change temperature amplitude at normal temperatures and be approximately 480K, this does not meet actual yet.And other semiconductors are about 1 * 10 as silicon intrinsic carrier concentration under the temperature of 300K ¹⁰Cm ^-3, intrinsic carrier concentration is from 10 ¹⁵Cm ^-3Or 10 ¹⁶Cm ^-3All fall far short.So these intrinsic semiconductors all are not suitable for the Terahertz surface plasma wave temp control switch among the present invention.

Comparatively speaking, it is all very little to make that the intrinsic carrier concentration of indium arsenide and indium antimonide reaches the required temperature change of 1THz.Reach 1THz such as indium arsenide intrinsic carrier concentration under the temperature of about 250K, indium antimonide intrinsic carrier concentration under the temperature of about 333K reaches 1THz.These temperature all hardly differ with normal temperature 300K, so still be that the angle of cost considers that indium arsenide and indium antimonide all are more suitable for making near the Terahertz surface plasma wave temp control switch of modulation wave band 1THz than some other semiconductor from performance no matter.

If as intrinsic semiconductor, change to 30 ℃ from-30 ℃ when temperature with indium antimonide so, the plasma frequency of indium arsenide changes to 2.0THz from 0.8THz.If the THz surface plasma wave frequency of transmitting is between 0.8THz and 2.0THz, such as the wideband THz surface plasma wave that is distributed in 0.9THz to 1.9THz, change to 30 ℃ from-30 ℃ when temperature so, the wideband THz surface plasma wave that transmits just becomes logical by breaking.On the contrary, if temperature changes to-30 ℃ from 30 ℃, the wideband THz surface plasma wave that transmits just by logical become disconnected.

If as intrinsic semiconductor, change to 127 ℃ from 30 ℃ when temperature with indium arsenide so, the plasma frequency of indium arsenide changes to 1.4THz from 0.4THz.If the THz surface plasma wave frequency of transmitting is between 0.4THz and 1.4THz, such as the THz surface plasma wave that is positioned at 0.5THz and two frequencies of 1.3THz, change to 127 ℃ from 30 ℃ when temperature so, just can make the THz surface plasma wave of these two frequencies of transmitting just become logical by breaking simultaneously.On the contrary, if the temperature of semiconductor wafer changes to 30 ℃ from 127 ℃, just can make simultaneously these two frequencies of transmitting just by disconnected become logical.

So select suitable intrinsic semiconductor, just can carry out switch control to certain wave band THz surface plasma wave.In order to carry out switch control to wideer THz surface plasma wave, variations in temperature is the bigger the better.But our semiconductor surface uniformity of temperature profile of needing the Terahertz surface plasma wave to flow through simultaneously, temperature controller is just very important preferably to select performance so for use.General current-modulation temperature controller has two surfaces, and when positive current was passed through temperature controller, heat can be transferred to another surface from a surface; If negative current passes through, the heat transmission direction is opposite.The electric current that temperature controller flows through is more big, and the temperature difference on two surfaces is more big, but a limit is arranged.

Suppose that we need the temperature of intrinsic semiconductor to change in-40 ℃ to 50 ℃ scope, because-40 ℃ temperature differs bigger with the room temperature ratio, we can adopt structure as shown in Figure 3, adopt multistage temperature controller and water cooling plant to realize.Topmost the upper surface of one-level temperature controller is close to an intrinsic semiconductor wafer, and its lower surface is close to a copper sheet.Below copper sheet, be close to two temperature controllers again, then at the lower surface filled with water device for cooling of these two temperature controllers.So just can be so that heat can transfer out from semiconductor quickly.If make conductor temperature than room temperature height, as long as we just can reach the pyrogenicity effect opposite the direction of the current delivery of top all temperature controllers.In order to make semi-conductive variations in temperature even, we can adopt the bigger temperature controller of area, are the temperature controller of 5cm * 5cm such as surface area.The area of copper sheet will make it greater than the area of two temperature controllers, such as adopt thickness be 2cm, area is the copper sheet of 5cm * 15cm.

The said temperature controller has adopted the two-stage temperature controller, if still can not reach the lower temperature of expection, we can also adopt three grades: i.e. temperature controller of ground floor, two temperature controllers of the second layer, the 3rd layer of three temperature controller.Each layer centre is separated by with copper sheet, and the temperature controller of basecoat contacts water cooling plant respectively.

Claims (2)

1. Terahertz surface plasma wave temp control switch, it is characterized in that this switch comprises that a plasma frequency is in the intrinsic semiconductor wafer (2) of terahertz wave band at normal temperatures, the blade of two parallel placements (3), an and temperature controller (5), two blades (3) are perpendicular to intrinsic semiconductor wafer (2), the edge of a knife of two blades (3) is from the distance of intrinsic semiconductor wafer (2) the upper surface aerial decay distance of Terahertz surface plasma wave (4) less than peak frequency, the distance between two blades (3) less than the Terahertz surface plasma wave (4) of peak frequency in the semiconductor surface propagation distance; The thickness of intrinsic semiconductor wafer (2) is greater than the decay distance of Terahertz surface plasma wave (4) in semiconductor of minimum frequency; Temperature controller (5) is close to the lower surface of intrinsic semiconductor wafer (2), the temperature regulating range of temperature controller (5) should make intrinsic semiconductor wafer (2) plasma frequency can along with variations in temperature greater than with less than the surface plasma wave frequency of propagating, described intrinsic semiconductor has indium arsenide and indium antimonide.

2. the control method of a Terahertz surface plasma wave temp control switch as claimed in claim 1, it is characterized in that adopting blade (3) that THz wave (1) is converted into Terahertz surface plasma wave (4) and the Terahertz surface plasma wave (4) of conducting is converted into THz wave (1), THz wave (1) incide one of them blade (3) at a certain angle thus knife-edge part realize maximum coupling efficiency; Control intrinsic semiconductor wafer (2) temperature by temperature controller (5), thereby change the carrier concentration of this intrinsic semiconductor (2); When the carrier concentration of semiconductor (2) changed, its plasma frequency also changed, thereby its dielectric constant will change; When the frequency of Terahertz surface plasma wave (4) during greater than the plasma frequency of intrinsic semiconductor wafer (2), this semiconductor (2) shows as dielectric property, and its real part of permittivity is for just; When the frequency of Terahertz surface plasma wave (4) during less than the plasma frequency of intrinsic semiconductor wafer (2), this semiconductor (2) shows as metallic character, its real part of permittivity is for negative, because Terahertz surface plasma wave (4) can only be propagated at the opposite two media interface of dielectric constant, so Terahertz surface plasma wave (4) can be in the propagation of semiconductor (2) surface when showing as metallic character when semiconductor (2), and when semiconductor (2) when showing as dielectric property Terahertz surface plasma wave (4) can not propagate on semiconductor (2) surface, thereby realized the function of switch.

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