CN202394004U - Light modulator - Google Patents

Abstract

The utility model relates to a light modulator which comprises a support, a first medium and a second medium, wherein the first medium is enclosed by an incident plane, an emergent plane perpendicular to the incident plane and a first critical plane for connecting the incident plane and the emergent plane; a first electrode which is arranged in the first medium is adjacent to the boundary of the incident plane and the emergent plane; the second medium is enclosed by a transmission plane parallel to the incident plane, a second critical plane parallel to the first critical plane and an interface for connecting the transmission plane and the second critical plane; a second electrode which is arranged in the second medium is adjacent to the boundary of the transmission plane and the interface; the first medium and the second medium are fixedly positioned by the support; the first critical plane and the second critical plane are adjacent and keeps a gap to form an optical quantum tunnel structure; and both the first medium and the second medium have materials with inverse piezoelectric effect. According to the light modulator, the electrodes apply electric fields to control the width of the optical quantum tunnel and control the electromagnetic beam transmittance. The light modulator achieves the effect of controlling the electromagnetic beam transmittance by virtue of a simple structure.

Description

A kind of photomodulator

Technical field

The utility model relates to a kind of photomodulator, specifically a kind of transmission-type photomodulator that can be used to the modulated electromagnetic wave transmitance.

Background technology

Photomodulator is a kind of device that can distribute and modulate the one dimension or the two-dimensional space of light wave intensity, and its output light signal is the function with the room and time of control signal variation.Liquid crystal light valve is to use wider a kind of photomodulator at present, and it uses twisted nematic liquid crystals to work in transmission-type, its principle of work of brief description.Liquid crystal be a kind of between solid-state and liquid between material, be organic compound with systematicness molecules align, if can present the liquid condition of transparence to its heating, the muddy solid state of crystalline particle then its cooling can appear.Just because of its this specific character, so be referred to as liquid crystal, like Fig. 2, shown in Figure 3, there is polaroid the liquid crystal cell both sides, and wherein the polaroid of top is a linear polariser, and the polaroid of below is linear analyzer.Their polarizing axis is parallel to each other, and all the liquid crystal molecule whereabouts with liquid crystal cell top-side substrate inside surface place is consistent.When not adding external electric field, when incident light arrives the bottom of box, polarization surface will be vertical with the polarizing axis of analyzer, and light is blocked by analyzer, and the liquid crystal cell of seeing over is opaque from the back side, and is as shown in Figure 2.Behind the extra electric field, do not deflect during incident light process liquid crystal cell, can pass from analyzer, liquid crystal cell is transparent, as shown in Figure 3 seemingly.This device is operated between these two states, and when the liquid crystal deflecting element certain angle, corresponding, incident light has certain transmitance.And principle of work has also determined this device to have certain defective: 1, because incident light will pass through a polarizer, convert natural light to polarized light, so the maximum transmitance of this device is merely 50%; 2, electro-optic response speed is slow; 3, light transmission with close not thoroughly, still have light to be stopped when promptly opening state, still have light transmission during off status, in other words be poor contrast.

When electromagnetic wave is n from refractive index ₁It is n that medium is injected refractive index ₂Medium, incident angle α ₁With refraction angle α ₂Satisfy refraction law: n ₁* sin α ₁=n ₂* sin α ₂If n ₁Greater than n ₂, α then ₂Greater than α ₁, promptly when electromagnetic wave during from optically denser medium directive optically thinner medium, the refraction angle will be greater than incident angle.When incident angle is a certain numerical value, the refraction angle will equal 90 °, and this incident angle is claimed critical angle.Critical angle c=arcsin (n ₂/ n ₁).At this moment in optically thinner medium refraction wave will not appear.If incident angle greater than critical angle, does not then have refraction, all electromagnetic wave all turns back to optically denser medium, and this phenomenon is called total reflection.At this moment do not have electromagnetic wave to inject in the optically thinner medium, but the disturbance that has produced certain ripple in the optically thinner medium, this ripple is called as evanescent wave, and it does not carry any energy, and the disturbance of this ripple is along with from the increase of interface distance and weaken to disappearance rapidly.Can be got by mathematical computations, the electric field intensity of this ripple can be expressed as:

${\stackrel{\‾}{E}}^{\left(2\right)}={\stackrel{\‾}{E}}_0^{\left(2\right)}\exp [-\frac{\mathrm{\ω}}{v_2}{\left(\frac{{\sin }^2{\mathrm{\θ}}_1}{n^2}\right)}^{\frac{1}{2}}z]*\exp \left[\mathrm{i\ω}(\frac{{\sin \mathrm{\θ}}_1}{v_{2}n}x-t)\right]$

Wherein be designated as 1 under the physical quantity in the optically denser medium, be designated as 2 or subscript (2) in the optically thinner medium under the physical quantity.Can see that from formula this is the wave process of a damping vibration attenuation, the represented transmitted wave of this formula is to propagate along z to the special fluctuation that is exponential damping along the x direction, and this ripple is evanescent wave.The ripple cophasal surface of discussing in the past overlaps with equal-amplitude surface, is homogeneous wave; And the cophasal surface of evanescent wave is vertical with equal-amplitude surface, is inhomogeneous wave.This fluctuation can only be close to the interface propagation and can not go deep into optically thinner medium inside, and the amplitude of evanescent wave reduces very soon with getting into depth z.

When electromagnetic wave generation total reflection; If the parallel first optically denser medium next door that is placed on of another piece optically denser medium; Just can find out the relation between this phenomenon and the tunnel effect; If move two media very closely, let evanescent wave pass the surface of second medium, a branch of transmitted light has occurred in second medium.Two medium distances are near more, and the transmitted light that reappears is strong more.Two media near the time transmitted light reason that strengthens be that in the clearance of " be under an embargo through ", the wave amplitude of evanescent wave is decayed greatly not enough.This phenomenon is called and receives to press down inner total reflection, is that the optics of de Broglie wave quantum tunneling effect is corresponding.In other words, can control electromagnetic transmitance through gap length between the change medium.Can know by above-mentioned formula, as get n=1/1.52, θ 1=π/4, then Getting z=v2/ ω=λ 2/2 π is the number of wavelengths magnitude, as z=λ 2/2 π, $\mathrm{Exp}[-\sqrt{{\left(\frac{{\mathrm{Sin}\mathrm{\θ}}_1}{n}\right)}^2-1}]\≈0.6740;$ Z=10 λ 2/2 π, $\mathrm{Exp}[1-10\sqrt{{\left(\frac{{\mathrm{Sin}\mathrm{\θ}}_1}{n}\right)}^2-1}]\≈0.0194;$ Z=20 λ 2/2 π, $\mathrm{Exp}[-20\sqrt{{\left(\frac{{\mathrm{Sin}\mathrm{\θ}}_1}{n}\right)}^2-1}]$

It is thus clear that along 20 times of the about number of wavelengths magnitude of z direction degree of depth increase, amplitude is reduced to 4/10000ths approximately, energy is reduced to 16/100000000ths approximately.Hence one can see that, and the width of optically thinner medium and electromagnetic wave transmitance have one to one relation, and when the width of optically thinner medium was wavelength 3.2 (20/2 π) times, the electromagnetic wave transmitance was 16/100000000ths.Hence one can see that, through the continuous variation of optically thinner medium width, the electromagnetic wave transmitance changed continuously in 0～100% scope.Optically thinner medium is the quantum optics tunnel structure in the utility model.

Piezoelectric effect: when some dielectric was out of shape in the effect that on certain orientation, receives external force, its inner meeting produced polarization phenomena, on its two apparent surfaces, occurred positive and negative opposite electric charge simultaneously.After external force was removed, it can return to uncharged state again, and this phenomenon is called direct piezo electric effect.When the direction of acting force changed, the polarity of electric charge also changed thereupon.On the contrary, when on the polarization of dielectric direction, applying electric field, these dielectrics also can deform, and after electric field removed, dielectric distortion disappeared thereupon, and this phenomenon is called inverse piezoelectric effect, or is called electrostriction phenomena.

The utility model content

Technical matters: the utility model provides a kind of simple in structure, usable range is extensive, contrast is big transmission-type photomodulator.

Technical scheme: a kind of photomodulator of the utility model; Comprise support, first medium and second medium; First medium is to center on by the plane of incidence, perpendicular to the exit facet of the plane of incidence, first critical surface that connects exit facet and the plane of incidence to form; Be provided with first electrode in first medium, the border of first electrode and the plane of incidence and exit facet is adjacent; Second medium is to be centered on and formed by the transmission plane that is parallel to the plane of incidence, second critical surface that is parallel to said first critical surface, the interface that connects transmission plane and second critical surface; Be provided with second electrode in second medium, the border at second electrode and transmission plane and interface is adjacent; Support is connected respectively with second medium with first medium, and with both stationary positioned, first critical surface is adjacent with second critical surface and gapped, and said gap constitutes the quantum optics tunnel structure, and first medium and second medium are the material with inverse piezoelectric effect.

In the utility model; The material of the inverse piezoelectric effect that first medium and second medium adopt; Can be crystal such as zinc paste, cadmium sulfide, aluminium nitride, contain the polyvinylidene fluoride ene compound of carbon-fluorine bond with big dipole moment, or some ferroelectric crystals; Comprise: contain the iron transistor of oxygen octahedra, for example barium titanate crystal, lithium niobate, tantalum niobate and have the strontium barium niobate crystal of tungsten bronze structure with lithium niobate structure; The iron transistor that contains hydrogen bond, for example potassium dihydrogen phosphate, ammonium dihydrogen phosphate (ADP) and phosphoric acid hydrogen plumbous (and the phosphoric acid deuterium is plumbous) crystal; Contain the bismuth titanates crystal of layer structure etc.When these transparent materials were applied electric field, they can deform.

When the photomodulator of the utility model was worked, incident light was injected by the below, is at first got into first medium and is arrived first critical surface by the plane of incidence.Attend electric field level that institute making alive size change medium on applied through regulating electrode this moment, because inverse piezoelectric effect, thereby control medium deformation is big or small, and then control the size in slit between first medium and second medium.When slit between first medium and second medium is the width of quantum optics tunnel structure when being breadth extreme (lambda1-wavelength 3.2 times), 99.99% incident light can not see through, and total reflection takes place at the first critical surface place, and arrives exit facet and be absorbed.This kind situation is an off status.The slit is that the width of quantum optics tunnel structure is a minimum widith between first medium and second medium, and when promptly first medium contacts with second medium, incident light will not have any reflection and get into second medium by second critical surface, and then transmission plane penetrates from the top.When slit between first medium and second medium is that the width of quantum optics tunnel structure is between minimum and the breadth extreme during a certain value, corresponding, incident light has certain transmitance.

Used medium need have inverse piezoelectric effect in the utility model, and according to the difference of used medium, the utility model can be operated in different electromagnetic wave bands: medium is transparent for the electromagnetic wave infrared band, and the utility model is the infrared light photomodulator; Medium is transparent for the electromagnetic wave visible light wave range, and the utility model is the visible light photomodulator; Medium is transparent for electromagnetic wave ultraviolet light wave band, and the utility model is the ultraviolet light photomodulator.

Beneficial effect: the photomodulator of the utility model has the following advantages with respect to prior art:

The first, the principle that the utility model utilized is very ingenious, relates to electromagnetic total reflection and quantum optics tunnel effect.When electromagnetic wave during from optically denser medium directive optically thinner medium, the refraction angle will be greater than incident angle.When incident angle is a certain numerical value, the refraction angle will equal 90 °, and this incident angle is claimed critical angle.When incident angle during greater than critical angle, total reflection will take place, do not have electromagnetic wave to inject in the optically thinner medium this moment; Only there is the evanescent wave that does not carry energy to get into optically thinner medium; Evanescent wave decay is very fast, can in very short distance, decay, if at this moment with another optically denser medium near former optically denser medium; Make evanescent wave before having decayed, get into second optically denser medium; At this moment projection ripple (this effect is called quantum tunneling effect) in second optically denser medium, will occur, this projection wave intensity is relevant with the degree that evanescent wave is decayed in optically thinner medium, and the path length of promptly in optically thinner medium, propagating with evanescent wave is relevant.According to this principle, just can control the transmitance of transmitted wave by the propagation distance of evanescent wave in optically thinner medium.How to control on the problem of optically thinner medium width in solution, the utility model has utilized the inverse piezoelectric effect of medium, just can very like a cork this width be controlled through applying electric field.Formally based on principle cleverly; Make the utility model structure also very simple, whole utility model only comprises medium, electrode and support, and liquid crystal light valve commonly used at present then needs liquid crystal cell and polaroid etc.; Wherein the manufacture craft of liquid crystal cell is just very complicated; Comprise steps such as being coated with polyimide acid, friction orientation, envelope box, filling crystalline substance, Comparatively speaking, we can say that the utility model is simply a lot.

The second, electromagnetic wave transmitance adjustable extent is big during the utility model work, is 0～100%.When distance between two optically denser mediums was 0, the electromagnetic wave transmitance was 100%; When distance between two optically denser mediums more than or equal to 3.2 times when seeing through electromagnetic wavelength, the electromagnetic wave transmitance is 0; When distance between two optically denser mediums between above-mentioned between the two the time, the electromagnetic wave transmitance is an a certain numerical value between 0 to 100%.Hence one can see that, and the contrast of the utility model (being defined as the ratio of maximum transmission and minimum transmitance) is big.And because liquid crystal light valve when work, electromagnetic wave need pass through polaroid, and is well-known, when natural light becomes polarized light through a polaroid, plays energy and is reduced to original half at least, so the maximum transmission of liquid crystal light valve is merely 50%.And liquid crystal light valve is when working in OFF state, because the defective of its principle still has the fraction electromagnetic wave to see through, promptly its minimum transmitance is also less than 0, so its contrast is very low.Comparatively speaking the benefit of the utility model clearly.

The 3rd, fast based on the inverse piezoelectric effect speed of medium, the electro-optic response speed of the utility model is fast.And the electro-optic response speed of liquid crystal light valve is slow.

Description of drawings

Fig. 1 is the perspective view of the utility model transmission-type photomodulator;

Fig. 2 is transmission-type liquid crystal light valve principle figure (a light blocking state);

Fig. 3 is transmission-type liquid crystal light valve principle figure (a light transmission state);

Fig. 4 (a) is that quantum optics tunnel width and light pass through situation synoptic diagram (the less state of transmitance);

Fig. 4 (b) is that quantum optics tunnel width and light pass through situation synoptic diagram (the medium state of transmitance);

Fig. 4 (c) is that quantum optics tunnel width and light pass through situation synoptic diagram (the big state of transmitance);

Fig. 5 is the facade structures synoptic diagram of the utility model transmission-type photomodulator.

Fig. 6 is the vertical view of the utility model transmission-type photomodulator.

Fig. 7 is the left view of the utility model transmission-type photomodulator.

Fig. 8 is the right view of the utility model transmission-type photomodulator.

Have among the figure: 1. support; 2. first medium; 3. first electrode; 4. second electrode; 5. second medium; 6. quantum optics tunnel structure; 7. incident light; 8. polaroid; 9. liquid crystal molecule; 10. emergent light; 21. the plane of incidence; 22. exit facet; 23. first critical surface; 51. transmission plane; 52. second critical surface; 53. interface.

Embodiment

Below in conjunction with accompanying drawing and embodiment the utility model is further described.

A kind of photomodulator of the utility model; Comprise and support 1, first medium 2 and second medium 5; First medium 2 be by the plane of incidence 21, perpendicular to the exit facet 22 of the plane of incidence 21, connect exit facet 22 and the plane of incidence 21 first critical surface 23 around forming; It is adjacent with the border of the plane of incidence 21 and exit facet 22 to be provided with first electrode, 3, the first electrodes 3 in first medium 2; Second medium 5 is to be centered on and formed by the transmission plane that is parallel to the plane of incidence 21 51, second critical surface 52 that is parallel to said first critical surface 23, the interface 53 that connects transmission plane 51 and second critical surface 52; It is adjacent with the border at transmission plane 51 and interface 53 to be provided with second electrode, 4, the second electrodes 4 in second medium 5; Supporting 1 is connected respectively with second medium 5 with first medium 2; With both stationary positioned; First critical surface 23 is adjacent and gapped with second critical surface 52, and said gap constitutes quantum optics tunnel structure 6, the first media 2 and second medium 5 is the material with inverse piezoelectric effect.

Among the embodiment of the utility model; First medium 2 and second medium 5 are the prismatic medium of right angle trigonometry; Two media are placed up and down relatively; Support 1 and be four root posts around being distributed in, first medium 2 and second medium 5 be attached to supporting on 1, stationary positioned and keep both slit under the effect of support 1.

Among another embodiment of the utility model; Support 1 for around being distributed in and with the light transmissive material of the outside surface coating of first medium 2 and second medium 5; First medium 2 and second medium 5 are supporting stationary positioned under 1 the effect and are keeping both slit; Adopt light transmissive material owing to support 1, so do not influence the transmission of light wave.

Electromagnetic beam supports direction incident from the below by being parallel to, and after electromagnetic beam gets into first medium 2, in the interphase place generation total reflection of first medium 2 with quantum optics tunnel structure 6, has evanescent wave to get in the quantum optics tunnel 6.On first electrode 3 and second electrode 4, apply the voltage that sets; First medium 2 and second medium 6 are in the electric field of certain electric field intensity; Because inverse piezoelectric effect; Deformation takes place in first medium 2 and second medium 5 then, so the width in quantum optics tunnel 6 changes, and forms required width.According to aforementioned background knowledge, will there be a certain proportion of electromagnetic beam to get in second medium 5, and then from the top outgoing of photomodulator.Just realized transmitance thus by the electric control electromagnetic beam.

According to aforementioned background knowledge, the width of quantum optics tunnel structure 6 and electromagnetic wave transmitance have relation one to one.The refractive index of getting first medium 2 and second medium 5 is 1.52, and this moment, the electromagnetic wave transmitance was 16/100000000ths when being 3.2 times of wavelength when the width of quantum optics tunnel structure 6; Hence one can see that; Through the continuous variation of quantum optics tunnel structure 6 width, the electromagnetic wave transmitance is similar in 0～100% scope continuously changes, as being that the red visible light of 600nm is when passing through when wavelength; If needing its transmitance of modulation is 67.4, the width that can make quantum optics tunnel 6 is 95.5nm; If needing its transmitance of modulation is 1.9%, the width that can make quantum optics tunnel 6 is 950.5nm.

Claims (1)

1. a photomodulator is characterized in that, comprises support (1), first medium (2) and second medium (5),

Said first medium (2) be by the plane of incidence (21), perpendicular to the exit facet (22) of the said plane of incidence (21), connect said exit facet (22) and the plane of incidence (21) first critical surface (23) around forming; Be provided with first electrode (3) in said first medium (2), said first electrode (3) is adjacent with the border of the plane of incidence (21) and exit facet (22);

Said second medium (5) be by the transmission plane that is parallel to the plane of incidence (21) (51), be parallel to said first critical surface (23) second critical surface (52), connect said transmission plane (51) and second critical surface (52) interface (53) around forming; Be provided with second electrode (4) in said second medium (5), said second electrode (4) is adjacent with the border of transmission plane (51) and interface (53);

Said support (1) is connected respectively with second medium (5) with first medium (2); With both stationary positioned; Said first critical surface (23) is adjacent and gapped with second critical surface (52); Said gap constitutes quantum optics tunnel structure (6), and described first medium (2) and second medium (5) are the material with inverse piezoelectric effect.

Images