CN202394004U - Light modulator - Google Patents

Abstract

An optical modulator of the present invention includes a support, a first medium and a second medium, the first medium is surrounded by an incident surface, an outgoing surface perpendicular to the incident surface, and a first critical surface connecting the outgoing surface and the incident surface. In this way, the first electrode set in the first medium is adjacent to the boundary between the incident surface and the outgoing surface; the second medium is composed of a transmission surface parallel to the incident surface, a second critical surface parallel to the first critical surface, and a connection The interface between the transmission surface and the second critical surface is surrounded, and the second electrode set in the second medium is adjacent to the boundary between the transmission surface and the interface; the support fixes the first medium and the second medium, and the first critical surface and the second The two critical surfaces are adjacent to each other and have a gap to form an optical quantum tunnel structure, and both the first medium and the second medium are materials with inverse piezoelectric effect. The utility model controls the width of the optical quantum tunnel by applying an electric field to the electrodes, controls the transmittance of the electromagnetic wave beam, and realizes the control of the transmittance of the electromagnetic wave beam with a simple structure.

Description

a light modulator

technical field

The utility model relates to an optical modulator, in particular to a transmissive optical modulator which can be used to modulate the transmittance of electromagnetic waves. the

Background technique

An optical modulator is a device that can modulate the one-dimensional or two-dimensional spatial distribution of light wave intensity, and its output optical signal is a function of space and time that changes with the control signal. The liquid crystal light valve is a kind of light modulator widely used at present. It uses twisted nematic liquid crystal to work in the transmissive mode. The working principle is briefly described below. Liquid crystal is a substance between solid and liquid. It is an organic compound with regular molecular arrangement. If it is heated, it will appear in a transparent liquid state, and when it is cooled, it will appear in a turbid solid state of crystalline particles. It is precisely because of its characteristics that it is called liquid crystal. As shown in Figure 2 and Figure 3, there are polarizers on both sides of the liquid crystal cell, of which the upper polarizer is a linear polarizer, and the lower polarizer is a linear polarizer. Analyzer. Their polarization axes are parallel to each other, and they are all in the same direction as the liquid crystal molecules on the inner surface of the top substrate of the liquid crystal cell. When no external electric field is applied, when the incident light reaches the bottom of the cell, the polarization plane of the light will be perpendicular to the polarization axis of the analyzer, and the light will be blocked by the analyzer, making the liquid crystal cell opaque when viewed from the back, as shown in Figure 2. After the electric field is applied, the incident light does not deflect when passing through the liquid crystal cell, but can pass through the analyzer, and the liquid crystal cell seems to be transparent, as shown in Figure 3. The device works between these two states. When the liquid crystal molecules deflect at a certain angle, the incident light has a certain transmittance accordingly. The working principle also determines that this device has certain defects: 1. Since the incident light passes through a polarizer to convert natural light into polarized light, the maximum transmittance of the device is only 50%; 2. The electro-optic response The speed is slow; 3. The light transmission and closure are not complete, that is, the light is still blocked in the on state, and the light is still transmitted in the off state, in other words, the contrast is poor. the

When an electromagnetic wave enters a medium with a refractive index of n ₁ from a medium with a refractive index of n ₁ , the incident angle α ₁ and the refracted angle α ₂ satisfy the law of refraction: n ₁ *sinα ₁ =n ₂ *sinα ₂ . If n ₁ is greater than n ₂ , then α ₂ is greater than α ₁ , that is, when an electromagnetic wave shoots from an optically denser medium to an optically rarer medium, the angle of refraction will be greater than the angle of incidence. When the incident angle is a certain value, the refraction angle will be equal to 90°, which is called the critical angle. Critical angle c=arcsin(n ₂ /n ₁ ). At this time, no refracted waves will appear in the optically sparse medium. If the incident angle is greater than the critical angle, there will be no refraction, and all electromagnetic waves will return to the optically dense medium. This phenomenon is called total reflection. At this time, no electromagnetic wave is emitted into the optically sparse medium, but some kind of wave disturbance is produced in the optically sparse medium. This wave is called evanescent wave, which does not carry any energy. The disturbance of this wave increases with the distance from the interface. rapidly diminished to disappear. From mathematical calculations, the electric field strength of this wave can be expressed as:

${\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>}\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; sin</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; no</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span>}^{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}}\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; i\&omega;</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>$

The subscript of the physical quantity in the optically dense medium is 1, and the subscript of the physical quantity in the optically sparse medium is 2 or superscript (2). It can be seen from the formula that this is a wave process of damping and attenuation. The transmitted wave represented by this formula is a special wave that propagates along the x direction and decays exponentially along the z direction. This wave is called an evanescent wave. The equi-phase plane and constant-magnitude plane discussed above coincide, which is a uniform wave; and the equi-phase plane of the evanescent wave is perpendicular to the constant-amplitude plane, which is a non-uniform wave. This kind of fluctuation can only propagate close to the interface and cannot go deep into the optically sparse medium, and the amplitude of the evanescent wave decreases very quickly with the depth z. the

可见沿z方向深度增加约波长数量级的20倍，振幅约减小为万分 之4，能量约减小为亿分之16。由此可知，光疏介质的宽度与电磁波透过率具有一一对应的关系，当光疏介质的宽度为波长3.2(20/2π)倍时，电磁波透过率为亿分之16。由此可知，通过光疏介质宽度的连续变化，可使电磁波透过率在0～100％范围内连续变化。光疏介质在本实用新型中即为光学量子隧道结构。  When the electromagnetic wave undergoes total reflection, if another optically dense medium is placed parallel to the first optically dense medium, the relationship between this phenomenon and the tunnel effect can be seen. If the two mediums are moved very close, Let the evanescent wave pass through the surface of the second medium, and a beam of transmitted light appears in the second medium. The closer the two media are, the stronger the reappearance of the transmitted light. The reason why the transmitted light increases when the two media are close is that the amplitude of the evanescent wave is not attenuated enough in the "forbidden" air gap. This phenomenon, called frustrated total internal reflection, is the optical counterpart of de Broglie wave quantum tunneling. That is to say, the transmittance of electromagnetic waves can be controlled by changing the size of the gap between the media. It can be seen from the above formula that if n=1/1.52, θ1=π/4, then Take z=v2/ω=λ2/2π as the wavelength order of magnitude, when z=λ2/2π, $\exp [-\sqrt{{\left(\frac{{\sin \mathrm{\&theta;}}_1}{\mathrm{no}}\right)}^2-1}]\&ap;0.6740;$ z=10λ2/2π, $\exp [1-10\sqrt{{\left(\frac{{\sin \mathrm{\&theta;}}_1}{\mathrm{no}}\right)}^2-1}]\&ap;0.0194;$ z=20λ2/2π, $\exp [-20\sqrt{{\left(\frac{{\sin \mathrm{\&theta;}}_1}{\mathrm{no}}\right)}^2-1}]$

It can be seen that the depth along the z direction increases about 20 times of the wavelength order, the amplitude decreases to about 4/10,000, and the energy decreases to about 16/100,000,000. It can be seen that there is a one-to-one relationship between the width of the optically thinning medium and the electromagnetic wave transmittance. When the width of the optically thinning medium is 3.2 (20/2π) times the wavelength, the electromagnetic wave transmittance is 16 parts per billion. It can be known that the electromagnetic wave transmittance can be continuously changed in the range of 0-100% by continuously changing the width of the optically rarefied medium. The optical thinning medium in the utility model is an optical quantum tunnel structure.

Piezoelectric effect: When some dielectrics are deformed by external forces in a certain direction, polarization will occur inside them, and at the same time, opposite charges will appear on its two opposite surfaces. When the external force is removed, it will return to the uncharged state. This phenomenon is called the positive piezoelectric effect. When the direction of the force changes, the polarity of the charge also changes. On the contrary, when an electric field is applied in the polarization direction of the dielectric, these dielectrics will also deform. After the electric field is removed, the deformation of the dielectric will disappear. This phenomenon is called the inverse piezoelectric effect, or the electrostrictive phenomenon. the

Utility model content

Technical problem: The utility model provides a transmissive light modulator with simple structure, wide application range and high contrast. the

Technical solution: A light modulator of the present invention includes a support, a first medium and a second medium, the first medium is composed of an incident surface, an outgoing surface perpendicular to the incident surface, and a first adjacent surface connecting the outgoing surface and the incident surface. Surrounded by the interface, the first medium is provided with a first electrode, and the first electrode is adjacent to the boundary between the incident surface and the outgoing surface; the second medium is composed of a transmission surface parallel to the incident surface, parallel to the first critical surface Surrounded by the second critical surface and the interface connecting the transmission surface and the second critical surface, the second medium is provided with a second electrode, and the second electrode is adjacent to the boundary between the transmission surface and the interface; the support is connected with the first medium and the second medium The two media are respectively connected, and the two are fixedly positioned. The first critical surface is adjacent to the second critical surface and there is a gap. The gap constitutes an optical quantum tunnel structure. Both the first medium and the second medium have an inverse piezoelectric effect. Material. the

In the utility model, the materials of the inverse piezoelectric effect adopted by the first medium and the second medium can be crystals such as zinc oxide, cadmium sulfide, aluminum nitride, etc., which contain polysegregated carbon-fluorine bonds with a relatively large dipole moment. Vinyl fluoride, or some ferroelectric crystals, including: iron transistors containing oxygen octahedrons, such as barium titanate crystals, lithium niobate with lithium niobate structure, tantalum niobate, and strontium barium niobate with tungsten bronze structure ; Iron transistors containing hydrogen bonds, such as potassium dihydrogen phosphate, ammonium dihydrogen phosphate, and lead hydrogen phosphate (and deuterated lead phosphate) crystals; bismuth titanate crystals containing layered structures, etc. When an electric field is applied to these transparent materials, they deform. the

When the light modulator of the present invention is working, the incident light enters from below, first enters the first medium from the incident surface and reaches the first critical surface. At this time, the magnitude of the electric field applied to the medium is changed by adjusting the voltage applied to the electrodes. Due to the inverse piezoelectric effect, the deformation of the medium is controlled, thereby controlling the size of the gap between the first medium and the second medium. When the gap between the first medium and the second medium, that is, the width of the optical quantum tunnel structure is the maximum width (3.2 times the wavelength of the incident light), 99.99% of the incident light cannot pass through, and total reflection occurs at the first critical surface. And reach the exit surface and be absorbed. This situation is off state. When the gap between the first medium and the second medium, that is, the width of the optical quantum tunnel structure is the minimum width, that is, when the first medium is in contact with the second medium, the incident light will enter the second medium from the second critical surface without any reflection. , and then emitted from the upper transmissive surface. When the gap between the first medium and the second medium, that is, the width of the optical quantum tunnel structure is a certain value between the minimum and maximum width, correspondingly, the incident light has a certain transmittance. the

The medium used in the utility model needs to have an inverse piezoelectric effect. According to the difference of the medium used, the utility model can work in different electromagnetic wave bands: the medium is transparent to the electromagnetic wave infrared light band, and the utility model is an infrared light modulator; the medium is for The electromagnetic wave is transparent in the visible light band, and the utility model is a visible light modulator; the medium is transparent to the electromagnetic wave ultraviolet light band, and the utility model is an ultraviolet light modulator. the

Beneficial effects: the light modulator of the present utility model has the following advantages compared with the prior art:

First, the principle utilized by the utility model is very ingenious, involving total reflection of electromagnetic waves and optical quantum tunneling effect. When an electromagnetic wave travels from an optically denser medium to an optically rarer medium, the angle of refraction will be greater than the angle of incidence. When the incident angle is a certain value, the refraction angle will be equal to 90°, which is called the critical angle. When the incident angle is greater than the critical angle, total reflection will occur. At this time, no electromagnetic wave is emitted into the optically sparse medium, and only the evanescent wave without energy enters the optically sparse medium. If the attenuation within the distance is completed, if another optically dense medium is used close to the original optically dense medium, the evanescent wave enters the second optically dense medium before the attenuation is completed, and the projected wave will appear in the second optically dense medium (This effect is called quantum tunneling effect), and the intensity of the projected wave is related to the degree of attenuation of the evanescent wave in the optically sparse medium, that is, to the length of the path of the evanescent wave propagating in the optically sparse medium. According to this principle, the transmittance of the transmitted wave can be controlled by the propagation distance of the evanescent wave in the optically sparse medium. To solve the problem of how to control the width of the optically thinning medium, the utility model utilizes the inverse piezoelectric effect of the medium, and can easily control the width by applying an electric field. Formally based on the ingenious principle, the structure of the utility model is also very simple. The whole utility model only includes the medium, electrodes and supports, while the current commonly used liquid crystal light valves need liquid crystal cells and polarizers, etc., and the manufacturing process of the liquid crystal cells is very simple. Complicated, including steps such as suspension coating polyimide acid, rubbing orientation, sealing box, filling crystal, etc., it can be said that the utility model is much simpler in comparison. the

Second, when the utility model works, the electromagnetic wave transmittance can be adjusted in a large range, which is 0-100%. When the distance between the two optically dense media is 0, the electromagnetic wave transmittance is 100%; when the distance between the two optically dense media is greater than or equal to 3.2 times the wavelength of the electromagnetic wave transmitted, the electromagnetic wave transmittance is 0; when the two optically dense media When the distance between the dense media is between the above two, the electromagnetic wave transmittance is a certain value between 0 and 100%. It can be seen that the contrast ratio (defined as the ratio of the maximum transmittance to the minimum transmittance) of the present invention is large. When the liquid crystal light valve is working, the electromagnetic wave needs to pass through the polarizer. As we all know, when natural light passes through a polarizer and becomes polarized light, the energy is at least reduced to half of the original, so the maximum transmittance of the liquid crystal light valve is only 50%. . However, when the liquid crystal light valve works in the off state, due to the defect of its principle, a small part of electromagnetic waves still passes through, that is, the minimum transmittance is less than 0, so its contrast is very low. In comparison, the benefits of the present utility model are obvious. the

Thirdly, the inverse piezoelectric effect based on the medium is fast, and the electro-optical response speed of the utility model is fast. However, the electro-optic response speed of the liquid crystal light valve is slow. the

Description of drawings

Fig. 1 is the three-dimensional structure schematic diagram of the utility model transmissive light modulator;

Figure 2 is a schematic diagram of a transmissive liquid crystal light valve (light blocking state);

Figure 3 is a schematic diagram of a transmissive liquid crystal light valve (light transmission state);

Figure 4(a) is a schematic diagram of the width of the optical quantum tunnel and the passage of light (the state with a small transmittance);

Figure 4(b) is a schematic diagram of the width of the optical quantum tunnel and the passage of light (moderate transmittance state);

Figure 4(c) is a schematic diagram of the width of the optical quantum tunnel and the passage of light (in a state with a large transmittance);

Fig. 5 is a schematic diagram of the elevation structure of the transmissive light modulator of the present invention. the

Fig. 6 is a top view of the transmissive light modulator of the present invention. the

Fig. 7 is a left view of the transmissive light modulator of the present invention. the

Fig. 8 is a right view of the transmissive light modulator of the present invention. the

In the figure: 1. support; 2. first medium; 3. first electrode; 4. second electrode; 5. second medium; 6. optical quantum tunnel structure; 7. incident light; 8. polarizer; 9 .Liquid crystal molecules; 10. Outgoing light; 21. Incident surface; 22. Outgoing surface; 23. First critical surface; 51. Transmission surface; 52. Second critical surface; 53. Interface. the

Detailed ways

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

A light modulator of the present utility model includes a support 1, a first medium 2 and a second medium 5, the first medium 2 is composed of an incident surface 21, an outgoing surface 22 perpendicular to the incident surface 21, and a connection between the outgoing surface 22 and the incident surface. Surrounded by the first critical surface 23 of the surface 21, the first electrode 3 is arranged in the first medium 2, and the first electrode 3 is adjacent to the boundary between the incident surface 21 and the outgoing surface 22; the second medium 5 is made of The transmission surface 51 of the surface 21, the second critical surface 52 parallel to the first critical surface 23, and the interface 53 connecting the transmission surface 51 and the second critical surface 52 are surrounded, and the second medium 5 is provided with a second electrode 4. The second electrode 4 is adjacent to the boundary between the transmissive surface 51 and the interface 53; the support 1 is connected to the first medium 2 and the second medium 5 respectively, and the two are fixedly positioned. The first critical surface 23 and the second critical surface 52 Adjacent to each other there is a gap, the gap constitutes an optical quantum tunnel structure 6, and both the first medium 2 and the second medium 5 are materials with inverse piezoelectric effect. the

In one embodiment of the present utility model, the first medium 2 and the second medium 5 are right-angled triangular prism-shaped mediums, the two mediums are placed opposite each other up and down, the support 1 is four columns distributed around, the first medium 2 and the second medium The second medium 5 is attached to the support 1, fixedly positioned under the action of the support 1 and maintains the gap between the two. the

In another embodiment of the present utility model, the support 1 is a light-transmitting material that is distributed around and covers the outer surfaces of the first medium 2 and the second medium 5, and the first medium 2 and the second medium 5 are placed on the surface of the support 1. Under the action, the positioning is fixed and the gap between the two is maintained. Since the support 1 is made of a light-transmitting material, it does not affect the transmission of light waves. the

The electromagnetic beam is incident from below parallel to the supporting direction. After the electromagnetic beam enters the first medium 2 , total reflection occurs at the interface between the first medium 2 and the optical quantum tunnel structure 6 , and evanescent waves enter the optical quantum tunnel 6 . Apply the set voltage on the first electrode 3 and the second electrode 4, so that the first medium 2 and the second medium 6 are in an electric field with a certain electric field strength. Due to the inverse piezoelectric effect, the first medium 2 and the second medium 5 is then deformed, so the width of the optical quantum tunnel 6 changes to form the required width. According to the aforementioned background knowledge, a certain proportion of the electromagnetic beam will enter the second medium 5, and then exit from the top of the light modulator. Thus, the transmittance of the electromagnetic beam can be controlled electrically. the

According to the foregoing background knowledge, the width of the optical quantum tunnel structure 6 has a one-to-one relationship with the electromagnetic wave transmittance. The refractive index of the first medium 2 and the second medium 5 is 1.52. At this time, when the width of the optical quantum tunnel structure 6 is 3.2 times the wavelength, the electromagnetic wave transmittance is 16 per billion. It can be seen that, through the optical quantum tunnel The continuous change of the width of the structure 6 can make the transmittance of electromagnetic waves change continuously within the range of approximately 0-100%. The width of 6 is 95.5nm; if its transmittance needs to be modulated to 1.9%, the width of optical quantum tunnel 6 can be 950.5nm. the

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.

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