TW201326917A - An electromagnetic wave polarizing component - Google Patents

Abstract

The present invention relates to an electromagnetic wave polarizing component for converting non-polarized electromagnetic wave into a polarized electromagnetic wave of a single polarization direction. The structure of the electromagnetic wave polarizing component is formed by a plurality of structural units arranged in a specific interval. The geometric figures of the units can convert two polarized electromagnetic wave into one polarized electromagnetic wave of a single polarization direction.

Description

Electromagnetic wave polarizing element

This invention relates to a polarizing element, and more particularly to an electromagnetic wave polarizing element.

The polarization characteristics of electromagnetic waves and light waves are widely used in solid-state light sources, display systems, lighting, visual identification, communication systems, and the like. Traditional polarizers are mostly absorptive or reflective. The material of the absorbing polarizer absorbs electromagnetic waves in a polarized direction, that is, at least half of the electromagnetic wave energy is lost, so the light transmittance is first reduced by half. The reflective polarizing element can penetrate a single polarization and reflect another orthogonal polarized light wave. However, if this polarized light wave is to be converted to another polarization direction, additional structure and space are required for polarization recovery. Therefore, although the conventional polarizer can achieve the polarization effect, the light transmittance is not reduced much, that is, the accessory needs to be added to increase the cost.

The electromagnetic wave polarizing element of the invention is composed of a plurality of unit structures arranged according to a specific period, and the period of the arrangement is smaller than the wavelength of the electromagnetic wave, and the unit structure has a special design geometric pattern, so that the unpolarized electromagnetic wave incident on the structure can be converted into a high single polarization. Polarized electromagnetic waves. Compared to the prior art, the polarizing element of the present invention has a single high polarization and a high transmittance.

The present invention provides an electromagnetic wave polarizing element comprising at least a plurality of unit structures, each of the unit structures having at least one geometric pattern, and the geometric pattern having a main resonant polarization axis. The geometric patterns between adjacent unit structures have an arrangement interval which is smaller than a wavelength of the incident electromagnetic wave. The incident electromagnetic wave includes a first polarized electromagnetic wave and a second polarized electromagnetic wave, and when the first polarized electromagnetic wave passes through the geometric pattern, a first polarization direction of the first polarized electromagnetic wave Turning to the main resonant polarization axis direction, while the second polarized electromagnetic wave passes through the geometric pattern, a second polarization direction of the second polarized electromagnetic wave is turned to the main resonant polarization axis direction And obtain a third polarized electromagnetic wave.

In an embodiment of the invention, the shape of the geometric pattern comprises a vertical strip, a horizontal strip or a combination thereof, a continuous spiral, a circle, an ellipse, a polygon, or a combination thereof.

In an embodiment of the invention, the electromagnetic wave polarizing element is further formed on a substrate and divided into the plurality of unit structures, wherein the geometric pattern is a protrusion.

In an embodiment of the invention, the electromagnetic wave polarizing element is a metal film layer, and the geometric pattern is hollow or filled with a dielectric substance.

The above described features and advantages of the present invention will be more apparent from the following description.

The present invention provides an electromagnetic wave polarizing element that is converted into a single polarized electromagnetic wave when the unpolarized electromagnetic wave passes through the electromagnetic wave polarizing element. The electromagnetic wave polarizing element is composed of a plurality of unit structures arranged at a specific interval, and the interval (period) of the array is smaller than the wavelength of the electromagnetic wave. The unit structure is designed to have a specific geometry, so that the unpolarized electromagnetic wave incident on the polarizing element can be converted into a single polarization, and the electromagnetic wave of the incident electromagnetic wave is low, that is, the electromagnetic wave polarizing element has a high transmittance.

1A is a schematic view of an electromagnetic wave polarizing element, FIG. 1B is an enlarged perspective view of a unit structure of FIG. 1A, and FIG. 1C is a top view of FIG. 1B. As shown in FIG. 1A, the electromagnetic wave polarizing element 100 itself is a film or a film, such as a metal film layer, having a thickness t. The electromagnetic wave polarizing element 100 includes a plurality of unit structures 102 (divided in dashed lines), each unit structure 102 is designed with a geometric pattern 104 of a particular geometry, and the spacing between adjacent unit structures 102 is d. Since each of the unit structures 102 in this embodiment has a geometric pattern 104 of the same spiral shape, and each of the unit structures 102 is substantially square (upper viewing direction), the arrangement period of the geometric patterns 104 is also the arrangement of the geometric patterns 104. Interval d. In accordance with the principles of the present invention, the arrangement spacing d (i.e., the arrangement period) of the geometric patterns 104 between adjacent unit structures 102 needs to be less than the wavelength of the incident electromagnetic waves.

As shown in FIGS. 1B and 1C, the geometric pattern 104 having a spiral shape in the unit structure 102 is hollow (ie, through the unit structure 102), and the helical pitch of the geometric pattern 104 of the hollow spiral shape is the same as the spiral width, and the spiral length is calculated. as follows:

Where n is the number of turns of the spiral half turn (ie, the spiral is considered as a continuous combination of multiple half turns), w is the spiral width, and R is the radius of the spiral. In the present embodiment, the length of the spiral radius R is gradually increased by a spiral width w length with a half circle number n .

Regarding the wavelength range or product requirement of the incident electromagnetic wave to be polarized, the spiral form of the geometric pattern 104, the spiral width w , the spiral length, the inter-spiral distance, or even the thickness of the film structure (ie, the electromagnetic wave polarizing element 100) in the present invention. t can be adjusted accordingly. In an embodiment, the wavelength of the incident electromagnetic wave is defined as λ, and the width w of the spiral line may be 0.05λ~0.3 λ, and the thickness t of the electromagnetic wave polarizing element 100 may be 0.003λ~0.1 λ. For example, when the incident electromagnetic wave is in the visible light band of 400 nm to 750 nm, the spiral width w can be 50 to 100 nm, and the thickness of the electromagnetic wave polarizing element 100 can be 50 nm. When the infrared light is 1 μm~10 μm, the spiral width w can be 160 nm, and the thickness of the penetrating electromagnetic wave polarizing element 100 can be 200 nm. In the megahertz band of 2 THz to 10 THz (30 μm to 150 μm), the spiral width w may be 1 μm, and the thickness t of the penetrating electromagnetic wave polarizing element 100 may be 0.1 μm. In the microwave band of 2 GHz to 10 GHz, the spiral width w can be 1 mm, and the thickness t of the electromagnetic wave polarizing element 100 can be 0.1 mm. When the geometric pattern 104 is in a spiral shape, the ellipsometric ratio of the electromagnetic wave penetrating the electromagnetic wave polarizing element 100 may be less than 0.1, and the electromagnetic wave polarizing element 100 may have a transmittance T greater than 0.7.

In fact, the unit structure of the electromagnetic wave polarizing element provided by the present invention is designed to have a specific geometric pattern, and the specific geometric pattern may include a combination of vertical and horizontal strips, continuous spiral, circular, elliptical, polygonal or a combination thereof. . The shape of the specific geometric pattern here is designed to have a polarization modulation function, that is, to adjust the polarization direction of incident electromagnetic waves.

2A-2C are top plan views of geometric patterns of a single unit structure. As shown in FIG. 2A, the L-shaped geometric pattern 104 in the unit structure 102 is hollow, where the L-shaped hollow geometric pattern 104 can be considered to be a combination of vertical and horizontal elongated shapes. Similarly, in FIG. 2B, the geometric pattern 104 having a C shape in the unit structure 102 is hollow, while in other embodiments, the geometric pattern 104 may be filled with a transparent dielectric substance. Here, the geometric pattern 104 of the C shape can be regarded as a change design of the circular pattern. In Figure 2C, the single unit structure 102 has an eccentrically shaped geometric pattern 104, and the geometric pattern 104 may be hollow or more filled with a transparent dielectric material. The geometric pattern 104 of the crucible shape is an eccentric design, that is, at least one of the conditions of the lateral side β1>the lateral side β3 and the longitudinal side β2>the longitudinal side β4, or the lateral side β1≠the lateral side β3, the longitudinal side When the β2 longitudinal edge β4 is satisfied, the eccentricity requirement can be achieved.

According to another embodiment, the electromagnetic wave polarizing element of the present invention can be designed to be formed on a substrate.

3A is a schematic view of an electromagnetic wave polarizing element, and FIG. 3B is an enlarged top view of a unit structure of FIG. 3A. As shown in FIG. 3A, the electromagnetic wave polarizing element is formed on a transparent substrate 101. The substrate 101 can be divided into a plurality of unit structures 102 (divided by broken lines), and each unit structure 102 is designed with a geometric pattern of a specific geometric shape. 104, wherein the geometric pattern 104 is a protrusion (projecting above the surface of the substrate), and the arrangement interval between the unit structures 102 is d. Each of the unit structures 102 in this embodiment has the same geometric pattern 104, that is, two identically sized regular hexagonal ring frames are diagonally arranged to form the geometric pattern 104. Here, the convex geometric pattern 104 is formed of a metal film layer and formed on the substrate 101 by, for example, electroplating, deposition etching, or filming. The electromagnetic wave polarizing element formed on the substrate 101 itself can be regarded as a plurality of discontinuous metal film patterns arranged in a specific cycle.

Each of the unit structures 102 is substantially square (upper viewing direction), and therefore, the arrangement period of the geometric patterns 104 is the arrangement interval d of the geometric patterns 104. In accordance with the principles of the present invention, the arrangement spacing d (i.e., the arrangement period) of the geometric patterns 104 needs to be less than the wavelength of the incident electromagnetic waves.

The periodic arrangement of the geometric patterns includes a periodic arrangement such as staggered arrangement, rectangular arrangement, triangular arrangement, hexagonal arrangement, and ring arrangement.

4A is a top plan view of a single geometric pattern, and FIG. 4B is a top view of an electromagnetic wave polarizing element formed by the periodic arrangement of the geometric patterns of FIG. 4A. As shown in FIG. 4A, the geometry is a spiral-shaped hollow geometric pattern 104 having a helical pitch equal to the helical width w . The hollow geometric pattern 104 having two spiral shapes in the single unit structure 102, but the spiral openings are arranged in different directions (which may be arranged at an angle of, for example, about 90 degrees) to constitute an electromagnetic wave polarizing element.

In general, an unpolarized electromagnetic wave can be regarded as being divided into two orthogonal polarized electromagnetic waves, that is, the incident electromagnetic wave can include a first polarized electromagnetic wave and a second polarized electromagnetic wave, and the first and the second orthogonal polarization When the polarized electromagnetic wave is incident on the electromagnetic wave polarizing element, when the first and second polarized electromagnetic waves pass through the geometric pattern 104, since the geometric pattern 104 has a main resonant polarization axis (as indicated by FIG. 5A - FIG. 5F, the dotted arrow axis) a primary resonant polarization axis), wherein a first polarization direction of the first polarized electromagnetic wave is turned to the main resonant polarization axis direction of the geometric pattern 104, and a second polarized electromagnetic wave passes through the geometric pattern 104, the second pole thereof The direction of the polarization also shifts to the direction of the main resonant polarization axis of the geometric pattern 104, that is, when two orthogonally polarized electromagnetic waves pass through the electromagnetic wave polarizing element, they are simultaneously rotated to their main resonant polarization axis to achieve a single polarization, resulting in a third Polarized electromagnetic waves.

5A-5D are schematic views of polarization directions of different spiral geometries. Referring to Fig. 5A, when the direction of the spiral opening is 90 degrees with respect to the X-axis, the main resonance polarization axis y' is 125 degrees. Referring to Fig. 5B, when the direction of the spiral opening is 180 degrees with respect to the X-axis, the main resonant polarization axis y' is 212 degrees. Referring to Fig. 5C, when the direction of the spiral opening is 270 degrees with respect to the X-axis, the main resonance polarization axis y' is 294 degrees. Referring to Fig. 5D, when the direction of the spiral opening is 0 degrees with respect to the X-axis, the main resonant polarization axis y' is 26 degrees, and the opening of the geometric pattern 104 showing the spiral shape affects the angle of the main resonant polarization axis. In addition, please refer to Fig. 5E and Fig. 5F. When the number of turns of the spiral half circle changes, the angle of the polarization axis of the main resonance is also affected. Therefore, the user can adjust the number of spiral openings and the number of half turns to achieve the required Main resonance polarization axis angle.

Figure 6 shows an ellipsometric diagram of the polarization directions of two different, orthogonal incident polarized electromagnetic waves at a resonant frequency with an incident electromagnetic wave wavelength λ of 46.15 microns.

As shown in FIG. 6, if the hollow geometric pattern 104 having a spiral shape in the unit structure 102 is exemplified, the spiral pitch of the spiral-shaped hollow geometric pattern 104 is the same as the spiral width ( w is a spiral width), and the spiral has 5 In the case of a half turn ( n is the number of turns of the spiral half turn, n is 5), the two orthogonal polarizations are divided into 75 degrees and 165 degrees when the polarization angles of the polarization directions of the two different orthogonal polarizations are divided into 75 degrees and 165 degrees. The polarization directions of the electromagnetic waves are all rotated to a position of 120 degrees, and the emitted electromagnetic waves have a single polarization. And because the two different, orthogonal incident polarized electromagnetic waves are all converted into the same polarization direction, they have a high transmittance.

The electromagnetic wave polarizing element of the present invention may itself be a film layer having a geometric pattern arranged in a specific period, or a geometric pattern group having a specific period of arrangement formed on the surface of the substrate. The electromagnetic wave polarizing element of the present invention can be independently formed into a diaphragm to modulate the polarization of the electromagnetic wave, or the semiconductor manufacturing process can be directly used, and the polarizing element of the present invention can be fabricated on a solid-state light source or a substrate. Since the electromagnetic wave polarizing element of the present invention can convert the unpolarized electromagnetic wave into a polarized electromagnetic wave having a single polarization, unlike the conventional polarizer, the electromagnetic wave energy is greatly depleted, so the electromagnetic wave transmittance of the polarizing element in the present case is good.

Compared with the prior art, the electromagnetic wave polarizing element of the present invention has high polarization adjustment because of its simple structure, low manufacturing cost, and adjustment according to the needs of products or applications. Moreover, the polarizing element of the present invention has a high light transmittance, and has no problem of electromagnetic wave loss.

The electromagnetic wave polarizing element of the present invention can be widely applied, for example, to a light source for manufacturing high polarization and high light transmittance, for use in a liquid crystal display system. It can be applied to solid-state light sources, lighting, visual identification, communication systems and other fields. For example, a micro-projection display applied to liquid crystal on silicon (LCoS) can reduce the use of components such as a two-color spectrophotometer, a polarizing splitter, a polarizer, and a polarized light recovery, thereby improving light utilization, reducing the size and reduction of the optical machine. Energy consumption. Alternatively, the use of an LCD backlight module can improve polarization efficiency, and in an image recognition system, a polarized light source can enhance image sharpness. It can even be used in optical communication systems to suppress signal noise. .

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

100. . . Electromagnetic wave polarizing element

101. . . Substrate

102. . . Unit structure

104. . . Geometric patterns

d. . . Arrange interval

Fig. 1A is a schematic view of an electromagnetic wave polarizing element.

Figure 1B is an enlarged perspective view of a unit structure of Figure 1A.

Figure 1C is a top plan view of Figure 1B.

2A-2C are top plan views of geometric patterns of a single unit structure.

Fig. 3A is a schematic view of an electromagnetic wave polarizing element.

Figure 3B is an enlarged top plan view of a unit structure of Figure 3A.

Figure 4A is a top plan view of a single geometric pattern.

Figure 4B is a top plan view of an electromagnetic wave polarizing element comprising the periodic arrangement of the geometric patterns of Figure 4A.

5A-5F are schematic views of polarization directions of different spiral geometries.

Figure 6 is an ellipsometric diagram of the polarization directions of two different, orthogonal incident polarized electromagnetic waves at a resonant frequency.

100. . . Electromagnetic wave polarizing element

102. . . Unit structure

104. . . Geometric patterns

d. . . Arrange interval

Claims (11)

An electromagnetic wave polarizing element for polarizing an incident electromagnetic wave, comprising: a plurality of unit structures, wherein each of the unit structures has at least one geometric pattern, the geometric pattern having a main resonant polarization axis, and adjacent to the unit structure The geometric pattern has an arrangement interval which is smaller than a wavelength of the incident electromagnetic wave, wherein the incident electromagnetic wave comprises a first polarized electromagnetic wave and a second polarized electromagnetic wave, when the first polarization When the electromagnetic wave passes through the geometric pattern, a first polarization direction of the first polarized electromagnetic wave is turned to the main resonant polarization axis direction, and when the second polarized electromagnetic wave passes through the geometric pattern, One of the second polarized electromagnetic waves has a second polarization direction that is turned to the main resonant polarization axis direction to obtain a third polarized electromagnetic wave. The electromagnetic wave polarizing element according to claim 1, wherein the shape of the geometric pattern comprises a vertical strip, a horizontal strip, a circle, an ellipse, a polygon, or a combination thereof. The electromagnetic wave polarizing element of claim 1, wherein the shape of the geometric pattern comprises a continuous spiral shape. The electromagnetic wave polarizing element according to claim 3, wherein one of the geometric patterns has a spiral pitch which is the same as a spiral width. The electromagnetic wave polarizing element of claim 4, wherein one of the geometric patterns has a spiral length that satisfies: Where n is the number of turns of the spiral half circle, w is the spiral line width, and R is the spiral radius. The electromagnetic wave polarizing element according to claim 5, wherein the spiral radius increases the spiral width length successively with the number of half circles. The electromagnetic wave polarizing element according to claim 3, wherein the wavelength of the incident electromagnetic wave is λ, the spiral width is 0.05λ~0.3λ, and the thickness of the transparent electromagnetic wave polarizing element can be 0.003. λ~0.1 λ. The electromagnetic wave polarizing element according to claim 1, wherein the electromagnetic wave polarizing element is formed on a substrate, and the substrate is divided into the plurality of unit structures, wherein the geometric pattern is a protrusion. The electromagnetic wave polarizing element according to claim 1, wherein the electromagnetic wave polarizing element is a metal film layer, and the geometric pattern is hollow. The electromagnetic wave polarizing element of claim 9, wherein the geometric pattern is filled with a dielectric substance. The electromagnetic wave polarizing element of claim 1, wherein the geometric pattern is an eccentric shape.