KR102061114B1 - Unit cell meta structure device operating bandwidth of terahertz and polarizing apparatus including the same - Google Patents

Abstract

The unit cell metastructure device operating in the terahertz band according to an embodiment of the present invention includes a dielectric substrate and a metamaterial portion including a first pattern portion and a second pattern portion on the dielectric substrate, and the first pattern The portion extends by a first length along the X-axis direction, extends by a second length along the Y-axis direction, spaced apart by a first interval along the X-axis direction, and spaced apart by a second interval along the Y-axis direction The first patterns include first patterns, and the second pattern portion includes second patterns extended by a third length along the X-axis direction and spaced apart by a third interval along the Y-axis direction.

Description

Unit cell meta-structure element operating in the terahertz wave band and a polarizing device including the same TECHNICAL FIELD

The present invention relates to a unit cell meta structure device and a polarizer including the same, and more particularly, to a unit cell meta structure device that operates in a terahertz wave band using a metamaterial and a polarizer including the same. .

The terahertz wave having a band of about 300 GHz to 3 THz in the electromagnetic spectrum simultaneously has the transmittance of the radio wave and the straightness of the light wave, and has a characteristic that the vibration frequency region of the molecular motion is present in the terahertz wave frequency band. Because terahertz waves have low energy levels that are harmless to the human body, together with their transmission characteristics, they can be applied to medical imaging technology for cancer diagnosis and can be used for component analysis of materials. In addition, the terahertz wave frequency band may be utilized in a high-speed wireless communication technology, which requires a technique for controlling polarization characteristics.

In order to utilize terahertz wave technology in various fields, it is necessary to develop various devices that can be used in the terahertz wave band. To develop devices usable in the terahertz wave band, metamaterials are being developed. Metamaterials are artificial materials that realize unique properties by periodically arranging dielectric or metal resonator structures of a size much smaller than the wavelength of electromagnetic waves. Metamaterials can be recognized as uniform materials from a macroscopic perspective. However, the device using the conventional metamaterial is difficult to change the polarization characteristics because the band characteristics for the terahertz incident wave is fixed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above technical problem, and an object of the present invention includes a unit cell meta-structure device operating in a terahertz wave band capable of converting polarization characteristics of a terahertz incident wave based on metamaterials, and It is to provide a polarizing device.

The unit cell metastructure device operating in the terahertz band according to an embodiment of the present invention includes a dielectric substrate and a metamaterial portion including a first pattern portion and a second pattern portion on the dielectric substrate, and the first pattern The portion extends by a first length along the X-axis direction, extends by a second length along the Y-axis direction, spaced apart by a first interval along the X-axis direction, and spaced apart by a second interval along the Y-axis direction The first pattern may include first patterns, and the second pattern part may include second patterns extended by a third length along the X-axis direction and spaced apart by a third interval along the Y-axis direction.

In one embodiment, the second pattern portion may be formed spaced apart from the first pattern portion.

In one embodiment, the meta-material portion exhibits the characteristics of a parallel LC resonant circuit with respect to the terahertz incident wave X-polarized in the X axis direction, and the terahertz incident wave Y-polarized in the Y axis direction. The characteristics of the series LC resonant circuit can be shown.

In one embodiment, the meta-material portion has a bandpass characteristic for the terahertz wave component X-polarized in the X-axis direction, and the band erasing characteristic for the terahertz wave component Y-polarized in the Y-axis direction Can have

In one embodiment, the first resonant frequency for the bandpass characteristic and the second resonant frequency for the bandpass characteristic may be the same.

In one embodiment, the metamaterial portion may have a phase difference of 90 degrees between the terahertz wave component X-polarized in the X-axis direction and the terahertz wave component Y-polarized in the Y-axis direction.

A terahertz wave polarizer according to an embodiment of the present invention includes a dielectric substrate and a metamaterial layer including a plurality of first pattern portions and a plurality of second pattern portions on the dielectric substrate. Each of the first pattern portions extends by a first length along the X-axis direction, extends by a second length along the Y-axis direction, spaced apart by a first interval along the X-axis direction, and second along the Y-axis direction. First patterns spaced apart by an interval, and each of the plurality of second pattern portions extends by a third length along the X-axis direction, and includes second patterns spaced by a third interval along the Y-axis direction do.

In one embodiment, the terahertz wave polarizer has a bandpass characteristic for the terahertz wave component X-polarized in the X axis direction in the transmission mode, and the terahertz Y-polarized in the Y axis direction. The wave component may have a band cancellation characteristic.

In one embodiment, the terahertz wave polarizer has a band cancellation characteristic with respect to the terahertz wave component X-polarized in the X-axis direction in the reflection mode, and the terahertz Y-polarized in the Y-axis direction. The wave component may have a bandpass characteristic.

In one embodiment, the terahertz wave polarizer includes a 90-degree angle between the terahertz wave component X-polarized in the X-axis direction and the terahertz wave component Y-polarized in the Y-axis with respect to the terahertz incident wave. It can be made to have a phase difference.

In one embodiment, the terahertz incident wave may be polarized into a terahertz wave of circular polarization.

The unit cell metastructure device operating in the terahertz wave band according to an embodiment of the present invention may perform polarization conversion so that a phase difference of 90 degrees occurs between the terahertz wave in the X direction and the terahertz wave in the Y direction in the wideband frequency range. have. Accordingly, the unit cell meta-structure device according to the embodiment of the present invention can convert terahertz waves of linear polarization into terahertz waves of circular polarization with low insertion loss in a wide band.

1 is a block diagram of a unit cell meta structure device operating in a terahertz wave band according to an embodiment of the present invention.
2A and 2B are views illustrating a terahertz wave of linearly polarized light transmitted through a polarizer according to an exemplary embodiment of the present invention.
3A to 3D show examples of the first pattern portion of the metamaterial portion of FIG. 1.
4A and 4B are diagrams for describing response characteristics of the first pattern unit of FIGS. 3A to 3D.
5A and 5B are views illustrating examples of the second pattern portion of the metamaterial portion of FIG. 1.
6A to 6C are diagrams for describing response characteristics of the second pattern unit of FIGS. 5A and 5B.
7A to 7D are diagrams illustrating examples of the metamaterial part including the first pattern part and the second pattern part of FIG. 1.
8A to 8D are diagrams for describing response characteristics of the metamaterial part of FIGS. 7A to 7D.
FIG. 9 illustrates a unit cell meta structure device of FIG. 7A.
10A and 10B are diagrams for comparing response characteristics of an X-polarized terahertz wave and a Y-polarized terahertz wave of a unit cell metastructure device according to an exemplary embodiment of the present invention.
11A to 11C illustrate transmission characteristics of a unit cell meta structure device.
12A to 12C illustrate reflection characteristics of a unit cell metastructure device.
13A to 13C illustrate test results of response characteristics of the unit cell metastructure device.
14 is a diagram illustrating a polarizer according to one embodiment of the present invention.
FIG. 15 is a diagram illustrating an example in which terahertz waves of linearly polarized light are converted to terahertz waves of circularly polarized light by the polarizer of FIG. 14.
16 illustrates an example in which a polarizer according to an embodiment of the present invention is applied to a quantum cascade laser (QCL).
17 illustrates an example in which a polarizer is applied to a curved object according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, details such as detailed configurations and structures are provided merely to assist the overall understanding of the embodiments of the present invention. Therefore, modifications of the embodiments described in the present disclosure may be performed by those skilled in the art without departing from the spirit and scope of the present invention. Moreover, descriptions of well-known functions and structures are omitted for the sake of clarity and brevity. Terms used in the present specification are terms defined in consideration of the functions of the present invention, and are not limited to the specific functions. Definitions of terms may be determined based on matters described in the detailed description.

Modules in the following figures or detailed description can be connected to other than components shown in the drawings or described in the detailed description. Connections between modules or components can be direct or non-direct, respectively. The connections between the modules or components may each be a communication connection or a physical connection.

Components described with reference to terms such as units or units, modules, layers, etc. used in the detailed description may be implemented in the form of software, hardware, or a combination thereof. By way of example, the software may be machine code, firmware, embedded code, and application software. For example, the hardware may include electrical circuits, electronic circuits, processors, computers, integrated circuits, integrated circuit cores, pressure sensors, inertial sensors, Micro Electro Mechanical Systems (MEMS), passive components, or combinations thereof. Can be.

Unless defined otherwise, all terms including technical or scientific meanings used in the text have a meaning that can be understood by those skilled in the art. Generally, the terms defined in the dictionary are interpreted to have the same meaning as the contextual meaning in the related technical field, and are not interpreted to have the ideal or excessively formal meaning unless clearly defined in the text.

Hereinafter, with reference to the accompanying drawings, it will be described in detail with respect to the unit cell meta-structure element and the polarizer operating in the terahertz wave band according to the present invention.

1 is a block diagram of a unit cell meta structure device operating in a terahertz wave band according to an embodiment of the present invention. Referring to FIG. 1, the unit cell meta structure element 10 may include a meta material portion 100 and a dielectric substrate 200.

The metamaterial part 100 may be formed of a metamaterial having a predetermined pattern on the dielectric substrate 200. The meta material part 100 may include a first pattern part 110 and a second pattern part 120 to form a predetermined pattern. The meta-material part 100 may be a two-dimensional array including the first pattern part 110 and the second pattern part 120. The meta-material unit 100 may polarize the incident wave (hereinafter, referred to as the terahertz incident wave) in the terahertz wave band through the first pattern unit 110 and the second pattern unit 120. Detailed description of the first pattern unit 110 and the second pattern unit 120 will be described later with reference to FIGS. 3A through 6C.

In exemplary embodiments, the dielectric substrate 200 may include an ultra thin film-type resin. For example, the dielectric substrate 200 may be a thin film type resin having a thickness of about 20 to 30 μm, and may be a zeonor film.

The unit cell meta-structure device 10 according to an embodiment of the present invention may polarize the terahertz incident wave through the metamaterial part 100, and the metamaterial part 100 may have a unique response to the terahertz incident wave. Can have properties.

2A and 2B are views illustrating a terahertz wave of linearly polarized light transmitted through a polarizing device according to an exemplary embodiment of the present invention. 1, 2A, and 2B, the polarizer 1000 may include a plurality of unit cell meta structure elements 10. The polarizer 1000 may output a terahertz transmitted wave whose phase is changed by changing a phase of the terahertz incident wave.

In FIG. 2A, an example is shown in which the terahertz wave X-polarized in the X-axis direction passes through the polarizer 1000. As shown in the first region a1, the phase of the X-polarized terahertz wave may be changed through the polarizer 1000. In FIG. 2B, an example is shown in which the terahertz wave Y-polarized in the Y-axis direction passes through the polarizer 1000. As shown in the second region a2, the phase of the Y-polarized terahertz wave may be changed through the polarizer 1000.

The polarization apparatus 1000 according to the exemplary embodiment may change the phase of the X-polarized terahertz wave and the Y-polarized terahertz wave differently. That is, the transmission characteristics for the X-polarized terahertz incident wave and the transmission characteristics for the Y-polarized terahertz wave may be different from each other. Detailed description thereof will be described later with reference to FIGS. 7A to 8D.

3A to 3D show examples of the first pattern portion of the metamaterial portion of FIG. 1. The first pattern unit 110 illustrated in FIGS. 3A to 3D may include a plurality of first patterns 110-1, respectively. Each of the plurality of first patterns 110-1 may be spaced apart by a first interval d1 along the X-axis direction, and spaced apart by a second interval d2 along the Y-axis direction.

Referring to FIG. 3A, the first pattern 110-1 may extend by a first length l 1 in the X-axis direction and extend by a second length l 2 in the Y-axis direction on the dielectric substrate. One end of the vertical metamaterial member V1 of the first pattern 110-1 may be connected to the central portion of the horizontal metamaterial member P1. Accordingly, the first pattern unit 110 of FIG. 3A may have a cutwire resonator shape.

Referring to FIG. 3B, the first pattern unit 110 may include a first pattern 110-1 and a rectangular metamaterial member S. Referring to FIG. The first pattern 110-1 may extend by the first length l1 along the X-axis direction on the dielectric substrate and extend by the second length l2 along the Y-axis direction. The first pattern 110-1 of FIG. 3B may be similar to the first pattern 110-1 of FIG. 3A, but may have a first length l1 in the X-axis direction and a second length l2 in the Y-axis direction. May be different from each other. For example, the first length l1 in the X-axis direction of the first pattern 110-1 of FIG. 3B is greater than the first length l1 in the X-axis direction of the first pattern 110-1 of FIG. 3A. Can be small. One end of the vertical metamaterial member V2 of the first pattern 110-1 may be connected to the central portion of the horizontal metamaterial member P2, and the other end thereof may be connected to the rectangular metamaterial member S. Accordingly, the first pattern unit 110 of FIG. 3B may have a split ring resonator (SRR) shape.

Referring to FIG. 3C, the first pattern 110-1 may extend by a first length l 1 along the X-axis direction and extend by a second length l 2 along the Y-axis direction on the dielectric substrate. The first pattern 110-1 may have a loop shape or a quadrangle. That is, the horizontal metamaterial members P3 of the first pattern 110-1 extend by the first length l1 along the X-axis direction, and the vertical metamaterial members V3 are formed along the Y-axis direction. It can be extended by two lengths l2.

Referring to FIG. 3D, the first pattern 110-1 may extend by a first length l 1 along the X-axis direction and extend by a second length l 2 along the Y-axis direction on the dielectric substrate. One end and the other end of the horizontal metamaterial member P4 of the first pattern 110-1 may be connected to the central portions of the vertical metamaterial members V4, respectively. Accordingly, the first pattern 110-1 may have a 'I' shape.

As described above, the first pattern part 110 extends by the first length l1 along the X-axis direction and extends by the second length l2 along the Y-axis direction. -1). In addition, the plurality of first patterns 110-1 may be spaced apart by a first interval d1 in the X-axis direction, and spaced apart by a second interval d2 in the Y-axis direction. Here, the first length l1, the second length l2, the first gap d1, and the second gap d2 may be differently determined according to the shape of the metamaterial part 100. That is, the first patterns 110-1 shown in FIGS. 3A to 3D have different first lengths l1 and second lengths l2, and different first intervals d1 and second intervals. may be spaced according to (d2).

4A and 4B are diagrams for describing response characteristics of the first pattern unit of FIGS. 3A to 3D. 4A shows an equivalent circuit of the first pattern portion 110 for X-polarized terahertz waves and Y-polarized terahertz waves. As shown in FIG. 4A, the first pattern unit 110 may exhibit characteristics of a series LC circuit for X-polarized terahertz waves and Y-polarized terahertz waves.

For example, for the X-polarized terahertz wave, the capacitance C may be determined based on the first distance d1 spaced apart in the X-axis direction of FIGS. 3A to 3D. The inductance L may be determined based on the length x1 extending in the X-axis direction. For the Y-polarized terahertz wave, the capacitance C may be determined based on the second interval d2 spaced apart in the Y-axis direction of FIGS. 3A to 3D. The inductance L may be determined based on the length l2 extending in the Y-axis direction.

FIG. 4B shows response characteristics of the first pattern unit 110 for X-polarized terahertz waves and Y-polarized terahertz waves. As shown in FIG. 4B, the first pattern unit 110 may have a band stop characteristic for the X-polarized terahertz wave and the Y-polarized terahertz wave.

That is, the first pattern unit 110 exhibits the characteristics of the series LC resonant circuit with respect to both the X-polarized terahertz wave and the Y-polarized terahertz wave, and may have a band erasing characteristic. The response characteristic of the first pattern unit 110 may be combined with the second pattern unit 120 to vary.

5A and 5B are views illustrating examples of the second pattern portion of the metamaterial portion of FIG. 1. As shown in FIGS. 5A and 5B, the second pattern unit 120 may include a plurality of second patterns 120-1. The second patterns 120-1 may extend by a third length l3 along the X-axis direction, and may be spaced apart by a third interval d3 along the Y-axis direction. That is, the second pattern unit 120 may be formed such that the plurality of second patterns 120-1 are disposed parallel to the X-axis direction at regular intervals.

As shown in FIGS. 5A and 5B, the number of the second patterns 120-1 may be two or three, but the number of the second patterns 120-1 included in the second pattern unit 120 may be increased. The number is not limited by what is shown in FIGS. 5A and 5B. The third length l3 and the third gap d3 of the second pattern 120-1 may be differently determined according to the shape of the metamaterial part 100.

6A to 6C are diagrams for describing response characteristics of the second pattern unit of FIGS. 5A and 5B. Specifically, FIG. 6A shows an equivalent circuit of the second pattern portion 120 for an X-polarized terahertz wave. 6B shows an equivalent circuit of the second pattern portion 120 for the Y-polarized terahertz wave. FIG. 6C shows the response characteristics of the second pattern portion 120 for X-polarized terahertz waves and Y-polarized terahertz waves.

As shown in FIG. 6A, the second pattern portion 120 may exhibit characteristics of the series LR circuit with respect to the X-polarized terahertz wave. For example, for the X-polarized terahertz wave, the inductance L may be determined based on the third length 13 extending in the X-axis direction of FIGS. 5A and 5B. As shown in FIG. 6B, the second pattern portion 120 may exhibit characteristics of the R circuit with respect to the Y-polarized terahertz wave. Accordingly, the response characteristics of the second pattern unit 120 with respect to the X-polarized terahertz wave and the Y-polarized terahertz wave may increase as the frequency size increases as shown in FIG. 6C.

As described above, the first pattern unit 110 and the second pattern unit 120 may have different response characteristics with respect to the terahertz incident wave. The response characteristics described with reference to FIGS. 3A through 6C may be response characteristics when the meta-material portion 100 includes only each pattern portion. When the first pattern part 110 and the second pattern part 120 having such response characteristics are combined, the response of the meta material part 100 including the first pattern part 110 and the second pattern part 120 is provided. Characteristics may vary.

7A to 7D are diagrams illustrating examples of the metamaterial part including the first pattern part and the second pattern part of FIG. 1. In detail, FIG. 7A illustrates the metamaterial part 100 including the first pattern part 110 of FIG. 3A and the second pattern part 120 of FIG. 5A. FIG. 7B illustrates the metamaterial part 100 including the first pattern part 110 of FIG. 3B and the second pattern part 120 of FIG. 5A. FIG. 7C illustrates the metamaterial part 100 including the first pattern part 110 of FIG. 3C and the second pattern part 120 of FIG. 5B. FIG. 7D illustrates the metamaterial part 100 including the first pattern part 110 of FIG. 3D and the second pattern part 120 of FIG. 5B.

As shown in FIGS. 7A to 7D, the first pattern portion 110 may be located between the second pattern portions 120. As shown in FIG. 7A, the first pattern part 110 may be directly connected to the second pattern part 120 to form the meta material part 100. As shown in FIGS. 7B to 7D, the first pattern part 110 may be spaced apart from the second pattern part 120 to form the meta material part 100.

8A to 8D are diagrams for describing response characteristics of the metamaterial part of FIGS. 7A to 7D. 8A shows an equivalent circuit of metamaterial portion 100 for an X-polarized terahertz wave. FIG. 8B shows the response characteristic of the metamaterial portion 100 to the X-polarized terahertz wave. For the X-polarized terahertz wave, the metamaterial portion 100 may exhibit the characteristics of a parallel LC circuit.

The meta-material part 100 includes a first pattern part 110 and a second pattern part 120, and the first pattern part 110 exhibits characteristics of a series LC circuit with respect to an X-polarized terahertz wave. The second pattern unit 120 may represent characteristics of the LR circuit. Accordingly, the meta-material part 100 including both the first pattern part 110 and the second pattern part 120 may exhibit characteristics of a parallel LC circuit with respect to the X-polarized terahertz wave. That is, the response characteristic of the metamaterial unit 100 may exhibit a band pass characteristic as shown in FIG. 8B.

When the meta-material part 100 according to an embodiment of the present invention includes only the first pattern part 110, the meta-material part 100 exhibits a band erasing characteristic with respect to the X-polarized terahertz wave, but the second pattern part 120 ) Can further exhibit bandpass characteristics for X-polarized terahertz waves. That is, the response characteristics to the X-polarized terahertz wave may vary.

8C shows an equivalent circuit of the metamaterial portion 100 for a Y-polarized terahertz wave. FIG. 8D shows response characteristics of the metamaterial portion 100 to Y-polarized terahertz waves. For the Y-polarized terahertz wave, the metamaterial portion 100 may exhibit the characteristics of a series LC circuit.

The meta-material part 100 includes a first pattern part 110 and a second pattern part 120, and the first pattern part 110 exhibits characteristics of a series LC circuit with respect to the Y-polarized terahertz wave. The second pattern portion 120 may exhibit characteristics of the R circuit. Accordingly, the metamaterial part 100 including both the first pattern part 110 and the second pattern part 120 may exhibit the characteristics of the series LC circuit with respect to the Y-polarized terahertz wave. That is, the response characteristic of the metamaterial unit 100 may exhibit a band erasing characteristic as shown in FIG. 8D.

When the meta-material part 100 according to an embodiment of the present invention includes only the first pattern part 110, the meta-material part 100 exhibits a band erasing characteristic with respect to the Y-polarized terahertz wave, and the second pattern part 120 is provided. Even if is further included, the band erasing characteristics can be maintained. That is, the response characteristic for the Y-polarized terahertz wave may not be changed.

As described above, the unit cell meta structure element 10 according to the embodiment of the present invention includes a meta material portion 100 including a first pattern portion 110 and a second pattern portion 120, and a unit The cell meta-structure element 10 may have different response characteristics for X-polarized terahertz waves and Y-polarized terahertz waves. That is, the unit cell meta structure element 10 may have complementary response characteristics.

Meta-material unit 100 according to an embodiment of the present invention is not limited to that shown in Figures 3a to 7d, it may be formed in various shapes within the scope of the invention.

Hereinafter, for convenience of description, the unit cell meta structure element 10 will be described in detail using the meta material portion 100 of FIG. 7A, but the present invention is not limited thereto.

FIG. 9 illustrates a unit cell meta structure device of FIG. 7A. 9, a portion 10 ′ of the unit cell meta structure element 10 may include a first pattern portion 110 ′ and a second pattern portion 120 ′. The second pattern portion 120 ′ may include outermost metamaterial members 111 and 112 having a first length x1 in the X-axis direction. The first pattern part 110 ′ may include internal longitudinal metamaterial members 121 and 122 having a first length y1 in the Y-axis direction. The first pattern part 110 ′ may include inner horizontal metamaterial members 123 and 124 connected to ends of the inner vertical metamaterial members 121 and 122. The inner transverse metamaterial members 123 and 124 of the first pattern portion 110 ′ are parallel to the outermost transverse metamaterial members 111 and 112 of the second pattern portion 120 ′ 121. , 122). The first length y1 of the inner longitudinal metamaterial members 121 and 122 may be determined in a range of λ / 10 to λ / 20. In this specification, λ refers to the wavelength of the incident terahertz wave.

The first length x1 of the outermost transverse metamaterial members 121 and 122 may be greater than the thickness of the dielectric substrate 200 than the second length x2 of the inner transverse metamaterial members 123 and 124. For example, the thickness of the dielectric substrate 200 may be λ / 20, and the first length x1 may be greater than or equal to λ / 20 than the second length x2. The second length x2 of the inner transverse metamaterial members 123 and 124 may be determined in the range of λ / 4 to λ / 3.

The inner horizontal metamaterial members 123 and 124 may be spaced apart by a second length y2 in the Y-axis direction. This separation distance may be determined in the range of λ / 50 to λ / 30.

10A and 10B are diagrams for comparing response characteristics of X-polarized terahertz waves and Y-polarized terahertz waves of a unit cell metastructure device according to an exemplary embodiment of the present invention. Referring to FIG. 10A, the unit cell meta structure element 10 may have a bandpass characteristic for the X-polarized terahertz wave and a band erasing characteristic for the Y-polarized terahertz wave. As shown in FIG. 10A, the resonant frequency for the bandpass response and the resonant frequency for the band erase response may be matched. For example, the resonant frequencies may be matched based on the intervals y2 or lengths y1, x1, and x2 of the metamaterial members of the unit cell metastructure element 10 of FIG. 9.

Referring to FIG. 10B, the phase response of the unit cell meta structure device 10 for X-polarized terahertz waves and Y-polarized terahertz waves is shown. As shown in FIG. 10A, when the resonant frequency for the X-polarized terahertz wave and the resonant frequency for the Y-polarized terahertz wave match, the phase response and Y- for the X-polarized terahertz wave are matched. The difference in phase response for polarized terahertz waves can be 90 degrees at broadband.

As shown in FIGS. 10A and 10B, when the unit cell meta structure element 10 is designed such that the resonant frequencies are matched, the unit cell meta structure element 10 is Y-polarized with X-polarized terahertzerpa. For terahertz waves, the phase difference can be 90 degrees wide at broadband. If the phase difference becomes 90 at the wideband, circular polarization conversion may be possible at the wideband.

11A to 11C illustrate transmission characteristics of a unit cell meta structure device. 12A to 12C illustrate reflection characteristics of a unit cell metastructure device. 11A and 12A, when the unit cell meta structure element 10 operates in the transmission mode, the unit cell meta structure element 10 exhibits a band erasure characteristic with respect to the Y-polarized terahertz wave, and when operated in the reflection mode, the Y-polarization Bandpass for the terahertz waves. Similarly, the unit cell meta structure element 10 may have an opposite phase response to the Y-polarized terahertz wave depending on the operating mode.

11B and 12B, when the unit cell meta structure element 10 operates in a transmission mode, the unit cell meta structure element 10 exhibits a bandpass characteristic for an X-polarized terahertz wave, and when operated in a reflection mode, X-polarized light. The band-erasing characteristics for the terahertz waves. Similarly, the unit cell meta structure element 10 may have an opposite phase response to the X-polarized terahertz wave, depending on the mode of operation.

Referring to FIG. 11C, when the unit cell meta structure element 10 operates in the transmission mode, the difference between the phase response of the X-polarized terahertz wave and the phase response of the Y-polarized terahertz wave is 90 degrees. Can be. Referring to FIG. 12C, when the unit cell meta structure element 10 operates in the reflection mode, the difference between the phase response of the X-polarized terahertz wave and the phase response of the Y-polarized terahertz wave is 90 degrees. Can be.

As shown in FIGS. 11A to 12C, the unit cell meta structure element 10 has a phase difference of 90 degrees with respect to the X-polarized terahertz wave and the Y-polarized terahertz wave even when operated in the transmission mode or the reflection mode. You can do that.

13A to 13C illustrate test results of response characteristics of the unit cell metastructure device. Referring to FIG. 13A, bandpass characteristics of both X-polarized terahertz waves and simulation results are shown. Referring to FIG. 13B, both the measurement results and the simulation results for the Y-polarized terahertz wave show band cancellation characteristics. Referring to FIG. 13C, the phase difference between the X-polarized terahertzer wave and the Y-polarized terahertz wave is 90 degrees in the broadband in both the measurement result and the simulation result.

14 is a diagram illustrating a polarizer according to one embodiment of the present invention. Referring to FIG. 14, the polarizer 1000 may include a metamaterial layer 300 and a dielectric substrate 400. The metamaterial layer 300 may be formed on the dielectric substrate 400.

The metamaterial layer 300 may include a plurality of first pattern portions 310 and a plurality of second pattern portions 320. The first pattern part 310 and the second pattern part 320 may correspond to the first pattern part 110 and the second pattern part 120 of the unit cell meta structure element 10 of FIG. 1. That is, the meta material layer 300 may be formed of a meta material having a pattern in which the first pattern part 310 and the second pattern part 320 are repeated. Since the first pattern part 310 and the second pattern part 320 are similar to the first pattern part 110 and the second pattern part 120 of FIG. 1, a detailed description thereof will be omitted.

The polarizer 1000 may be formed by repeating the unit cell meta structure element 10 of FIG. 1 without being spaced in the X-axis direction and being spaced apart in the Y-axis direction. For example, the distance d spaced in the Y-axis direction may be determined in a range of λ / 50 to λ / 30 which is a second length y2 from which the inner transverse metamaterial members 123 and 124 of FIG. 9 are spaced apart. have.

FIG. 15 is a diagram illustrating an example in which terahertz waves of linearly polarized light are converted to terahertz waves of circularly polarized light by the polarizer of FIG. 14. Referring to FIG. 15, the terahertz incident wave of linearly polarized light incident from right to left may be converted into a terahertz transmitted wave of circularly polarized light through the polarizer 1000.

The terahertz incident wave of linearly polarized light may be incident on the polarizer 1000 at an angle inclined by θ in the Y-axis direction with respect to the X-axis. The terahertz incident wave of linearly polarized light can be separated into an X-polarized terahertz component and a Y-polarized terahertz component. The X-polarized terahertz component and the Y-polarized terahertz component may be 90 degrees out of phase through the polarizer 1000. Therefore, the terahertz incident wave of linearly polarized light may be converted into a terahertz wave of circularly polarized light.

When the X-polarized terahertz component and the Y-polarized terahertz component of the terahertz incident wave are the same size, accurate circular polarization conversion can be made. By adjusting the angle θ of the terahertz incident wave, the magnitudes of the X-polarized terahertz component and the Y-polarized terahertz component can be the same. For example, when the angle θ of the terahertz incident wave is 45 degrees, the magnitude of the X-polarized terahertz component and the Y-polarized terahertz component may be the same.

The polarization apparatus 1000 according to the embodiment of the present invention may enable circular polarization conversion having a low insertion loss of 4 to 10 dB and an ideal ellipticity of 0.997.

16 illustrates an example in which a polarizer according to an embodiment of the present invention is applied to a quantum cascade laser (QCL). The quantum waterfall laser (QCL) can produce linearly polarized terahertz waves. The polarizer 1000 according to the exemplary embodiment of the present invention may be lithographically patterned on a quantum waterfall laser QCL. Accordingly, the quantum waterfall laser QCL may generate circularly polarized light, and polarization performance may be improved.

The polarizer 1000 according to the exemplary embodiment of the present invention may be applied to all devices capable of generating linearly polarized terahertz waves as well as a quantum waterfall laser (QCL). For example, the polarizer 1000 may be applied to a resonant tunneling diode (RTD).

17 illustrates an example in which a polarizer is applied to a curved object according to an embodiment of the present invention. The polarizer 1000 of the present invention may be formed using a flexible substrate. The flexible substrate may include a sticker to be attached to the curved object. The polarizer 1000 may be attached to the curved object using a sticker. By injecting the linearly polarized terahertz wave into the polarizer 1000, it is possible to measure various elements of the curved object.

The foregoing is specific embodiments for practicing the present invention. The present invention will include not only the above-described embodiments but also embodiments that can be simply changed in design or easily changed. In addition, the present invention will also include techniques that can be easily modified and practiced using the embodiments. Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be determined by the equivalents of the claims of the present invention as well as the following claims.

10: unit cell meta-structure element
100: metamaterial part
110: first pattern portion
120: second pattern portion
200, 400: dielectric substrate
300: metamaterial layer
1000: polarizer

Claims (11)

Dielectric substrates; And
A metamaterial part including a first pattern part and a second pattern part on the dielectric substrate,
The first pattern portion extends by a first length along the X-axis direction, extends by a second length along the Y-axis direction, spaced apart by a first interval along the X-axis direction, and second along the Y-axis direction. Including first patterns spaced apart by an interval,
The second pattern part includes second patterns extending along the X axis direction by a third length and spaced apart by a third interval along the Y axis direction,
The metamaterial part is a unit cell meta structure device operating in a terahertz wave band having a phase difference of 90 degrees between a terahertz wave component X-polarized in the X-axis direction and a terahertz wave component Y-polarized in the Y-axis direction. . The method of claim 1,
And the second pattern part is operated in a terahertz wave band formed to be spaced apart from the first pattern part. The method of claim 1,
The meta-material portion exhibits the characteristics of a parallel LC resonant circuit with respect to the terahertz incident wave X-polarized in the X-axis direction, and the characteristics of the series LC resonant circuit with respect to the terahertz incident wave Y-polarized in the Y-axis direction. A unit cell metastructure device operating in a terahertz wave band. The method of claim 1,
The meta-material portion has a bandpass characteristic for the terahertz wave component X-polarized in the X-axis direction, and has a band-pass characteristic for the terahertz wave component Y-polarized in the Y-axis direction. A unit cell meta structure device in operation. The method of claim 4, wherein
And a first resonant frequency for the bandpass characteristic and a second resonant frequency for the bandpass characteristic operate in the same terahertz wave band. delete Dielectric substrates; And
A metamaterial layer comprising a plurality of first pattern portions and a plurality of second pattern portions on the dielectric substrate,
Each of the plurality of first pattern portions extends by a first length in the X-axis direction, extends by a second length in the Y-axis direction, spaced apart by a first interval in the X-axis direction, and in the Y-axis direction Along the first patterns spaced apart by a second interval,
Each of the plurality of second pattern parts extends by a third length in the X-axis direction and includes second patterns spaced by a third interval in the Y-axis direction,
The meta-material layer is a terahertz wave polarizing device having a phase difference of 90 degrees between a terahertz wave component X-polarized in the X-axis direction and a terahertz wave component Y-polarized in the Y-axis direction with respect to the terahertz incident wave. . The method of claim 7, wherein
The terahertz wave polarizer has a bandpass characteristic with respect to the terahertz wave component X-polarized in the X-axis direction in the transmission mode, and has a band cancellation characteristic with respect to the terahertz wave component Y-polarized in the Y-axis direction. Terahertz wave polarizing device having a. The method of claim 7, wherein
The terahertz wave polarizer has a band cancellation characteristic with respect to the terahertz wave component X-polarized in the X-axis direction in the reflection mode, and has a bandpass characteristic for the terahertz wave component Y-polarized in the Y-axis direction. Terahertz wave polarizing device having a. delete The method of claim 7, wherein
The terahertz wave polarizer of the terahertz incident wave is polarized into a terahertz wave of circular polarization.

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