CN211670305U - Terahertz band-pass filter based on multilayer super surface structure - Google Patents
Terahertz band-pass filter based on multilayer super surface structure Download PDFInfo
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- CN211670305U CN211670305U CN202020511119.6U CN202020511119U CN211670305U CN 211670305 U CN211670305 U CN 211670305U CN 202020511119 U CN202020511119 U CN 202020511119U CN 211670305 U CN211670305 U CN 211670305U
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Abstract
The utility model relates to a super surperficial technical field of electromagnetism discloses a terahertz band-pass filter based on super surface structure of multilayer, and it includes that at least one N layer is super surface structure, super surface structure of at least one N layer is periodic arrangement and forms super surface by seamless concatenation, wherein, N is the integer, and N is more than or equal to 2; each N-layer super-surface structure comprises N super-surface units which are arranged in parallel in the same direction, and an air layer is arranged between every two adjacent super-surface units; every super surface unit all includes metal frame, cross resonance body and dielectric substrate, the metal frame with the cross resonance body all sets up on the dielectric substrate, the cross resonance body is located in the metal frame, the metal frame is sub-wavelength size. The utility model discloses make terahertz band-pass filter have the flat effect of passband.
Description
Technical Field
The utility model belongs to the technical field of the super surface of electromagnetism technique and specifically relates to a terahertz band-pass filter is now related to based on super surface structure of multilayer.
Background
The terahertz wave is an electromagnetic wave with the frequency of 0.1 THz-10 THz and the wavelength of 0.03 mm-3 mm, and is between microwave and infrared in an electromagnetic spectrum. The terahertz technology has a good application prospect in the fields of medical detection, communication and the like, so that the terahertz technology attracts wide attention. In practical application, due to the limitation of application environment noise and application requirements, noise in an unnecessary frequency range needs to be filtered, and the performance of a system is improved, so that the terahertz band-pass filter plays an important role in terahertz technology application.
The terahertz band-pass filter is generally located at the rear end of the receiver and is mainly used for filtering noise and interference outside a signal effective frequency band, so that the signal-to-noise ratio is improved to the maximum extent, which means that the band-pass filter has a good amplitude-frequency characteristic curve, namely, the band-pass filter is flat in band-pass. However, the attenuation of the transmission band of the existing terahertz band-pass filter is large, and the passband is not flat, so that how to design the terahertz band-pass filter with the flat passband becomes a problem to be solved urgently in the field.
SUMMERY OF THE UTILITY MODEL
Not enough to prior art exists, the utility model aims at providing a terahertz band-pass filter based on super surface structure of multilayer, it has the flat effect of passband.
The above utility model discloses an above-mentioned utility model purpose can realize through following technical scheme:
a terahertz band-pass filter based on a multilayer super-surface structure comprises at least one N-layer super-surface structure, wherein the at least one N-layer super-surface structure is periodically arranged and seamlessly spliced to form a super-surface, N is an integer and is more than or equal to 2; each N-layer super-surface structure comprises N super-surface units which are arranged in parallel in the same direction, and an air layer is arranged between every two adjacent super-surface units; every super surface unit all includes metal frame, cross resonance body and dielectric substrate, the metal frame with the cross resonance body all sets up on the dielectric substrate, the cross resonance body is located in the metal frame, the metal frame is sub-wavelength size.
By adopting the technical scheme, the terahertz band-pass filter is designed by stacking the multilayer electromagnetic super-surface resonance structure, can perfectly transmit the electromagnetic waves of working frequency, filter out the electromagnetic waves of other frequencies, is suitable for parallel polarized waves and vertical polarized waves, can realize good regulation and control effect on the terahertz wave band, and enables the passband of the terahertz band-pass filter to have high transmittance and high flatness of the passband.
The present invention may be further configured in a preferred embodiment as: the cross-shaped resonance body is formed by mutually and vertically crossing two identical rectangular metal strips, and the centers of the two rectangular metal strips are superposed.
By adopting the technical scheme, the super-surface unit structure has high symmetry, the transmissivity of a passband is improved, and the filtering effect is not influenced when the direction change of incident electromagnetic waves is not particularly large.
The present invention may be further configured in a preferred embodiment as: the shape and the size of the outer side of the metal frame are the same as those of the dielectric substrate.
By adopting the technical scheme, as long as the size of the metal frame is ensured to be sub-wavelength, namely, the electromagnetic wave with the wavelength larger than the aperture of the metal frame cannot penetrate through the metal frame, the inner side of the metal frame can be in any shape; and the shape and the size of the outer side of the metal frame are the same as those of the medium substrate, so that the super-surface units can be spliced conveniently.
The present invention may be further configured in a preferred embodiment as: including three super surface unit and setting two air beds between the three super surface unit, two air beds are the first air bed and the second air bed that set gradually along the electromagnetic wave incident direction.
The present invention may be further configured in a preferred embodiment as: the thickness of the first air layer is 35 μm, and the thickness of the second air layer is 32.5 μm.
By adopting the technical scheme, the terahertz band-pass filter with the passband of 1.44-1.82THz can be obtained by stacking three super-surface structures and enabling the layer distances to be 70 micrometers and 65 micrometers in sequence.
The present invention may be further configured in a preferred embodiment as: including four super surface unit and setting up three air bed between four super surface unit, three air bed is third air bed, fourth air bed and the fifth air bed that sets gradually along the electromagnetic wave incident direction.
The present invention may be further configured in a preferred embodiment as: the thickness of the third air layer and the thickness of the fifth air layer are both 28 μm, and the thickness of the fourth air layer is 33.5 μm.
By adopting the technical scheme, the terahertz band-pass filter with the passband of 1.44-1.9THz can be obtained by stacking four layers of super-surface structures and enabling the layer distances to be 56 micrometers, 67 micrometers and 56 micrometers in sequence.
The present invention may be further configured in a preferred embodiment as: the metal frame and the cross-shaped resonance body are arranged concentrically.
By adopting the technical scheme, the super-surface unit structure has high symmetry and high transmittance.
The present invention may be further configured in a preferred embodiment as: the sub-wavelength size of the metal frame is 75 micrometers, the thickness of the metal frame is 17.5 micrometers, and the width of the metal frame is 12.5 micrometers; the length of the rectangular metal strip is 40 micrometers, the width of the rectangular metal strip is 10 micrometers, and the thickness of the rectangular metal strip is 17.5 micrometers; the thickness of the dielectric substrate is 9.5 μm.
To sum up, the utility model discloses a following at least one useful technological effect:
1. the terahertz band-pass filter is designed by stacking the multilayer electromagnetic super-surface resonance structure, can perfectly transmit electromagnetic waves with working frequency, filters out electromagnetic waves with other frequencies, is suitable for parallel polarized waves and vertical polarized waves, and can realize good regulation and control effect on a terahertz wave band, so that the passband of the terahertz band-pass filter has high transmittance and the flatness of the passband is high;
2. the super-surface unit structure has high symmetry, the transmissivity of a passband is improved, and the filtering effect is not influenced when the direction change of incident electromagnetic waves is not particularly large;
3. the shape of the inner frame of the metal frame may be any shape as long as the size of the metal frame is ensured to be sub-wavelength, that is, electromagnetic waves with a wavelength larger than the aperture of the metal frame are not capable of penetrating through the metal frame.
Drawings
Fig. 1 is a schematic perspective view of a single three-layer super-surface structure in an embodiment of the present invention.
Fig. 2 is the xy plane structure sketch map of each layer of super surface that the concatenation of the super surface structure of multilayer formed in the embodiment of the utility model.
Fig. 3 and 4 are schematic xy plane structures of the super-surface unit in the embodiment of the present invention.
Fig. 5 is a schematic perspective view of a single four-layer super-surface structure in the second embodiment of the present invention.
Fig. 6 is a schematic perspective view of a single two-layer super-surface structure in the third embodiment of the present invention.
Fig. 7 is a graph of the results of FDTD and CMT fitting for the transmittance of a single layer super-surface structure in an embodiment of the invention.
FIG. 8 shows the fitting parameters γ, γ' with d in the third embodiment of the present invention6A graph of the variation relationship of (c).
FIG. 9 shows the pass band width and the minimum transmittance along with d of the fitting parameters in the third embodiment of the present invention6A graph of the variation relationship of (c).
FIG. 10 shows a fitting parameter d according to the third embodiment of the present inventionijWith d6A graph of the variation relationship of (c).
FIG. 11 shows a transmission spectrum with d calculated by FDTD in the third embodiment of the present invention6A graph of the variation relationship of (c).
Fig. 12 is a graph of the fitting results of FDTD transmittance and CMT transmittance according to the third embodiment of the present invention.
Fig. 13 is a graph of the fitting results of the transmittance FDTD and the CMT according to the first embodiment of the present invention.
Fig. 14 is a graph of the fitting results of the transmittance FDTD and the CMT according to the second embodiment of the present invention.
In the figure, 1, a super-surface unit, 11, a metal frame, 12, a cross-shaped resonator, 13, a dielectric substrate, 21, a first air layer, 22, a second air layer, 23, a third air layer, 24, a fourth air layer, 25, a fifth air layer, 26 and a sixth air layer.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The first embodiment is as follows:
referring to fig. 1 and 2, in order to disclose a terahertz band-pass filter based on a multilayer super-surface structure according to an embodiment of the present invention, the terahertz band-pass filter includes at least one three-layer super-surface structure, the at least one three-layer super-surface structure is periodically arranged and seamlessly spliced to form a super-surface; each three-layer super-surface structure comprises a super-surface unit 1, a first air layer 21, a super-surface unit 1, a second air layer 22 and the super-surface unit 1 which are sequentially overlapped along the incident direction A of electromagnetic waves. Thickness d of first air layer 21135 μm, the thickness d of the second air layer 222It was 32.5 μm.
As shown in fig. 3, each super-surface unit 1 includes a metal frame 11, a cross-shaped resonator 12, and a dielectric substrate 13, the metal frame 11 and the cross-shaped resonator 12 are both disposed on the dielectric substrate 13, the cross-shaped resonator 12 is located in the metal frame 11, the metal frame 11 is of a sub-wavelength size, and all super-surface units 1 are disposed in the same direction, that is, for any super-surface unit 1, an incident electromagnetic wave firstly passes through the metal frame 11 and the cross-shaped resonator 12, and then passes through the dielectric substrate 13.
Optionally, the shape and size of the outer side of the metal frame 11 are the same as those of the outer frame of the dielectric substrate 13 and the metal frame 11, and the maximum size of the outer side shape is a subwavelength; the inner shape of the metal frame 11 may be a square, rectangle, circle, oval or diamond shape, and the maximum size of the inner shape is larger than that of the cross-shaped resonator 12. Specifically, taking a square shape and a circular shape as an example, as shown in fig. 3, the inner side and the outer side of the metal frame 11 are both square, the side length p of the outer side is a sub-wavelength size and is 75 μm, and the width mw of the frame is 12.5 μm; as shown in FIG. 4, the metal frame 11 has a square outer shape and a circular inner shape, and has an outer side length p of 75 μm in a sub-wavelength size and a frame width mw of 12.5 μm.
Optionally, the dielectric substrate 13 has a dielectric constant of 3.1 and a thickness l2And 9.5 μm.
Preferably, the planar shape of the metal frame 11 is a symmetrical shape, and the metal frame and the cross-shaped resonator 12 can form a highly symmetrical metal super-surface structure.
Preferably, a crossThe resonance body 12 is formed by mutually and vertically crossing two identical rectangular metal strips, and the centers of the two rectangular metal strips are superposed; the metal frame 11 and the cross-shaped resonant body 12 are concentrically arranged, that is, the cross-shaped resonant body 12 coincides with the center of the metal frame 11. Specifically, as shown in FIG. 3, the rectangular metal strip has a length cl of 40 μm and a width cw of 10 μm, and has a thickness l equal to the thickness l of the metal frame 111The same size, 17.5 μm.
In this embodiment, the metal frame 11 and the cross-shaped resonator 12 may be made of copper.
It should be noted that the electromagnetic wave incidence direction a in fig. 1, 5, and 6 is only an example, and the electromagnetic wave incidence angle is not limited to this case.
Example two:
referring to fig. 2 and 5, in order to disclose a terahertz band-pass filter based on a multilayer super-surface structure according to an embodiment of the present invention, the terahertz band-pass filter includes at least one four-layer super-surface structure, the at least one four-layer super-surface structure is periodically arranged and seamlessly spliced to form a super-surface; each four-layer super-surface structure comprises a super-surface unit 1, a third air layer 23, a super-surface unit 1, a fourth air layer 24, a super-surface unit 1, a fifth air layer 25 and a super-surface unit 1 which are sequentially overlapped along the incident direction A of electromagnetic waves; thickness d of the third air layer 233Thickness d of fifth air layer 255Each 28 μm, the thickness d of the fourth air layer 244It was 33.5 μm.
Example three:
referring to fig. 2 and 6, in order to disclose a terahertz band-pass filter based on a multilayer super-surface structure according to an embodiment of the present invention, the terahertz band-pass filter includes at least one two-layer super-surface structure, the at least one two-layer super-surface structure is periodically arranged and seamlessly spliced to form a super-surface; each two-layer super-surface structure comprises a super-surface unit 1, a sixth air layer 26 and a super-surface unit 1 which are sequentially overlapped along the incident direction A of the electromagnetic waves; thickness d of the sixth air layer 26635 μm.
Since the structures of the super surface unit 1 in the second and third embodiments are the same as the super surface unit 1 in the first embodiment, the description thereof is omitted.
It should be noted that the number of the multi-layer super-surface structures adopted in the above embodiments is related to the area of the incident electromagnetic wave, and fig. 2 only shows an example of a super-surface obtained by splicing 25 multi-layer super-surface structures in a 5 × 5 array.
The principle applied by the above embodiments is described in detail below.
The metal frame 11 produces a cut-off frequency below which the metal frame 11 is optically opaque; meanwhile, a cross-shaped resonator 12 is added to the metal frame 11. For this type of system, the transmission coefficient can be derived from the CMT theory as:
in the formula, t0Representing the transmission of the background medium, f1Which represents the frequency of the resonance, is,1representing radiation loss, d11、d21Representing the local resonance and the coupling between the two ports. Analysis of multiple resonant structures using equation (1) is cumbersome, so further assuming that the background medium is completely opaque, the transmission coefficient can be written as:
and is provided with
Where η represents an asymmetric factor, the transmittance of a single super-surface unit 1 (T ═ T ∞ can be fitted using equation (2)2) The fitting results are shown in fig. 7.
Further, the transmission coefficient for two super surface units 1 stacked together in the third embodiment can be expressed as:
wherein,
for a two-layer structure, it is only necessary to fit the two parameters γ, γ' and obtain the distance d between them with two super-surface units 16The relationship of the changes is shown in fig. 8.
As can be seen from fig. 8, 9, 10, and 11, as the distance between the two super-surface units 1 becomes larger, the width of the passband becomes narrower, but the flatness of the passband becomes better. Based on this, for the two-layer structure, d is selected6A terahertz band-pass filter with a passband of 1.56 to 1.68THz was obtained, and the transmittance of the filter was fitted as shown in fig. 12; three-layer structure d1＝35μm,d2A terahertz band-pass filter having a passband of 1.44 to 1.82THz and a center frequency of 1.6THz was obtained at 32.5 μm, and the transmittance fitting result thereof is shown in fig. 13; four-layer structure d3＝d5＝28μm，d4A terahertz band-pass filter having a passband of 1.44 to 1.9THz and a center frequency of 1.6THz was obtained, and the transmittance was fitted as shown in fig. 14.
The embodiment of this specific implementation mode is the preferred embodiment of the present invention, not limit according to this the utility model discloses a protection scope, so: all equivalent changes made according to the structure, shape and principle of the utility model are covered within the protection scope of the utility model.
Claims (9)
1. A terahertz band-pass filter based on a multilayer super-surface structure is characterized by comprising at least one N-layer super-surface structure, wherein the at least one N-layer super-surface structure is periodically arranged and seamlessly spliced to form a super-surface, N is an integer and is not less than 2; each N-layer super-surface structure comprises N super-surface units (1) which are arranged in parallel in the same direction, and an air layer is arranged between every two adjacent super-surface units (1); every super surface unit (1) all includes metal frame (11), cross resonance body (12) and dielectric substrate (13), metal frame (11) with cross resonance body (12) all set up on dielectric substrate (13), cross resonance body (12) are located in metal frame (11), metal frame (11) are the subwavelength size.
2. The terahertz band-pass filter based on the multilayer super-surface structure is characterized in that the cross-shaped resonator (12) is formed by two identical rectangular metal strips which are perpendicularly crossed with each other, and the centers of the two rectangular metal strips are overlapped.
3. The terahertz band-pass filter based on the multilayer super-surface structure is characterized in that the inner side of the metal frame (11) is square, rectangular, circular, oval or rhombic, and the outer side of the metal frame (11) is the same as the dielectric substrate (13) in shape and size.
4. The terahertz band-pass filter based on the multilayer super-surface structure according to claim 3, comprising three super-surface units (1) and two air layers arranged between the three super-surface units (1), wherein the two air layers are a first air layer (21) and a second air layer (22) which are arranged in sequence along the incident direction of the electromagnetic wave.
5. The terahertz band-pass filter based on the multilayer super-surface structure, according to claim 4, wherein the thickness of the first air layer (21) is 35 μm, and the thickness of the second air layer (22) is 32.5 μm.
6. The terahertz band-pass filter based on the multilayer super-surface structure according to claim 3, comprising four super-surface units (1) and three air layers arranged between the four super-surface units (1), wherein the three air layers are a third air layer (23), a fourth air layer (24) and a fifth air layer (25) which are arranged in sequence along the incident direction of the electromagnetic wave.
7. The terahertz band-pass filter based on the multilayer super-surface structure is characterized in that the thickness of the third air layer (23) and the thickness of the fifth air layer (25) are both 28 μm, and the thickness of the fourth air layer (24) is 33.5 μm.
8. The terahertz band-pass filter based on the multilayer super-surface structure as claimed in any one of claims 2 to 7, wherein the metal frame (11) and the cross-shaped resonator (12) are concentrically arranged.
9. The terahertz band-pass filter based on the multilayer super-surface structure is characterized in that the sub-wavelength size of the metal frame (11) is 75 μm, the thickness is 17.5 μm, and the frame width is 12.5 μm; the length of the rectangular metal strip (121) is 40 micrometers, the width of the rectangular metal strip is 10 micrometers, and the thickness of the rectangular metal strip is 17.5 micrometers; the thickness of the dielectric substrate (13) is 9.5 mu m.
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| CN113708028A (en) * | 2021-09-03 | 2021-11-26 | 合肥工业大学 | Broadband mechanical tunable filter |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113708028A (en) * | 2021-09-03 | 2021-11-26 | 合肥工业大学 | Broadband mechanical tunable filter |
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