Graphene strip-shaped metamaterial three-channel optical filter based on rectangular defect cavity

Abstract

The utility model relates to a graphene strip-shaped metamaterial three-channel optical filter based on rectangular defect cavities. The graphene strip-shaped metamaterial three-channel optical filter comprises a silicon substrate, continuous graphene, a first rectangular defect cavity, a second rectangular defect cavity and a third rectangular defect cavity, the continuous graphene, the first rectangular defect cavity, the second rectangular defect cavity and the third rectangular defect cavity are respectively arranged on the upper surface of the silicon substrate; and the first rectangular defect cavity, the second rectangular defect cavity and the third rectangular defect cavity are sequentially and uniformly arranged along the front-back direction of the optical filter. According to the utility model, the problems of narrow bandwidth and poor filtering effect of an optical filter with a graphene metamaterial structure are solved; the ultra-compact structure is realized, the size of the three-channel optical filter with the graphene metamaterial structure is reduced, and the problem that the optical filter with the graphene metamaterial structure is not easy to integrate in an on-chip plasmon optical path is solved.

Description

Technical Field

[0001] This utility model relates to the field of optical communication technology, specifically to a three-channel optical filter based on a rectangular defect cavity graphene ribbon metamaterial. Background Technology

[0002] Optical filters enable wavelength division multiplexing (WDM) and bandpass or bandstop wavelength selection, making them crucial components in optical communication technology. With the development of large-scale integrated all-optical devices, the demand for small-size, dynamically tunable multi-channel optical filters in the terahertz band is becoming increasingly apparent. Therefore, realizing dynamically tunable multi-channel optical filters with a new operating mechanism that is dynamically tunable, small-size, and easy to integrate is of paramount importance.

[0003] Surface plasmon polaritons (SPPs) are evanescent electromagnetic waves that propagate along the metal-dielectric interface and decay exponentially in the direction perpendicular to the metal surface. SPPs possess the ability to overcome the traditional optical diffraction limit and exhibit strong localized optical field enhancement characteristics, thus enabling the guidance and manipulation of light at the subwavelength level. SPP waves can serve as carriers of energy and information, and they hold significant application value in high-density integrated photonic circuits.

[0004] Currently, numerous photonic devices based on SPPs have emerged, such as bandpass filters, bandstop filters, multiplexers (demultiplexers), Mach-Zehnder interferometers (MZIs), optical switches, sensors, and logic gates. Due to the low loss and good out-of-band suppression characteristics of SPP bandpass or bandstop filters, and because SPP-based optical filters are crucial components in high-density integrated photonic circuits, many SPP optical filters based on metamaterials and metasurface structures have also appeared. Therefore, realizing SPP metamaterial optical filters with compact device size, multiple channels, wide bandwidth, dynamic tunability, and easy integration is a future development trend.

[0005] Currently, slow-light devices based on the plasmon-induced transparency (PIT) effect in SPPs (Slow-Light Polymers) are attracting increasing attention. The PIT phenomenon is similar to the electromagnetically induced transparency (EIT) effect in atomic gases. However, compared to the EIT phenomenon in atomic gases, which is determined by the absorption characteristics of the material, the EIT-like phenomenon generated by the geometry of a resonant cavity coupled to a plasma waveguide system has greater application prospects due to its advantages such as room-temperature operation, compatibility with chip integration, tunability of the transmission band, and controllable bandwidth. In metamaterial structures, the PIT effect is generated by the mutual coupling interference between bright and dark modes, thereby realizing multi-channel optical filters. Because the PIT effect produces a transparency peak in the transmission spectrum, it is suitable for application in optical filters.

[0006] In recent years, graphene, a two-dimensional material consisting of a single carbon atom layer, has provided a novel and low-loss method for confining and controlling surface-mount filters (SPPs), and is therefore widely used in the design of SPP devices. Considering the unique properties of graphene, graphene-based micro- and nanostructures can generate very strong localized SPPs from the near-infrared region to the terahertz band. The PIT effect is generated in graphene metamaterial structures, and by changing the Fermi level of graphene, PIT effect optical filters can be dynamically tuned.

[0007] The shortcomings of existing technology are:

[0008] 1. Because traditional SPP waveguide systems produce a single PIT effect, they can only realize single-channel optical filters, resulting in a lack of multi-task processing capabilities.

[0009] 2. Traditional SPP optical filters are typically static and non-tunable, resulting in insufficient flexibility and difficulty in adapting to dynamic scenarios.

[0010] 3. Traditional MZI-based and fiber Bragg grating-based filters are large in size, which is not conducive to large-scale integration of devices. In addition, these filters have disadvantages such as narrow bandwidth and poor out-of-band suppression, which are not conducive to the application and development of optical filters in broadband high-speed optical communication networks. Utility Model Content

[0011] This invention addresses the aforementioned problems by providing a three-channel optical filter based on a rectangular defect cavity made of graphene ribbon metamaterial. Its purpose is to achieve excellent filtering performance, solve the problems of narrow bandwidth and poor filtering effect in graphene metamaterial structure optical filters, realize an ultra-compact structure, reduce the size of the graphene metamaterial structure three-channel optical filter, and solve the problem of difficulty in integrating graphene metamaterial structure optical filters in on-chip plasmon optical paths.

[0012] To solve the above problems, the technical solution provided by this utility model is as follows:

[0013] A three-channel optical filter based on a graphene ribbon metamaterial with rectangular defect cavities comprises a silicon substrate, continuous graphene, a first rectangular defect cavity, a second rectangular defect cavity, and a third rectangular defect cavity, wherein:

[0014] The continuous graphene, wherein the first rectangular defect cavity, the second rectangular defect cavity, and the third rectangular defect cavity are respectively disposed on the upper surface of the silicon substrate; the first rectangular defect cavity, the second rectangular defect cavity, and the third rectangular defect cavity are uniformly arranged sequentially along the front-back direction of the optical filter; the continuous graphene is arranged around the outside of the first rectangular defect cavity, the second rectangular defect cavity, and the third rectangular defect cavity, and is continuously arranged along the front-back direction of the optical filter; the continuous graphene is directly coupled to the incident light, and the SPPs are directly excited on its surface by the perpendicularly incident light; the incident light is indirectly coupled to the first rectangular defect cavity, the second rectangular defect cavity, and the third rectangular defect cavity through the continuous graphene, and the SPPs are indirectly excited on the surface of the first rectangular defect cavity, the second rectangular defect cavity, and the third rectangular defect cavity.

[0015] Preferably, the thickness of the silicon substrate is 0.15 µm.

[0016] Preferably, the continuous graphene has a length of 10 µm and a width of 6 µm.

[0017] Preferably, the length of the first rectangular defect cavity, the second rectangular defect cavity, and the third rectangular defect cavity are all 5.5 µm, and the width is 1.5 µm.

[0018] Preferably, the distance between the first rectangular defect cavity and the second rectangular defect cavity is 0.5 µm; the distance between the second rectangular defect cavity and the third rectangular defect cavity is 0.5 µm.

[0019] Preferably, the optical filter uses a single layer of graphene with a thickness of 0.2 nm.

[0020] Preferably, the Fermi level of the continuous graphene is fixed at 1.2 eV.

[0021] Preferably, the size of the optical filter is on the order of micrometers.

[0022] Compared with the prior art, this utility model has the following advantages:

[0023] 1. This invention realizes a small-size, wide-bandwidth, highly effective, dynamically tunable, and easily integrated three-channel optical filter based on a rectangular defect cavity graphene ribbon metamaterial in the terahertz band. The three-PIT effect generated by the rectangular defect cavity graphene ribbon metamaterial structure is applied to the integrated three-channel optical filter. The spectral bandwidths of the three transmission windows are 0.91 THz, 0.93 THz, and 0.79 THz, respectively, and the maximum spectral bandwidth of the filter can reach 0.93 THz. The peak value of the transparency peak has a very high contrast with the transmittance of the transmission depression, achieving excellent filtering performance. This solves the problems of narrow bandwidth and poor filtering performance of graphene metamaterial structure optical filters.

[0024] 2. The three-channel optical filter based on a rectangular defect cavity of graphene ribbon metamaterial of this invention has a size on the micrometer scale, which can realize an ultra-compact structure, greatly reducing the size of the three-channel optical filter of graphene metamaterial structure, and solving the problem of the difficulty in integrating the optical filter of graphene metamaterial structure in on-chip plasmon optical path. Attached Figure Description

[0025] Figure 1 A schematic diagram of the structure of a graphene ribbon metamaterial three-channel optical filter based on a rectangular defect cavity, according to a specific embodiment of this utility model;

[0026] Figure 2 This is a schematic diagram of the system transmission spectrum of a graphene ribbon metamaterial three-channel optical filter based on a rectangular defect cavity, which is a specific embodiment of this utility model.

[0027] Wherein: 1. silicon substrate, 2. continuous graphene, 3. first rectangular defect cavity, 4. second rectangular defect cavity, 5. third rectangular defect cavity Detailed Implementation

[0028] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are only for illustrating the present invention and are not intended to limit the scope of the present invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0029] This utility model application claims protection for a three-channel optical filter based on a rectangular defect cavity in a graphene ribbon metamaterial, such as... Figure 1As shown, it includes a silicon substrate 1, continuous graphene 2, a first rectangular defect cavity 3, a second rectangular defect cavity 4, and a third rectangular defect cavity 5, wherein:

[0030] Continuous graphene 2, a first rectangular defect cavity 3, a second rectangular defect cavity 4, and a third rectangular defect cavity 5 are respectively disposed on the upper surface of silicon substrate 1; the first rectangular defect cavity 3, the second rectangular defect cavity 4, and the third rectangular defect cavity 5 are uniformly arranged sequentially along the front-back direction of the optical filter; continuous graphene 2 is arranged around the outside of the first rectangular defect cavity 3, the second rectangular defect cavity 4, and the third rectangular defect cavity 5, and is continuously arranged along the front-back direction of the optical filter; continuous graphene 2 is directly coupled to incident light, and SPPs are directly excited on its surface by perpendicularly incident light; incident light is indirectly coupled to the first rectangular defect cavity 3, the second rectangular defect cavity 4, and the third rectangular defect cavity 5 through continuous graphene 2, and SPPs are indirectly excited on the surface of the first rectangular defect cavity 3, the second rectangular defect cavity 4, and the third rectangular defect cavity 5.

[0031] It should be noted that this invention utilizes a laser emitted by a laser to vertically irradiate the device structure from the top, and uses a spectrometer to detect the transmission spectrum at the bottom of the device.

[0032] It should be noted that the purpose of this invention is to realize a small-sized, multi-channel, wide-bandwidth, dynamically tunable, and easily integrated graphene metamaterial structure SPPs optical filter. This invention uses FDTD-solution software simulation to determine the structural parameters of a three-channel optical filter based on a rectangular defect cavity in a graphene ribbon metamaterial.

[0033] In this specific embodiment, the thickness of the silicon substrate 1 is 0.15 µm.

[0034] In this specific embodiment, the continuous graphene 2 has a length of 10 µm and a width of 6 µm.

[0035] In this specific embodiment, the length of the first rectangular defect cavity 3, the second rectangular defect cavity 4, and the third rectangular defect cavity 5 are all 5.5 µm, and the width of each is 1.5 µm.

[0036] In this specific embodiment, the distance between the first rectangular defect cavity 3 and the second rectangular defect cavity 4 is 0.5 µm; the distance between the second rectangular defect cavity 4 and the third rectangular defect cavity 5 is 0.5 µm.

[0037] In this specific embodiment, the optical filter uses a single layer of graphene with a thickness of 0.2 nm.

[0038] In this specific embodiment, the Fermi level of continuous graphene 2 is fixed at 1.2 eV.

[0039] In this specific embodiment, the size of the optical filter is on the order of micrometers, which can reduce the size of the optical filter in the graphene metamaterial structure.

[0040] It should be noted that, in order to form the triple-PIT effect in the transmission spectrum, the incident light is perpendicular to the device structure, such as... Figure 1 As shown, in the entire structure, continuous graphene 2 is directly coupled to the incident light. Therefore, continuous graphene 2 exhibits a wide-bandwidth bright mode in the structure, and only perpendicularly incident light is needed to directly excite SPPs on its surface. Since the first rectangular defect cavity 3, the second rectangular defect cavity 4, and the third rectangular defect cavity 5 cannot directly couple with the perpendicularly incident light, they exhibit three narrow-bandwidth dark modes in the structure. The first rectangular defect cavity 3, the second rectangular defect cavity 4, and the third rectangular defect cavity 5 can indirectly excite SPPs on their surface through near-field coupling with continuous graphene 2. That is, the incident light is indirectly coupled to the first rectangular defect cavity 3, the second rectangular defect cavity 4, and the third rectangular defect cavity 5 through continuous graphene 2. Therefore, the destructive interference between the three dark modes and one bright mode produces the three-PIT effect.

[0041] It should be noted that, as Figure 2 As shown, three significant PIT-effect transmission windows were observed in the transmission spectrum. The center frequencies of the three transparent peaks were 2.88 THz, 3.86 THz, and 4.67 THz, and the peak values ​​were 0.75, 0.76, and 0.61 THz, respectively. The generation of these three transmission peaks is related to the near-field coupling between the bright and dark modes in the system. Figure 2 As can be seen, the theoretical calculation results of the coupling mode in the transmission spectrum are completely consistent with the FDTD simulation results. The frequencies of the four transmission depressions are 2.45 THz, 3.36 THz, 4.29 THz, and 5.08 THz, and the transmittances of the four transmission depressions are 0.01, 0.01, 0.01, and 0.005, respectively. The spectral bandwidth of the first and second transmission depressions in the transmission spectrum is 0.91 THz, the spectral bandwidth of the second and third transmission depressions is 0.93 THz, and the spectral bandwidth of the third and fourth transmission depressions is 0.79 THz. The maximum spectral bandwidth of the filter can reach 0.93 THz. Furthermore, the peak value of the transparent peak has a very large contrast with the transmittance of the transmission depressions, thus achieving excellent filtering performance.

[0042] It should be noted that, in the terahertz band, this invention discloses a three-channel SPPs optical filter based on a rectangular defect cavity graphene ribbon metamaterial. By changing the Fermi level of graphene, the PIT effect transmission spectrum can be dynamically tuned, realizing an ultra-compact and dynamically tunable multi-channel optical filter with a graphene metamaterial structure, with device size on the micrometer scale. This novel working mechanism of the graphene metamaterial structure multi-channel optical filter has significant scientific research value and application potential in the future field of photonic device integration, supporting the development of future all-optical communication networks and all-optical signal processing technologies.

[0043] In the above detailed description, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the present invention is in a state with fewer features than all of the disclosed individual embodiments. Therefore, the appended claims are hereby clearly incorporated into the detailed description, wherein each claim stands alone as a preferred embodiment of the present invention.

[0044] The disclosed embodiments have been described above to enable any person skilled in the art to implement or use this invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit and scope of this disclosure. Therefore, this disclosure is not limited to the embodiments given herein, but is consistent with the widest scope of the principles and novel features disclosed in this application.

[0045] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," as interpreted when used as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

[0046] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A three-channel optical filter based on a rectangular defect cavity in a graphene ribbon metamaterial, characterized in that: It includes a silicon substrate (1), continuous graphene (2), a first rectangular defect cavity (3), a second rectangular defect cavity (4), and a third rectangular defect cavity (5), wherein: The continuous graphene (2), the first rectangular defect cavity (3), the second rectangular defect cavity (4), and the third rectangular defect cavity (5) are respectively disposed on the upper surface of the silicon substrate (1); the first rectangular defect cavity (3), the second rectangular defect cavity (4), and the third rectangular defect cavity (5) are uniformly arranged in sequence along the front-back direction of the optical filter; the continuous graphene (2) is arranged around the outside of the first rectangular defect cavity (3), the second rectangular defect cavity (4), and the third rectangular defect cavity (5), and is continuously arranged along the front-back direction of the optical filter; the continuous graphene (2) is directly coupled to the incident light, and the SPPs are directly excited on its surface by the perpendicularly incident light; the incident light is indirectly coupled to the first rectangular defect cavity (3), the second rectangular defect cavity (4), and the third rectangular defect cavity (5) through the continuous graphene (2), and the SPPs are indirectly excited on the surface of the first rectangular defect cavity (3), the second rectangular defect cavity (4), and the third rectangular defect cavity (5).

2. The three-channel optical filter based on a rectangular defect cavity graphene ribbon metamaterial according to claim 1, characterized in that: The thickness of the silicon substrate (1) is 0.15 µm.

3. The three-channel optical filter based on a rectangular defect cavity graphene ribbon metamaterial according to claim 2, characterized in that: The continuous graphene (2) has a length of 10 µm and a width of 6 µm.

4. The three-channel optical filter based on a rectangular defect cavity graphene ribbon metamaterial according to claim 3, characterized in that: The length of the first rectangular defect cavity (3), the second rectangular defect cavity (4), and the third rectangular defect cavity (5) is 5.5 µm, and the width is 1.5 µm.

5. The three-channel optical filter based on a rectangular defect cavity graphene ribbon metamaterial according to claim 4, characterized in that: The distance between the first rectangular defect cavity (3) and the second rectangular defect cavity (4) is 0.5 µm; the distance between the second rectangular defect cavity (4) and the third rectangular defect cavity (5) is 0.5 µm.

6. The three-channel optical filter based on a rectangular defect cavity graphene ribbon metamaterial according to claim 5, characterized in that: The optical filter uses a single layer of graphene with a thickness of 0.2 nm.

7. The three-channel optical filter based on a rectangular defect cavity graphene ribbon metamaterial according to claim 6, characterized in that: The Fermi level of the continuous graphene (2) is fixed at 1.2 eV.

8. The three-channel optical filter based on a rectangular defect cavity graphene ribbon metamaterial according to claim 7, characterized in that: The size of the optical filter is on the order of micrometers.

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