Slow light device based on graphene nano-strip waveguide coupling four rectangular cavities

Abstract

The utility model relates to a slow light device based on coupling of a graphene nano-strip waveguide and four rectangular cavities. The slow light device comprises a silicon substrate, a sapphire layer, the graphene nano-strip waveguide, a first graphene rectangular resonant cavity, a second graphene rectangular resonant cavity, a third graphene rectangular resonant cavity and a fourth graphene rectangular resonant cavity. The sapphire layer is arranged above the silicon substrate; the upper surface of the sapphire layer is provided with a graphene nanometer strip waveguide, a first graphene rectangular resonant cavity, a second graphene rectangular resonant cavity, a third graphene rectangular resonant cavity and a fourth graphene rectangular resonant cavity. According to the utility model, an infrared graphene structure slow light device with large group refractive index and wide bandwidth is realized, an ultra-compact graphene slow light device is realized, and the size of the graphene structure slow light device is greatly reduced.

Description

Technical Field

[0001] This utility model relates to the field of optical communication technology, specifically to a slow-light device based on a graphene nanostrip waveguide coupled with a quadrangular cavity. Background Technology

[0002] In the field of optical communication, with the increase in transmission capacity, the "electronic bottleneck" phenomenon in optical-electrical-optical data routing and switching methods has become more prominent, becoming a major factor restricting the bandwidth, size, cost, power consumption, and speed of communication networks. To overcome this "electronic bottleneck," all-optical networks have emerged, becoming an inevitable trend in the development of communication networks. All-optical networks rely on the ability to generate and control data buffering, logic conversion, and signal delay. By utilizing slow-optical devices for signal delay and buffering, they can avoid the problems of large size and complex structure of traditional fiber optic delay lines, and can achieve tunable delay.

[0003] Slow light refers to light pulses propagating in a medium at a group velocity less than the speed of light in a vacuum. In all-optical communication networks and all-optical signal processing, slow-light devices are key components for building next-generation information technologies such as all-optical intelligent interconnection and real-time high-speed measurement and control. With the rapid development of integrated slow-light devices based on key technologies such as signal delay, data buffering, and switching, the demand for small size, large delay, wide bandwidth, and dynamic tunability in infrared slow-light devices is becoming increasingly apparent. Therefore, it is crucial to realize slow-light devices with compact device size, large group refractive index, wide bandwidth, dynamic tunability, and easy integration based on new operating mechanisms. The application of such novel slow-light devices in data routing, signal delay, data buffering, and switching technologies in all-optical communication networks and signal processing is becoming increasingly widespread.

[0004] 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.

[0005] Currently, slow-light devices based on SPPs have been extensively studied, such as slow-light buffers based on metamaterials and metasurface structures. Due to the strong localized optical field enhancement properties of SPPs and their ability to overcome the traditional diffraction limit, SPP-based slow-light devices exhibit small structural dimensions and wide bandwidths. The propagation direction of SPPs is parallel to the device surface, facilitating chip integration and design. Therefore, realizing SPP slow-light devices with compact device size, large group refractive index, wide bandwidth, dynamic tunability, and ease of integration is a future development trend.

[0006] Currently, slow-light devices based on the plasmon-induced transparency (PIT) effect, particularly those using SPPs (strip waveguides), 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 with a plasmonic waveguide system has greater application potential due to its advantages such as room-temperature operation, compatibility with chip integration, tunability of the transmission band, and controllable bandwidth. In a graphene nanostrip waveguide coupled with a rectangular cavity structure system, the PIT effect is generated by the mutual coupling interference between bright and dark modes, thus realizing slow light. Because the PIT effect has a large quality factor in its transparency peak, a relatively steep transmission spectrum, and strong dispersion leading to a large group delay, the PIT effect is suitable for application in slow-light devices.

[0007] 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 pulses (SPPs), and is therefore widely used in the design of SPP devices. Considering the unique properties of graphene, graphene-based micro / nanostructures can generate very strong localized SPPs from the near-infrared region to the terahertz band. The PIT effect is generated in a graphene nanostrip waveguide coupled to a rectangular cavity structure, and by changing the Fermi level of graphene, the slow light of the PIT effect can be dynamically tuned.

[0008] The shortcomings of existing technology are:

[0009] 1. Traditional slow-light devices have low group refractive index and narrow bandwidth, which limits their application and development in all-optical communication networks and all-optical signal processing technologies.

[0010] 2. Traditional slow-light devices based on fiber delay lines or micro-ring resonator structures are large in size, which is not conducive to the large-scale integration of optical devices.

[0011] 3. Traditional metal waveguide coupling structures produce a single PIT effect, which can only realize single-channel slow light. The graphene nanostrip waveguide coupled four rectangular cavity structure system designed in this invention can realize a three-channel slow light device with a dynamically tunable three PIT effect. Utility Model Content

[0012] To address the aforementioned problems, this invention provides a slow-light device based on a graphene nanostrip waveguide coupled with four rectangular cavities. The aim is to achieve a slow-light device with a large group refractive index and wide bandwidth, while simultaneously realizing an ultra-compact graphene slow-light device, thus significantly reducing the size of the graphene slow-light device.

[0013] To solve the above problems, the technical solution provided by this utility model is as follows:

[0014] A slow-light device based on a graphene nanostrip waveguide coupled with four rectangular cavities, comprising a silicon substrate, a sapphire layer, a graphene nanostrip waveguide, a first graphene rectangular resonant cavity, a second graphene rectangular resonant cavity, a third graphene rectangular resonant cavity, and a fourth graphene rectangular resonant cavity, wherein:

[0015] The sapphire layer is disposed above the silicon substrate; the upper surface of the sapphire layer is provided with the graphene nanostrip waveguide, the first graphene rectangular resonant cavity, the second graphene rectangular resonant cavity, the third graphene rectangular resonant cavity, and the fourth graphene rectangular resonant cavity; the first and second graphene rectangular resonant cavities are disposed on one side of the graphene nanostrip waveguide, and the third and fourth graphene rectangular resonant cavities are disposed on the other side of the graphene nanostrip waveguide; the first and third graphene rectangular resonant cavities are directly coupled to the graphene nanostrip waveguide; the second graphene rectangular resonant cavity is indirectly coupled to the graphene nanostrip waveguide through the first graphene rectangular resonant cavity; and the fourth graphene rectangular resonant cavity is indirectly coupled to the graphene nanostrip waveguide through the third graphene rectangular resonant cavity.

[0016] Preferably, the thickness of the silicon substrate is 300 nm; the thickness of the sapphire layer is 200 nm.

[0017] Preferably, the width of the graphene nanostrip waveguide is 10 nm.

[0018] Preferably, the length of the first graphene rectangular resonant cavity, the second graphene rectangular resonant cavity, the third graphene rectangular resonant cavity, and the fourth graphene rectangular resonant cavity is 140 nm, and the width is 20 nm.

[0019] Preferably, the coupling spacing between the first graphene rectangular resonant cavity, the third graphene rectangular resonant cavity, and the graphene nanostrip waveguide is 15 nm.

[0020] Preferably, the coupling distance between the first graphene rectangular resonant cavity and the second graphene rectangular resonant cavity is 20 nm; the coupling distance between the third graphene rectangular resonant cavity and the fourth graphene rectangular resonant cavity is 20 nm.

[0021] Preferably, the thickness of the single-layer graphene used in the slow-light device is 0.2 nm; the distance between the dipole of the slow-light device exciting the SPPs and the center of the first graphene rectangular resonant cavity, the second graphene rectangular resonant cavity, the third graphene rectangular resonant cavity, and the fourth graphene rectangular resonant cavity is fixed at 150 nm; the spacing between the center of the first graphene rectangular resonant cavity, the second graphene rectangular resonant cavity, the third graphene rectangular resonant cavity, and the fourth graphene rectangular resonant cavity and the detector is 150 nm.

[0022] Preferably, the Fermi level of the graphene nanostrip waveguide is 0.40 eV; the Fermi level of the first graphene rectangular resonant cavity is 0.40 eV; the Fermi level of the second graphene rectangular resonant cavity is 0.42 eV; the Fermi level of the third graphene rectangular resonant cavity is 0.42 eV; and the Fermi level of the fourth graphene rectangular resonant cavity is 0.44 eV.

[0023] Preferably, the size of the slow-light device is less than 0.05. μ m 2 .

[0024] Compared with the prior art, this utility model has the following advantages:

[0025] Because this invention applies the three-PIT effect generated by the graphene structure to an integrated slow-light device, the slow-light device based on a graphene nanostrip waveguide coupled with four rectangular cavities can realize three-channel slow light. The group refractive indices at the center wavelengths of the three transmission windows are 120, 115, and 96, respectively, with the maximum group refractive index reaching 120. Three significant PIT effect transmission windows are generated in the transmission spectrum, with spectral bandwidths of 350 nm, 260 nm, and 278 nm, respectively, with the maximum spectral bandwidth reaching 350 nm. Thus, an infrared graphene structure slow-light device with a large group refractive index and wide bandwidth is realized.

[0026] Because the slow-light device based on graphene nanostrip waveguide coupled with four rectangular cavities of this invention has a size of less than 0.05 μm. 2 This enables the realization of ultra-compact graphene slow-light devices, greatly reducing the size of graphene slow-light devices and facilitating their integration in on-chip plasmon optical paths. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a slow-light device based on a graphene nanostrip waveguide coupled with four rectangular cavities, which is a specific embodiment of this utility model.

[0028] Figure 2A schematic diagram of the system transmission spectrum of a slow-light device based on a graphene nanostrip waveguide coupled to four rectangular cavities, which is a specific embodiment of this utility model;

[0029] Figure 3 This is a schematic diagram of the transmission spectrum phase shift and system group refractive index of a slow-light device based on a graphene nanostrip waveguide coupled to a four rectangular cavity, which is a specific embodiment of this utility model.

[0030] Among them: 1. silicon substrate, 2. sapphire layer, 3. graphene nanostrip waveguide, 4. first graphene rectangular resonant cavity, 5. second graphene rectangular resonant cavity, 6. third graphene rectangular resonant cavity, 7. fourth graphene rectangular resonant cavity. Detailed Implementation

[0031] 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.

[0032] This utility model application claims protection for a slow-light device based on a graphene nanostrip waveguide coupled with a four-rectangular cavity, such as... Figure 1 As shown, it includes a silicon substrate 1, a sapphire layer 2, a graphene nanostrip waveguide 3, a first graphene rectangular resonant cavity 4, a second graphene rectangular resonant cavity 5, a third graphene rectangular resonant cavity 6, and a fourth graphene rectangular resonant cavity 7, wherein:

[0033] A sapphire layer 2 is disposed above a silicon substrate 1. A graphene nanostrip waveguide 3, a first graphene rectangular resonant cavity 4, a second graphene rectangular resonant cavity 5, a third graphene rectangular resonant cavity 6, and a fourth graphene rectangular resonant cavity 7 are disposed on the upper surface of the sapphire layer 2. The first graphene rectangular resonant cavity 4 and the second graphene rectangular resonant cavity 5 are disposed on one side of the graphene nanostrip waveguide 3, and the third graphene rectangular resonant cavity 6 and the fourth graphene rectangular resonant cavity 7 are disposed on the other side of the graphene nanostrip waveguide 3. The first graphene rectangular resonant cavity 4 and the third graphene rectangular resonant cavity 6 are directly coupled to the graphene nanostrip waveguide 3, respectively. The second graphene rectangular resonant cavity 5 is indirectly coupled to the graphene nanostrip waveguide 3 through the first graphene rectangular resonant cavity 4. The fourth graphene rectangular resonant cavity 7 is indirectly coupled to the graphene nanostrip waveguide 3 through the third graphene rectangular resonant cavity 6.

[0034] It should be noted that in practical applications, SPPs on graphene nanostrip waveguides can be excited using gratings or prisms. This invention uses a dipole to excite surface plasmons of boundary mode at the front end of the graphene nanostrip waveguide and sets a detector at the rear end of the graphene nanostrip waveguide.

[0035] It should be noted that the purpose of this invention is to realize a graphene-structured slow-light device with small size, high group refractive index, wide bandwidth, and easy integration. This invention uses FDTD-solution software simulation to determine the structural parameters of a slow-light device based on a graphene nanostrip waveguide coupled with four rectangular cavities.

[0036] In this specific embodiment, the thickness of the silicon substrate 1 is 300 nm; the thickness of the sapphire layer 2 is 200 nm. In the silicon-sapphire waveguide, light only causes a propagation loss as low as 1.9 dB / cm at a distance of 5.18 μm.

[0037] In this specific embodiment, the width of the graphene nanostrip waveguide 3 is 10 nm.

[0038] In this specific embodiment, the lengths of the first graphene rectangular resonant cavity 4, the second graphene rectangular resonant cavity 5, the third graphene rectangular resonant cavity 6, and the fourth graphene rectangular resonant cavity 7 are all 140 nm and the widths are all 20 nm.

[0039] In this specific embodiment, the coupling distance between the first graphene rectangular resonant cavity 4, the third graphene rectangular resonant cavity 6 and the graphene nanostrip waveguide 3 is 15 nm.

[0040] In this specific embodiment, the coupling distance between the first graphene rectangular resonant cavity 4 and the second graphene rectangular resonant cavity 5 is 20 nm; the coupling distance between the third graphene rectangular resonant cavity 6 and the fourth graphene rectangular resonant cavity 7 is 20 nm.

[0041] In this specific embodiment, the thickness of the single-layer graphene used in the slow-light device is 0.2 nm; the distance between the dipole of the slow-light device exciting the SPPs and the center of the first graphene rectangular resonant cavity 4, the second graphene rectangular resonant cavity 5, the third graphene rectangular resonant cavity 6, and the fourth graphene rectangular resonant cavity 7 is fixed at 150 nm; the spacing between the center of the first graphene rectangular resonant cavity 4, the second graphene rectangular resonant cavity 5, the third graphene rectangular resonant cavity 6, and the fourth graphene rectangular resonant cavity 7 and the detector is 150 nm.

[0042] It should be noted that, in order to avoid substrate loss in the mid-infrared band, the substrate material used in the structure is sapphire Al2O3, whose refractive index and loss factor k are approximately 1.60 and 0.0004 at a wavelength of 5.37 μm, respectively.

[0043] In this specific embodiment, the Fermi level of the graphene nanostrip waveguide 3 is 0.40 eV; the Fermi level of the first graphene rectangular resonant cavity 4 is 0.40 eV; the Fermi level of the second graphene rectangular resonant cavity 5 is 0.42 eV; the Fermi level of the third graphene rectangular resonant cavity is 0.42 eV; and the Fermi level of the fourth graphene rectangular resonant cavity 7 is 0.44 eV.

[0044] In this specific embodiment, the size of the slow-light device is less than 0.05. μ m 2 It can realize ultra-compact graphene slow light devices.

[0045] It should be noted that, as Figure 1 As shown, in the entire structure, the first graphene rectangular resonator 4 and the third graphene rectangular resonator 6 are directly coupled to the light in the graphene nanostrip waveguide 3. Therefore, the first graphene rectangular resonator 4 and the third graphene rectangular resonator 6 exhibit a wide bandwidth bright mode in the structure, and only the light in the graphene nanostrip waveguide 3 is needed to directly excite SPPs on its surface. Since the second graphene rectangular resonator 5 and the fourth graphene rectangular resonator 7 cannot directly couple with the light in the graphene nanostrip waveguide 3, the second graphene rectangular resonators 5 and 7 exhibit narrow-bandwidth dark modes in the structure. Therefore, the first graphene rectangular resonator 4 and the second graphene rectangular resonator 5 generate the PIT effect due to the coupling between the bright and dark modes. The third graphene rectangular resonator 6 and the fourth graphene rectangular resonator 7 also generate the PIT effect due to the coupling between the bright and dark modes. Furthermore, since the first graphene rectangular resonator 4, the second graphene rectangular resonator 5, the third graphene rectangular resonator 6, the fourth graphene rectangular resonator 7, and the graphene nanostrip waveguide 3 form a cavity-side coupled waveguide structure, the PIT effect can be formed. Therefore, this structure realizes the triple PIT effect.

[0046] In this specific embodiment, such as Figure 2 As shown, three significant PIT effect transmission windows were generated in the transmission spectrum, with transmission depression wavelengths of 5750 nm, 6100 nm, 6360 nm, and 6638 nm, and transmission peak wavelengths of 5935 nm, 6185 nm, and 6440 nm, respectively. The spectral bandwidth of the first and second transmission depressions in the transmission spectrum is 350 nm, the spectral bandwidth of the second and third transmission depressions is 260 nm, and the spectral bandwidth of the third and fourth transmission depressions is 278 nm, with the largest spectral bandwidth reaching 350 nm. Figure 2 It can be seen that the theoretical calculation results of the coupling mode of the transmission spectrum are completely consistent with the FDTD simulation results.

[0047] According to formulas 1 and 2:

[0048] (1)

[0049] (2)

[0050] Where: θ( ω () represents the phase shift in the transmission spectrum. n g For group refractive index, v g For group velocity, τ g For transmission spectral group delay, c The speed of light in a vacuum. l The thickness of the graphene system is given by the group refractive index, which can be used to quantitatively characterize the slow light performance. Figure 3 The transmission spectrum phase shift and system group refractive index of a slow-light device based on a graphene nanostrip waveguide coupled to a four rectangular cavity are presented.

[0051] It should be noted that, as Figure 3 As shown, a slow-light device based on a graphene nanostrip waveguide coupled with four rectangular cavities can realize three-channel slow light. The group refractive index at the center wavelength of the first transmission window is 120, the group refractive index at the center wavelength of the second transmission window can reach 115, and the group refractive index at the center wavelength of the third transmission window is 96. Therefore, by utilizing the steep dispersion characteristics of the PIT effect, the speed of light can be effectively slowed down, and the maximum group refractive index can reach 120, thus realizing an excellent slow-light device.

[0052] It should be noted that this invention realizes a three-channel slow-light device based on the three-PIT effect in the infrared band. Utilizing the strong local optical field enhancement characteristics of SPPs generated by graphene and the steep dispersion characteristics of the PIT effect, an ultra-compact slow-light device with a large group refractive index of graphene structure is realized, with a device size of less than 0.05 μm². This novel graphene-structured slow-light device has significant scientific research value and potential for future application in the field of photonic device integration, playing a supporting role in the development of future all-optical communication networks and all-optical signal processing technologies.

[0053] 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.

[0054] 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.

[0055] 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."

[0056] 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 slow-light device based on a graphene nanostrip waveguide coupled with a four-rectangular cavity, characterized in that: It includes a silicon substrate (1), a sapphire layer (2), a graphene nanostrip waveguide (3), a first graphene rectangular resonant cavity (4), a second graphene rectangular resonant cavity (5), a third graphene rectangular resonant cavity (6), and a fourth graphene rectangular resonant cavity (7), wherein: The sapphire layer (2) is disposed above the silicon substrate (1); the upper surface of the sapphire layer (2) is provided with the graphene nanostrip waveguide (3), the first graphene rectangular resonant cavity (4), the second graphene rectangular resonant cavity (5), the third graphene rectangular resonant cavity (6), and the fourth graphene rectangular resonant cavity (7); the first graphene rectangular resonant cavity (4) and the second graphene rectangular resonant cavity (5) are disposed on one side of the graphene nanostrip waveguide (3), and the third graphene rectangular resonant cavity (6) and the fourth graphene rectangular resonant cavity (7) are disposed on the other side of the sapphire layer (2). The four graphene rectangular resonant cavities (7) are disposed on the other side of the graphene nanostrip waveguide (3); the first graphene rectangular resonant cavity (4) and the third graphene rectangular resonant cavity (6) are directly coupled to the graphene nanostrip waveguide (3); the second graphene rectangular resonant cavity (5) is indirectly coupled to the graphene nanostrip waveguide (3) through the first graphene rectangular resonant cavity (4); the fourth graphene rectangular resonant cavity (7) is indirectly coupled to the graphene nanostrip waveguide (3) through the third graphene rectangular resonant cavity (6).

2. The slow-light device based on graphene nanostrip waveguide coupled with four rectangular cavities according to claim 1, characterized in that: The thickness of the silicon substrate (1) is 300 nm; the thickness of the sapphire layer (2) is 200 nm.

3. The slow-light device based on graphene nanostrip waveguide coupled with four rectangular cavities according to claim 2, characterized in that: The width of the graphene nanostrip waveguide (3) is 10 nm.

4. The slow-light device based on graphene nanostrip waveguide coupled with four rectangular cavities according to claim 3, characterized in that: The first graphene rectangular resonant cavity (4), the second graphene rectangular resonant cavity (5), the third graphene rectangular resonant cavity (6), and the fourth graphene rectangular resonant cavity (7) all have a length of 140 nm and a width of 20 nm.

5. The slow-light device based on graphene nanostrip waveguide coupled with four rectangular cavities according to claim 4, characterized in that: The coupling distance between the first graphene rectangular resonant cavity (4), the third graphene rectangular resonant cavity (6) and the graphene nanostrip waveguide (3) is 15 nm.

6. The slow-light device based on graphene nanostrip waveguide coupled with four rectangular cavities according to claim 5, characterized in that: The coupling distance between the first graphene rectangular resonant cavity (4) and the second graphene rectangular resonant cavity (5) is 20 nm; the coupling distance between the third graphene rectangular resonant cavity (6) and the fourth graphene rectangular resonant cavity (7) is 20 nm.

7. The slow-light device based on graphene nanostrip waveguide coupled with four rectangular cavities according to claim 6, characterized in that: The thickness of the single-layer graphene used in the slow-light device is 0.2 nm; the distance between the dipole of the slow-light device that excites SPPs and the center of the first graphene rectangular resonant cavity (4), the second graphene rectangular resonant cavity (5), the third graphene rectangular resonant cavity (6), and the fourth graphene rectangular resonant cavity (7) is fixed at 150 nm; the spacing between the center of the first graphene rectangular resonant cavity (4), the second graphene rectangular resonant cavity (5), the third graphene rectangular resonant cavity (6), and the fourth graphene rectangular resonant cavity (7) and the detector is 150 nm.

8. The slow-light device based on graphene nanostrip waveguide coupled with four rectangular cavities according to claim 7, characterized in that: The Fermi level of the graphene nanostrip waveguide (3) is 0.40 eV; the Fermi level of the first graphene rectangular resonator (4) is 0.40 eV; the Fermi level of the second graphene rectangular resonator (5) is 0.42 eV; the Fermi level of the third graphene rectangular resonator is 0.42 eV; and the Fermi level of the fourth graphene rectangular resonator (7) is 0.44 eV.

9. The slow-light device based on graphene nanostrip waveguide coupled with four rectangular cavities according to claim 8, characterized in that: The size of the slow-light device is less than 0.

05. μ m 2 .

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