Logic AND gate based on graphene nano-strip waveguide coupling rectangular resonant cavity

Abstract

The utility model relates to a logic AND gate based on a graphene nano-strip waveguide coupling rectangular resonant cavity. The logic AND gate comprises a silicon substrate, a sapphire layer, a graphene nano-strip waveguide and a graphene rectangular resonant cavity. The sapphire layer is arranged above the silicon substrate; a graphene nano-strip waveguide and a graphene rectangular resonant cavity are arranged on the upper surface of the sapphire layer; the graphene nano-strip waveguide comprises a first graphene nano-strip waveguide, a second graphene nano-strip waveguide and a third graphene nano-strip waveguide; the first graphene nano-strip waveguide, the second graphene nano-strip waveguide and the third graphene nano-strip waveguide are sequentially arranged from front to back; the graphene rectangular resonant cavity comprises a first graphene rectangular resonant cavity and a second graphene rectangular resonant cavity; and the first graphene rectangular resonant cavity and the second graphene rectangular resonant cavity are sequentially connected in series from front to back. According to the utility model, compact device size, high extinction ratio, high contrast ratio, ultrafast response rate and easy integration are realized.

Description

Technical Field

[0001] The utility model relates to the technical field of all-optical communication networks, and particularly to a logic AND gate based on a graphene nanoribbon waveguide-coupled rectangular resonator. Background Art

[0002] In an all-optical communication network, an all-optical logic gate is a key component for realizing functions such as optical signal calculation, optical signal switching, all-optical address recognition, and all-optical signal extraction. With the rapid development of large-scale integrated photonic devices, the requirements for small size, high extinction ratio, high contrast, and ultra-fast speed of optical logic gates are becoming increasingly obvious. Therefore, it is very important to realize an all-optical logic gate device with a new working mechanism that has a compact device size, a high extinction ratio, a high contrast, an ultra-fast response rate, and is easy to integrate. Such new types of optical logic gate devices are becoming more and more widely used in all-optical communication networks and all-optical signal processing.

[0003] Surface Plasmon Polaritons (SPPs for short) are a kind of surface electromagnetic evanescent wave that propagates along the metal-dielectric interface and decays exponentially in the direction perpendicular to the metal surface. SPPs have the characteristics of being able to break through the traditional optical diffraction limit and having a strong local optical field enhancement, so they can realize the guiding and manipulation of light at the sub-wavelength level. The SPP wave can be used as a carrier of energy and information, and it has important application value in high-density integrated photonic circuits.

[0004] Currently, optical logic gate devices based on SPPs have been widely studied, such as Mach-Zehnder Interferometer (MZI) and microring resonator structures. In 2014, researchers such as K.J.A. Ooi proposed a graphene surface plasmon logic gate based on Mach-Zehnder Interferometer in the mid-infrared band. This logic gate has a compact device size and a relatively high average extinction ratio (15 dB). In 2015, researchers such as T. Birr used the linear interference between dielectric cross waveguides to realize ultra-fast all-optical AND, OR, NOT, and XOR gates. The size of the device reached 10μm×20μm, and a half adder was realized based on this logic gate. Recently, researchers such as B. Zhu studied a magnetically controlled graphene logic gate in a bilayer graphene waveguide structure based on the principle of non-reciprocal coupling. The minimum extinction ratios of the designed OR gate and AND gate reached 13.6 dB and 17.5 dB respectively. Therefore, realizing an SPP optical logic gate device with a compact device size, a high extinction ratio, a high contrast, an ultra-fast response rate, and easy integration is the future development trend.

[0005] In recent years, graphene, a two-dimensional material with a single atomic layer, has provided a novel and low-loss way to confine and control SPPs, and thus has been applied in the design of SPP devices. Experimental studies by A.E. Nikolaenko et al. have shown that graphene has an ultrafast response time on the order of 1 ps and can effectively achieve an ultra-fast repetition rate for optical logic gates.

[0006] Defects of the prior art are as follows:

[0007] 1. For traditional logic AND gate devices based on MZI or micro-ring resonator structures, the obtained average extinction ratio and contrast ratio are relatively low, which limits the application and development of logic AND gate devices in all-optical signal processing technologies.

[0008] 2. Since traditional logic AND gate devices based on MZI or micro-ring resonator structures are large in size, it is not conducive to large-scale integration of the devices.

[0009] 3. Since the response rate of some materials is slow, the response rate of logic AND gate devices is reduced, which is not conducive to the application and development of ultra-fast logic AND gate devices in broadband high-speed optical communication networks and all-optical signal processing technologies.

[0010] 4. Since the actual logic AND gate device should be three-dimensional and fabricated on a substrate, but many of the proposed device structures currently only study two-dimensional planar structures and do not consider the gold film thickness and out-of-plane loss, which is not conducive to the structural design and performance analysis of logic AND gate devices. Summary of the Invention

[0011] The present utility model aims at the above problems and provides a logic AND gate based on a graphene nanoribbon waveguide-coupled rectangular resonator, aiming to achieve a compact device size, a high extinction ratio, a high contrast ratio, an ultra-fast response rate and easy integration.

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

[0013] The logic AND gate based on a graphene nanoribbon waveguide-coupled rectangular resonator includes a silicon substrate, a sapphire layer, a graphene nanoribbon waveguide, and a graphene rectangular resonator, wherein:

[0014] The sapphire layer is disposed above the silicon substrate; the graphene nanoribbon waveguide and the graphene rectangular resonator are disposed on the upper surface of the sapphire layer;

[0015] The graphene nanoribbon waveguide includes a first graphene nanoribbon waveguide, a second graphene nanoribbon waveguide, and a third graphene nanoribbon waveguide;

[0016] The first graphene nanoribbon waveguide, the second graphene nanoribbon waveguide, and the third graphene nanoribbon waveguide are arranged in sequence from front to back;

[0017] The graphene rectangular resonator includes a first graphene rectangular resonator and a second graphene rectangular resonator;

[0018] The first graphene rectangular resonator and the second graphene rectangular resonator are connected in series in sequence from front to back.

[0019] Preferably, the thickness of the silicon substrate is 300 nm; the thickness of the sapphire layer is 300 nm.

[0020] Preferably, the coupling distance between the graphene nanoribbon waveguide and the graphene rectangular resonator is 10 nm.

[0021] Preferably, the coupling length between the first graphene nanoribbon waveguide and the first graphene rectangular resonator is 60 nm; the coupling length between the second graphene nanoribbon waveguide and the second graphene rectangular resonator is 60 nm; the distance between the first graphene nanoribbon waveguide and the second graphene nanoribbon waveguide is 20 nm; the distance between the second graphene nanoribbon waveguide and the third graphene nanoribbon waveguide is 20 nm; the distance between the first graphene rectangular resonator and the second graphene rectangular resonator is 80 nm.

[0022] Preferably, the length of the first graphene rectangular resonator is 140 nm and the width is 10 nm; the length of the second graphene rectangular resonator is 140 nm and the width is 10 nm.

[0023] Preferably, the width of the first graphene nanoribbon waveguide is 10 nm; the width of the second graphene nanoribbon waveguide is 10 nm; the width of the third graphene nanoribbon waveguide is 10 nm.

[0024] Preferably, the relaxation time of the graphene used in the present invention is 0.5 ps; the thickness of the single-layer graphene is 0.2 nm.

[0025] Preferably, the distance between the dipole exciting the surface plasmon polariton and the center of the graphene rectangular resonator is fixed at 150 nm; the distance between the center of the graphene rectangular resonator and the detector is 150 nm.

[0026] Preferably, the refractive index and loss factor of the sapphire layer are 1.60 and 0.0004 respectively at a wavelength of 5.37 μm.

[0027] Preferably, the chemical potential of the graphene nanostrip waveguide is fixed at 0.6eV; when the chemical potential of the first graphene rectangular resonant cavity and the second graphene rectangular resonant cavity is 0.6eV, the logic output of this logic AND gate is "1"; when the chemical potential of the first graphene rectangular resonant cavity and the second graphene rectangular resonant cavity is 0.2eV, the logic output of this logic AND gate is "0".

[0028] Compared with the prior art, the utility model has the following advantages:

[0029] 1. Since the utility model adopts a graphene nanostrip waveguide structure, the graphene nanostrip waveguide coupled rectangular resonant cavity system is applied to the integrated graphene logic AND gate device, thereby solving the problems of low extinction ratio and low contrast of the graphene logic AND gate device.

[0030] 2. Since the size of the logic AND gate device based on the graphene nanostrip waveguide coupled rectangular resonant cavity of the utility model is less than 0.05μm 2 , which can realize an ultra-compact structure, thereby greatly reducing the size of logic AND gate devices and solving the problem that logic AND gate devices are difficult to integrate on a large scale in on-chip plasmon optical paths.

[0031] 3. Since the graphene response time used in the utility model is on the order of 1 ps, an ultra-fast response rate of the logic AND gate device is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a structural schematic diagram of a logic AND gate based on a graphene nanostrip waveguide coupled rectangular resonant cavity according to a specific embodiment of the utility model;

[0033] Figure 2a Schematic diagram of the transmission spectrum of the logic AND gate system based on the graphene nanostrip waveguide coupled rectangular resonant cavity when the logic inputs are "1 1" respectively;

[0034] Figure 2b Schematic diagram of the transmission spectrum of the logic AND gate system based on the graphene nanostrip waveguide coupled rectangular resonant cavity when the logic inputs are "1 0" respectively;

[0035] Figure 2c Schematic diagram of the transmission spectrum of the logic AND gate system based on graphene nanostrip waveguide coupled rectangular resonant cavity when the logic inputs are "0 0" respectively.

[0036] Wherein: 1. Silicon substrate, 2. Sapphire layer, 3. Graphene nanoribbon waveguide, 4. Graphene rectangular resonator, 3.1. First graphene nanoribbon waveguide, 3.2. Second graphene nanoribbon waveguide, 3.3. Third graphene nanoribbon waveguide, 4.1. First graphene rectangular resonator, 4.2. Second graphene rectangular resonator, 5. Forward, 6. Backward Detailed implementation manners

[0037] The present invention will be further illustrated below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. After reading the present invention, those skilled in the art's various equivalent modifications of the present invention all fall within the scope defined by the appended claims of this application.

[0038] As Figure 1 shown, a logic AND gate based on a graphene nanoribbon waveguide-coupled rectangular resonator includes a silicon substrate 1, a sapphire layer 2, a graphene nanoribbon waveguide 3, and a graphene rectangular resonator 4, wherein:

[0039] The sapphire layer 2 is disposed above the silicon substrate 1; the upper surface of the sapphire layer 2 is provided with a graphene nanoribbon waveguide 3 and a graphene rectangular resonator 4.

[0040] The graphene nanoribbon waveguide 3 includes a first graphene nanoribbon waveguide 3.1, a second graphene nanoribbon waveguide 3.2, and a third graphene nanoribbon waveguide 3.3.

[0041] The first graphene nanoribbon waveguide 3.1, the second graphene nanoribbon waveguide 3.2, and the third graphene nanoribbon waveguide 3.3 are arranged in sequence from front to back.

[0042] The graphene rectangular resonator 4 includes a first graphene rectangular resonator 4.1 and a second graphene rectangular resonator 4.2.

[0043] The first graphene rectangular resonator 4.1 and the second graphene rectangular resonator 4.2 are arranged in series in sequence from front to back.

[0044] It should be noted that the SPPs on the graphene nanoribbon waveguide 3 can be excited by a grating or a prism. In this utility model, a dipole is used to excite the surface plasmon of the boundary mode at the front end of the graphene nanoribbon waveguide 3, and a detector is arranged at the rear end of the graphene nanoribbon waveguide 3.

[0045] It should be noted that this utility model adopts the method of simulation by FDTD–solution software to determine the structural parameters of the logic AND gate device based on the graphene nanoribbon waveguide 3 coupled with the graphene rectangular resonator 4.

[0046] In this specific embodiment, the thickness of the silicon substrate 1 is 300 nm; the thickness of the sapphire layer 2 is 300 nm.

[0047] In this specific embodiment, the coupling distance between the graphene nanoribbon waveguide 3 and the graphene rectangular resonator 4 is 10 nm.

[0048] In this specific embodiment, the coupling length between the first graphene nanoribbon waveguide 3.1 and the first graphene rectangular resonator 4.1 is 60 nm; the coupling length between the second graphene nanoribbon waveguide 3.2 and the second graphene rectangular resonator 4.2 is 60 nm; the distance between the first graphene nanoribbon waveguide 3.1 and the second graphene nanoribbon waveguide 3.2 is 20 nm; the distance between the second graphene nanoribbon waveguide 3.2 and the third graphene nanoribbon waveguide 3.3 is 20 nm; the distance between the first graphene rectangular resonator 4.1 and the second graphene rectangular resonator 4.2 is 80 nm.

[0049] In this specific embodiment, the length of the first graphene rectangular resonator 4.1 is 140 nm and the width is 10 nm; the length of the second graphene rectangular resonator 4.2 is 140 nm and the width is 10 nm.

[0050] In this specific embodiment, the width of the first graphene nanoribbon waveguide 3.1 is 10 nm; the width of the second graphene nanoribbon waveguide 3.2 is 10 nm; the width of the third graphene nanoribbon waveguide 3.3 is 10 nm.

[0051] In this specific embodiment, the relaxation time of the graphene used in this utility model is 0.5 ps; the thickness of the single-layer graphene is 0.2 nm.

[0052] In this specific embodiment, the distance of the dipole exciting the surface plasmon polariton from the center of the graphene rectangular resonator 4 is fixed at 150 nm; the distance between the center of the graphene rectangular resonator 4 and the detector is 150 nm.

[0053] It should be noted that in order to avoid the substrate loss in the mid-infrared band, the substrate material used in the structure is sapphire Al2O3.

[0054] In this specific embodiment, the refractive index and loss factor of the sapphire layer 2 at a wavelength of 5.37 μm are 1.60 and 0.0004 respectively.

[0055] In this specific embodiment, the chemical potential of the graphene nanoribbon waveguide 3 is fixed at 0.6 eV; when the chemical potentials of the first graphene rectangular resonator 4.1 and the second graphene rectangular resonator 4.2 are 0.6 eV, the logic output by this logic AND gate is "1"; when the chemical potentials of the first graphene rectangular resonator 4.1 and the second graphene rectangular resonator 4.2 are 0.2 eV, the logic output by this logic AND gate is "0".

[0056] In this specific embodiment, the size of the logic AND gate device based on the graphene nanoribbon waveguide-coupled rectangular resonator is less than 0.05 μm 2 , thus enabling an ultra-compact graphene logic AND gate device.

[0057] As Figure 2a , Figure 2b , Figure 2c shown, in this specific embodiment, when the logic input is "1 1", the graphene rectangular resonators 4 in the forward 5 and backward 6 directions are both turned on, and the amplitude value of the transmission peak at 5.37 μm is close to 0.42. At this time, the extinction ratio reaches -3.77 dB.

[0058] It should be noted that compared with the simulation results in Figure 2a , the reason for the significant reduction in the amplitude of the transmission peak is that the two graphene rectangular resonators 4 are in series, and at this time, the absorption loss of the sapphire layer 2 and the transmission loss of the SPPs itself both increase relatively. When the logic input is "1 0" or "0 1", since the phase matching condition is not satisfied between the graphene nanoribbon waveguide 3 and the graphene rectangular resonator 4, the SPPs cannot pass through the system structure, and the transmittance at 5.37 μm is reduced to 1.9×10 -3 , and the extinction ratio reaches -27.21 dB. When the logic input is "0 0", since the graphene rectangular resonators 4 in the front and back directions do not satisfy the phase matching condition, the two graphene rectangular resonators 4 cannot be turned on, so the transmittance at 5.37 μm drops sharply to 3.4×10 -6 , and the extinction ratio at this time reaches -55.02 dB.

[0059] As shown in Table 1, the maximum difference in extinction ratio between the on state with an output of 1 and the off state with an output of 0 reaches 51.25 dB. The above simulation results show that the present invention can realize a graphene logic AND gate device with a high extinction ratio and high contrast.

[0060] Table 1. Truth table and extinction ratio of the logic AND gate based on the graphene nanoribbon waveguide-coupled rectangular resonator

[0061]

[0062] In the foregoing detailed description, various features are combined in a single embodiment to simplify the present disclosure. This method of disclosure should not be construed as reflecting an intention that the embodiments of the claimed subject matter require more features than are clearly recited in each claim. On the contrary, as reflected in the appended claims, the invention lies in less than the full scope of features of the single disclosed embodiment. Accordingly, the appended claims are hereby expressly incorporated into the detailed description, where each claim stands on its own as a separate preferred embodiment of the invention.

[0063] The above-described disclosed embodiments are described to enable any person skilled in the art to make or use the present invention. For those skilled in the art, various modifications to these embodiments are obvious, and the general principles defined herein can also be applied to other embodiments without departing from the spirit and scope of the present disclosure. Therefore, the present disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0064] The foregoing description includes examples of one or more embodiments. Of course, it is not possible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but those of ordinary skill in the art should recognize that the various embodiments can be further combined and arranged. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. In addition, with respect to the term "comprising" used in the specification or claims, this term is inclusive in a manner similar to the term "including" as interpreted when used as a transitional word in a claim. In addition, any use of the term "or" in the specification or claims of the patent application is intended to mean "non-exclusive or".

[0065] The specific embodiments described above further elaborate on the object, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A logic AND gate based on a graphene nanoribbon waveguide-coupled rectangular resonator, characterized in that: It includes a silicon substrate (1), a sapphire layer (2), a graphene nanoribbon waveguide (3), and a graphene rectangular resonator (4), where: The sapphire layer (2) is disposed above the silicon substrate (1); the graphene nanoribbon waveguide (3) and the graphene rectangular resonator (4) are disposed on the upper surface of the sapphire layer (2); The graphene nanoribbon waveguide (3) includes a first graphene nanoribbon waveguide (3.1), a second graphene nanoribbon waveguide (3.2), and a third graphene nanoribbon waveguide (3.3); The first graphene nanoribbon waveguide (3.1), the second graphene nanoribbon waveguide (3.2), and the third graphene nanoribbon waveguide (3.3) are arranged in sequence from front to back; The graphene rectangular resonator (4) includes a first graphene rectangular resonator (4.1) and a second graphene rectangular resonator (4.2); The first graphene rectangular resonator (4.1) and the second graphene rectangular resonator (4.2) are arranged in series in sequence from front to back; The chemical potential of the graphene nanoribbon waveguide (3) is fixed at 0.6 eV; when the chemical potentials of the first graphene rectangular resonator (4.1) and the second graphene rectangular resonator (4.2) are fixed at 0.6 eV, the logic output by this logic AND gate is "1"; when the chemical potentials of the first graphene rectangular resonator (4.1) and the second graphene rectangular resonator (4.2) are fixed at 0.2 eV, the logic output by this logic AND gate is "0"; the distance of the dipole exciting the surface plasmon polariton from the center of the graphene rectangular resonator (4) is fixed at 150 nm; the distance between the center of the graphene rectangular resonator (4) and the detector is 150 nm.

2. The logic AND gate based on a graphene nanoribbon waveguide-coupled rectangular resonator 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 300 nm; the length of the first graphene rectangular resonator (4.1) is 140 nm and the width is 10 nm; the length of the second graphene rectangular resonator (4.2) is 140 nm and the width is 10 nm; the width of the first graphene nanoribbon waveguide (3.1) is 10 nm; the width of the second graphene nanoribbon waveguide (3.2) is 10 nm; the width of the third graphene nanoribbon waveguide (3.3) is 10 nm.

3. The logic AND gate based on a graphene nanoribbon waveguide-coupled rectangular resonator according to claim 2, characterized in that: The coupling distance between the graphene nanoribbon waveguide (3) and the graphene rectangular resonator (4) is 10 nm.

4. The logic AND gate based on a graphene nanoribbon waveguide-coupled rectangular resonator according to claim 3, wherein: The coupling length between the first graphene nanoribbon waveguide (3.1) and the first graphene rectangular resonator (4.1) is 60 nm; the coupling length between the second graphene nanoribbon waveguide (3.2) and the second graphene rectangular resonator (4.2) is 60 nm.

5. The logic AND gate based on a graphene nanoribbon waveguide-coupled rectangular resonator according to claim 4, characterized in that: The distance between the first graphene nanoribbon waveguide (3.1) and the second graphene nanoribbon waveguide (3.2) is 20 nm; the distance between the second graphene nanoribbon waveguide (3.2) and the third graphene nanoribbon waveguide (3.3) is 20 nm; the distance between the first graphene rectangular resonator (4.1) and the second graphene rectangular resonator (4.2) is 80 nm.

6. The logic AND gate based on a graphene nanoribbon waveguide-coupled rectangular resonator according to claim 5, characterized in that: The relaxation time of the graphene used in the present utility model is 0.5 ps; the thickness of the single-layer graphene is 0.2 nm.

7. The logic AND gate based on a graphene nanoribbon waveguide-coupled rectangular resonator according to claim 6, wherein: The refractive index and loss factor of the sapphire layer (2) are 1.60 and 0.0004 respectively at a wavelength of 5.37 μm.

Images