Four-port optical router based on graphene-silicon waveguide micro-ring resonators

Abstract

The invention discloses a four-port optical router based on graphene-silicon waveguide micro-ring resonators. The four-port optical router comprises ten graphene-silicon waveguide micro-ring resonators, five optical waveguides, four input ports, four output ports and two terminal nodes. Each graphene-silicon waveguide micro-ring resonator is composed of a micro-ring silicon waveguide and a graphene modulation area, and has the same resonant wavelength; by utilizing the resonance characteristic of the micro-ring resonator to a specific wavelength and respectively applying 0.84 V and 3.96 V voltages to the metal electrode of the graphene-silicon waveguide micro-ring resonator, the Fermi level of graphene can be changed, and then the resonance state of the micro-ring is changed, so that the transmission path of the graphene-silicon waveguide micro-ring optical switch is changed, and the transmission efficiency of the graphene-silicon waveguide micro-ring optical switch is improved. The non-blocking routing exchange of the four bidirectional ports is realized; the design not only optimizes the structure of the optical router and reduces the cost, but also significantly reduces the insertion loss and crosstalk.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated optics and the switching technology for realizing routing switching between multiple ports in an on-chip optical network system, and particularly relates to a four-port optical router based on a graphene-silicon waveguide microring resonator. Background Art

[0002] With the rapid growth of communication demands and the wide application of multi-core processing technologies, traditional electrical interconnection systems have gradually exposed bottlenecks in terms of bandwidth, latency, and power consumption, making it difficult to meet the requirements of high-speed and large-scale data transmission. In contrast, optical interconnection, with its advantages of high bandwidth, low latency, and low power consumption, has become a key development direction for future on-chip network interconnection. Among them, as the core device of an on-chip optical network system, an optical router undertakes the important task of path control and routing selection for optical signals. Modern optical router architectures are mainly constructed based on microring resonators (MRRs) and Mach-Zehnder interferometers (MZIs). Two major technical routes have been derived based on microring resonators (MRRs): one is to use a passive structure with fixed wavelength selection to achieve low-power real-time transmission; the other is to rely on active device regulation to achieve dynamic link reconfiguration, with stronger flexibility and scalability.

[0003] However, traditional silicon-based optical routers generally have problems such as large device size, high power consumption, and slow regulation speed under the thermo-optical regulation mechanism, which limit their application in high-density integration and wide-spectrum wavelength division multiplexing systems. The introduction of graphene provides a new breakthrough. This two-dimensional material has excellent electro-optical modulation performance, and at the same time, the material can change its Fermi level through voltage regulation, thereby flexibly changing its optical constants and achieving efficient dynamic regulation. In addition, the atomic-level thickness and good CMOS compatibility of graphene make it very suitable for heterogeneous integration with silicon photonic devices. A new type of optical router based on a graphene-silicon waveguide integrated structure is expected to achieve a better balance among miniaturization, low power consumption, and broadband response, promoting the development of on-chip optical interconnection technology towards higher density, stronger reconfigurability, and lower energy consumption, and becoming one of the key paths to solve the bottleneck of future high-performance computing interconnection. Summary of the Invention

[0004] The present invention proposes a four-port optical router based on a graphene-silicon waveguide microring resonator to solve the problems of existing optical routers such as large size, high cost, and large insertion loss.

[0005] To solve the above problems, the present invention is realized through the following technical solutions:

[0006] A four-port optical router based on a graphene-silicon waveguide microring resonator, comprising 10 graphene-silicon waveguide microring resonators, 5 optical waveguides, 4 input ports, 4 output ports and 2 terminal nodes. The 10 graphene-silicon waveguide microring resonators are numbered sequentially starting from M1. The optical waveguide from input port 1 to output port 3 is optical waveguide 1. The waveguide from the first terminal node to output port 1 is waveguide 2. The optical waveguide from input port 4 to output port 2 is optical waveguide 3. The optical waveguide from input port 3 to the second terminal node is optical waveguide 4. The optical waveguide from input port 2 to output port 4 is optical waveguide 5. This router has a total of 5 cross nodes. Each graphene-silicon waveguide microring resonator (M1~M 10 ) has a graphene modulation region (2-6) integrated in a partial area. The graphene layer (2-6-3) of the graphene modulation region (2-6) is stacked into bilayer graphene by the mechanical exfoliation method and extends under the metal electrode (2-6-5). By applying different voltages to the electrodes of the graphene-silicon waveguide microring optical switch, the Fermi level of graphene is changed, the effective refractive index of the graphene-silicon waveguide is dynamically adjusted, and then the resonant state of the microring is changed, so that the transmission path of the graphene-silicon waveguide microring optical switch can be changed, and finally the wavelength-selective optical routing function is realized.

[0007] In the above solution, among the 10 graphene-silicon waveguide microring resonators, M1, M2 and M 10 are parallel graphene-silicon waveguide microring resonators.

[0008] In the above solution, among the 10 graphene-silicon waveguide microring resonators, M3, M4, M5, M6, M7, M8 and M9 are cross graphene-silicon waveguide microring resonators.

[0009] In the above solution, the resonant wavelengths of the 10 graphene-silicon waveguide microring resonators are the same.

[0010] In the above solution, this optical router operates with a single wavelength or WDM multi-wavelength signal and can be extended to a more-port optical router structure.

[0011] In the above solution, by utilizing the resonant characteristics of the microring resonator for a specific wavelength, by applying voltages of 0.84V and 3.96V respectively at the metal electrodes of the graphene-silicon waveguide microring resonator, the Fermi level of graphene can be changed, and then the resonant state of the microring can be changed, thereby changing the transmission path of the graphene-silicon waveguide microring optical switch, and realizing non-blocking routing exchange of four bidirectional ports.

[0012] Compared with the prior art, the present invention has the following characteristics:

[0013] 1. The present invention completely independently designs a four-port optical router based on a graphene-silicon waveguide microring resonator, and realizes non-blocking routing switching between 4 input and 4 output ports through the combination of the graphene-silicon waveguide microring resonator, optical waveguide and terminal nodes. This design not only optimizes the structure of the optical router and reduces costs, but also significantly reduces insertion loss and crosstalk.

[0014] 2. The present invention combines two graphene-silicon waveguide microring resonator structures with different structures but the same resonant wavelength, reduces the number of cross nodes of the optical router, effectively reduces the energy consumption of the optical switch and the router, and more importantly, achieves a breakthrough improvement in the equivalent refractive index tuning sensitivity and the dimension of functional realization.

[0015] 3. The present invention realizes optical path switching through voltage regulation, selects a material with a higher dielectric constant as the insulating layer of the graphene modulation region, reduces the applied voltage range, can effectively reduce the loss of the optical router, and improves the stability of optical path switching. Brief Description of the Drawings

[0016] Figure 1 It is a schematic structural diagram of a four-port optical router based on a graphene-silicon waveguide microring resonator;

[0017] Figure 2 It is a schematic structural diagram of a cross graphene-silicon waveguide microring optical switch;

[0018] Figure 3 It is a schematic structural diagram of a parallel graphene-silicon waveguide microring optical switch;

[0019] Figure 4 It is a sectional view taken along line A-A at the graphene modulation region;

[0020] Figure 5 It is a schematic structural diagram of a traditional cross waveguide optical switch in the Cross state;

[0021] Figure 6 It is a schematic structural diagram of a traditional cross waveguide optical switch in the Bar state;

[0022] Figure 7 It is an electric field distribution diagram of a cross graphene-silicon waveguide microring optical switch when the graphene chemical potential is 0.55 eV;

[0023] Figure 8 It is an electric field distribution diagram of a cross graphene-silicon waveguide microring optical switch when the graphene chemical potential is 1.2 eV;

[0024] Figure 9 It is a schematic structural diagram of a traditional parallel waveguide optical switch in the Cross state;

[0025] Figure 10 Schematic diagram of the structure of a traditional parallel waveguide optical switch in the Bar state;

[0026] Figure 11 Electric field distribution diagram when the chemical potential of graphene in a parallel graphene-silicon waveguide microring optical switch is 0.55 eV;

[0027] Figure 12 Electric field distribution diagram when the chemical potential of graphene in a parallel graphene-silicon waveguide microring optical switch is 1.2 eV. Specific implementation mode

[0028] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with specific examples.

[0029] As Figure 1 shown, a four-port optical router based on a graphene-silicon waveguide microring resonator includes 10 graphene-silicon waveguide microring resonators, 5 optical waveguides, 4 input ports, 4 output ports and 2 terminal nodes. The 10 graphene-silicon waveguide microring resonators are numbered sequentially starting from M1. The optical waveguide from input port 1 to output port 3 is optical waveguide 1, the optical waveguide from the first terminal node to output port 1 is waveguide 2, the optical waveguide from input port 4 to output port 2 is optical waveguide 3, the optical waveguide from input port 3 to the second terminal node is optical waveguide 4, and the optical waveguide from input port 2 to output port 4 is optical waveguide 5; the router has a total of 5 intersections.

[0030] Part of each graphene-silicon waveguide microring silicon waveguide (M1~M 10 ) is integrated with a graphene modulation region (2-6); see Figure 4 , the graphene layer (2-6-3) of the graphene modulation region (2-6) is stacked into bilayer graphene by mechanical exfoliation method and extends under the metal electrode (2-6-5). By applying voltages of 0.84 V and 3.96 V (corresponding to the chemical potential of graphene being 0.55 eV and 1.2 eV) at the metal electrodes of the graphene-silicon waveguide microring resonator respectively, the Fermi level of graphene can be changed, and then the resonance state of the microring can be changed, thereby changing the transmission path of the graphene-silicon waveguide microring optical switch, realizing non-blocking routing exchange of four bidirectional ports.

[0031] As Figure 2As shown, the cross graphene-silicon waveguide micro-ring optical switch is composed of straight waveguides (1, 4, 5, 7), a micro-ring silicon waveguide (2), a cross-coupling waveguide (3), and a graphene modulation region (2-6). In this example, the straight waveguides (1, 4, 5, 7) and the micro-ring silicon waveguide (2) both adopt strip waveguide structures, with a height of 220 nm and a width of 450 nm; the height of the cross-coupling waveguide (3) is set to 220 nm and the total length is set to 200 nm; the coupling distance between the micro-ring silicon waveguide (2) and the straight waveguides (1, 5) is set to 100 nm; the radius of the micro-ring silicon waveguide (2-2) is set to 6.2 μm, and the coverage range of the graphene modulation region (2-6) is defined by the arc length corresponding to the micro-ring circle (the arc length formula is ); the arc length corresponding to the central angle of 180° of the micro-ring for the graphene modulation region is set to 6.2π μm, the inner diameter and outer diameter of the modulation region are consistent with the micro-ring silicon waveguide, and its position is set near the maximum value of the cross-sectional electromagnetic field intensity of the micro-ring. See Figure 3 It can be seen that the parallel graphene-silicon waveguide micro-ring optical switch is composed of straight waveguides (8, 9), a micro-ring silicon waveguide (2), and a graphene modulation region (2-6). The structural dimensions of the straight waveguides (8, 9) and the micro-ring silicon waveguide (2), the coupling distance between the micro-ring silicon waveguide (2) and the straight waveguides (8, 9), the radius of the micro-ring silicon waveguide (2), and the coverage range of the graphene modulation region (2-6) are all consistent with those of the cross graphene-silicon waveguide micro-ring optical switch, and the two have the same resonant wavelength.

[0032] Figure 4 Figure A-A of the graphene modulation region (2-6) shown is arranged from bottom to top as follows: a SiO2 substrate layer (1), a silicon waveguide layer (2-6-1), an upper insulating layer (2-6-2), a graphene layer (2-6-3), a lower insulating layer (2-6-2), a silicon waveguide layer (2-6-1), and a SiO2 cladding layer; the thickness of the SiO2 substrate (1) is set to 3 μm. The graphene layer is stacked into a bilayer graphene structure by mechanical exfoliation. The insulating layer (2-6-2) is made of HfO2 with a thickness of 5 nm and a refractive index of 1.98. HfO2 is deposited above the micro-ring silicon waveguide, and then graphene is mechanically exfoliated and set above HfO2, and then another layer of HfO2 material is deposited to form a voltage regulation region; the metal electrode material (2-6-4) is set to Au, and a metal electrode Pd material (2-6-5) is arranged below the metal electrode Au at the graphene end. This material can ensure ohmic contact. The metal electrode at the graphene end is connected to the positive electrode, and the metal electrode at the Si waveguide end is connected to the negative electrode to form a capacitive structure.

[0033] Figure 5 and Figure 6Schematic diagrams of the structures of a traditional cross - waveguide optical switch in the Cross state and the Bar state respectively. When the wavelength of the input optical signal is the same as the resonance wavelength of the micro - ring, the optical signal enters the drop direction through micro - ring resonance. When the wavelength of the input optical signal is different from the resonance wavelength of the micro - ring, the optical signal directly passes through and outputs to the through direction.

[0034] Figure 7 and Figure 8 They are respectively the electric - field distribution diagrams of a cross - graphene - silicon - waveguide micro - ring optical switch at a light wavelength of 1555.25 nm when the chemical potential of graphene is 0.55 eV and 1.2 eV. When the chemical potential is 0.55 eV, the optical signal resonates and is output by the cross - output section (5); when the chemical potential is 1.2 eV, the optical signal does not resonate and is output by the direct - through output section (4).

[0035] Figure 9 and Figure 10 Schematic diagrams of the structures of a traditional parallel - waveguide optical switch in the Cross state and the Bar state respectively. When the wavelength of the input optical signal is the same as the resonance wavelength of the micro - ring, the optical signal enters the drop direction through micro - ring resonance. When the wavelength of the input optical signal is different from the resonance wavelength of the micro - ring, the optical signal directly passes through and outputs to the through direction.

[0036] Figure 11 and Figure 12 They are respectively the electric - field distribution diagrams of a parallel - graphene - silicon - waveguide micro - ring optical switch at a light wavelength of 1555.25 nm when the chemical potential of graphene is 0.55 eV and 1.2 eV. When the chemical potential is 0.55 eV, the optical signal resonates and is output by the lower - end output section (9); when the chemical potential is 1.2 eV, the optical signal does not resonate and is output by the direct - through output section.

[0037] Combined with Figure 7 and Figure 8 ; the switching state of the cross - graphene - silicon - waveguide micro - ring optical switch when the chemical potential of graphene is 0.55 eV is set as the Cross state, and the switching state when the chemical potential is 1.2 eV is set as the Bar state; combined with Figure 11 and Figure 12 , the switching state of the parallel - graphene - silicon - waveguide micro - ring optical switch when the chemical potential of graphene is 0.55 eV is set as the Cross state, and the switching state when the chemical potential is 1.2 eV is set as the Bar state. In this example, all micro - ring silicon waveguides are initialized to the Bar state, and from this, the corresponding relationship between the communication lines of the optical router and the Cross state of the micro - ring silicon waveguides is obtained, as shown in Table 1 below:

[0038]

[0039] Table 1 shows the corresponding relationship between the communication lines of this optical router and the Cross state of the micro - ring silicon waveguides

[0040] In summary, the present invention proposes a four-port optical router based on a graphene-silicon waveguide microring resonator, which is composed of 10 graphene-silicon waveguide microring resonators, 5 optical waveguides, 4 input ports, 4 output ports and 2 terminal nodes, realizing the switching of the optical signal direction between 4 input ports and 4 output ports. The graphene-silicon waveguide microring optical switches of the two structures adopted by the router have the same resonant wavelength. By applying voltages of 0.84V and 3.96V to the metal electrodes respectively, the chemical potential of graphene can be dynamically regulated to 0.55eV and 1.2eV respectively, realizing the switching of its working state between the Cross state and the Bar state, and realizing the wavelength-selective optical routing function.

[0041] It should be noted that although the embodiments described above of the present invention are illustrative, this is not a limitation of the present invention. Therefore, the present invention is not limited to the above specific embodiments. Without departing from the principle of the present invention, any other embodiments obtained by those skilled in the art under the inspiration of the present invention are regarded as within the protection scope of the present invention.

Claims

1. A four-port optical router based on a graphene-silicon waveguide microring resonator, comprising 10 graphene-silicon waveguide microring resonators, 5 optical waveguides, 4 input ports, 4 output ports, and 2 terminal nodes. The 10 graphene-silicon waveguide microring resonators are numbered sequentially starting from M1. The optical waveguide from input port 1 to output port 3 is optical waveguide 1. The waveguide from the first terminal node to output port 1 is waveguide 2. The optical waveguide from input port 4 to output port 2 is optical waveguide 3. The optical waveguide from input port 3 to the second terminal node is optical waveguide 4. The optical waveguide from input port 2 to output port 4 is optical waveguide 5. This router has a total of 5 cross nodes.

2. The four-port optical router based on a graphene-silicon waveguide microring resonator according to claim 1, characterized in that: Among the 10 graphene-silicon waveguide microring resonators, M1, M2, and M 10 are parallel graphene-silicon waveguide microring resonators.

3. The four-port optical router based on a graphene-silicon waveguide microring resonator according to claim 1, wherein: Among the 10 graphene-silicon waveguide microring resonators, M3, M4, M5, M6, M7, M8, and M9 are cross graphene-silicon waveguide microring resonators.

4. A four-port optical router based on a graphene-silicon waveguide microring resonator according to claim 1, characterized in that: The resonant wavelengths of the 10 graphene-silicon waveguide microring resonators are the same.

5. A four-port optical router based on a graphene-silicon waveguide microring resonator according to claim 1, characterized in that: By utilizing the resonant characteristics of the microring resonator for a specific wavelength, by applying voltages of 0.84 V and 3.96 V respectively at the metal electrodes of the graphene-silicon waveguide microring resonator, the Fermi level of graphene can be changed, thereby changing the resonant state of the microring, and further changing the transmission path of the graphene-silicon waveguide optical switch, realizing non-blocking routing and switching of four bidirectional ports.

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