4*4 non-blocking optical router based on graphene-silicon waveguide

Abstract

The invention discloses a 4 * 4 non-blocking optical router based on graphene-silicon waveguide. The 4 * 4 non-blocking optical router comprises a SiO2 substrate and 12 graphene-silicon waveguide micro-ring optical switch units, twelve graphene-silicon waveguide micro-ring optical switches are mutually connected to form a 4 * 4 matrix structure, so that four input ports and four output ports are formed. Each graphene-silicon waveguide micro-ring optical switch is composed of a straight waveguide, a micro-ring silicon waveguide, a cross coupling waveguide and a graphene modulation area, and the structural size and the performance parameter of each graphene-silicon waveguide micro-ring optical switch are kept consistent. Different voltages are applied to the electrodes of the graphene-silicon waveguide micro-ring optical switch, so that the Fermi level of graphene is changed, the effective refractive index of graphene-silicon waveguide is dynamically adjusted, the resonance state of the micro-ring is changed, the transmission path of the graphene-silicon waveguide micro-ring optical switch is changed, and finally the wavelength selective optical routing function is achieved. The invention has the advantages of simple structure, small insertion loss and good integration level.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated optics and the technical field of switches for realizing routing switching between multiple ports in an on-chip optical network system, and particularly relates to a 4x4 non-blocking optical router based on graphene-silicon waveguide. Background Art

[0002] On-chip (SoC) interconnect technologies can be categorized into two main systems, electrical interconnect (ENoC) and optical interconnect (ONoC), based on the transmission medium. Compared to traditional electrical interconnect networks, which inherently suffer from limited bandwidth, high transmission latency, and high power consumption, optical interconnect networks, with their terahertz-level bandwidth, sub-picosecond latency, and ultra-low power consumption, have become a key technology for breaking through the performance bottlenecks of SoCs. As the core control unit of optical interconnect networks, the structural design and performance optimization of optical routers have become a current research hotspot.

[0003] Modern optical router architectures are primarily based on two fundamental optical devices: microring resonators (MRRs) and Mach-Zehnder interferometers (MZIs). Existing MRR-based optical routers have evolved into two main approaches: the first is a passive router based on wavelength routing (such as a crossbar structure), where routing selection is determined by the wavelength of the optical signal provided at the input; the second is a switch-type router based on active microrings, which leverages the electro-optical effect of the microrings to achieve dynamic link reconfiguration. The essential difference between these two architectures lies in the fixed and reconfigurable nature of the optical path connection state, which directly determines their applicability in wavelength division multiplexing (WDM) systems.

[0004] The core challenge facing optical routers today lies in the conflict between device miniaturization and wavelength adaptability. Traditional solutions, limited by the thermo-optical control mechanism of silicon-based waveguides, suffer from common issues such as large device size and high insertion loss, limiting their application in portable device integration and broadband WDM systems. The introduction of graphene offers a breakthrough in this technological dilemma. This two-dimensional material's unique voltage-tunable Fermi level, combined with its atomically thin (0.34nm) and broadband response, offers an innovative solution for the development of high-density reconfigurable optical routers through heterogeneous integration with silicon waveguides. Summary of the Invention

[0005] This paper proposes a 4x4 non-blocking optical router based on graphene-silicon waveguides. By applying different voltages to the electrodes of each graphene-silicon waveguide micro-ring optical switch, the transmission path of the switches can be changed, thereby transmitting the optical signal from a specific input port to a specific output port. However, existing optical routers suffer from complex structures, high insertion loss, and poor integration.

[0006] To solve the above problems, the present invention is achieved through the following technical solutions:

[0007] A 4x4 non-blocking optical router based on graphene-silicon waveguide includes a SiO2 substrate and 12 graphene-silicon waveguide micro-ring optical switches. The 12 graphene-silicon waveguide micro-ring optical switches are interconnected to form a 4x4 matrix structure, thereby forming four input ports and four output ports. Each graphene-silicon waveguide microring optical switch is composed of straight waveguides (2-1, 2-4, 2-5, 2-7), a microring silicon waveguide (2-2), a cross-coupled waveguide (2-3) and a graphene modulation region (2-6), and the structural dimensions and performance parameters are consistent; a portion of the microring silicon waveguide (2-2) is integrated with a graphene modulation region (2-6), and the graphene layer (2-6-3) of the graphene modulation region (2-6) is stacked into a double-layer graphene by a mechanical exfoliation method and extends to the bottom of a metal electrode (2-6-5). By applying different voltages to the electrodes of the graphene-silicon waveguide microring optical switch, the Fermi level of the graphene is changed, the effective refractive index of the graphene-silicon waveguide is dynamically adjusted, and the resonant state of the microring is changed, thereby changing the transmission path of the graphene-silicon waveguide microring optical switch, and finally realizing a wavelength-selective optical routing function.

[0008] In the above scheme, the output ports (2-4, 2-5) of the graphene-silicon waveguide micro-ring optical switch (2) are connected to the input ports (2-1, 2-7) of the next graphene-silicon waveguide micro-ring optical switch to form a 4x4 matrix structure.

[0009] In the above scheme, self-communication is prohibited between the input / output ports of the optical router, and no graphene-silicon waveguide micro-ring optical switch (2) is set on the main diagonal of the 4x4 matrix structure.

[0010] In the above solution, the sizes and parameter performances of the 12 graphene-silicon waveguide micro-ring optical switches are consistent, but the switching states are not necessarily the same.

[0011] In the above scheme, by applying voltages of 0.84V and 3.96V to the electrodes of the graphene-silicon waveguide microring optical switch respectively, the transmission path of the graphene-silicon waveguide microring optical switch can be changed, thereby transmitting the optical signal of a certain input port to the specified output port.

[0012] In the above solution, the optical router is a non-blocking optical router, that is, any input port can be routed to any available output port without using the same physical path.

[0013] In the above solution, the optical router operates with a single wavelength or WDM multi-wavelength signal and can be expanded to a multi-port optical router structure.

[0014] In the above scheme, the router's 12 graphene-silicon waveguide micro-ring optical switches are all coated with SiO2 to form a protective structure.

[0015] Compared with the prior art, the present invention has the following characteristics:

[0016] 1. This paper independently designs a non-blocking optical router structure based on graphene-silicon waveguides. By combining multiple graphene-silicon waveguide micro-ring optical switches, it achieves non-blocking routing switching between four input and four output ports, solving the problems of conventional optical routers such as complex structure, high insertion loss, and poor integration.

[0017] 2. The present invention uses graphene-silicon waveguide micro-ring optical switch devices for cascading and selects materials with higher dielectric constants to construct the insulating layer, which achieves a breakthrough improvement in the equivalent refractive index tuning sensitivity and functional realization dimensions.

[0018] 3. The present invention realizes optical path switching by voltage regulation. The voltage regulation range is only 3.12V, which can effectively reduce the loss of optical switches and optical routers and improve the stability of optical path switching. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the three-dimensional structure of a 4x4 non-blocking optical router based on graphene-silicon waveguide;

[0020] Figure 2 A top-down schematic diagram of a 4x4 non-blocking optical router based on graphene-silicon waveguide;

[0021] Figure 3 Schematic diagram of the top view of the graphene-silicon waveguide micro-ring optical switch;

[0022] Figure 4 AA cross-section of the graphene modulation region;

[0023] Figure 5 is a graph showing the relationship between the chemical potential of graphene and the applied voltage;

[0024] Figure 6 The graphs are the relationship between the transmittance output at the straight waveguide (2-4) and the operating wavelength when the chemical potential of graphene in the graphene-silicon waveguide micro-ring optical switch is 0.55eV and 1.2eV respectively;

[0025] Figure 7 The graph shows the relationship between the transmittance output at the cross-coupled waveguide (2-3) and the operating wavelength when the graphene chemical potential of the graphene-silicon waveguide micro-ring optical switch is 0.55eV and 1.2eV respectively;

[0026] Figure 8This is a schematic diagram of the structure of a traditional cross-waveguide optical switch in the Cross state;

[0027] Figure 9 This is a schematic diagram of the structure of a traditional cross-waveguide optical switch in the Bar state;

[0028] Figure 10 The electric field distribution diagram of the graphene-silicon waveguide micro-ring optical switch when the graphene chemical potential is 0.55eV;

[0029] Figure 11 This is the electric field distribution diagram of the graphene-silicon waveguide microring optical switch when the graphene chemical potential is 1.2eV and no resonance occurs. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific examples.

[0031] A 4x4 non-blocking optical router based on graphene-silicon waveguide, such as Figure 1 and Figure 2 As shown, it is composed of a SiO2 substrate (1) and 12 graphene-silicon waveguide micro-ring optical switches (2); the output ports (2-4, 2-5) of the graphene-silicon waveguide micro-ring optical switch (2) are connected to the input ports (2-1, 2-7) of the next graphene-silicon waveguide micro-ring optical switch, thereby forming a 4x4 matrix structure of 4 input ports and 4 output ports. In this example, the optical router has a total of 14 crosspoints, which are numbered from M1 for the graphene-silicon waveguide micro-ring optical switches (2) from left to right; since self-communication is prohibited between the input / output ports of the router, the 4 graphene-silicon waveguide micro-ring optical switches on the main diagonal are removed.

[0032] like Figure 3 As shown, the graphene-silicon waveguide micro-ring optical switch (2) is composed of straight waveguides (2-1, 2-4, 2-5, 2-7), micro-ring silicon waveguides (2-2), cross-coupled waveguides (2-3) and graphene modulation regions (2-6). In this example, the straight waveguides (2-1, 2-4, 2-5, 2-7) and the micro-ring silicon waveguides (2-2) all adopt strip waveguide structures, with the heights of the straight waveguides (2-1, 2-4, 2-5, 2-7) and the widths of the micro-ring silicon waveguides (2-2) all being 220 nm and 450 nm, respectively; the height of the cross-coupled waveguides (2-3) being 220 nm and the total length being 200 nm, respectively; the coupling spacing between the micro-ring silicon waveguides (2-2) and the straight waveguides (2-1, 2-5) being 100 nm, the radius of the micro-ring silicon waveguides (2-2) being 6.2 μm, and the coverage of the graphene modulation region (2-6) being defined by the arc length corresponding to the micro-ring circle (the arc length formula is ); the graphene modulation area is set to an arc length of 6.2πμm corresponding to a central angle of 180° of the microring, the inner and outer diameters of the modulation area are consistent with those of the microring silicon waveguide, and its position is set near the maximum electromagnetic field intensity of the microring cross section.

[0033] Figure 4 The figure shows the AA cross-section of the graphene modulation region (2-6), which is arranged from bottom to top as follows: SiO2 substrate layer (1), silicon waveguide layer (2-6-1), insulating upper layer (2-6-2), graphene layer (2-6-3), insulating lower layer (2-6-2), silicon waveguide layer (2-6-1) and SiO2 cladding; the thickness of the SiO2 substrate (1) is set to 3μm. The graphene layers are stacked into a double-layer 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 on top of the micro-ring silicon waveguide, and then graphene is placed on top of the HfO2 by mechanical exfoliation. Subsequently, a layer of HfO2 material is deposited to form a voltage control region. The metal electrode material (2-6-4) is Au material, and a metal electrode Pd material (2-6-5) is provided under 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 capacitor structure.

[0034] like Figure 5 As shown in the figure, this is a graph showing the relationship between the chemical potential of graphene and the applied voltage; using the formula Calculate the graphene chemical potential (μ c ) and applied voltage (V), set the height of the insulating layer (HfO2) to 5nm, set ε r The relative dielectric constant of the insulating layer (HfO2) is 20; V0 is the offset voltage generated by natural doping and is set to 0V; the Fermi velocity ν F Set to 1.1×10 6 m / s. As can be seen from the figure, as the applied voltage increases, the chemical potential of graphene increases accordingly. Therefore, the chemical potential of graphene can be controlled by adjusting the voltage.

[0035] Figure 6 and Figure 7The graphs show the variation of transmittance of the through output section (2-4) and the cross output section (2-5) of the graphene-silicon waveguide microring optical switch (2) with wavelength at different chemical potentials at a wavelength of 1550nm and in TE mode. In this example, when the graphene chemical potential is set to 0.55eV, the microring resonates at 1555.25nm; when the graphene chemical potential is set to 1.2eV, the microring resonates at 1551.86nm; as the graphene chemical potential increases, the resonance curve exhibits a blue shift. Therefore, when an optical signal is input from the input section (2-1), voltages of 0.84V and 3.96V can be applied to the graphene modulation region through electrodes, respectively, to shift the resonant wavelength of the microring, thereby changing the transmission direction of the optical switch and achieving an optical routing function.

[0036] Figure 8 and Figure 9 The following are structural diagrams of the 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 resonant wavelength of the microring, the optical signal enters the drop direction through the microring resonance. When the wavelength of the input optical signal is different from the resonant wavelength of the microring, the optical signal is directly output in the through direction.

[0037] Figure 10 and Figure 11 The electric field distribution diagrams are respectively when the graphene chemical potential is 0.55eV and 1.2eV, and the light wavelength is set to 1555.25nm. At 0.55eV, the light signal resonates and is output from the cross output section (5); at 1.2eV, the light signal does not resonate and is output from the straight output section (4);

[0038] Combine Figure 2 、 Figure 10 and Figure 11 , the switching state when the graphene chemical potential is 0.55eV is set to the Cross state, and the switching state when the chemical potential is 1.2eV is set to the Bar state. In this example, all micro-ring silicon waveguides are initialized to the Bar state, thereby obtaining the corresponding relationship between the optical router communication line and the micro-ring silicon waveguide Cross state, as shown in Table 1 below:

[0039]

[0040] Table 1 shows the correspondence between the optical router communication line and the cross state of the micro-ring silicon waveguide.

[0041] In summary, this paper proposes a 4×4 non-blocking optical router based on graphene-silicon waveguides. This router consists of 12 graphene-silicon waveguide micro-ring optical switches arranged in a matrix within the router, enabling optical signal exchange between four input ports and four output ports. The switches are numbered sequentially from M1 and have uniform structural dimensions and performance parameters, but their operating states can be switched between Cross and Bar modes as needed. By dynamically regulating the switch states with voltage, parallel transmission and multiplexing of multi-channel links are achieved, preventing inter-channel interference and significantly improving switch utilization and the overall transmission rate of the router.

[0042] It should be noted that although the embodiments of the present invention described above are illustrative, they are not intended to limit the present invention. Therefore, the present invention is not limited to the above-mentioned specific embodiments. Without departing from the principles of the present invention, any other embodiments obtained by those skilled in the art under the guidance of the present invention are deemed to be within the protection of the present invention.

Claims

1. A 4x4 non-blocking optical router based on graphene-silicon waveguide, characterized by: The invention comprises a SiO2 substrate and 12 graphene-silicon waveguide micro-ring optical switches; the 12 graphene-silicon waveguide micro-ring optical switches are interconnected to form a 4x4 matrix structure, thereby forming 4 input ports and 4 output ports. Each graphene-silicon waveguide microring optical switch is composed of straight waveguides (2-1, 2-4, 2-5, 2-7), a microring silicon waveguide (2-2), a cross-coupled waveguide (2-3) and a graphene modulation region (2-6), and the structural dimensions and performance parameters are consistent; a portion of the microring silicon waveguide (2-2) is integrated with a graphene modulation region (2-6), and the graphene layer (2-6-3) of the graphene modulation region (2-6) is stacked into a double-layer graphene by a mechanical exfoliation method and extends to the bottom of a metal electrode (2-6-5). By applying different voltages to the electrodes of the graphene-silicon waveguide microring optical switch, the Fermi level of the graphene is changed, the effective refractive index of the graphene-silicon waveguide is dynamically adjusted, and the resonant state of the microring is changed, thereby changing the transmission path of the graphene-silicon waveguide microring optical switch, and finally realizing a wavelength-selective optical routing function.

2. The 4x4 non-blocking optical router based on graphene-silicon waveguide according to claim 1, characterized in that: The output ports (2-4, 2-5) of the graphene-silicon waveguide micro-ring optical switch (2) are connected to the input ports (2-1, 2-7) of the next graphene-silicon waveguide micro-ring optical switch to form a 4x4 matrix structure.

3. The 4x4 non-blocking optical router based on graphene-silicon waveguide according to claim 1, characterized in that: Self-communication is prohibited between the input / output ports of the router, and no graphene-silicon waveguide micro-ring optical switch (2) is set on the main diagonal of the 4x4 matrix structure.

4. The 4x4 non-blocking optical router based on graphene-silicon waveguide according to claim 1, characterized in that: The sizes and parameter performances of the 12 graphene-silicon waveguide micro-ring optical switches are consistent, but the switching states are not necessarily the same.

5. The 4x4 non-blocking optical router based on graphene-silicon waveguide according to claim 1, characterized in that: By applying voltages of 0.84V and 3.96V to the electrodes of the graphene-silicon waveguide microring optical switch respectively, the transmission path of the graphene-silicon waveguide microring optical switch can be changed, thereby transmitting the optical signal of a certain input port to the specified output port.

6. The 4x4 non-blocking optical router based on graphene-silicon waveguide according to claim 1, characterized in that: The router is a non-blocking optical router, that is, any input port can be routed to any available output port without using the same physical path.

7. The 4x4 non-blocking optical router based on graphene-silicon waveguide according to claim 1, characterized in that: The router works with single wavelength or WDM multi-wavelength signals and can be expanded to a multi-port optical router structure.

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