An optoelectronic logic gate device based on d-shaped fiber graphene integrated components

Abstract

The present application belongs to the field of optoelectronic computing, and provides an optoelectronic logic gate device based on a D-shaped optical fiber graphene integrated element, to solve the defects of traditional electrical logic gate heating and bandwidth limitation, slow response of optical logic gate, and also to solve the problems of low speed and wavelength limitation of traditional laser scanning based on phase matching condition to realize graphene surface plasmon nonlinear generation. The present application first designs a graphene surface plasmon excitation element based on a D-shaped optical fiber, then designs a closed light path, so that the pump light and the probe light are incident on the element at the same time, and the graphene surface plasmon is excited through the difference frequency generation effect; on this basis, the gate voltage is taken as the logic input, and a plurality of different frequency graphene surface plasmon peaks are generated through the gate voltage control; finally, the transmission wavelengths of the three optical fiber bandpass filters are matched and designed, the graphene surface plasmon peaks are selectively filtered out, and the logic output is realized.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic computing, and relates to two-dimensional material optoelectronics and micro-nano fabrication technology. Specifically, it provides an optoelectronic logic gate device based on D-shaped fiber graphene integrated elements. Background Technology

[0002] Photonics technology offers a perfect solution to the bandwidth limitations of computers and avoids photo-to-electric conversion, significantly improving energy efficiency. Therefore, it is widely considered to have significant application potential in ultrafast data transmission and processing. In recent years, the development of optical computing has driven tremendous progress in high-speed modulation and demodulation, photoelectric convolution, machine learning, and quantum computing. Logic gates are the fundamental units of various complex computing systems; therefore, the development of optical logic gates is crucial for the development of optical computing systems. There are precedents of successfully implementing optical logic operations on chips using linear interference in microrings or microcouplers. However, due to the diffraction limit's size limitations, these optoelectronic devices are difficult to integrate at the nanometer scale, making it difficult for optical computing systems to achieve the high integration of VLSI electronic circuits. Furthermore, the development of optical logic gates also needs to consider manufacturing processes, manufacturing costs, response speed, relaxation speed, repeatability, and ease of integration into mainstream electrical systems. Given these factors, a suitable solution has yet to be found.

[0003] Since British scientists A.K. Geim and K.S. Novoselov obtained few-layer and even monolayer graphene using micromechanical exfoliation in 2004, graphene has received widespread attention and driven the development of multiple disciplines. Graphene is a semi-metallic two-dimensional material with many excellent optoelectronic properties, such as high refractive index, strong nonlinearity, high carrier mobility, and high-efficiency optoelectronic tunability. In recent years, the maturity of graphene preparation, assembly, and transfer processes has provided an opportunity for the integration of graphene with optical fibers. Unlike surface plasmons in metals, graphene surface plasmons have longer lifetimes and stronger field confinement capabilities. More importantly, the Fermi level of graphene can be controlled through electrical, thermal, and doping methods, which gives graphene surface plasmons a crucial characteristic distinct from metal surface plasmons: electrical tunability, a property vital for dynamic information processing. Simultaneously, the two-dimensional nature of graphene facilitates the miniaturization and integration of devices. Therefore, graphene devices have significant application value in the field of highly integrated optoelectronic devices.

[0004] However, existing graphene plasmon excitation requires a large supporting system, and the response speed is difficult to meet the needs of logic operations. Specifically, the traditional method of achieving nonlinear generation of plasmons on the graphene surface based on laser scanning to meet the phase matching condition has the disadvantages of slow speed, large wavelength limitation, and difficulty in achieving photoplasmon phase matching quickly and accurately, which is insufficient to meet the actual needs of ultrafast logic operations. Summary of the Invention

[0005] The purpose of this invention is to provide an optoelectronic logic gate device based on D-shaped fiber graphene integrated elements, which solves the defects of traditional electrical logic gates such as heat generation and bandwidth limitations, and optical logic gates such as slow response. It also addresses the problems of low speed and large wavelength limitations in traditional methods of achieving nonlinear generation of plasmon resonances on the graphene surface based on laser scanning to meet phase-matching conditions. Compared with existing optoelectronic logic gates, this invention has the advantage of fast response speed and also possesses hyper-integration potential, providing a new approach for large-scale integrated optical computing systems and an implementation scheme for the design of optoelectronic computing systems based on graphene surface plasmon resonances.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A photoelectric logic gate device based on a D-shaped fiber graphene integrated element includes: an optical frequency comb laser 7, a 1×2 type single-mode fiber coupler 8, a first single-mode fiber attenuator 9, a first single-mode fiber polarization controller 10, a first single-mode fiber circulator 11, an erbium-doped fiber amplifier (EDFA) 12, a fiber delay line 13, a second single-mode fiber attenuator 14, a second single-mode fiber polarization controller 15, a second single-mode fiber circulator 16, a D-shaped fiber graphene integrated element 17, a first voltage regulator 18, a second voltage regulator 19, a third voltage regulator 20, a first fiber bandpass filter 21, a second fiber bandpass filter 22, a third fiber bandpass filter 23, a spectrometer 24, and a 1×3 type single-mode fiber coupler 25.

[0008] The optical frequency comb laser 7 emits an optical frequency comb laser as a light source. This light source is input to a 1×2 type single-mode fiber coupler 8, where it is split into two, outputting from the first and second output ports of the coupler respectively. The light output from the second output port of the 1×2 type single-mode coupler serves as pump light. This pump light passes sequentially through a first single-mode fiber attenuator 9, a first single-mode fiber polarization controller 10, and a first single-mode fiber circulator 11 before being input to one end of a D-shaped fiber graphene integrated element 17. The first output port of the 1×2 type single-mode coupler is connected to an erbium-doped fiber amplifier (EDFA) 12. The EDFA outputs a supercontinuum laser as probe light, which is then transmitted through an optical fiber... After passing through the fiber delay line 13, the light sequentially passes through the second single-mode fiber attenuator 14, the second single-mode fiber polarization controller 15, and the second single-mode fiber loop 16 before being input to the other end of the D-shaped fiber graphene integrated element 17. The pump light passes through the D-shaped fiber graphene integrated element 17 and is output to the spectrometer 24 via the second single-mode fiber circulator. The probe light passes through the D-shaped fiber graphene integrated element 17 and is output to the 1×3 type single-mode fiber coupler 25 via the first single-mode fiber circulator. The 1×3 type single-mode fiber coupler 25 splits the light into three parts, which are then output to the spectrometer 24 after passing through the first fiber bandpass filter 21, the second fiber bandpass filter 22, and the third fiber bandpass filter 23, respectively.

[0009] The first voltage regulator provides source-drain voltage for the D-shaped fiber graphene integrated element 17, and the second and third voltage regulators are connected in series to provide gate voltage for the D-shaped fiber graphene integrated element 17.

[0010] Furthermore, the D-shaped fiber graphene integrated element comprises a D-shaped fiber 1 and a graphene film 2, a source electrode 3, a drain electrode 4, a gate electrode 5, and a dielectric film 6 disposed on the polished surface of the D-shaped fiber. The graphene film covers the polished surface of the D-shaped fiber and is located at the center of the polished surface. The source electrode and the drain electrode are disposed on the graphene film and are respectively located on both sides of the region above the core of the D-shaped fiber. The source electrode, the graphene film, and the drain electrode together form an electrode-graphene-electrode heterojunction. The dielectric film covers the electrode-graphene-electrode heterojunction. The gate electrode is disposed on the dielectric film and is located in the region above the core of the D-shaped fiber.

[0011] Furthermore, the D-shaped optical fiber is prepared by polishing a standard single-mode optical fiber. The standard single-mode optical fiber has a cladding diameter of 125μm, a core diameter of 8μm to 10μm, a polishing depth of 53μm to 57.5μm, and a polishing length of 7 to 15mm. The insertion loss of the D-shaped optical fiber is <1dB.

[0012] Furthermore, the graphene film has a length of 200-500 μm and a width of 125 μm, the source, drain and gate electrodes each have a thickness of 30-50 nm, and the dielectric film has a thickness of 20-50 nm.

[0013] Furthermore, the positive and negative terminals of the first voltage regulator are connected to the source and drain of the D-shaped fiber graphene integrated element via probes, respectively, while the negative terminal of the first voltage regulator is grounded; the positive terminals of the second and third voltage regulators are connected in series and then connected to the gate of the D-shaped fiber graphene integrated element via probes, while the negative terminal is grounded.

[0014] Furthermore, the optical frequency comb laser emits an optical frequency comb laser with a center wavelength of 1560nm, a repetition rate of 38.7MHz, and a pulse width of 400fs, and the average output power of the optical frequency comb laser is greater than or equal to 1mW; the wavelength range of the probe light is 1500nm~2100nm, the repetition rate is 38.7MHz, and the pulse width is 100fs; the transmission wavelengths of the first fiber bandpass filter, the second fiber bandpass filter, and the third fiber bandpass filter are 1610nm~1630nm, 1790nm~1830nm, and 1910nm~1930nm, respectively.

[0015] Furthermore, the single-mode fiber polarization controller controls the pump light and probe light to be TM light.

[0016] Furthermore, the optical fiber delay line adjusts the optical path of the probe light so that the pump light and the probe light simultaneously reach the position of the D-shaped fiber graphene integrated element 17 and excite the plasmons on the graphene surface.

[0017] Furthermore, the operation process of the aforementioned optoelectronic logic gate device is as follows:

[0018] Set the first voltage regulator's output source drain voltage to 0.1V, and set the second and third voltage regulators' independent output gate voltages to 0V or 1V respectively;

[0019] If we define logic input 0 when the output gate voltage of the second or third voltage source is 0V and logic input 01 when the output gate voltage is 1V, then we get logic inputs (0,0), (0,1), (1,0), and (1,1) in sequence.

[0020] Define the first, second, or third fiber bandpass filter as having a logic output of 0 when there is no graphene surface plasmon peak in its output signal, and a logic output of 1 when there is a graphene surface plasmon peak. Then: the output of the first fiber bandpass filter is 1, 0, 0, 0 in sequence, implementing the "NOT" gate logic; the output of the second fiber bandpass filter is 0, 1, 1, 0 in sequence, implementing the "OR" gate logic; and the output of the third fiber bandpass filter is 0, 0, 0, 1 in sequence, implementing the "AND" gate logic.

[0021] In terms of working principle:

[0022] In this invention, a frequency comb laser with a center wavelength of 1560 nm is used as the pump light, and a supercontinuum frequency comb pulse covering wavelengths from 1500 nm to 2100 nm is used as the probe light. Both the pump and probe light have a repetition rate of 38.7 MHz. Two single-mode fiber polarization controllers are adjusted to minimize the output of both the pump and probe light. The pump and signal light are incident on a D-shaped fiber from opposite directions, scanning the fiber delay line so that the pump and probe light pulses reach the graphene simultaneously. At this point, the pump and probe light satisfy the energy-momentum matching condition, exciting plasmons on the graphene surface through the difference frequency generation (DFG) effect. Analysis of the spectrum and intensity of the emitted probe light reveals the enhanced probe light signal resulting from the plasmon generation on the graphene surface. Using the energy-momentum relationship equation during the DFG process, the intensity and frequency of the plasmons on the graphene surface can be inferred from the enhancement peak of the probe light.

[0023] According to the Drude model, the frequency f of plasmons on the graphene surface is... sp The graphene dispersion is determined by its Fermi level, and therefore the frequency of graphene surface plasmons is closely related to the graphene carrier concentration. Graphene surface plasmons integrated into a D-shaped optical fiber will couple with the silicon dioxide substrate at appropriate frequencies (i.e., graphene carrier concentrations), causing the graphene surface plasmon dispersion curve to split and generating more than one energy-momentum matching condition. At the same time, since the probe wavelength covers a very wide range of 1500nm to 2100nm, multiple energy-momentum matching conditions can be satisfied simultaneously. Therefore, multiple graphene surface plasmons of different frequencies can be generated simultaneously in one device.

[0024] Furthermore, logic gates can be implemented through gate modulation. By fixing the source-drain voltage of the first regulated source at 0.1V and changing the gate voltage (0V, 1V, 2V), the carrier concentration of graphene can be controlled, thereby controlling the Fermi level. Generally, the higher the carrier concentration, the higher the frequency f of the plasmons on the graphene surface. sp The higher the level, the lower the Fermi level of graphene; when the Fermi level of graphene is very low: the plasmon frequency f on the graphene surface. sp The frequency is too low, and the difference between the frequency and the phonon frequency of silica (optical fiber) is too large, so plasmon-silica phonon coupling does not occur on the graphene surface, resulting in only one phase-matching case and only one enhancement peak in the probe light; gradually increasing the Fermi level of graphene, f spAs the energy level gradually increases, the plasmon energy on the graphene surface resonates and couples with the phonons of 24 THz silica, causing the dispersion curve to split into two beams. This results in both phase-matching conditions being met simultaneously, leading to two enhancement peaks in the probe light energy. Further increasing the Fermi level results in a similar situation: the plasmon energy on the graphene surface resonates and couples with the phonons of 24 THz and 35 THz silica, causing the dispersion curve to split into three beams, ultimately resulting in the observation of three enhancement peaks. Two regulated power sources are connected in series as gate inputs. Defining a regulated power source output of 0V as 0 and a regulated power source output of 1V as 1, three gate voltages can be provided: (0,0): low potential 0V, (0,1) or (1,0): medium potential 1V, and (1,1): high potential 2V, corresponding to one, two, and three graphene surface plasmon peaks, respectively. By matching the transmission wavelengths of three fiber bandpass filters (BPF1-BPF3), the wavelength of the probe light enhancement peak is selectively filtered out. It is defined that no graphene surface plasmon peaks are present after passing through the bandpass fiber bandpass filters. The peak is 0, and the plasmon peak on the graphene surface is 1, so when the input is (0,0), BPF1 outputs 1 and all other output signals output 0; when the input is (0,1) or (1,0), the wavelength of the first plasmon peak on the graphene surface is no longer within the wavelength range of BPF1 due to frequency modulation, so BPF1 outputs 0, BPF2 outputs 1, and BPF3 outputs 0; similarly, when the input is (1,1), BPF3 outputs 1 and all other input signals output 0; thus, BPF1 can be used as a NOT gate, BPF2 can be used as an OR gate, and BPF3 can be used as an AND gate.

[0025] In summary, the beneficial effects of the present invention are as follows:

[0026] This invention provides an optoelectronic logic gate device based on a D-shaped fiber graphene integrated element. First, a D-shaped fiber graphene integrated element is designed as a graphene surface plasmon excitation element. Then, a closed optical path is designed so that pump light and probe light are simultaneously incident on the D-shaped fiber graphene integrated element. The probe light is set to a supercontinuum light with a wavelength covering 1500–2100 nm, ensuring that the pump light and probe light satisfy the phase matching condition. At this point, the D-shaped fiber graphene integrated element excites graphene surface plasmons through difference frequency generation (DFG) effect. Based on this, by controlling the gate voltage to change the Fermi level of graphene and the frequency of graphene surface plasmons, the graphene surface plasmons are coupled with silicon dioxide phonons, generating multiple graphene surface plasmon peaks of different frequencies. Finally, by matching the transmission wavelengths of three fiber bandpass filters (BPF1-BPF3), the graphene surface plasmon peaks (probe light enhancement peaks) are selectively filtered out to achieve logic operation. Specifically: the gate voltage is defined as the input of the optoelectronic logic gate, namely (0,0): low potential 0V, (0,1) or (1,0): medium potential 1V, (1,1): high potential 2V; the output of the fiber bandpass filter is defined as the output of the optoelectronic logic gate, namely 0 for the plasmon peak without graphene surface and 1 for the plasmon peak with graphene surface; when the inputs are set to (0,0), (0,1), (1,0), (1,1) in sequence, the output of the first fiber bandpass filter is 1, 0, 0, 0 in sequence, that is, the "NOT" gate logic is implemented; the output of the second fiber bandpass filter is 0, 1, 1, 0 in sequence, that is, the "OR" gate logic is implemented; the output of the third fiber bandpass filter is 0, 0, 0, 1 in sequence, that is, the "AND" gate logic is implemented. In addition, the response speed of the optoelectronic logic gate device in this invention is about 500fs, and it is integrated on an all-fiber platform, providing a new approach for optical logic gates and optical computing. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the D-shaped fiber graphene integrated element in this invention;

[0028] Figure 2 This is a schematic diagram of the optoelectronic logic gate device based on D-shaped fiber graphene integrated elements in this invention.

[0029] Figure 3 The diagram shows the output signals of the "AND", "OR", and "NOT" logic gates in the optoelectronic logic gate device based on D-shaped fiber graphene integrated elements according to an embodiment of the present invention.

[0030] In the above figures, 1 is a D-shaped optical fiber, 2 is a graphene film, 3 is the source electrode, 4 is the drain electrode, 5 is the gate electrode, 6 is an alumina dielectric film, 7 is an optical frequency comb laser, 8 is a 1×2 type single-mode fiber coupler, 9 is a first single-mode fiber attenuator, 10 is a first single-mode fiber polarization controller, 11 is a first single-mode fiber circulator, 12 is an erbium-doped fiber amplifier (EDFA), 13 is a fiber delay line, 14 is a second single-mode fiber attenuator, 15 is a second single-mode fiber polarization controller, 16 is a second single-mode fiber circulator, 17 is a D-shaped fiber graphene integrated element, 18 is a first voltage regulator, 19 is a second voltage regulator, 20 is a third voltage regulator, 21 is a first fiber bandpass filter, 22 is a second fiber bandpass filter, 23 is a third fiber bandpass filter, 24 is a spectrometer, and 25 is a 1×3 type single-mode fiber coupler. Detailed Implementation

[0031] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0032] This embodiment provides an optoelectronic logic gate device based on D-shaped fiber graphene integrated elements, the structure of which is as follows: Figure 2 As shown, the specific components include: an optical frequency comb laser 7, a 1×2 type single-mode fiber coupler 8, a first single-mode fiber attenuator 9, a first single-mode fiber polarization controller 10, a first single-mode fiber circulator 11, an erbium-doped fiber amplifier (EDFA) 12, a fiber delay line 13, a second single-mode fiber attenuator 14, a second single-mode fiber polarization controller 15, a second single-mode fiber circulator 16, a D-shaped fiber graphene integrated element 17, a first voltage regulator 18, a second voltage regulator 19, a third voltage regulator 20, a first fiber bandpass filter 21, a second fiber bandpass filter 22, a third fiber bandpass filter 23, a spectrometer 24, and a 1×3 type single-mode fiber coupler 25; wherein, the structure of the D-shaped fiber graphene integrated element is as follows. Figure 1 As shown, it consists of a D-shaped optical fiber 1, a graphene film 2, a source electrode 3, a drain electrode 4, a gate electrode 5, and an aluminum oxide dielectric film layer 6.

[0033] Furthermore, the D-shaped fiber graphene integrated element 17, as... Figure 1As shown, the structure comprises a D-shaped optical fiber 1 and a graphene film 2, a source electrode 3, a drain electrode 4, a gate electrode 5, and an alumina dielectric film 6 disposed on the polished surface of the D-shaped optical fiber. The D-shaped optical fiber 1 is fabricated by polishing a single-mode optical fiber. The graphene film 2 covers the polished surface of the D-shaped optical fiber and is located at the center of the polished surface. The source electrode 3 and the drain electrode 4 are disposed on the graphene film 2 and are located on both sides of the region above the core of the D-shaped optical fiber, respectively. The source electrode, the graphene film, and the drain electrode together form an electrode-graphene-electrode heterojunction. The alumina dielectric film 6 covers... The gate 5 is disposed on an alumina dielectric film and located above the core of a D-shaped optical fiber, covering an electrode-graphene-electrode heterojunction. The standard single-mode optical fiber has a cladding diameter of 125 μm, a core diameter of 8 μm to 10 μm, a polishing depth of 53 μm to 57.5 μm, and a polishing length of 7 to 15 mm. The insertion loss of the D-shaped optical fiber is <1 dB. The graphene film has a length of 200 to 500 μm and a width of 125 μm. The thickness of the source, drain, and gate is 30 to 50 nm. The thickness of the alumina dielectric film is 20 to 50 nm.

[0034] Furthermore, the optical frequency comb laser 7 emits an optical frequency comb laser with a center wavelength of 1560nm, a repetition rate of 38.7MHz, and a pulse width of 400s as a light source. This light source is input to a 1×2 type single-mode fiber coupler 8, where it is split into two, outputting from the first and second output ports of the coupler respectively. The power ratio between the first and second output ports of the 1×2 type single-mode fiber coupler is 1:9. The light output from the second output port of the 1×2 type single-mode coupler serves as the pump light, which sequentially passes through the first single-mode fiber coupler... The fiber optic attenuator 9, the first single-mode fiber polarization controller 10, and the first single-mode fiber circulator 11 are input to one end of the D-shaped fiber graphene integrated element 17 (the D-shaped fiber end); the first output port of the 1×2 type single-mode coupler is connected to the erbium-doped fiber amplifier (EDFA) 12. The EDFA outputs supercontinuum laser as the probe light. The probe light is connected to the fiber delay line 13. The optical path length of the fiber delay line can be changed by adjusting the optical path length. After passing through the fiber delay line, the probe light passes sequentially through the second single-mode fiber attenuator 14 and the second single-mode fiber polarization controller 15. The second single-mode fiber loop 16 is then input to the other end of the D-shaped fiber-graphene integrated element 17 (the other end of the D-shaped fiber); the system optical path forms a closed loop, with the pump light input to the first port of the first single-mode fiber circulator 11, then through the second port of the first single-mode fiber circulator 11 to one end of the D-shaped fiber-graphene integrated element 17, then through the D-shaped fiber-graphene integrated element 17 to the second port of the second single-mode fiber circulator, and finally through the third port of the second single-mode fiber circulator to the spectrometer 24; similarly, the probe light is input to the second single-mode fiber loop 16. The first port of the circulator 16 is connected to the other end of the D-shaped fiber graphene integrated element 17 via the second port of the second single-mode fiber circulator 16. After passing through the D-shaped fiber graphene integrated element 17, it is connected to the second port of the first single-mode fiber circulator 11 and output to the 1×3 type single-mode fiber coupler 25 via the third port of the second single-mode fiber circulator 11. The 1×3 type single-mode fiber coupler 25 splits the fiber into three parts, which are then output to the spectrometer 24 after passing through the first fiber bandpass filter 21, the second fiber bandpass filter 22, and the third fiber bandpass filter 23, respectively.

[0035] The wavelength range of the probe light is 1500nm to 2100nm; the transmission wavelengths of the first fiber bandpass filter 21, the second fiber bandpass filter 22, and the third fiber bandpass filter 23 are 1610nm to 1630nm, 1790nm to 1830nm, and 1910nm to 1930nm, respectively; the single-mode fiber attenuator reduces the optical power by changing the optical loss, and can attenuate the optical power to a level that is indistinguishable by the spectrometer (below -100dBm); the single-mode fiber polarization controller is used to change the polarization state of the propagated light in the fiber, so that both the pump light and the probe light are TM light, specifically manifested as the D-shaped fiber graphene integrated element 17 absorbing the two beams of light most strongly, i.e., having the highest loss; the adjustment range of the fiber delay line 13 is 0 to 2ns, and the fiber delay line is scanned until the probe light spectrum shows an enhancement peak. At this time, the pump light and the probe light simultaneously reach the position of the D-shaped fiber graphene integrated element 17 and successfully excite the plasmons on the graphene surface through the DFG.

[0036] Furthermore, the positive and negative terminals of the first voltage regulator 18 are connected to the source and drain of the D-shaped fiber-optic graphene integrated element 17 via probes, respectively, while the negative terminal of the first voltage regulator 18 is grounded; the positive terminals of the second voltage regulator 19 and the third voltage regulator 20 are connected in series and connected to the gate of the D-shaped fiber-optic graphene integrated element 17 via probes, while the negative terminal is grounded; the first voltage regulator provides the source-drain voltage V. sd The second and third voltage regulators together provide the gate voltage V. g Each of the three voltage regulators can independently provide a stable voltage output of 0V-20V.

[0037] In this embodiment, the source-drain voltage V of the first regulated power source is fixed. sd The voltage is 0.1V; the second and third voltage sources are set to independently output 0V or 1V voltage, and the second and third voltage sources are connected in series to output three gate voltages V. g 0V, 1V, 2V correspond to the Fermi level of graphene |E f | is 0.1eV, 0.4eV or 0.7eV.

[0038] Based on the above structure, in this embodiment, when the optoelectronic logic gate device performs logic operations, the second voltage source and the third voltage source respectively output voltage V. A V B The specific details are as follows:

[0039] The probe light passes through three fiber bandpass filters. If an enhancement peak can be detected after the fiber bandpass filter, the output of the fiber bandpass filter is recorded as 1. If no enhancement peak is detected, the output of the fiber bandpass filter is recorded as 0.

[0040] In V A V B When both are 0V, |Ef |=0.1eV, at this time, since the plasmon frequency on the graphene surface is much lower than the phonon frequency of silicon dioxide, it cannot be significantly coupled with the silicon dioxide phonon, and there is only one plasmon peak on the graphene surface. The output of BPF1 (first fiber bandpass filter) is 1, and the rest of the outputs are 0.

[0041] In V A V B When one is 1V and the other is 0V, |E f |=0.4eV. At this time, due to the coupling between the plasmons on the graphene surface and the phonons of 24THz silicon dioxide, there are two plasmon peaks on the graphene surface. Considering the frequency modulation of the first plasmon peak on the graphene surface by the voltage, by matching the transmission wavelengths of the three fiber bandpass filters, the output of BPF2 (the second fiber bandpass filter) is 1, and the outputs of BPF1 and BPF3 (the third fiber bandpass filters) are 0.

[0042] In V A V B When both are 1V, |E f |=0.7eV. At this time, due to the coupling between the plasmons on the graphene surface and the phonons of 24THz and 35THz silicon dioxide, there are three plasmon peaks on the graphene surface. By matching the transmission wavelengths of the three fiber bandpass filters, the outputs of BPF2 and BPF3 are 1 and the output of BPF1 is 0.

[0043] Therefore, BPF3 can be used as an AND gate, BPF2 as an OR gate, and BPF1 as a NOT gate to implement logical operations.

[0044] like Figure 3 The output signal is shown for various input voltage conditions, where, Figure 3 The upper middle figure shows the voltage signal V input to the second regulated power source. A and the voltage signal V from the third regulated power supply B , Figure 3 The lower figure shows the changes in the output optical signal intensity of three fiber bandpass filters. The figure shows that the present invention has successfully implemented the three logic gates: AND, OR, and NOT.

[0045] In summary, the main principle of graphene surface plasmon excitation in this invention is the transfer of pump energy to low-frequency light and graphene surface plasmons. Reverse pumping technology is employed to achieve phase matching. Precise responses of the graphene surface plasmons are obtained by measuring precise changes in the optical signal, enabling the detection and capture / extraction of small signals from the graphene surface plasmons. By adjusting the gate voltage at 0V, 1V, and 2V, the graphite carrier concentration and Fermi level are altered, thereby changing the graphene surface plasmon dispersion and ultimately affecting the graphene surface plasmon frequency. Different graphene surface plasmon-silica phonon coupling conditions occur at different graphene surface plasmon frequencies, resulting in varying numbers of graphene surface plasmon peaks. A fiber optic bandpass filter of a specific wavelength is used at the signal output end to achieve signal filtering and output. Therefore, this invention excites plasmons on the graphene surface by reverse-incidence of pump light and probe light, and achieves simultaneous excitation of up to three graphene surface plasmons by adjusting the gate voltage. A fiber bandpass filter is matched to realize a logic gate. The optoelectronic logic gate device in this invention has a response speed of about 500 fs and is integrated on an all-fiber platform, providing a new approach for optical logic gates and optical computing.

[0046] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A photoelectric logic gate device based on D-shaped fiber graphene integrated elements, comprising: Optical frequency comb laser (7), 1×2 type single-mode fiber coupler (8), first single-mode fiber attenuator (9), first single-mode fiber polarization controller (10), first single-mode fiber circulator (11), erbium-doped fiber amplifier (12), fiber delay line (13), second single-mode fiber attenuator (14), second single-mode fiber polarization controller (15), second single-mode fiber circulator (16), D-shaped fiber graphene integrated element (17), first voltage regulator (18), second voltage regulator (19), third voltage regulator (20), first fiber bandpass filter (21), second fiber bandpass filter (22), third fiber bandpass filter (23), spectrometer (24), 1×3 type single-mode fiber coupler (25); The optical frequency comb laser (7) emits an optical frequency comb laser as a light source. The light source is input to a 1×2 type single-mode fiber coupler (8) and then splits into two, outputting from the first output interface and the second output port of the 1×2 type single-mode fiber coupler respectively. The output light from the second output port of the 1×2 type single-mode coupler is used as pump light. The pump light passes through the first single-mode fiber attenuator (9), the first single-mode fiber polarization controller (10), and the first single-mode fiber circulator (11) in sequence before being input to one end of the D-shaped fiber graphene integrated element (17). The first output port of the 1×2 type single-mode coupler is connected to an erbium-doped fiber amplifier (12). The erbium-doped fiber amplifier (12) outputs a supercontinuum laser as a probe light. The probe light passes through a fiber delay line (13). After passing through the second single-mode fiber attenuator (14), the second single-mode fiber polarization controller (15), and the second single-mode fiber circulator (16), the light is input to the other end of the D-shaped fiber graphene integrated element (17). The pump light passes through the D-shaped fiber graphene integrated element (17) and is output to the spectrometer (24) through the second single-mode fiber circulator. The probe light passes through the D-shaped fiber graphene integrated element (17) and is output to the 1×3 type single-mode fiber coupler (25) through the first single-mode fiber circulator. The 1×3 type single-mode fiber coupler (25) splits the light into three parts, which are then output to the spectrometer (24) after passing through the first fiber bandpass filter (21), the second fiber bandpass filter (22), and the third fiber bandpass filter (23). The first voltage regulator provides the source-drain voltage for the D-shaped fiber graphene integrated device (17), and the second and third voltage regulators are connected in series to provide the gate voltage for the D-shaped fiber graphene integrated device (17). The D-shaped fiber graphene integrated element consists of a D-shaped fiber (1) and a graphene film (2), a source (3), a drain (4), a gate (5), and a dielectric film (6) disposed on the polished surface of the D-shaped fiber. The graphene film covers the polished surface of the D-shaped fiber and is located at the center of the polished surface of the D-shaped fiber. The source and drain are disposed on the graphene film and are located on both sides of the area above the core of the D-shaped fiber. The source, the graphene film, and the drain together form an electrode-graphene-electrode heterojunction. The dielectric film covers the electrode-graphene-electrode heterojunction. The gate is disposed on the dielectric film and is located in the area above the core of the D-shaped fiber.

2. The optoelectronic logic gate device based on D-shaped fiber graphene integrated elements as described in claim 1, characterized in that, The D-shaped optical fiber is made by polishing a standard single-mode optical fiber. The standard single-mode optical fiber has a cladding diameter of 125μm, a core diameter of 8μm~10μm, a polishing depth of 53μm~57.5μm, and a polishing length of 7~15mm. The insertion loss of the D-shaped optical fiber is less than 1dB.

3. The optoelectronic logic gate device based on D-shaped fiber graphene integrated elements as described in claim 1, characterized in that, The graphene film has a length of 200-500 μm and a width of 125 μm, the source, drain and gate electrodes each have a thickness of 30-50 nm, and the dielectric film has a thickness of 20-50 nm.

4. The optoelectronic logic gate device based on D-shaped fiber graphene integrated elements as described in claim 1, characterized in that, The positive and negative terminals of the first voltage regulator are connected to the source and drain of the D-shaped fiber graphene integrated element through probes, respectively, while the negative terminal of the first voltage regulator is grounded; the positive terminals of the second and third voltage regulators are connected in series and then connected to the gate of the D-shaped fiber graphene integrated element through probes, while the negative terminal is grounded.

5. The optoelectronic logic gate device based on D-shaped fiber graphene integrated elements as described in claim 1, characterized in that, The optical frequency comb laser emits an optical frequency comb laser with a center wavelength of 1560nm, a repetition rate of 38.7MHz, and a pulse width of 400fs. The average output power of the optical frequency comb laser is greater than or equal to 1mW. The wavelength range of the probe light is 1500nm~2100nm, and the repetition rate is 38.7MHz. The transmission wavelengths of the first fiber bandpass filter, the second fiber bandpass filter, and the third fiber bandpass filter are 1610nm~1630nm, 1790nm~1830nm, and 1910nm~1930nm, respectively.

6. The optoelectronic logic gate device based on D-shaped fiber graphene integrated elements as described in claim 1, characterized in that, The single-mode fiber polarization controller controls the pump light and probe light to be TM light.

7. The optoelectronic logic gate device based on D-shaped fiber graphene integrated elements as described in claim 1, characterized in that, The fiber delay line adjusts the optical path of the probe light, so that the pump light and the probe light arrive at the location of the D-shaped fiber graphene integrated element at the same time and excite the plasmons on the graphene surface.

8. The optoelectronic logic gate device based on D-shaped fiber graphene integrated elements as described in claim 1, characterized in that, The operation process of the optoelectronic logic gate device is as follows: Set the first voltage regulator's output source drain voltage to 0.1V, and set the second and third voltage regulators' independent output gate voltages to 0V or 1V respectively; If the output gate voltage of the second or third voltage source is defined as 0V, it is logic input 0, and the output gate voltage is defined as 1V, then the logic inputs (0,0), (0,1), (1,0), and (1,1) are obtained in sequence. The output signal of the first, second, or third fiber bandpass filter is defined as having no graphene surface plasmon peaks and is defined as having logic output 0, and has logic output 1 when there are graphene surface plasmon peaks. Then: the outputs of the first fiber bandpass filter are 1, 0, 0, 0 in sequence, implementing the "NOT" gate logic; the outputs of the second fiber bandpass filter are 0, 1, 1, 0 in sequence, implementing the "OR" gate logic; the outputs of the third fiber bandpass filter are 0, 0, 0, 1 in sequence, implementing the "AND" gate logic.

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