Optical pulse neuron

Abstract

The application relates to an optical pulse neuron, which comprises a first wavelength division multiplexer connected with a single-mode optical fiber, the first wavelength division multiplexer being used for inputting excitatory pulse from a neuron dendrite into the optical pulse neuron; a graphene-silicon hybrid waveguide connected with the first wavelength division multiplexer through the single-mode optical fiber, the graphene-silicon hybrid waveguide being used for realizing a pulse firing threshold and generating a pulse. The application utilizes the graphene-silicon hybrid waveguide to make the optical pulse neuron, the graphene-silicon hybrid waveguide can manipulate free carriers at an atomic scale, has the advantages of fast refractory period recovery, low saturated absorption threshold, low pulse emission width and energy, and high pulse firing rate, is an ideal unit for constructing an optical pulse neural network, and is favorable for improving the performance of a photonic SNN.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of artificial intelligence and optical computing technology, and in particular to an optical pulse neuron. BACKGROUND

[0002] At present, artificial neural networks (ANN) is an operation model to abstract and simulate the structure and function of biological neural system, and plays an important role in the field of information processing and pattern recognition. Modern neuroscience experiments show that many biological neural systems such as vision and hearing use the time of neuron firing pulses to encode information, and the movement of pulse signals in the nervous system is the basis for the brain to think. Therefore, according to the latest research results of modern neuroscience, the third generation of artificial neural networks with more biological explainability, spiking neural networks (SNN), has emerged as the times require. SNN has its inherent advantages compared with traditional computing architecture. SNN has small computing amount, uses pulse sequence composed of 0 or 1 to encode, reduces the computing amount of dot multiplication and summation from the mathematical point of view, and only the neurons reaching the threshold value are activated and participate in the operation in each iteration propagation process. SNN has high hardware efficiency and stronger robustness, complex algorithms can be implemented with less hardware, and has lower power consumption. Therefore, developing high-speed, high-bandwidth and low-power SNN based on optical hardware is an important way to realize its powerful capacity.

[0003] Pulse neuron is the basis of SNN implementation. The currently widely used leaky integrate and fire (LIF) neuron model is a pulse neuron model that is generally recognized as achieving the best balance between biological interpretability and implementation complexity. In the "integration" process, the neuron will accumulate input pulses over time, threshold decision will determine whether to fire a pulse, and if the threshold is not reached and no new pulse is accumulated, the neuron will gradually "leak" the existing accumulation to the resting state. After the neuron fires a pulse, it enters a short refractory period, during which the neuron cannot fire a pulse, and after returning to the resting state, it resumes "integration". In the field of optics, the LIF model is also commonly used as the implementation of optical pulse neurons. Early optical pulse neurons based on semiconductor optical amplifiers (SOA) and electro absorption modulators (EAM) have been proposed. The technology is mature, but SOA and EAM have the problem of large volume and difficulty in integration. Optical pulse neurons based on micro ring resonators (MRR) and phase change materials (PCM) are small in size and easy to integrate, but MRR is difficult to control and PCM has a limited lifespan.

[0004] In related technologies, there are many schemes for implementing optical pulse neurons based on lasers and saturable absorbers (SA). For example, optical pulse neurons are implemented by using distributed feedback lasers and vertical cavity surface emitting lasers. However, the optical pulse neurons implemented in this way cannot effectively meet the performance requirements of photonic SNNs, such as fast pulse accumulation, narrow pulse firing, and low saturation energy. Therefore, it is necessary to design a new optical pulse neuron. SUMMARY

[0005] The present application provides an optical pulse neuron, which can solve the technical problem that the currently implemented optical pulse neurons in related technologies cannot effectively improve the performance of photonic SNNs.

[0006] In a first aspect, an embodiment of the present application provides an optical pulse neuron, comprising: a first wavelength division multiplexer connected with a single-mode optical fiber, the first wavelength division multiplexer being configured to input excitatory pulses from neuron dendrites into the optical pulse neuron; and a graphene-silicon hybrid waveguide connected with the first wavelength division multiplexer through the single-mode optical fiber, the graphene-silicon hybrid waveguide being configured to implement a pulse firing threshold and generate a pulse.

[0007] In combination with the first aspect, in an implementation, the optical spiking neuron further comprises an optical coupler connecting the graphene-silicon hybrid waveguide and the first wavelength division multiplexer via a single mode fiber, the optical coupler being configured to couple the pulse generated by the graphene-silicon hybrid waveguide to an output port.

[0008] In combination with the first aspect, in an implementation, the optical spiking neuron further comprises an erbium-doped fiber connecting between the first wavelength division multiplexer and the graphene-silicon hybrid waveguide via the single mode fiber, the erbium-doped fiber being configured as a gain medium to provide pulse integration.

[0009] In combination with the first aspect, in an implementation, the optical spiking neuron further comprises a second wavelength division multiplexer connecting between the erbium-doped fiber and the graphene-silicon hybrid waveguide via the single mode fiber. The second wavelength division multiplexer can input inhibitory pulses from neuron dendrites into the optical spiking neuron via the second wavelength division multiplexer.

[0010] In combination with the first aspect, in an implementation, the second wavelength division multiplexer further comprises a pump laser connected via a single mode fiber, the pump laser being configured to maintain a carrier concentration in the erbium-doped fiber and to couple pump light into the optical spiking neuron via the second wavelength division multiplexer.

[0011] In combination with the first aspect, in an implementation, the optical spiking neuron further comprises an isolator connecting between the first wavelength division multiplexer and the graphene-silicon hybrid waveguide via a single mode fiber, the isolator being configured to ensure unidirectional transmission of optical signals within the optical spiking neuron.

[0012] In combination with the first aspect, in an implementation, the optical spiking neuron further comprises a polarization controller connecting between the isolator and the graphene-silicon hybrid waveguide via a single mode fiber, the polarization controller being configured to ensure that optical signals are maintained in a constant polarization state within the optical spiking neuron.

[0013] In combination with the first aspect, in an implementation, the optical spiking neuron further comprises an erbium-doped fiber, a second wavelength division multiplexer, an isolator, a polarization controller, and an optical coupler; the erbium-doped fiber connecting the first wavelength division multiplexer and the second wavelength division multiplexer via a single mode fiber, the isolator connecting the second wavelength division multiplexer and the polarization controller via a single mode fiber, the polarization controller connecting the graphene-silicon hybrid waveguide via a single mode fiber, and the optical coupler connecting the graphene-silicon hybrid waveguide and the first wavelength division multiplexer via a single mode fiber.

[0014] In combination with the first aspect, in an implementation form of the graphene-silicon hybrid waveguide, the graphene is attached to the silicon waveguide by a photolithography process.

[0015] The technical scheme provided by the embodiments of the present application has at least the following beneficial effects:

[0016] By using the graphene-silicon hybrid waveguide to make the optical pulse neuron, the graphene-silicon hybrid waveguide can manipulate free carriers at the atomic scale, has the advantages of fast refractory period recovery, low saturation absorption threshold, low pulse emission width and energy, and high pulse firing rate, is an ideal unit for constructing an optical pulse neural network, and is beneficial to improving the performance of the photonic SNN, thereby solving the technical problem that the performance of the photonic SNN cannot be effectively improved in the related art. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0018] Figure 1 A structural schematic diagram of the graphene-silicon hybrid waveguide provided by the embodiments of the present application is shown in the figure.

[0019] Figure 2 A structural schematic diagram of the optical pulse neuron based on the graphene-silicon hybrid waveguide embedded laser excitable laser provided by the embodiments of the present application is shown in the figure.

[0020] Figure 3 A structural schematic diagram of the optical pulse neuron based on the graphene-silicon hybrid waveguide embedded laser excitable laser provided by the embodiments of the present application is shown in the figure.

[0021] In the figure:

[0022] 1, first wavelength division multiplexer; 2, single-mode optical fiber; 3, graphene-silicon hybrid waveguide; 4, optical coupler;

[0023] 5, erbium-doped optical fiber; 6, second wavelength division multiplexer; 7, pump laser; 8, isolator; 9, polarization controller. DETAILED DESCRIPTION

[0024] In the following, the technical solutions in the embodiments of the present application will be described clearly and completely in conjunction with the drawings in the embodiments of the present application, so that those skilled in the art can better understand the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0025] The optical pulse neuron provided by the embodiments of the present application can solve the technical problem that the optical pulse neuron currently implemented in the related art cannot effectively improve the performance of a photonic SNN.

[0026] Referring to Figure 2 As shown in the figure, the optical pulse neuron provided by the embodiments of the present application can include: a first wavelength-division multiplexer 1 (WDM) connected with a single-mode optical fiber 2, the first wavelength-division multiplexer 1 being configured to input an excitatory pulse from a neuron dendrite into the optical pulse neuron, the first wavelength-division multiplexer 1 being connectable to an input port and being configured to input the pulse input from the input port into the single-mode optical fiber 2 connected with the first wavelength-division multiplexer 1; and a graphene / silicon hybrid waveguide 3 (GSHW) connected with the first wavelength-division multiplexer 1 through the single-mode optical fiber 2, the graphene / silicon hybrid waveguide 3 being configured to implement a pulse firing threshold and generate a pulse, thereby implementing the nonlinearity of the pulse neuron. In the embodiments, the single-mode optical fiber 2 is used to connect all optical devices of the optical pulse neuron, and each device of the entire optical pulse neuron can be connected through the single-mode optical fiber 2. The optical pulse neuron is integrated with all-fiber devices, and is simple to operate and convenient to adjust.

[0027] Experiments show that, Figure 1 The graphene / silicon hybrid waveguide (GSHW) shown in the figure has the following excellent characteristics:

[0028] 1. The graphene / silicon hybrid waveguide (GSHW) can manipulate free carriers at the atomic scale.

[0029] 2. Compared with graphene attached to an optical fiber, attaching graphene to a silicon waveguide using a standard photolithography process can achieve a two-order-of-magnitude rate improvement of the interaction between light and matter.

[0030] 3. A large number of photo-generated carriers are generated when the incident light enters the GSHW and recombine at the graphene / silicon interface. The carrier recombination time near the graphene / silicon interface is as low as 1.82 ps, which is three orders of magnitude faster than the carrier recombination time in silicon.

[0031] 4. The carrier response rate of the GSHW is nearly three orders of magnitude faster than that of the corresponding silicon waveguide. The extremely fast carrier response rate is conducive to the generation of narrow pulses. When the graphene / silicon hybrid waveguide is applied to a mode-locked laser, a pulse emission frequency of 54.37 MHz and a pulse width of 542 fs are achieved.

[0032] 5. The small mode field area of the GSHW reduces the saturation pulse energy by two orders of magnitude compared to optical fibers.

[0033] In this embodiment, the graphene-silicon hybrid waveguide 3 has the above excellent performance. By using the graphene-silicon hybrid waveguide 3 in combination with a first wavelength division multiplexer 1 and other optical devices to make an optical pulse neuron, the graphene-silicon hybrid waveguide 3 can manipulate free carriers at the atomic scale, has the advantages of fast refractory period recovery, low saturation absorption threshold, low pulse emission width and energy, and high pulse emission rate, is an ideal unit for constructing an optical pulse neural network, is conducive to improving the performance of a photonic SNN, has important significance in the field of artificial intelligence and optical computing technology, and solves the technical problem that the performance of a photonic SNN cannot be effectively improved in the related art.

[0034] Referring to Figure 2 In some embodiments, the optical pulse neuron can further include an optical coupler 4 connected between the graphene-silicon hybrid waveguide 3 and the first wavelength division multiplexer 1 through a single-mode optical fiber 2, that is, one end of the optical coupler 4 is connected to the graphene-silicon hybrid waveguide 3 through the single-mode optical fiber 2, and the other end is connected to the first wavelength division multiplexer 1 through the single-mode optical fiber 2. The optical coupler 4 is used to couple the pulses generated by the graphene-silicon hybrid waveguide 3 to an output port.

[0035] Referring to Figure 2 In an embodiment, the optical pulse neuron can further include an erbium-doped fiber 5 (EDF) connected between the first wavelength division multiplexer 1 and the graphene-silicon hybrid waveguide 3 through the single-mode optical fiber 2. The erbium-doped fiber 5 serves as a gain medium and is used to provide pulse integration.

[0036] Referring to Figure 2As shown, in an embodiment, the optical pulse neuron further comprises a second wavelength-division multiplexer 6 (WDM) connected between the Erbium-doped fiber 5 and the graphene-silicon hybrid waveguide 3 through the single-mode fiber 2, which can input inhibitory pulses from neuron dendrites into the optical pulse neuron through the second wavelength-division multiplexer 6.

[0037] In some optional embodiments, the second wavelength-division multiplexer 6 is further connected with a pump laser 7 through the single-mode fiber 2, which is used to maintain the carrier concentration in the Erbium-doped fiber 5 and couple pump light into the optical pulse neuron through the second wavelength-division multiplexer 6.

[0038] Referring to Figure 2 As shown, in an embodiment, the optical pulse neuron further comprises an isolator 8 (ISO) connected between the first wavelength-division multiplexer 1 and the graphene-silicon hybrid waveguide 3 through the single-mode fiber 2, which is used to ensure unidirectional transmission of optical signals within the optical pulse neuron.

[0039] Referring to Figure 2 As shown, in an embodiment, the optical pulse neuron further comprises a polarization controller 9 (PC) connected between the isolator 8 and the graphene-silicon hybrid waveguide 3 through the single-mode fiber 2, which is used to ensure that the optical signals within the optical pulse neuron are kept in a constant polarization state, thereby making the pulse output more stable.

[0040] Referring to Figure 2As shown, preferably, the optical pulse neuron further comprises an erbium-doped fiber 5, a second wavelength division multiplexer 6, an isolator 8, a polarization controller 9 and an optical coupler 4; the erbium-doped fiber 5 is connected to the first wavelength division multiplexer 1 and the second wavelength division multiplexer 6 through a single-mode fiber 2, the isolator 8 is connected to the second wavelength division multiplexer 6 and the polarization controller 9 through a single-mode fiber 2, the polarization controller 9 is connected to the graphene-silicon hybrid waveguide 3 through a single-mode fiber 2, and the optical coupler 4 is connected to the graphene-silicon hybrid waveguide 3 and the first wavelength division multiplexer 1 through a single-mode fiber 2. That is, the single-mode fiber 2 connects the first wavelength division multiplexer 1, the erbium-doped fiber 5, the second wavelength division multiplexer 6, the isolator 8, the polarization controller 9, the graphene-silicon hybrid waveguide 3, the optical coupler 4 and the first wavelength division multiplexer 1 in sequence, and the second wavelength division multiplexer 6 is connected to the pump laser 7 through a single-mode fiber 2, so that the graphene-silicon hybrid waveguide 3 is connected to these common optical devices through a single-mode fiber 2, forming an optical pulse neuron and realizing an optical pulse neuron based on the laser excitable graphene-silicon hybrid waveguide 3.

[0041] Referring to Figure 1 As shown, preferably, the graphene-silicon hybrid waveguide 3 comprises graphene and a silicon waveguide, and the graphene is attached to the silicon waveguide by using a photolithography process. In this embodiment, compared with graphene attached to an optical fiber, attaching graphene to a silicon waveguide by using a standard photolithography process can achieve a two-order-of-magnitude rate improvement of optical matter interaction.

[0042] Referring to Figure 2 As shown, it is a schematic diagram of the optical pulse neuron based on the laser excitable graphene-silicon hybrid waveguide 3. The GSHW and the EDF as a gain medium are embedded in the optical pulse neuron, the pump laser 7 is used to maintain the carrier concentration in the doped fiber and couple the pump light into the optical pulse neuron through the WDM, the PC is used to ensure that the optical signal in the laser is kept in a constant polarization state, thereby making the pulse output more stable, and the ISO is used to ensure the unidirectional transmission of the optical signal in the laser. Excitatory input pulses from the neuron dendrites enter the optical pulse neuron through the WDM and make the EDF increase the carrier concentration in the gain region. Enough excitatory exceeds the saturation absorption threshold of the GSHW, causing the optical pulse neuron to emit pulses and output through the output port connected by the optical coupler 4. Subsequently, the GSHW enters the refractory period, and input pulses in the refractory period cannot make the optical pulse neuron fire pulses.

[0043] Figure 3The schematic diagram of the optical pulse neuron based on the graphene-silicon hybrid waveguide 3 with simultaneous excitatory and inhibitory inputs. The GSHW is embedded with EDF as the gain medium, and there is no additional pump input. The PC is used to ensure that the polarization state of the optical signal is kept constant in the laser, thereby making the pulse output more stable. The ISO is used to ensure the unidirectional transmission of the optical signal in the laser. The excitatory and inhibitory inputs from the neuron dendrites enter the optical pulse neuron through two WDMs (i.e., the first wavelength division multiplexer 1 and the second wavelength division multiplexer 6). If the excitatory input lags behind the inhibitory input in time, the output pulse is closely related to the bias condition of the optical pulse neuron and the relative strength and time difference of the excitatory and inhibitory inputs. As the inhibitory input gradually approaches the excitatory input, the pulse output is gradually suppressed to 0. When the excitatory input precedes the inhibitory input, the pulse output suppression can be ignored unless the inhibitory input is in the corresponding time of the optical pulse neuron.

[0044] The application utilizes the excellent characteristics of the fast refractory period recovery, low saturation absorption threshold, low pulse emission width and energy of the GSHW and other common optical devices to realize an optical pulse neuron based on the graphene-silicon hybrid waveguide 3 with a laser excitation. The all-fiber device can be integrated, and the operation is simple and convenient to adjust.

[0045] In the description of the application, it should be noted that the terms "upper", "lower", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application. Unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be a fixed connection, or a detachable connection, or an integral connection; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the communication between two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0046] It should be noted that, in the present application, the relational terms such as "first" and "second", and the like, are used solely to distinguish one entity or action from another, without necessarily requiring or implying any actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0047] The foregoing is merely illustrative of the principles of the application and various modifications can be made by those skilled in the art without departing from the spirit and scope of the application. The above embodiments are illustrative, and not restrictive, of the scope of the application.

Claims

1. A light-pulsing neuron, characterized in that, It includes: A first wavelength division multiplexer (1) is connected to a single-mode optical fiber (2). The first wavelength division multiplexer (1) is used to input excitatory pulses from neuronal dendrites into the optical pulse neuron. A graphene-silicon hybrid waveguide (3) is connected to the first wavelength division multiplexer (1) through the single-mode optical fiber (2). The graphene-silicon hybrid waveguide (3) is used to realize the pulse delivery threshold and generate pulses. The optical pulse neuron also includes an erbium-doped fiber (5), a second wavelength division multiplexer (6), an isolator (8), a polarization controller (9), and an optical coupler (4). The erbium-doped fiber (5) is connected to the first wavelength division multiplexer (1) and the second wavelength division multiplexer (6) via a single-mode fiber (2). The isolator (8) is connected to the second wavelength division multiplexer (6) and the polarization controller (9) via a single-mode fiber (2). The polarization controller (9) is connected to the graphene-silicon hybrid waveguide (3) via a single-mode fiber (2). The optical coupler (4) is connected to the graphene-silicon hybrid waveguide (3) and the first wavelength division multiplexer (1) via a single-mode fiber (2). The second wavelength division multiplexer (6) is also connected to a pump laser (7) via a single-mode fiber (2). The pump laser (7) is used to maintain the carrier concentration in the erbium-doped fiber (5) and couple the pump light to the optical pulse neuron via the second wavelength division multiplexer (6).

2. The optical pulse neuron as described in claim 1, characterized in that, The optical pulse neuron also includes an optical coupler (4), which connects the graphene-silicon hybrid waveguide (3) to the first wavelength division multiplexer (1) via a single-mode optical fiber (2). The optical coupler (4) is used to couple the pulse generated by the graphene-silicon hybrid waveguide (3) to the output port.

3. The optical pulse neuron as described in claim 1, characterized in that, The optical pulse neuron also includes an erbium-doped fiber (5), which is connected between the first wavelength division multiplexer (1) and the graphene-silicon hybrid waveguide (3) via the single-mode fiber (2). The erbium-doped fiber (5) serves as a gain medium to provide pulse integration.

4. The optical pulse neuron as described in any one of claims 3, characterized in that, The optical pulse neuron also includes a second wavelength division multiplexer (6), which is connected between the erbium-doped fiber (5) and the graphene-silicon hybrid waveguide (3) via the single-mode fiber (2).

5. The optical pulse neuron as described in any one of claims 1-4, characterized in that, The optical pulse neuron also includes an isolator (8), which is connected between the first wavelength division multiplexer (1) and the graphene-silicon hybrid waveguide (3) via a single-mode optical fiber (2). The isolator (8) is used to ensure that the optical signal is transmitted unidirectionally within the optical pulse neuron.

6. The optical pulse neuron as described in claim 5, characterized in that, The optical pulse neuron also includes a polarization controller (9), which is connected between the isolator (8) and the graphene-silicon hybrid waveguide (3) via a single-mode fiber (2). The polarization controller (9) is used to ensure that the optical signal is kept in a constant polarization state within the optical pulse neuron.

7. The optical pulse neuron as described in claim 1, characterized in that, The graphene-silicon hybrid waveguide (3) includes graphene and silicon waveguide, wherein the graphene is attached to the silicon waveguide by photolithography.

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