Dual-microring coupling system for realizing optical nonlinear response

Abstract

The application provides a double-microring coupling system for realizing optical nonlinear response, and relates to the technical field of microwave photonics. The double-microring coupling system comprises: a first microring waveguide; a second microring waveguide coupled with the first microring waveguide, wherein a light splitting ratio control module is arranged at the coupling position of the first microring waveguide and the second microring waveguide, and is used for determining the optical coupling coefficient between the first microring waveguide and the second microring waveguide; the first microring waveguide and the second microring waveguide are respectively provided with gain control modules and phase control modules; wherein the parameters of the gain control modules and the phase control modules are adjusted; when the difference between the net gain of the first microring waveguide and the net loss of the second microring waveguide is greater than or equal to the optical coupling coefficient, or when the difference between the net loss of the first microring waveguide and the net gain of the second microring waveguide is greater than or equal to the optical coupling coefficient, the optical nonlinear response is generated between the first microring waveguide and the second microring waveguide.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microwave photonics, and particularly relates to a double-microring coupling system for realizing optical nonlinear response. BACKGROUND

[0002] Parity-time symmetry (PT symmetry) originates from non-Hermitian physics. In quantum mechanics, a closed system is described by a Hermitian Hamiltonian with real eigenvalues and orthogonal eigenvectors. A non-Hermitian Hamiltonian describes an open system, which exchanges energy with the environment. The eigenvalues of the non-Hermitian Hamiltonian are complex numbers, and the eigenvectors are not orthogonal. In 1998, Bender found that under the condition of parity-time inversion symmetry, the non-Hermitian Hamiltonian also has real eigenvalues, which brought a milestone development to the study of non-Hermitian physics. In 2007, R. El-Ganainy proposed to construct a PT symmetric optical system by using the mathematical isomorphism between the optical paraxial wave equation and the Schrodinger equation. The optical system has become an ideal platform for studying non-Hermitian physics, and has rapidly triggered research interest in related fields.

[0003] Optical neural networks are one of the most popular research directions, and are the most promising representative scheme for breaking through the von Neumann bottleneck and the slowdown bottleneck of Moore's law. In the neural network model, a certain form of nonlinearity is needed to realize the threshold value of the neuron, to respond to multiple optical inputs, and to generate an output suitable for driving other optical neurons, such as a nonlinear activation function. In this context, how to realize pure optical nonlinear response is an important problem in modern optical research. SUMMARY

[0004] In view of the above problems, the present application provides a double-microring coupling system for realizing optical nonlinear response.

[0005] According to the double-microring coupling system for realizing optical nonlinear response provided by the present application, the system comprises: a first microring waveguide; a second microring waveguide coupled with the first microring waveguide, wherein a light splitting ratio control module is arranged at the coupling position of the first microring waveguide and the second microring waveguide, for determining the optical coupling coefficient between the first microring waveguide and the second microring waveguide, and the first microring waveguide and the second microring waveguide are respectively provided with gain control modules and phase control modules; wherein the parameters of the gain control modules and the phase control modules are adjusted, and when the difference between the net gain of the first microring waveguide and the net loss of the second microring waveguide is greater than or equal to the optical coupling coefficient, or when the difference between the net loss of the first microring waveguide and the net gain of the second microring waveguide is greater than or equal to the optical coupling coefficient, the optical nonlinear response is generated between the first microring waveguide and the second microring waveguide.

[0006] According to an embodiment of the present application, the dual-microring coupling system for realizing optical nonlinear response further comprises: an input waveguide coupled to one side of the first microring waveguide for inputting an optical signal; and an output waveguide coupled to one side of the second microring waveguide away from the input waveguide for outputting the optical signal modulated by the first microring waveguide and the second microring waveguide.

[0007] According to an embodiment of the present application, the first microring waveguide and the second microring waveguide are passive waveguide structures.

[0008] According to an embodiment of the present application, the calculation method of the optical coupling coefficient is as follows:

[0009]

[0010] wherein k represents the optical coupling coefficient, I1 represents the optical intensity of the first microring waveguide after coupling, and I2 represents the optical intensity of the second microring waveguide after coupling.

[0011] According to an embodiment of the present application, the material of the first microring waveguide or the material of the second microring waveguide comprises one of a silicon waveguide, a lithium niobate waveguide and a silicon nitride waveguide.

[0012] According to an embodiment of the present application, the type of the splitting ratio control module comprises one of a beam splitter, a directional coupler, a Mach-Zehnder modulator and a microring filter.

[0013] According to an embodiment of the present application, the type of the gain control module comprises a semiconductor optical amplifier or an erbium-doped fiber amplifier.

[0014] According to an embodiment of the present application, the type of the phase control module comprises an electro-optic phase modulator or a thermo-optic phase modulator.

[0015] According to an embodiment of the present application, the material of the input waveguide or the material of the output waveguide comprises a lithium niobate waveguide or a silicon nitride waveguide.

[0016] According to an embodiment of the present application, the dual-microring coupling system is integrated on a silicon optical platform through a semiconductor process.

[0017] According to the dual-microring coupling system for realizing optical nonlinear response provided by the present application, when the difference between the net gain of one ring and the net loss of the other ring in the dual-microring coupling system is greater than or equal to the optical coupling coefficient of the splitting ratio control module by adjusting the gain control module and the phase control module, the dual-microring coupling system works in a parity-time symmetry breaking state, at which time the optical intensity output by the output waveguide nonlinearly changes with the increase of the optical intensity input by the input waveguide, and the optical nonlinear function is realized.

[0018] The double-microring coupling system for realizing optical nonlinear response provided by the application can realize high-speed nonlinear conversion in the optical domain by using the characteristics of large bandwidth, low delay and low power consumption of photonic information processing.

[0019] The double-microring coupling system for realizing optical nonlinear response provided by the application can be integrated on a silicon optical platform through a semiconductor process, thereby reducing spatial redundancy. BRIEF DESCRIPTION OF DRAWINGS

[0020] The above content and other purposes, features and advantages of the application will be more apparent through the following description of the embodiments of the application with reference to the accompanying drawings, in which:

[0021] Figure 1 The structure diagram of the double-microring coupling system for realizing optical nonlinear response according to the embodiment of the application is schematically shown.

[0022] REFERENCE NUMERALS

[0023] 1 - input waveguide;

[0024] 2 - output waveguide;

[0025] 31 - first microring waveguide; 32 - second microring waveguide;

[0026] 4 - light splitting ratio control module;

[0027] 5 - gain control module;

[0028] 6 - phase control module. DETAILED DESCRIPTION

[0029] To make the purposes, technical solutions and advantages of the application clearer, the application will be further described in detail below with reference to the embodiments and the accompanying drawings. Obviously, the described embodiments are only some of the embodiments of the application, but not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application. The terms used herein are only for describing the specific embodiments, and are not intended to limit the application. The terms "comprise", "contain" and the like used herein indicate the existence of the described features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0030] In the present application, unless specifically defined otherwise and limited, the terms "mount", "connect", "connection", "fixed", and the like should be construed as broadly as possible, for example, can be fixed connection, can also be detachable connection, or integrated; can be mechanical connection, can also be electrical connection or can communicate with each other; can be direct connection, or indirect connection through intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0031] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "length", "circumferential", "front", "back", "left", "right", "top", "bottom", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the subsystems 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 of the present application.

[0032] Throughout the drawings, the same elements are denoted by the same or similar reference numerals. When it may cause confusion in understanding the present application, the conventional structure or configuration will be omitted. And the shape, size, positional relationship of the components in the drawing do not reflect the true size, proportion and actual positional relationship.

[0033] Similarly, in order to simplify the present application and help understand one or more of the various inventive aspects, in the above description of the exemplary embodiments of the present application, various features of the present application are sometimes grouped together in a single embodiment, figure or description thereof. The description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the description, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0034] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0035] In the case of using expressions such as "at least one of A, B, and C", it generally means one or more of A, B, and C, unless it is specifically stated otherwise. For example, "at least one of A, B, and C" shall mean A alone, B alone, C alone, combinations with two of A, B, and C, or combinations of all of A, B, and C.

[0036] In the technical solutions of the present application, the collection, storage, use, processing, transmission, provision, disclosure, and application of the data (such as including but not limited to user personal information) involved all comply with the provisions of relevant laws and regulations, necessary security measures are taken, and the public order and good customs are not violated.

[0037] Figure 1 A structure diagram of a dual-microring coupling system for realizing optical nonlinear response is schematically shown.

[0038] As shown in Figure 1 The dual-microring coupling system for realizing optical nonlinear response of the present embodiment comprises a first microring waveguide 31 and a second microring waveguide 32.

[0039] The second microring waveguide 32 is coupled with the first microring waveguide 31, and a splitting ratio control module 4 is arranged at the coupling position of the first microring waveguide 31 and the second microring waveguide 32, for determining the optical coupling coefficient between the first microring waveguide 31 and the second microring waveguide 32.

[0040] The first microring waveguide 31 and the second microring waveguide 32 are respectively provided with a gain control module 5 and a phase control module 6. The gain control module 5 is used for controlling the gain of the optical signal, and the phase control module 6 is used for controlling the phase of the optical signal.

[0041] When the optical gain in a single ring is greater than the optical loss in the ring, it shows net gain, and when the optical gain in a single ring is less than the optical loss in the ring, it shows net loss. By adjusting the parameters of the gain control module 5 and the phase control module 6, when the difference between the net gain of the first microring waveguide 31 and the net loss of the second microring waveguide 32 is greater than or equal to the optical coupling coefficient, or when the difference between the net loss of the first microring waveguide 31 and the net gain of the second microring waveguide 32 is greater than or equal to the optical coupling coefficient, the dual-microring coupling system works in the state of parity-time symmetry breaking, at this time, the light intensity output by the output waveguide nonlinearly changes with the increase of the light intensity input by the input waveguide, and the optical nonlinear function is realized, that is, the optical nonlinear response between the first microring waveguide 31 and the second microring waveguide 32 is generated.

[0042] On the basis of the above-mentioned embodiment, the dual-microring coupling system for realizing optical nonlinear response of the present embodiment further comprises an input waveguide 1 and an output waveguide 2.

[0043] The input waveguide 1 is coupled to one side of the first micro-ring waveguide 31 for inputting an optical signal.

[0044] The output waveguide 2 is coupled to one side of the second micro-ring waveguide 32 away from the input waveguide 1 for outputting the optical signal modulated by the first micro-ring waveguide 31 and the second micro-ring waveguide 32.

[0045] In the embodiment, the optical carrier carries data, and the nonlinear response is realized after the optical carrier enters the first micro-ring waveguide 31 and the second micro-ring waveguide 32 from the input waveguide 1, and the processed optical carrier is output by the output waveguide 2.

[0046] Based on the same principle as the above embodiment, by adjusting the parameters of the gain control module 5 and the phase control module 6, when the difference between the net gain of the first micro-ring waveguide 31 and the net loss of the second micro-ring waveguide 32 is greater than or equal to the optical coupling coefficient, or when the difference between the net loss of the first micro-ring waveguide 31 and the net gain of the second micro-ring waveguide 32 is greater than or equal to the optical coupling coefficient, the double micro-ring coupling system works in the state of parity-time symmetry breaking, at this time, the optical intensity output by the output waveguide nonlinearly changes with the increase of the optical intensity input by the input waveguide, and the optical nonlinear function is realized, that is, the optical nonlinear response is generated between the input waveguide 1 and the output waveguide 2.

[0047] According to the double micro-ring coupling system for realizing optical nonlinear response provided by the application, the characteristics of large bandwidth, low delay and low power consumption of photonic information processing can be used to realize high-speed nonlinear conversion in the optical domain.

[0048] On the basis of the above embodiment, in the double micro-ring coupling system for realizing optical nonlinear response of the embodiment, the first micro-ring waveguide 31 and the second micro-ring waveguide 32 are passive waveguide structures.

[0049] On the basis of the above embodiment, in the double micro-ring coupling system for realizing optical nonlinear response of the embodiment, the calculation method of the optical coupling coefficient determined by the light splitting ratio control module 4 is:

[0050]

[0051] Wherein, k represents the optical coupling coefficient, I1 represents the optical intensity of the first micro-ring waveguide after coupling, and I2 represents the optical intensity of the second micro-ring waveguide after coupling.

[0052] The optical coupling coefficient k represents the proportion of the light in one waveguide coupled into another waveguide, and the optical coupling coefficient in the embodiment is determined based on the distance between the first micro-ring waveguide and the second micro-ring waveguide and the coupling length.

[0053] On the basis of the above-mentioned embodiments, in the double-micro-ring coupling system for realizing optical nonlinear response of the embodiment, the material of the first micro-ring waveguide or the material of the second micro-ring waveguide may, for example, include a silicon waveguide, a lithium niobate waveguide, and a silicon nitride waveguide.

[0054] The silicon waveguide has a large refractive index difference, so that light can be efficiently transmitted in the silicon waveguide, the silicon waveguide can be combined with the existing silicon-based microelectronic technology to realize optoelectronic integration, in addition, the silicon has a large thermo-optic effect, and the transmission characteristics of light can be adjusted by heating.

[0055] The lithium niobate has a large nonlinear optical coefficient, and can be used to realize optical modulation, frequency conversion and other functions. The lithium niobate waveguide has a wide transparent window in the visible and infrared light range, and is suitable for various optical applications, in addition, the lithium niobate also has a large electro-optic coefficient, and the transmission characteristics of light can be adjusted by an electric field.

[0056] The silicon nitride has low optical absorption and scattering loss, and can realize low-loss optical transmission, and also has high thermal stability, and is suitable for applications in high-temperature environments.

[0057] On the basis of the above-mentioned embodiments, in the double-micro-ring coupling system for realizing optical nonlinear response of the embodiment, the type of the light splitting ratio control module may, for example, include a beam splitter, a directional coupler, a Mach-Zehnder modulator, and a micro-ring filter.

[0058] The beam splitter is an optical device that can divide a beam of light into two or more beams of light, and it is a key part of most interferometers, and is usually composed of a metal film or a dielectric film.

[0059] The directional coupler (DC coupler) is a general microwave / millimeter wave component, which can be used for signal isolation, separation and mixing, such as power monitoring, source output power amplitude stabilization, signal source isolation, transmission and reflection sweep frequency test, etc. The main technical indicators include directivity, standing wave ratio, coupling degree, and insertion loss.

[0060] The Mach-Zehnder modulator is a device that divides the input light into two equal signals and enters the two light branches of the modulator. The material used in the two light branches is electro-optic material, and the refractive index changes with the size of the external applied electric signal. The refractive index change of the light branch will cause the change of the signal phase, and when the two branch signals of the modulator output are combined together again, the synthesized light signal will be an interference signal with varying intensity, which is equivalent to converting the change of the electric signal into the change of the light signal, realizing the modulation of the light intensity. In short, by controlling the bias voltage of the modulator, different sideband modulation can be realized.

[0061] The basic structure of the microring filter includes a closed loop ring waveguide and one or two bus waveguides beside the loop, namely single-channel and double-channel microring resonators. The actual resonator can be in any shape, such as a circle, an ellipse, a racetrack, a polygon, or a sphere. The bus waveguide is generally a straight waveguide as an input and output channel. There is a small coupling gap between the microring and the channel, and mutual coupling occurs.

[0062] On the basis of the above-mentioned embodiment, in the double-microring coupling system for realizing optical nonlinear response of the embodiment, the type of the gain control module can include, for example: a semiconductor optical amplifier or an erbium-doped fiber amplifier.

[0063] A semiconductor optical amplifier (SOA) is a PN junction device with a strained quantum well structure. An external forward bias forms a population inversion, and external light causes stimulated radiation, forming optical signal amplification. The amplification characteristics mainly depend on the medium characteristics of the active layer and the characteristics of the laser cavity, and it has the advantages of supporting high speed, high bandwidth, low power consumption, high gain, miniaturization and easy integration.

[0064] An erbium-doped fiber amplifier (EDFA) is an optical signal amplifier in which erbium ions Er3+ are doped in the core of the signal passing fiber. It is the core of the erbium-doped fiber amplifier, which is a device that amplifies weak input optical signals without converting them into electrical signals.

[0065] On the basis of the above-mentioned embodiment, in the double-microring coupling system for realizing optical nonlinear response of the embodiment, the type of the phase control module can include, for example: an electro-optic phase modulator or a thermo-optic phase modulator.

[0066] An electro-optic modulator is an optical modulator based on the electro-optic effect, which controls the power, phase and polarization of a laser beam through an electronic control signal. Its types include electro-optic phase modulators, electro-optic polarization modulators and electro-optic amplitude modulators. In this embodiment, an electro-optic phase modulator is selected, in which an electric field (applied to the crystal through an electrode) changes the phase delay of the laser beam after entering the crystal. The polarization state of the incident light beam usually needs to be parallel to one of the optical axes of the crystal, so that the polarization state of the light beam does not change.

[0067] The thermo-optic modulator is a device for changing the temperature of silicon material by using any energy form and modulating the passing light signal, and the thermo-optic effect is that the molecular or crystal structure of the material changes at different temperatures, thereby changing the optical properties of the material.

[0068] On the basis of the above-mentioned embodiment, in the double-microring coupling system for realizing optical nonlinear response, the material of the input waveguide or the material of the output waveguide can include, for example, lithium niobate waveguide or silicon nitride waveguide.

[0069] On the basis of the above-mentioned embodiment, in the double-microring coupling system for realizing optical nonlinear response, the double-microring coupling system is integrated on a silicon optical platform through a semiconductor process.

[0070] Silicon photonics technology is an optical communication technology that uses laser beams to replace electronic semiconductor signals to transmit data, and is a new generation of technology based on silicon and silicon-based substrate materials, and uses existing CMOS process to develop and integrate optical devices.

[0071] According to the double-microring coupling system for realizing optical nonlinear response provided by the application, the double-microring coupling system can be integrated on a silicon optical platform through a semiconductor process, so that spatial redundancy is reduced.

[0072] The first microring waveguide and the second microring waveguide of the embodiment have no specific shape limitation, as long as they can constitute an optical circuit to produce resonance, and other shaped waveguides are suitable for the technical solution.

[0073] According to the double-microring coupling system for realizing optical nonlinear response provided by the application, by adjusting the gain control module and the phase control module, when the difference between the net gain of one ring and the net loss of the other ring in the double-microring coupling system is greater than or equal to the optical coupling coefficient of the light splitting ratio control module, the double-microring coupling system works in the parity-time symmetry breaking state, at this time, the light intensity output by the output waveguide nonlinearly changes with the increase of the input light intensity of the input waveguide, and the optical nonlinear function is realized.

[0074] The computer program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0075] Those skilled in the art will appreciate that the features recited in the various embodiments of the present application can be combined or / and integrated in a variety of ways, even if such combinations or integrations have not been explicitly set forth in the present application. In particular, the features recited in the various embodiments of the present application can be combined and / or integrated in a variety of ways without departing from the spirit and teachings of the present application. All such combinations and / or integrations are within the scope of the present application.

[0076] The embodiments of the present application have been described above. However, these embodiments are merely for the purpose of illustration and are not intended to limit the scope of the present application. Although the embodiments are described separately above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Those skilled in the art can make various substitutions and modifications without departing from the scope of the present application, and these substitutions and modifications shall fall within the scope of the present application.

Claims

1. A dual-microring coupling system for realizing optical nonlinear response, characterized in that: include: The first microring waveguide; a second microring waveguide coupled to the first microring waveguide, wherein a splitting ratio control module is provided at the coupling point between the first microring waveguide and the second microring waveguide, for determining the optical coupling coefficient between the first microring waveguide and the second microring waveguide, and wherein the first microring waveguide and the second microring waveguide are each provided with a gain control module and a phase control module; The parameters of the gain control module and the phase control module are adjusted so that when the difference between the net gain of the first microring waveguide and the net loss of the second microring waveguide is greater than or equal to the optical coupling coefficient, or when the difference between the net loss of the first microring waveguide and the net gain of the second microring waveguide is greater than or equal to the optical coupling coefficient, an optical nonlinear response is generated between the first microring waveguide and the second microring waveguide.

2. The dual-microring coupling system for realizing optical nonlinear response according to claim 1, characterized in that: Also includes: an input waveguide coupled to one side of the first microring waveguide and used for inputting an optical signal; The output waveguide is coupled to a side of the second microring waveguide away from the input waveguide, and is used to output the optical signal modulated by the first microring waveguide and the second microring waveguide.

3. The dual-microring coupling system for realizing optical nonlinear response according to claim 1, characterized in that: The first microring waveguide and the second microring waveguide are passive waveguide structures.

4. The dual-microring coupling system for realizing optical nonlinear response according to claim 1, characterized in that: The optical coupling coefficient is calculated as follows: Wherein, k represents the optical coupling coefficient, I1 represents the light intensity of the first microring waveguide after coupling, and I2 represents the light intensity of the second microring waveguide after coupling.

5. The dual-microring coupling system for realizing optical nonlinear response according to claim 1, characterized in that: The material of the first microring waveguide or the material of the second microring waveguide includes: one of a silicon waveguide, a lithium niobate waveguide and a silicon nitride waveguide.

6. The dual-microring coupling system for realizing optical nonlinear response according to claim 1, characterized in that: The type of the splitting ratio control module includes: one of a beam splitter, a directional coupler, a Mach-Zehnder modulator and a micro-ring filter.

7. The dual-microring coupling system for realizing optical nonlinear response according to claim 1, characterized in that: The types of the gain control module include: semiconductor optical amplifier or erbium-doped fiber amplifier.

8. The dual-microring coupling system for realizing optical nonlinear response according to claim 1, characterized in that: The types of the phase control module include: electro-optical phase modulator or thermo-optical phase modulator.

9. The dual-microring coupling system for realizing optical nonlinear response according to claim 2, characterized in that: The material of the input waveguide or the material of the output waveguide includes: lithium niobate waveguide or silicon nitride waveguide.

10. The dual-microring coupling system for realizing optical nonlinear response according to claim 1, characterized in that: The dual microring coupling system is integrated on a silicon photonics platform through semiconductor technology.

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