On-chip all-optical wavelength conversion device for three-dimensional multiplexed signals based on single nonlinear waveguide

Abstract

The application discloses a three-dimensional multiplexing signal on-chip all-optical wavelength conversion device based on a single nonlinear waveguide. The wavelength conversion device mainly comprises a transverse magnetic mode demultiplexer, a transverse electric mode demultiplexer, a polarization beam splitter and a multimode nonlinear waveguide. The application utilizes wavelength multiplexing technology, mode multiplexing technology and polarization multiplexing technology, and combines the dispersion engineering of a silicon-based waveguide, so that a multi-wavelength-dual-polarization-dual-mode hybrid multiplexing signal realizes wideband and efficient all-optical wavelength conversion in a multimode nonlinear optical waveguide. Under the participation of pump light, the signal light is converted into idle frequency light carrying the same data as the signal light. The application can greatly improve the transmission capacity of a communication system, reduce the number of wavelength converters in a communication network, improve the flexibility of wavelength routing, and has the advantages of simple structure, high efficiency, small area, easy integration and expansion, and the like. The application can be widely applied to the field of super-large-capacity all-optical signal processing in an all-optical communication network.

Description

Technical Field

[0001] The present invention belongs to the field of on-chip optical communication and is an on-chip all-optical wavelength conversion device for silicon substrates, in particular an on-chip all-optical wavelength conversion device for three-dimensional multiplexed signals (wavelength-mode-polarization hybrid multiplexed signals) based on a single nonlinear waveguide. Background Art

[0002] All-optical wavelength conversion (AOWC) is a key foundational technology for processing all-optical signals in optical communications. AOWC plays a crucial role in eliminating network congestion, reducing wavelength continuity limitations, and improving wavelength resource utilization. It significantly enhances network flexibility, accuracy, timeliness, and scalability.

[0003] At the same time, with the promotion and application of technologies such as 5G, artificial intelligence, cloud computing, big data, and the Internet of Things, higher requirements have been placed on the capacity of optical communication networks, and people have begun to study various multiplexing technologies. With the rapid development and gradual maturity of planar optical waveguide technology and SOI (Silicon on Insulator) process technology, silicon-based on-chip (de)multiplexers have become a research hotspot. Among them, the main focus is on devices such as wavelength division multiplexing (WDM), mode division multiplexing (MDM), and polarization division multiplexing (PDM).

[0004] It is worth noting that single-dimensional multiplexing technology can no longer meet the future demand for ultra-large-capacity communications. Combining multiple multiplexing technologies to form efficient multi-dimensional hybrid multiplexing technology will become a viable solution with great significance. Therefore, in this field, studying all-optical wavelength conversion of multi-dimensional hybrid multiplexed signals is an inevitable trend in scientific and technological development. In 2017, Feng X et al. (Feng X, Wu Z, Wang X, et al. Integrated all-optical wavelength multicasting for 40Gbit / s PDM-QPSK signals using a single silicon waveguide [J]. Optics and Laser Technology, 2017, 94: 261-266.) proposed an all-optical wavelength conversion scheme for multi-wavelength and dual-polarization signals using four-wave mixing and angular polarization pumping in a silicon waveguide, and experimentally verified all-optical wavelength multicasting of 40Gbit / s PDM-QPSK signals. In 2023, Chen B et al. (Chen B, Zhao Y, Tan H, et al. Broadband wavelength conversion for hybrid multiplexing signals based on a parallel dispersion-engineered silicon waveguide [J]. IEEE Photonics Journal, 2023, 15 (1): 1-7.) proposed an all-optical wavelength conversion scheme for multi-wavelength-dual-mode signals, and experimentally realized broadband all-optical wavelength conversion of WDM-MDM signals. In addition, patent CN113484952A designed an all-optical wavelength conversion device for multi-wavelength-dual-polarization-dual-mode hybrid signals using multiple linear devices and two nonlinear waveguides. Although this design realizes all-optical wavelength conversion of three-dimensional hybrid multiplexing signals, the device contains more devices, is more complex, and is prone to more additional losses. In addition, the wavelength conversion in the device occurs separately in two multimode waveguides, and in essence, it still does not break through the problem of simultaneous wavelength conversion of wavelength-polarization-mode hybrid dimensional multiplexing signals. Therefore, it is necessary to propose a simple and efficient device for simultaneous all-optical wavelength conversion of multi-wavelength-dual-polarization-dual-mode hybrid multiplexing signals. Summary of the Invention

[0005] To address the challenges presented by the prior art, the present invention aims to provide a simple and efficient on-chip all-optical wavelength conversion device for three-dimensional multiplexing signals based on a single nonlinear waveguide. This device utilizes wavelength, mode, and polarization multiplexing technologies, combined with dispersion engineering in silicon-based waveguides, to achieve broadband and efficient all-optical wavelength conversion of multi-wavelength, dual-polarization, and dual-mode hybrid multiplexed signals within a single optical waveguide.

[0006] The technical solution adopted by the present invention to solve its technical problems is:

[0007] The three-dimensional multiplexed signal on-chip all-optical wavelength conversion device based on a single nonlinear waveguide comprises a multimode nonlinear waveguide, a transverse magnetic mode demultiplexer, a transverse electric mode demultiplexer, a polarization beam splitter, an adiabatic tapered waveguide, a first single-mode output waveguide, a second single-mode output waveguide, a third single-mode output waveguide and a fourth single-mode output waveguide; the input end of the multimode nonlinear waveguide serves as the input end of the all-optical wavelength conversion device, the output end of the multimode nonlinear waveguide is connected to the input end of the transverse magnetic mode demultiplexer, the second output end of the transverse magnetic mode demultiplexer is connected to the input end of the transverse electric mode demultiplexer, the first output end of the transverse electric mode demultiplexer is connected to the input end of the polarization beam splitter through the adiabatic tapered waveguide, and the first output end of the polarization beam splitter is connected to the second single-mode The first output end of the transverse magnetic mode demultiplexer is connected to the first single-mode output waveguide; the second output end of the transverse electric mode demultiplexer is connected to the fourth single-mode output waveguide; the second output end of the polarization beam splitter is connected to the third single-mode output waveguide; the first single-mode output waveguide, the second single-mode output waveguide, the third single-mode output waveguide and the fourth single-mode output waveguide serve as the first output, second output, third output and fourth output of the all-optical wavelength conversion device, respectively. The first output, second output, third output and fourth output of the all-optical wavelength conversion device are respectively connected to corresponding filters, and the four filters output idler light with signal light wavelengths corresponding to the first-order mode of the transverse magnetic mode, the fundamental mode of the transverse electric mode, the fundamental mode of the transverse magnetic mode and the first-order mode of the transverse electric mode, respectively.

[0008] The transverse magnetic mode demultiplexer includes a first input waveguide, a first coupling waveguide, a first output waveguide, a first curved waveguide, a second coupling waveguide, and a second curved waveguide. One end of the first input waveguide serves as the input end of the transverse magnetic mode demultiplexer, and the other end of the first input waveguide is connected to one end of the first output waveguide via the first coupling waveguide. The other end of the first output waveguide serves as the second output end of the transverse magnetic mode demultiplexer. A second coupling waveguide is provided on the side of the first coupling waveguide. The first coupling waveguide and the second coupling waveguide are coupled and connected. One end of the first curved waveguide is left vacant, and the other end of the first curved waveguide is connected to one end of the second curved waveguide via the second coupling waveguide. An optical signal containing only a first-order mode of a transverse magnetic mode is output from the second curved waveguide, and an optical signal containing other modes is output from the first output waveguide. The other end of the second curved waveguide serves as the first output end of the transverse magnetic mode demultiplexer.

[0009] The transverse electric mode demultiplexer includes a second input waveguide, a third coupling waveguide, a second output waveguide, a third curved waveguide, a fourth coupling waveguide and a fourth curved waveguide; one end of the second input waveguide serves as the input end of the transverse electric mode demultiplexer, the other end of the second input waveguide is connected to one end of the second output waveguide through the third coupling waveguide, and the other end of the second output waveguide serves as the first output end of the transverse electric mode demultiplexer; a fourth coupling waveguide is arranged on the side of the third coupling waveguide, the third coupling waveguide is coupled to the fourth coupling waveguide, one end of the third curved waveguide is left vacant, and the other end of the third curved waveguide is connected to one end of the fourth curved waveguide through the fourth coupling waveguide, an optical signal containing only the first-order mode of the transverse electric mode is output from the fourth curved waveguide, and an optical signal containing other modes is output from the second output waveguide, and the other end of the fourth curved waveguide serves as the second output end of the transverse electric mode demultiplexer.

[0010] The polarization beam splitter includes a fifth coupling waveguide, an intermediate waveguide, a sixth coupling waveguide and a fifth curved waveguide; both ends of the intermediate waveguide are vacant, and the fifth coupling waveguide and the sixth coupling waveguide are respectively arranged on both sides of the intermediate waveguide, the fifth coupling waveguide is coupled to the intermediate waveguide, and the intermediate waveguide is coupled to the sixth coupling waveguide; one end of the fifth coupling waveguide serves as the input end of the polarization beam splitter, and the other end of the fifth coupling waveguide serves as the first output end of the polarization beam splitter; one end of the sixth coupling waveguide is vacant, the other end of the sixth coupling waveguide is connected to one end of the fifth curved waveguide, and the other end of the fifth curved waveguide serves as the second output end of the polarization beam splitter.

[0011] The adiabatic tapered waveguide is long enough and its width changes slowly, so that the optical signal can be transmitted stably with low loss, and is used to connect two rectangular waveguides with different widths.

[0012] The multimode nonlinear waveguide is a waveguide that has undergone dispersion engineering and meets the conditions for an all-optical wavelength conversion process based on multiple four-wave mixing processes in which multi-wavelength, dual-polarization, and dual-mode multiplexed signals simultaneously undergo an all-optical wavelength conversion process. The conditions for the all-optical wavelength conversion process are that the signal light, pump light, and idler light satisfy energy conservation and momentum conservation and have low inter-modal crosstalk when the four-wave mixing effect occurs. The inter-modal crosstalk refers to the crosstalk between idler lights of different polarizations / modes generated when different types of four-wave mixing effects occur in the polarization-mode multiplexed signal.

[0013] The transverse magnetic mode demultiplexer, transverse electric mode demultiplexer and polarization beam splitter are all of the strongly confined small-section optical waveguide type, and their cross-sectional dimensions are in the nanometer order.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The present invention can perform all-optical wavelength conversion on a complex signal containing multiple multiplexing types. The signal contains multiple wavelengths, each of which has two polarization states: the transverse electric mode (TE) and the transverse magnetic mode (TM). Each polarization state also contains two modes: the fundamental mode (TE0 and TM0) and the first-order mode (TE1 and TM1). Utilizing a three-dimensional multiplexed signal of N wavelengths, two polarizations, and two modes, the transmission capacity of the communication system is increased by N×2×2 times.

[0016] 1. The all-optical wavelength conversion device of the present invention supports the simultaneous occurrence of multiple four-wave mixing processes in a multimode waveguide, enabling broadband and efficient all-optical wavelength conversion of dual-polarization, dual-mode hybrid multiplexed signals in a multimode nonlinear waveguide. This improves communication capacity while significantly reducing the number of wavelength converters in the communication network, thereby enhancing the flexibility and integration of wavelength routing networks.

[0017] 2. The transverse magnetic mode demultiplexer, transverse electric mode demultiplexer, and polarization beam splitter in this invention have been designed through multiple simulations and optimizations. Their nanometer-scale dimensions offer advantages such as good process tolerance, a small footprint, and ease of integration and expansion.

[0018] 3. The all-optical wavelength conversion device is realized by only a transverse magnetic mode demultiplexer, a transverse electric mode demultiplexer, a polarization beam splitter and a multimode nonlinear waveguide, showing the characteristics of simple structure, small size, low loss and strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of an on-chip all-optical wavelength conversion device for three-dimensional hybrid multiplexing signals.

[0020] Figure 2 This is a schematic diagram of the transverse magnetic mode demultiplexer structure.

[0021] Figure 3 This is a schematic diagram of the structure of the transverse electric mode demultiplexer.

[0022] Figure 4 It is a schematic diagram of the polarization beam splitter structure.

[0023] Figure 5 It is a schematic cross-sectional view of the multimode nonlinear waveguide in the device of the present invention.

[0024] Figure 6 This is a schematic diagram of the working principle of an on-chip all-optical wavelength conversion device for three-dimensional hybrid multiplexing signals.

[0025] Figure 7 1 is a diagram showing simulation results of the all-optical wavelength conversion device in the embodiment.

[0026] In the figure: multimode nonlinear waveguide 1, transverse magnetic mode demultiplexer 2, transverse electric mode demultiplexer 3, polarization beam splitter 5, adiabatic tapered waveguide 4, first single-mode output waveguide 6, second single-mode output waveguide 7, third single-mode output waveguide 8, fourth single-mode output waveguide 9. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] like Figure 1 As shown, the present invention includes a multimode nonlinear waveguide 1, a transverse magnetic mode demultiplexer 2, a transverse electric mode demultiplexer 3, a polarization beam splitter 5, an adiabatic tapered waveguide 4, a first single-mode output waveguide 6, a second single-mode output waveguide 7, a third single-mode output waveguide 8, and a fourth single-mode output waveguide 9; the input end of the multimode nonlinear waveguide 1 serves as the input end of the all-optical wavelength conversion device, the output end of the multimode nonlinear waveguide 1 is connected to the input end of the transverse magnetic mode demultiplexer 2, the second output end of the transverse magnetic mode demultiplexer 2 is connected to the input end of the transverse electric mode demultiplexer 3, the first output end of the transverse electric mode demultiplexer 3 is connected to the input end of the polarization beam splitter 5 through the adiabatic tapered waveguide 4, and the first output end of the polarization beam splitter 5 is connected to the second single-mode output waveguide 7; the transverse The first output end of the magnetic mode demultiplexer 2 is connected to the first single-mode output waveguide 6; the second output end of the transverse electric mode demultiplexer 3 is connected to the fourth single-mode output waveguide 9; the second output end of the polarization beam splitter 5 is connected to the third single-mode output waveguide 8; the first single-mode output waveguide 6, the second single-mode output waveguide 7, the third single-mode output waveguide 8, and the fourth single-mode output waveguide 9 serve as the first output, second output, third output, and fourth output of the all-optical wavelength conversion device, respectively. The first output, second output, third output, and fourth output of the all-optical wavelength conversion device are respectively connected to corresponding filters. The output end of each filter obtains idler light of the first-order transverse magnetic mode, the fundamental transverse electric mode, the fundamental transverse magnetic mode, and the first-order transverse electric mode corresponding to the wavelength of the signal light.

[0029] A signal is input from the input end of the all-optical wavelength conversion device, and efficient all-optical wavelength conversion based on the four-wave mixing effect is realized in the multimode nonlinear waveguide 1. The transverse magnetic mode demultiplexer 2 outputs the fundamental mode and the first-order mode of the transverse magnetic mode from its second output end and first output end, respectively. The transverse electric mode demultiplexer 3 outputs the fundamental mode and the first-order mode of the transverse electric mode from its first output end and second output end, respectively. The polarization beam splitter 5 outputs the fundamental mode of the transverse electric mode and the fundamental mode of the transverse magnetic mode from its first output end and second output end, respectively.

[0030] like Figure 2As shown, the transverse magnetic mode demultiplexer 2 includes a first input waveguide 21, a first coupling waveguide 22, a first output waveguide 23, a first curved waveguide 24, a second coupling waveguide 25 and a second curved waveguide 26; one end of the first input waveguide 21 serves as the input end of the transverse magnetic mode demultiplexer 2, and the input end signal is an idler light corresponding to the wavelength of the signal light, including idler light of the transverse electric mode fundamental mode, the transverse electric mode first-order mode, the transverse magnetic mode fundamental mode and the transverse magnetic mode first-order mode; the other end of the first input waveguide 21 is connected to one end of the first output waveguide 23 through the first coupling waveguide 22, and the other end of the first output waveguide 23 serves as the second input end of the transverse magnetic mode demultiplexer 2. output end; one end of the first curved waveguide 24 is vacant, and the other end of the first curved waveguide 24 is connected to one end of the second curved waveguide 26 through the second coupling waveguide 25, and the other end of the second curved waveguide 26 serves as the first output end of the transverse magnetic mode demultiplexer 2; a second coupling waveguide 25 is provided on the side of the first coupling waveguide 22, and the first coupling waveguide 22 is coupled to the second coupling waveguide 25; of the multiplexed signal input to the input end of the transverse magnetic mode demultiplexer 2, only the first-order transverse magnetic mode mode is output from the output end of the second curved waveguide 26, and the remaining transverse electric mode fundamental mode, transverse electric mode first-order mode and transverse magnetic mode fundamental mode light are still output from the output end of the first output waveguide 23;

[0031] The transverse magnetic mode demultiplexer 2 adopts a dual-waveguide asymmetric directional coupler structure. The waveguides in the coupling region include two rectangular waveguides, one wide and one narrow, which are the first coupling waveguide 22 and the second coupling waveguide 25. The first coupling waveguide 22 needs to support the transmission of the transverse electric mode fundamental mode, the transverse electric mode first-order mode, and the transverse magnetic mode fundamental mode and prevent the transmission of other modes. The waveguide width is selected to be 0.79 microns; the width of the second coupling waveguide 25 is selected to be 0.32 microns. In order to enable the transverse magnetic mode first-order mode to be coupled from the first coupling waveguide 22 to the second coupling waveguide under this size, the first coupling waveguide 22 needs to support the transmission of the transverse electric mode fundamental mode, the transverse electric mode first-order mode, and the transverse magnetic mode fundamental mode and prevent the transmission of other modes. The first coupling waveguide 22 and the second coupling waveguide 25 have the same axial length, which is called the coupling length, and the spacing between them is called the coupling gap. In the specific implementation, considering the coupling efficiency of the coupler, the compactness of the overall device and the size limitation of the process, the coupling gap is selected to be 0.2 microns; the first input waveguide 21 and the first output waveguide 23 are set as adiabatic tapered waveguides, which are used to connect two rectangular waveguides of different widths and enable low-loss and stable transmission of optical signals.

[0032] like Figure 3As shown, the transverse electric mode demultiplexer 3 includes a second input waveguide 31, a third coupling waveguide 32, a second output waveguide 33, a third curved waveguide 34, a fourth coupling waveguide 35 and a fourth curved waveguide 36; one end of the second input waveguide 31 serves as the input end of the transverse electric mode demultiplexer 3, and the input end signal includes the idler light of the transverse electric mode fundamental mode, the transverse electric mode first-order mode and the transverse magnetic mode fundamental mode; the other end of the second input waveguide 31 is connected to one end of the second output waveguide 33 through the third coupling waveguide 32, and the other end of the second output waveguide 33 serves as the first output end of the transverse electric mode demultiplexer 3; the third curved waveguide 34 serves as the input end of the transverse electric mode demultiplexer 3 One end of the curved waveguide 34 is left vacant, and the other end of the third curved waveguide 34 is connected to one end of a fourth curved waveguide 36 via a fourth coupling waveguide 35. The other end of the fourth curved waveguide 36 serves as the second output end of the transverse electric mode demultiplexer 3. A fourth coupling waveguide 35 is provided on the side of the third coupling waveguide 32, and the third coupling waveguide 32 and the fourth coupling waveguide 35 are coupled to each other. Of the multiplexed signals at the input end of the transverse electric mode demultiplexer 3, only the first-order transverse electric mode is output from the output end of the fourth curved waveguide 36, while the remaining transverse electric mode fundamental mode and transverse magnetic mode fundamental mode light are still output from the output end of the second output waveguide 33.

[0033] The transverse electric mode demultiplexer 3 adopts a dual-waveguide adiabatic tapered directional coupler structure. The waveguides in the coupling area include two adiabatic tapered waveguides, one wide and one narrow, namely the third coupling waveguide 32 and the fourth coupling waveguide 35. The gradual change in width can relax the width requirement of strict phase matching and have better process tolerance. The wide side width of the third coupling waveguide 32 needs to support the transmission of the transverse electric mode fundamental mode, the transverse electric mode first-order mode, and the transverse magnetic mode fundamental mode and prevent the transmission of other modes. The waveguide wide side width is selected to be 0.72 microns. The narrow side width of the third coupling waveguide 32 needs to support the transmission of the transverse electric mode fundamental mode and the transverse magnetic mode fundamental mode and prevent the propagation of other modes. The waveguide narrow side width is selected to be 0 .64 microns, the width range of the fourth coupling waveguide 35 needs to enable the first-order mode of the transverse electric mode to be coupled from the third coupling waveguide 32 to the fourth coupling waveguide 35 under this size, and the wide side width of the fourth coupling waveguide 35 only supports the fundamental mode of the transverse electric mode. The wide side width is selected to be 0.32 microns and the narrow side width is selected to be 0.22 microns; the third coupling waveguide 32 and the fourth coupling waveguide 35 have the same axial length, which is called the coupling length. The lateral adjacent sides of the two are parallel, and the distance between them is called the coupling gap. In a specific implementation, considering the coupling efficiency of the coupler, the compactness of the overall device and the size limitation of the process, the coupling gap is selected to be 0.12 microns.

[0034] like Figure 4As shown, the polarization beam splitter 5 includes a fifth coupling waveguide 51, an intermediate waveguide 52, a sixth coupling waveguide 53 and a fifth curved waveguide 54; one end of the fifth coupling waveguide 51 serves as the input end of the polarization beam splitter 5, and the input end signal includes idler light of the fundamental mode of the transverse electric mode and the fundamental mode of the transverse magnetic mode; the other end of the fifth coupling waveguide 51 serves as the first output end of the polarization beam splitter 5; both ends of the intermediate waveguide 52 are vacant; one end of the sixth coupling waveguide 53 is vacant, and the other end of the sixth coupling waveguide 53 is connected to one end of the fifth curved waveguide 54, and the other end of the fifth curved waveguide 54 serves as the output end of the polarization beam splitter 5 a second output end; an intermediate waveguide 52 is provided on the side of the fifth coupling waveguide 51, and the fifth coupling waveguide 51 is coupled to the intermediate waveguide 52; a sixth coupling waveguide 53 is provided on the other side of the intermediate waveguide 52, and the intermediate waveguide 52 is coupled to the sixth coupling waveguide 53; a signal input to the input end of the polarization beam splitter 5, wherein the fundamental mode of the transverse electric mode is transmitted through the fifth coupling waveguide 51 and directly output at its output end, and the fundamental mode of the transverse magnetic mode is first coupled to the intermediate waveguide 52 and converted into the first-order mode of the transverse magnetic mode, and then coupled to the sixth coupling waveguide 53 and converted into the fundamental mode of the transverse magnetic mode, and output from the output end of the fifth curved waveguide 54;

[0035] The polarization beam splitter 5 adopts a three-waveguide asymmetric directional coupler structure, which has higher design flexibility and better coupling efficiency than the two-waveguide directional coupler structure. Since the fundamental mode of the transverse magnetic mode in the polarization beam splitter 5 needs to undergo a transformation process from the fundamental mode of the transverse magnetic mode to the first-order mode of the transverse magnetic mode to the fundamental mode of the transverse magnetic mode in the fifth coupling waveguide 51-intermediate waveguide 52-sixth coupling waveguide 53, the width of the intermediate waveguide 52 is required to support the transmission of the first-order mode of the transverse magnetic mode, and the width is 0.79 microns. The fifth coupling waveguide 51 and the sixth coupling waveguide 53 only need to support the transmission of the fundamental mode, and the width is set to 0.32 microns. The side surfaces of the fifth coupling waveguide 51, the intermediate waveguide 52, and the sixth coupling waveguide 53 are parallel and arranged in sequence at equal intervals, with an interval of 0.2 microns. In a specific implementation, the coupling lengths of the fifth coupling waveguide 51 and the intermediate waveguide 52, and the coupling lengths of the intermediate waveguide 52 and the sixth coupling waveguide 53 are optimized through multiple simulations and are 8 microns and 8.5 microns, respectively.

[0036] The adiabatic tapered waveguide 4 is used to connect two rectangular waveguides of different widths. The length is long enough to allow the waveguide width to change slowly, so that the optical signal can be transmitted stably with low loss.

[0037] The multimode nonlinear waveguide 1 is a waveguide that has undergone dispersion engineering and meets the conditions for an all-optical wavelength conversion process based on four-wave mixing for multi-wavelength-dual-polarization-dual-mode multiplexing signals. The conditions for the all-optical wavelength conversion process are that the signal light, pump light and idler light satisfy energy conservation and momentum conservation and have low inter-mode crosstalk when four-wave mixing occurs. Inter-mode crosstalk refers to the crosstalk between idler lights of different polarizations / modes generated when different types of four-wave mixing occur in polarization-mode multiplexing signals. Taking the output signal of the first single-mode output waveguide 6 as an example, the main signal at the output end of the first single-mode output waveguide 6 should be the first-order mode of the transverse magnetic mode. At this time, the transverse electric mode fundamental mode, transverse magnetic mode fundamental mode and transverse electric mode first-order mode received at the output end are all crosstalk of the output port.

[0038] The multimode nonlinear waveguide 1 can support the transmission of the transverse electric mode fundamental mode, the transverse electric mode first-order mode, the transverse magnetic mode fundamental mode, and the transverse magnetic mode first-order mode. In specific implementation, its size selection needs to meet the dispersion requirements: first, the dispersion zero points of the transverse electric mode fundamental mode, the transverse electric mode first-order mode, the transverse magnetic mode fundamental mode, and the transverse magnetic mode first-order mode are distributed as much as possible at a wavelength of 1.55 microns; second, the dispersion curves of the transverse electric mode fundamental mode, the transverse electric mode first-order mode, the transverse magnetic mode fundamental mode, and the transverse magnetic mode first-order mode are flat and have small dispersion values ​​within a certain wavelength range; third, the dispersion curves of the transverse electric mode fundamental mode, the transverse electric mode first-order mode, the transverse magnetic mode fundamental mode, and the transverse magnetic mode first-order mode have little difference; in addition, the power of the pump light and the length of the multimode nonlinear waveguide 1 are adjusted to maximize the wavelength conversion efficiency and realize an efficient four-wave mixing effect in the waveguide; finally, the width of the multimode nonlinear waveguide 1 is selected to be 0.65 microns and the length is 5 mm.

[0039] The multimode nonlinear waveguide 1 in the device of the present invention is a nanowire optical waveguide based on silicon-on-insulator (SOI) material. The nanowire optical waveguide is mainly composed of a core layer 10, an upper cladding layer 11 and a substrate 12. The cross-sectional diagram of the nanowire optical waveguide is shown in FIG. Figure 5 As shown, the upper cladding 11 is made of silicon dioxide (SiO2) material, with a thickness of 1 micron and a refractive index of 1.44; the substrate 12 is made of silicon dioxide (SiO2) material, with a thickness of 2 microns and a refractive index of 1.44; the core layer 10 is made of silicon (Si) material, with a thickness of 0.34 microns and a refractive index of 3.47.

[0040] The height of the transverse magnetic mode demultiplexer 2, transverse electric mode demultiplexer 3, polarization beam splitter 5, adiabatic tapered waveguide 4, first single-mode output waveguide 6, second single-mode output waveguide 7, third single-mode output waveguide 8, and fourth single-mode output waveguide 9 in the device of the present invention are all 0.34 microns. They are nanowire optical waveguides based on silicon-on-insulator (SOI) materials and are all small-section optical waveguide types with cross-sectional dimensions on the nanometer scale.

[0041] The following describes the working process of the present invention as an all-optical wavelength conversion device on a silicon substrate for three-dimensional hybrid multiplexing signals:

[0042] The working principle of the present invention is as follows Figure 6 As shown, each wavelength (λ1, λ2…λ n ) signal light and a pump light beam with an operating wavelength of 1.55 microns are simultaneously input into the input port of the all-optical wavelength conversion device, and an idler light corresponding to the signal light wavelength is obtained at the output port. The pump light contains two modes: the fundamental transverse magnetic mode (TM0) and the fundamental transverse electric mode (TE0). The signal light and idler light contain two polarization states: the transverse magnetic mode (TM) and the transverse electric mode (TE). Each polarization state contains two modes: the fundamental mode (TM0, TE0) and the first-order mode (TM1, TE1). When the signal light and pump light are input into the all-optical wavelength conversion device, they first enter the multimode nonlinear waveguide 1. The four optical signals TM0, TE0, TM1, and TE1 undergo multiple four-wave mixing processes simultaneously and are converted into four idler optical signals TM0, TE0, TM1, and TE1 of corresponding wavelengths. Then, they enter the input end of the transverse magnetic mode demultiplexer 2 together. TM1 is downloaded by the transverse magnetic mode demultiplexer 2 and input to the input end of the first single-mode output waveguide 6, and is output from the output end of the first single-mode output waveguide 6, i.e., the first output port of the all-optical wavelength conversion device. The remaining optical signals enter the input end of the transverse electric mode multiplexer 3 together. TE1 is downloaded by the transverse electric mode demultiplexer 3 and input to the input end of the fourth single-mode output waveguide 9, and is output from the output end of the fourth single-mode output waveguide 9, i.e., the fourth output port of the all-optical wavelength conversion device. The remaining optical signals are input to the polarization beam splitter 5 together through the adiabatic tapered waveguide 4. TE0 enters the second single-mode output waveguide 7 from the first output end of the polarization beam splitter 5 and is output from the output end of the second single-mode output waveguide 7, i.e., the second output port of the all-optical wavelength conversion device. TM0 enters the third single-mode output waveguide 8 from the second output end of the polarization beam splitter 5 and is output from the output end of the third single-mode output waveguide 8, i.e., the third output port of the all-optical wavelength conversion device. Finally, the idler light output from the four output ports is filtered out by a filter to obtain the required idler light. The idler light output from the first output port of the all-optical wavelength conversion device carries the same signal as the TM1 signal light, the idler light output from the second output port of the all-optical wavelength conversion device carries the same signal as the TE0 signal light, the idler light output from the third output port of the all-optical wavelength conversion device carries the same signal as the TM0 signal light, and the idler light output from the fourth output port of the all-optical wavelength conversion device carries the same signal as the TE1 signal light.

[0043] The device of the present invention realizes broadband all-optical wavelength conversion of dual-polarization dual-mode hybrid multiplexed signals in a multimode nonlinear waveguide. The device is suitable for all-optical wavelength conversion of three-dimensional multiplexed signals of N wavelengths, 2 polarizations, and 2 modes. The conversion efficiency of the idler light output by the dual-polarization dual-mode signal light through the all-optical wavelength conversion device varies with the wavelength of the signal light as shown in the following relationship: Figure 7 As shown, the horizontal axis represents the signal light wavelength, and the vertical axis represents the wavelength conversion efficiency. Since it is necessary to simultaneously consider the conversion processes of the four idler frequency lights TM0, TE0, TM1, and TE1 to ensure the balance of their conversion, it can be seen from the simulation results that the device of the present invention can realize all-optical wavelength conversion of three-dimensional hybrid multiplexed signals, and has high conversion efficiency (about -20dB) and a large 3dB conversion bandwidth (about 40nm).

[0044] Finally, it should be noted that the above embodiments and explanations are intended only to illustrate the technical solutions of the present invention and are not intended to limit the present invention. It should be understood by those skilled in the art that modifications or equivalent substitutions to the technical solutions of the present invention may be made without departing from the spirit and scope of the technical solutions disclosed herein, and all such modifications or equivalent substitutions shall be encompassed within the scope of protection of the claims of the present invention.

Claims

1. An on-chip all-optical wavelength conversion device for three-dimensional multiplexing signals based on a single nonlinear waveguide, characterized in that: The invention comprises a multimode nonlinear waveguide (1), a transverse magnetic mode demultiplexer (2), a transverse electric mode demultiplexer (3), a polarization beam splitter (5), an adiabatic tapered waveguide (4), a first single-mode output waveguide (6), a second single-mode output waveguide (7), a third single-mode output waveguide (8) and a fourth single-mode output waveguide (9); the input end of the multimode nonlinear waveguide (1) serves as the input end of the all-optical wavelength conversion device, the output end of the multimode nonlinear waveguide (1) is connected to the input end of the transverse magnetic mode demultiplexer (2), the second output end of the transverse magnetic mode demultiplexer (2) is connected to the input end of the transverse electric mode demultiplexer (3), the first output end of the transverse electric mode demultiplexer (3) is connected to the input end of the polarization beam splitter (5) through the adiabatic tapered waveguide (4), the first output end of the polarization beam splitter (5) is connected to the second single-mode output waveguide (7); the first output end of the transverse magnetic mode demultiplexer (2) is connected to the first single-mode output waveguide (6); the second output end of the transverse electric mode demultiplexer (3) is connected to the fourth single-mode output waveguide (9); the second output end of the polarization beam splitter (5) is connected to the third single-mode output waveguide (8); the first single-mode output waveguide (6), the second single-mode output waveguide (7), the third single-mode output waveguide (8) and the fourth single-mode output waveguide (9) respectively serve as the first output, the second output, the third output and the fourth output of the all-optical wavelength conversion device, the first output, the second output, the third output and the fourth output of the all-optical wavelength conversion device are respectively connected to corresponding filters, and the four filters respectively output idler light with signal light wavelengths corresponding to the first-order mode of the transverse magnetic mode, the fundamental mode of the transverse electric mode, the fundamental mode of the transverse magnetic mode and the first-order mode of the transverse electric mode.

2. The on-chip all-optical wavelength conversion device for three-dimensional multiplexing signals based on a single nonlinear waveguide according to claim 1, characterized in that: The transverse magnetic mode demultiplexer (2) comprises a first input waveguide (21), a first coupling waveguide (22), a first output waveguide (23), a first curved waveguide (24), a second coupling waveguide (25), and a second curved waveguide (26); one end of the first input waveguide (21) serves as the input end of the transverse magnetic mode demultiplexer (2); the other end of the first input waveguide (21) is connected to one end of the first output waveguide (23) via the first coupling waveguide (22); the other end of the first output waveguide (23) serves as the second output end of the transverse magnetic mode demultiplexer (2); the first coupling waveguide (24) is connected to the first output waveguide (23) via the first coupling waveguide (22); A second coupling waveguide (25) is arranged on the side of the guide (22); the first coupling waveguide (22) is coupled to the second coupling waveguide (25); one end of the first curved waveguide (24) is left vacant; the other end of the first curved waveguide (24) is connected to one end of the second curved waveguide (26) through the second coupling waveguide (25); an optical signal containing only a first-order mode of a transverse magnetic mode is output from the second curved waveguide (26); an optical signal containing other modes is output from the first output waveguide (23); and the other end of the second curved waveguide (26) serves as the first output end of the transverse magnetic mode demultiplexer (2).

3. The on-chip all-optical wavelength conversion device for three-dimensional multiplexing signals based on a single nonlinear waveguide according to claim 1, characterized in that: The transverse electric mode demultiplexer (3) comprises a second input waveguide (31), a third coupling waveguide (32), a second output waveguide (33), a third curved waveguide (34), a fourth coupling waveguide (35) and a fourth curved waveguide (36); one end of the second input waveguide (31) serves as the input end of the transverse electric mode demultiplexer (3), the other end of the second input waveguide (31) is connected to one end of the second output waveguide (33) via the third coupling waveguide (32), and the other end of the second output waveguide (33) serves as the first output end of the transverse electric mode demultiplexer (3); the third coupling waveguide (34) is connected to one end of the second output waveguide (33) via the third coupling waveguide (32). A fourth coupling waveguide (35) is arranged on the side of the guide (32), the third coupling waveguide (32) is coupled to the fourth coupling waveguide (35), one end of the third curved waveguide (34) is left vacant, the other end of the third curved waveguide (34) is connected to one end of the fourth curved waveguide (36) through the fourth coupling waveguide (35), an optical signal containing only the first-order mode of the transverse electric mode is output from the fourth curved waveguide (36), and an optical signal containing other modes is output from the second output waveguide (33), and the other end of the fourth curved waveguide (36) serves as the second output end of the transverse electric mode demultiplexer (3).

4. The on-chip all-optical wavelength conversion device for three-dimensional multiplexing signals based on a single nonlinear waveguide according to claim 1, characterized in that: The polarization beam splitter (5) comprises a fifth coupling waveguide (51), an intermediate waveguide (52), a sixth coupling waveguide (53) and a fifth curved waveguide (54); both ends of the intermediate waveguide (52) are vacant, and the fifth coupling waveguide (51) and the sixth coupling waveguide (53) are respectively arranged on both sides of the intermediate waveguide (52); the fifth coupling waveguide (51) is coupled and connected to the intermediate waveguide (52), and the intermediate waveguide (52) is coupled and connected to the sixth coupling waveguide (53); one end of the fifth coupling waveguide (51) serves as the input end of the polarization beam splitter (5), and the other end of the fifth coupling waveguide (51) serves as the first output end of the polarization beam splitter (5); one end of the sixth coupling waveguide (53) is vacant, and the other end of the sixth coupling waveguide (53) is connected to one end of the fifth curved waveguide (54), and the other end of the fifth curved waveguide (54) serves as the second output end of the polarization beam splitter (5).

5. The on-chip all-optical wavelength conversion device for three-dimensional multiplexing signals based on a single nonlinear waveguide according to claim 1, characterized in that: The multimode nonlinear waveguide (1) is a waveguide that has undergone dispersion engineering and satisfies the conditions for an all-optical wavelength conversion process based on multiple four-wave mixing processes in which multi-wavelength-dual polarization-dual mode multiplexed signals simultaneously occur. The conditions for the all-optical wavelength conversion process are that the signal light, the pump light and the idler light satisfy energy conservation and momentum conservation and have low inter-mode crosstalk when the four-wave mixing effect occurs.

6. The on-chip all-optical wavelength conversion device for three-dimensional multiplexing signals based on a single nonlinear waveguide according to claim 1, characterized in that: The transverse magnetic mode demultiplexer (2), the transverse electric mode demultiplexer (3) and the polarization beam splitter (5) are all of the strongly confined small-section optical waveguide type, and their cross-sectional dimensions are on the nanometer scale.

Images