Optical beam splitting assembly, optical beam splitter and optical quantum computer

Abstract

The light splitting assembly, the light splitter and the optical quantum computer provided by the present application comprise a light mode conversion waveguide assembly, a light mode separation assembly and a light signal filtering assembly. The mode conversion waveguide assembly is configured to receive an incident light signal containing multiple modes, and convert a first part of the light signal transmitted in a first type of mode in the incident light signal into a light signal transmitted in a third type of mode. The light mode separation assembly is configured to receive and separate the light signal transmitted in the third type of mode and a light signal transmitted in a second type of mode from a second part of the light signal transmitted in the first type of mode, and convert a third part of the light signal transmitted in the third type of mode into a light signal transmitted in a fourth type of mode. The light signal filtering assembly is configured to receive and filter out the second part of the light signal transmitted in the first type of mode which is not converted after passing through the light mode conversion waveguide assembly, and the fourth part of the light signal transmitted in the third type of mode which is not converted after passing through the light mode separation assembly.

Description

Technical Field

[0001] This application relates to the field of optical device technology, and in particular to an optical beam splitter assembly, an optical beam splitter, and an optical quantum computer. Background Technology

[0002] With the rapid development of technologies such as AI and 5G, thin-film lithium niobate (LiNbO3) photonic integration platforms are becoming increasingly popular. The development of on-chip multifunctional photonic devices is leading to the wider application of LiNbO3 thin-film photonic chips. It achieves high-performance, highly integrated photonic chips by fabricating ultra-thin (typically several hundred nanometers) single-crystal LiNbO3 thin-film layers on specially designed substrates and then processing photonic devices such as optical waveguides, modulators, and detectors on these thin films.

[0003] Currently, many optical devices have been developed based on the thin-mode lithium niobate PIC photonic integration platform, such as electro-optic modulators, nonlinear devices, and polarization rotating beam splitters. Among them, the polarization rotating beam splitter is an optical communication technology that improves optical communication capacity by utilizing two orthogonal polarization states of light (i.e., TE and TM polarization modes) to transmit information simultaneously.

[0004] In particular, by designing optical devices with on-chip polarization management functions to perform polarization compensation for coherent transmission systems, and using on-chip polarization rotator beamsplitters (PSRs) to rotate one of the polarization states, the system only needs to manipulate the same polarization state. This can improve the integration and capacity of thin-mode lithium niobate photonics. Therefore, high-performance polarization rotator beamsplitters are indispensable functional devices for lithium niobate photonics platforms.

[0005] However, the polarization extinction ratio decreases because the polarization rotating beam splitter has low coupling efficiency during mode coupling or mode evolution. Summary of the Invention

[0006] In view of this, one embodiment of this application provides an optical beam splitter assembly, an optical beam splitter, and an optical quantum computer, aiming to solve the problems of low polarization extinction ratio and limited operating bandwidth of traditional polarization rotation beam splitters.

[0007] On one hand, an embodiment of this application provides an optical beam splitter component, which includes an optical mode conversion waveguide component, an optical mode separation component, and an optical signal filtering component. The mode conversion waveguide component is configured to receive an incident optical signal containing multiple modes, and convert a first portion of the incident optical signal transmitted in a first type mode into an optical signal transmitted in a third type mode, while the optical signal transmitted in a second type mode in the incident optical signal maintains its original mode characteristics. The optical mode separation component is configured to receive and separate the optical signal transmitted in the third type mode and the optical signal transmitted in the second type mode from the second portion of the optical signal transmitted in the first type mode, and convert the third portion of the optical signal transmitted in the third type mode into an optical signal transmitted in a fourth type mode, while the optical signal transmitted in the fourth type mode and the optical signal transmitted in the second type mode are transmitted in the same transmission mode. The optical signal filtering component is configured to receive and filter out the unconverted second part of the optical signal transmitted in the first type mode after passing through the optical mode conversion waveguide component and the unconverted fourth part of the optical signal transmitted in the third type mode after passing through the optical mode separation component, so as to obtain the optical signal transmitted in the second type mode and the optical signal transmitted in the fourth type mode.

[0008] Secondly, an embodiment of this application provides an optical beamsplitter comprising an insulating layer, an insulating layer, a first planar structure located on the insulating layer, an optical beamsplitter assembly located on the first planar structure, and a cladding layer located on the first planar structure and the optical beamsplitter assembly. The optical beamsplitter assembly includes any of the above-mentioned optical beamsplitter assemblies.

[0009] Thirdly, an embodiment of this application provides an optical quantum computer including any of the above-mentioned optical beam splitter, single-photon source, and single-photon detector. The optical beam splitter is used to receive and perform calculations on photons generated by the single-photon source, so that the single-photon detector can detect the final state of the photon and output the calculation result.

[0010] One embodiment of this application provides an optical beam splitter that first "evolves" the transmission mode of a portion of the input optical signal from one mode to another, completing energy transfer. Then, it separates the different transmission modes. This mode evolution method does not require phase matching; therefore, its performance is not only insensitive to wavelength changes, which is beneficial for improving bandwidth utilization and extending from the original C-band to the C+L band, and even to the O-band, thus improving data transmission capacity, but also has a high tolerance for manufacturing errors, thereby improving yield. Furthermore, this structure helps to further reduce crosstalk and loss, thereby further increasing the transmission distance.

[0011] Furthermore, the optical beam splitter provided in this application sets up an optical signal filtering component after the optical mode conversion waveguide component and the optical mode separation component. This filters out the portion of the optical signal entering the optical beam splitter that is not completely converted to a higher-order mode after passing through the optical mode conversion waveguide component and the portion that is not completely converted to a fundamental mode after passing through the optical mode separation component. This ensures that the transmission mode and polarization state of the optical signal output from the optical beam splitter are the same, thereby improving the extinction ratio and signal-to-noise ratio of the optical beam splitter and providing a prerequisite for further improving the transmission distance and data rate. Attached Figure Description

[0012] It should be understood that the following figures only show some embodiments of this application and should not be regarded as a limitation on the scope.

[0013] It should be understood that the same or similar reference numerals are used in the accompanying drawings to denote the same or similar elements.

[0014] It should be understood that the accompanying drawings are only schematic, and the dimensions and scales of the elements in the drawings are not necessarily precise.

[0015] Figure 1 This is a schematic diagram of the structure of an optical beam splitter provided in an embodiment of this application.

[0016] Figure 2 This is a schematic diagram of the structure of an optical signal filtering component provided in another embodiment of this application.

[0017] Figure 3 This is a schematic diagram of the structure of an optical signal filtering component provided in another embodiment of this application.

[0018] Figure 4 This is a schematic diagram of the structure of a partial optical beam splitter component provided in another embodiment of this application.

[0019] Figure 5 This is a schematic diagram of the structure of a partial optical beam splitter component provided in another embodiment of this application.

[0020] Figure 6 This is a schematic diagram of the structure of a partial optical beam splitter component provided in another embodiment of this application.

[0021] Figure 7 This is a schematic diagram of the structure of a partial optical beam splitter component provided in another embodiment of this application.

[0022] Figure 8 for Figure 7 A schematic diagram of the optical mode conversion waveguide component in the provided optical beam splitter assembly.

[0023] Figure 9 This is a schematic diagram of the structure of a partial optical beam splitter component provided in another embodiment of this application.

[0024] Figure 10 This is a schematic diagram of the structure of a partial optical beam splitter component provided in another embodiment of this application.

[0025] Figure 11 This is a cross-sectional structural schematic diagram of an optical beam splitter provided in an embodiment of this application.

[0026] Figure 12 A graph showing the effective refractive index of the ridge waveguide of an optical mode conversion waveguide component provided in an embodiment of this application as a function of the width of the ridge waveguide.

[0027] Figure 13 The diagram shows the optical transmission simulation results of an optical beam splitter provided in one embodiment of this application.

[0028] Figure 14 The diagram shows the optical transmission simulation results of an optical beam splitter provided in one embodiment of this application.

[0029] Figure 15 This is a graph showing the transmission mode of an optical beam splitter provided in one embodiment of this application as a function of wavelength.

[0030] Figure 16 This is a graph showing the transmission mode of an optical beam splitter provided in one embodiment of this application as a function of wavelength. Detailed Implementation

[0031] The embodiments of this application are described below with reference to the accompanying drawings. It should be understood that there are various ways to implement this application, and it should not be construed as being limited to the embodiments described herein. The embodiments described herein are only for a more thorough and clear understanding of this application.

[0032] The emergence of polarization rotating beams (PSRs) has broken through the physical limitations of single-polarization channels, doubling the transmission rate without increasing spectral resources, thereby improving optical communication capacity. Specifically, PSRs split the input mixed optical signal (e.g., TE fundamental mode, TM fundamental mode, etc.) into two single-polarization beams, while rotating one of the polarization states by 90° (e.g., TM→TE). This reduces the need for subsequent devices to support only a single polarization state (e.g., TE fundamental mode), thus lowering transmission costs and complexity.

[0033] Currently, the implementation principles of polarization rotating beam splitters mainly fall into two categories: mode coupling and mode evolution. Mode coupling is based on the resonant energy exchange between two different modes. Its core requirement is phase matching. When the phase matching condition is met, an input mode (such as TE0) will periodically and completely transfer its power to another mode (such as TM0) through this perturbation, thus achieving mutual coupling and conversion between different polarization states. However, mode-coupled devices are very sensitive to wavelength, and the phase matching condition (β_ TE =β_TM This type of optical device typically only works perfectly at a specific wavelength. Once the wavelength changes, the phase-matching condition is broken, leading to a sharp drop in conversion efficiency. Therefore, the performance of this type of optical device is extremely dependent on the precise dimensions of the waveguide (such as etching depth and sidewall angle).

[0034] The principle of mode evolution is based on the adiabatic principle. Its core idea is that the shape and size of the optical waveguide cross-section change very slowly (adiabatically) along the direction of light propagation. In such optical devices, the optical mode "adaptively" adjusts its field distribution, thus smoothly "evolving" from one mode to another. That is, by rationally designing the shape and size of the optical waveguide cross-section, the optical mode can gradually evolve the input TM0 mode into the output TE1 mode, completing energy transfer. Then, a multimode interferometer separates the TE0 and TE1 modes. Since the gradient process does not require phase matching, it allows waveguide width deviations of ±30 nm. However, "adiabatic" optical devices require sufficiently slow changes in the optical waveguide, which typically results in very long devices (hundreds of micrometers to millimeters). Moreover, the design of the gradient profile is very complex, requiring extensive numerical simulations for optimization. Simultaneously, such optical devices need to achieve smooth and precise gradient shapes (such as continuous sidewall angle changes), which places extremely high demands on nanofabrication techniques (such as the control of reactive ion etching).

[0035] Based on this, refer to Figures 1 to 14 One embodiment of this application provides an optical beam splitter assembly 100 (e.g., a polarization rotation beam splitter assembly), which includes an optical mode conversion waveguide assembly 110, an optical mode separation assembly 120, and an optical signal filtering assembly 130. It is understood that the incident optical signal S1 (i.e., the optical signal input to the optical beam splitter assembly) can be a mixed-mode optical signal, which may include transverse electric modes (i.e., TE modes) and transverse magnetic modes (i.e., TM modes), such as the TE0 mode (i.e., the fundamental mode of the transverse electric mode), the TM0 mode (i.e., the fundamental mode of the transverse magnetic mode), the TE1 mode (i.e., a higher-order mode of the transverse electric mode), etc. In one example, the input end of the optical mode conversion waveguide assembly 110 is connected to a single-mode optical waveguide, so that the transmission modes of the incident optical signal S1 include the TE0 mode and the TM0 mode.

[0036] It is important to understand that different transmission modes can reflect the spatial energy distribution of the optical signal in the waveguide, as well as the transmission characteristics of the optical signal (such as phase velocity, effective refractive index, cutoff characteristics, etc.). The incident optical signal S1, containing different transmission modes, passes through the optical mode conversion waveguide component 110, the optical mode separation component 120, and the optical signal filtering component 130 successively, and is then output in the same transmission mode (e.g., TE0 mode or TM0 mode). This allows subsequent transmission to only require manipulating the optical signal of one transmission mode, thereby improving the integration and capacity of lithium niobate photonics.

[0037] Specifically, refer to Figure 1 The mode-conversion waveguide component 110 receives the incident optical signal S1, which includes TM0 and TE0 modes, and converts the first part of the TM0 mode (i.e., the first type of mode) into a higher-order mode (i.e., the TE1 mode, the third type of mode), while maintaining the original mode characteristics of the optical signal transmitted in the TE0 mode (i.e., the second type of mode). It can be understood that the mode-conversion waveguide component 110 can be designed with its geometry (e.g., core diameter) and material properties (refractive index distribution) based on a predetermined mode conversion relationship to enable the TM0 mode conversion. There are many methods to convert the TM0 mode to the TE1 mode, such as through mode coupling or mode evolution; no specific limitations are made here. Of course, the first type of mode can also be other modes (e.g., TE0), which will not be elaborated here.

[0038] Thus, the output of the mode conversion waveguide component 110 simultaneously contains both TE0 and TE1 modes. However, due to manufacturing errors, after passing through a region with manufacturing errors, there is a certain probability that it will not convert to the TE1 mode (i.e., the second part, the TM0 mode) and will continue to remain in the TM0 mode. Therefore, the output of the mode conversion waveguide component 110 simultaneously contains TE0, TE1, and TM0 modes.

[0039] The optical mode separator 120 receives and separates the TE0 and TE1 modes. During the separation process, due to a sudden change in waveguide width, the third part of the TE1 mode is converted to the TE0 mode. Thus, both TE0 and TM0 modes exist simultaneously at the input of the optical mode separator 120. However, due to manufacturing errors, there is a certain probability that the mode will not be converted to the TE0 mode (i.e., the fourth part of the TE1 mode) after passing through a region with manufacturing errors, and will remain in the TE1 mode. Therefore, the input and output of the optical mode separator 120 simultaneously contain TE0, TM0, and TE1 modes.

[0040] It is understandable that there are many ways to separate optical signals transmitted in mixed modes, such as asymmetric directional couplers, multimode interference couplers, etc.

[0041] The optical signal filtering component 130 is used to receive TE0 mode, TM0 mode, and TE1 mode and filter out TM0 mode and TE1 mode to obtain TE0 mode. TM0 mode may not be converted to TE1 mode after passing through a region with process errors. TE1 mode may not be converted to TE0 mode after passing through a region with process errors.

[0042] The specific process is as follows: the incident optical signal S1 includes a TM0 mode and a TE0 mode. First, it passes through the mode conversion waveguide component 110. Based on a predetermined mode conversion relationship, the TM0 mode is converted to the TE1 mode. However, due to manufacturing errors, after passing through a region with manufacturing errors, the TM0 mode has a certain probability of not being converted to the TE1 mode (i.e., the first part of the TM0 mode is converted to the TE1 mode, and the second part of the TM0 mode is not converted to the TE1 mode), and continues to remain in the TM0 mode. In addition, the optical signal transmitted in the TE0 mode maintains its original mode characteristics. Furthermore, the output of the mode conversion waveguide component 110 simultaneously contains the TE0 mode, the TE1 mode, and the TM0 mode (i.e., the second optical signal S2 in a mixed mode).

[0043] Secondly, the second optical signal S2 in the aforementioned mixed mode passes through the optical mode separation component 120. Based on the differences in propagation characteristics of different modes in a specific waveguide structure (mainly the difference in effective refractive index), according to predetermined design rules, the higher-order mode (i.e., TE1 mode) and the lower-order mode (i.e., TE0 mode and TM0 mode) are separated, and at the same time, the TE1 mode is converted to the TE0 mode. However, due to manufacturing process errors, after passing through the region with process error, the TE1 mode has a certain probability of not being converted to the TE1 mode (i.e., the third part of the TE1 mode is converted to the TE0 mode, and the fourth part of the TE1 mode is not converted to the TE0 mode), and continues to remain in the TE1 mode. In addition, the optical signal transmitted in the TE0 mode maintains its original mode characteristics for transmission. Furthermore, the output of the optical mode separation component 120 simultaneously contains the TE0 mode, the TM0 mode, and the TE1 mode (i.e., the third optical signal S3 in the mixed mode).

[0044] Finally, the third optical signal S3 of the above-mentioned mixed mode passes through the optical signal filtering component 130. Based on the differences in the propagation characteristics of different modes in a specific waveguide structure (mainly the difference in effective refractive index), according to the predetermined design rules, the TM0 mode and TE1 mode are filtered out. Therefore, the output of the optical signal filtering component 130 only has the TE0 mode.

[0045] It is understandable that the TE0 mode output by the output terminal of the optical signal filtering component 130 includes the TE0 mode in the incident optical signal and the part of the TE1 mode converted into the TE0 mode when entering the optical mode separation component 120. Other transmission modes are filtered out, which is beneficial to further improve the extinction ratio and signal-to-noise ratio.

[0046] The optical beam splitter provided in this application first "evolves" the transmission mode of a portion of the input optical signal from one mode to another, completing energy transfer. Then, it separates the different transmission modes. This mode evolution method does not require phase matching. Therefore, its performance is not only insensitive to wavelength changes, which is beneficial to improving bandwidth utilization, but also extends from the original C-band to the C+L band, and even to the O-band, thereby improving data transmission capacity. Moreover, it has a high tolerance for manufacturing errors, which is beneficial to improving yield. In addition, this structure is also beneficial to further reduce crosstalk and loss, so as to further increase the transmission distance.

[0047] Furthermore, the optical beam splitter provided in this application sets up an optical signal filtering component 130 after the optical mode conversion waveguide component 110 and the optical mode separation component 120. This filters out the portion of the incident optical signal entering the optical beam splitter that is not completely converted to a higher-order mode after passing through the optical mode conversion waveguide component and the portion that is not completely converted to a fundamental mode after passing through the optical mode separation component. This ensures that the transmission mode of the optical signal output from the optical beam splitter is the same, thereby improving the extinction ratio and signal-to-noise ratio of the optical beam splitter and providing a prerequisite for further improving the transmission distance and data rate.

[0048] refer to Figure 2 The optical signal filtering component 130 may include a first thermally adiabatic tapered optical waveguide 131 and a second thermally adiabatic tapered optical waveguide 132. The width of the first thermally adiabatic tapered optical waveguide 131 gradually decreases along the propagation direction Z of the incident optical signal (i.e., W1 > W5 > W3), while the width of the second thermally adiabatic tapered optical waveguide 132 gradually increases along the propagation direction Z of the incident optical signal (i.e., W2 < W6 < W4), and the first and second thermally adiabatic tapered optical waveguides 131 and 132 are arranged opposite to each other. Furthermore, the input terminals of the first and second thermally adiabatic tapered optical waveguides 131 and 132 are respectively connected to the optical mode separation component 120. It should be noted that, in this application, the propagation direction of the incident optical signal is defined as Z.

[0049] It is understood that the geometric parameters of the first adiabatic tapered optical waveguide 131 and the second adiabatic tapered optical waveguide 132 satisfy the adiabatic condition (i.e., when the width of the optical waveguide changes sufficiently gently, the optical field can always be maintained on the local eigenmode for transmission, avoiding inelastic scattering between modes). That is, the tapered optical waveguide can be regarded as a locally invariant straight waveguide at any position, so that the optical wave mode can be "converted" from one cross section to another cross section mode without energy loss (conversion efficiency close to 100%) during propagation when the transverse dimensions (such as width or height) change slowly.

[0050] It is worth noting that, since the first adiabatic tapered optical waveguide 131 and the second adiabatic tapered optical waveguide 132 are arranged opposite to each other along the propagation direction of the incident light signal, the widths of the first adiabatic tapered optical waveguide 131 and the second adiabatic tapered optical waveguide 132 change in opposite directions. Therefore, the widest position 1311 (width W1) of the first adiabatic tapered optical waveguide 131 corresponds to the narrowest position (width W2) of the second adiabatic tapered optical waveguide 132, and the narrowest position (width W3) of the first adiabatic tapered optical waveguide 131 corresponds to the widest position (width W4) of the second adiabatic tapered optical waveguide 132. In this way, the first adiabatic tapered optical waveguide 131 and the second adiabatic tapered optical waveguide 132 form an adiabatic coupling filter.

[0051] It is understandable that adiabatic-coupled filters can control the adiabatic evolution between different modes through precisely designed geometric parameters of the tapered waveguide structure. Its wavelength selectivity stems from the dependence of coupling efficiency on wavelength. When the incident light wavelength meets the adiabatic conversion condition (i.e., the phase-matching condition), the optical field will be completely transferred from the first adiabatic tapered waveguide 131 to the second adiabatic tapered waveguide 132 and output from the port of the second adiabatic tapered waveguide 132; this wavelength is the passband center wavelength. Conversely, for wavelengths that do not meet the condition, the optical field cannot be effectively coupled and will remain in the first adiabatic tapered waveguide 131 to continue propagating, thus outputting from the port of the second adiabatic tapered waveguide 132. This mechanism enables the filtering or separation of specific wavelength components.

[0052] Because this structure is less sensitive to fabrication errors in wavelength dimensions and coupling gaps, its performance is more stable. Furthermore, this structure not only has a wider filtering bandwidth but also improves the extinction ratio. A relatively long-arm Mach-Zehnder interferometer (MZI) can be implemented within a relatively short length, which helps improve the compactness of the structure. Thus, a first coupling region 10 is formed between the first adiabatic tapered optical waveguide 131 and the second adiabatic tapered optical waveguide 132. The first coupling region 10 is used to further filter out other modes to obtain a specific transmission mode. Moreover, because this structure is less sensitive to fabrication errors in wavelength dimensions, it is beneficial to further eliminate wavelength sensitivity, which is conducive to achieving the characteristics of C+L wide bandwidth transmission.

[0053] refer to Figure 2In one example, the first position O corresponds to the width W5 at point AB of the second adiabatic tapered waveguide 131, and the first position corresponds to the width W6 at point CD of the first adiabatic tapered waveguide 132, where W5 = W6. Thus, by setting the first and second adiabatic tapered waveguides 131 and 132 with the same width, the TE0 mode satisfies the phase-matching relationship, thereby achieving the separation and filtering of specific modes. Moreover, this implementation method helps to further reduce fabrication difficulty while achieving coupling and filtering. Of course, coupling and filtering can also be achieved by designing other geometric parameters such as the same cross-sectional area or height.

[0054] To further reduce processing difficulty, under the premise of meeting the insulation requirements, the lengths of the first insulating tapered optical waveguide 131 and the second insulating tapered optical waveguide 132 are equal along the transmission direction Z of the incident light signal, i.e., d1 = d2. In one example, 948 micrometers < d1 < 952 micrometers, for example, d1 = 949 micrometers, 950 micrometers, or 951 micrometers, preferably d1 = 950 micrometers. At the same time, 948 micrometers < d2 < 952 micrometers, for example, d2 = 949 micrometers, 950 micrometers, or 951 micrometers, preferably d2 = 950 micrometers, which is beneficial to improving mode conversion efficiency and extinction ratio.

[0055] It should be noted that, under the condition of meeting thermal insulation requirements, the shapes of the first thermally insulating tapered optical waveguide 131 and the second thermally insulating tapered optical waveguide 132 can be isosceles trapezoids (see reference). Figure 2 It can also be a non-isosceles trapezoid (such as a right trapezoid, as long as it meets the insulation requirements).

[0056] It should also be noted that the width of the side 1311 of the first thermally insulated tapered optical waveguide 131 connected to the optical mode separation component 120 is 1.15 μm ≤ W1 ≤ 1.35 μm, for example, 1.15 μm, 1.25 μm, or 1.35 μm, preferably W1 = 1.25 μm. The width of the side of the first thermally insulated tapered optical waveguide 131 away from the optical mode separation component 120 is 0.8 μm ≤ W3 ≤ 1.0 μm, for example, 0.8 μm, 0.9 μm, or 1.0 μm, preferably W3 = 0.9 μm. The width of the side of the second thermally insulated tapered optical waveguide 132 close to the optical mode separation component 120 is 0.8 μm ≤ W2 ≤ 1.0 μm, for example, 0.8 μm, 0.9 μm, or 1.0 μm, preferably W2 = 0.9 μm. The width of the side of the second thermally adiabatic conical waveguide 132 away from the optical mode separation component 120 is 1.15 μm ≤ < W4 ≤ 1.35 μm, for example, 1.15 μm, 1.25 μm, or 1.35 μm, preferably W4 = 1.25 μm. The spacing d3 between the first thermally adiabatic conical waveguide 131 and the second thermally adiabatic conical waveguide 132 satisfies 4 μm < d5 < 8 μm, for example, 5 μm, 6 μm, or 7 μm, preferably d5 = 6 μm. Furthermore, to reduce manufacturing difficulty, the shapes of the first thermally adiabatic conical waveguide 131 and the second thermally adiabatic conical waveguide 132 are symmetrically arranged. For example, both the first thermally adiabatic conical waveguide 131 and the second thermally adiabatic conical waveguide 132 are isosceles trapezoids, or both are non-isosceles trapezoids (e.g., right trapezoids).

[0057] Combination Figures 1 to 7 The optical mode separation component 120 may include a first waveguide branch 121 with uniform width and a second waveguide branch 122 with uniform width. The width W7 of the first waveguide branch 121 is greater than the width W8 of the second waveguide branch 122. The output end of the first waveguide branch 121 is connected to the input end of the first adiabatic tapered optical waveguide 131. The first waveguide branch 121 is used to transmit the TE0 mode (TE0 mode in the incident optical signal evolves into TE0 mode) and the TM0 mode (the part of the incident optical signal that has not been converted into TE1 mode). The second waveguide branch 122 is used to transmit the TE0 mode (i.e., the part of TE1 mode converted into TE0 mode) and the TE1 mode (i.e., the part of TE1 mode that has not been converted into TE0 mode).

[0058] It is understandable that a portion of the TM0 mode in the incident optical signal S1 is converted to the TE1 mode after passing through the mode conversion waveguide component 110. The transmission mode of the TE0 mode in the incident optical signal S1 remains unchanged after passing through the mode conversion waveguide component 110. The TE1 and TE0 modes are separated after passing through the optical mode separation component 120. Since the optical mode separation component 120 includes a first waveguide branch 121 and a second waveguide branch 122 with different widths, the input mode evolves into the output mode with the closest effective index (i.e., optical signals of different modes tend to propagate in the mode with the closest effective refractive index; therefore, the TE1 mode is separated into the narrower second waveguide branch 122, and the TE0 and TM0 modes are separated into the wider first waveguide branch 121). Furthermore, when the TE1 mode is separated, due to the abrupt change in width, the TE1 mode transforms into the TE0 mode and enters the second waveguide branch 122 for transmission, while the TE0 mode transforms into the TE0 mode. The TE1 mode that is not completely converted to the TE0 mode also propagates in the second waveguide branch 122. Among them, the TE0 mode and the TM0 mode are transmitted in the first waveguide branch 121, which has a larger width.

[0059] It is understandable that, due to the different widths of the first waveguide branch 121 and the second waveguide branch 122, the higher-order mode (TE1 mode) and lower-order mode (TE0 mode and TM0 mode) at the output of the optical mode conversion waveguide component 110 are separated into different waveguide branches. The included angle α between the first waveguide branch 121 and the second waveguide branch 122 is ≥30°, which helps reduce fabrication difficulty and accommodate manufacturing errors. In this way, the input mode of the optical mode separation component 120 evolves into the output mode with the closest effective index; that is, both the separated TE1 mode and TE0 mode evolve into the TE0 mode. In other words, the TE1 mode is converted to the TE0 mode while being separated into the second waveguide branch 122, and then transmitted in the second waveguide branch 122. Conversely, the TE0 mode is converted to the TE0 mode while being separated into the first waveguide branch 121, and then transmitted in the first waveguide branch 121, thus allowing the TE0 mode to be transmitted in different waveguide branches.

[0060] It should be noted that the width W7 of the first waveguide branch 121 satisfies 1.15 μm ≤ W7 ≤ 1.35 μm (e.g., 1.15 μm, 1.25 μm, 1.35 μm, etc., preferably W7 = 1.25 μm), and the width W8 of the second waveguide branch 122 satisfies 1.05 μm ≤ W7 ≤ 1.25 μm (e.g., 1.05 μm, 1.15 μm, 1.25 μm, etc., preferably W8 = 1.15 μm). This is beneficial for improving mode conversion efficiency and reducing extinction ratio. The sum of the widths W7 of the first waveguide branch 121 and W8 of the second waveguide branch 122 is less than or equal to the width of the connecting portion of the optical mode conversion waveguide assembly 110, further reducing the processing difficulty. This is to further improve mode conversion efficiency and extinction ratio.

[0061] Furthermore, the distance between the first waveguide branch 121 and the second waveguide branch 122 at their starting positions is less than or equal to 200 nm and greater than or equal to 0, in order to improve the extinction ratio. The length of the first waveguide branch 121 satisfies a value greater than or equal to 410 μm and less than or equal to 412 μm, for example, 410 μm, 411 μm, 412 μm, etc. Preferably, the length of the first waveguide branch 121 is 411 μm to improve transmission efficiency. The length of the second waveguide branch 122 is the same as that of the first waveguide branch, and will not be described in detail.

[0062] refer to Figures 4 to 7 The optical signal filtering component 130 may further include a third adiabatic tapered optical waveguide 133 and a fourth adiabatic tapered optical waveguide 134. The input end of the third adiabatic tapered optical waveguide 133 is connected to the output end of the second waveguide branch 122, and the width of the third adiabatic tapered optical waveguide 133 gradually decreases along the transmission direction Z of the incident optical signal; the width of the fourth adiabatic tapered optical waveguide 134 gradually increases along the transmission direction Z of the incident optical signal, and the third adiabatic tapered optical waveguide 133 and the fourth adiabatic tapered optical waveguide 134 are arranged opposite to each other.

[0063] Understandably, similar in structure and function to the first and second adiabatic tapered waveguides 131 and 132, the third and fourth adiabatic tapered waveguides 133 and 134 form an adiabatic coupled filter. A second coupling region 20 exists between the third and fourth adiabatic tapered waveguides 133 and 134, used to further filter out other modes. Specifically, the TE1 mode (the portion where mode conversion did not occur due to manufacturing errors in the error region) and the TE0 mode (the portion converted from the TE1 mode) propagate in the second waveguide branch 122. Therefore, the TE1 and TE0 modes pass through the second branch 122 and enter the second coupling region 20, where the TE1 mode is further filtered to obtain the TE0 mode, thereby further improving the extinction ratio.

[0064] Similarly, the geometric parameters of the third adiabatic tapered optical waveguide 133 and the fourth adiabatic tapered optical waveguide 134 satisfy the adiabatic condition (i.e., when the width change of the optical waveguide is sufficiently gradual, the optical field can always be propagated on the local intrinsic modes, avoiding inelastic scattering between modes), that is, the tapered optical waveguide is regarded as a locally invariant straight waveguide at any position. Moreover, since the third adiabatic tapered optical waveguide 133 and the fourth adiabatic tapered optical waveguide 134 are arranged opposite to each other, and the width changes of the third adiabatic tapered optical waveguide 133 and the fourth adiabatic tapered optical waveguide 134 are opposite along the propagation direction of the incident light signal, the widest position of the third adiabatic tapered optical waveguide 133 corresponds to the narrowest position of the fourth adiabatic tapered optical waveguide 134, and the narrowest position of the third adiabatic tapered optical waveguide 133 corresponds to the widest position of the fourth adiabatic tapered optical waveguide 134.

[0065] In one example, reference Figure 5 At the second position O', the width W9 of the third adiabatic tapered waveguide is equal to the width W10 of the fourth adiabatic tapered waveguide. Thus, by setting the third adiabatic tapered waveguide 133 and the fourth adiabatic tapered waveguide 134 with the same width, the TE0 mode satisfies the phase matching relationship, thereby achieving the separation and filtering of specific modes. Moreover, this implementation method helps to further reduce fabrication difficulty while achieving coupling and filtering. Of course, coupling and filtering can also be achieved by designing the same cross-sectional area or height and other geometric parameters.

[0066] To further reduce the processing difficulty, while meeting the insulation requirements, the lengths of the third adiabatic conical waveguide 133 and the fourth adiabatic conical waveguide 134 are equal along the transmission direction Z of the incident light signal, i.e., d3 = d4 (reference). Figure 4 Of course, under the premise of meeting the insulation conditions, in order to further reduce the processing difficulty, in one example, d3 = d4 = d1 = d2. For example, 948 micrometers < d3 < 952 micrometers, such as d3 = 949 micrometers, 950 micrometers, 951 micrometers, preferably d3 = 950 micrometers. At the same time, 948 micrometers < d4 < 952 micrometers, such as d4 = 949 micrometers, 950 micrometers, 951 micrometers, preferably d4 = 950 micrometers, to improve the extinction ratio and transmission efficiency.

[0067] It should be noted that, under the condition of meeting the insulation requirements, the shapes of the third insulation conical optical waveguide 133 and the fourth insulation conical optical waveguide 134 can be isosceles trapezoids or non-isosceles trapezoids (such as right trapezoids), as long as they meet the insulation requirements, which helps to reduce the processing difficulty.

[0068] It should also be noted that the reference Figure 4 and Figure 5The width of the third adiabatic tapered optical waveguide 133 on the side closest to the optical mode separation component 120 is 1.05 μm ≤ W11 ≤ 1.25 μm, for example, 1.05 μm, 1.15 μm, or 1.25 μm; preferably, W11 = 1.15 μm. The width of the third adiabatic tapered optical waveguide 133 on the side furthest from the optical mode separation component 120 is 0.8 μm ≤ W13 ≤ 1.0 μm, for example, 0.8 μm, 0.9 μm, or 1.0 μm; preferably, W13 = 0.9 μm. The width of the fourth adiabatic tapered optical waveguide 134 on the side closest to the optical mode separation component 120 is 0.8 μm ≤ W12 ≤ 1.0 μm, for example, 0.8 μm, 0.9 μm, or 1.0 μm; preferably, W12 = 0.9 μm. The width of the side of the fourth adiabatic tapered optical waveguide 134 away from the optical mode separation component 120 is 1.05 μm ≤ W14 ≤ 1.25 μm, for example, 1.05 μm, 1.15 μm, or 1.25 μm, preferably W14 = 1.15 μm. The spacing d6 between the third adiabatic tapered optical waveguide 133 and the fourth adiabatic tapered optical waveguide 134 satisfies 3 μm < d6 < 7 μm, for example, 4 μm, 5 μm, or 6 μm, preferably d6 = 5 μm.

[0069] refer to Figure 10 The optical signal filtering component 130 may further include an eighth tapered optical waveguide 141 with uniform width and a ninth tapered optical waveguide 142 with uniform width. The input end of the eighth tapered optical waveguide 141 has the same width as the output end of the second adiabatic tapered optical waveguide 132, and the input end of the eighth tapered optical waveguide 141 is connected to the output end of the second adiabatic tapered optical waveguide 132 for transmitting TEO mode. The width of the eighth tapered optical waveguide 141 is greater than or equal to 1.15 micrometers and less than or equal to 1.35 micrometers, for example, 1.15 micrometers, 1.25 micrometers, or 1.35 micrometers. Preferably, the width of the eighth tapered optical waveguide 141 is 1.25 micrometers.

[0070] Continue to refer to Figure 9 The input end of the ninth tapered optical waveguide 142 has the same width as the output end of the fourth adiabatic tapered optical waveguide 134, and the input end of the ninth tapered optical waveguide 142 is connected to the output end of the fourth adiabatic tapered optical waveguide 134 for transmitting the TEO mode. The width of the ninth tapered optical waveguide 142 is greater than or equal to 1.05 micrometers and less than or equal to 1.25 micrometers, for example, 1.05 micrometers, 1.15 micrometers, or 1.25 micrometers. Preferably, the width of the ninth tapered optical waveguide 142 is 1.15 micrometers.

[0071] It is understandable that, since the TE0 mode satisfies the phase matching condition, the TE0 mode propagating in the first adiabatic tapered optical waveguide 131 is coupled to the second adiabatic tapered optical waveguide 132 for propagation, and then to the eighth tapered optical waveguide 141. Similarly, since the TE0 mode satisfies the phase matching condition, the TE0 mode located in the third adiabatic tapered optical waveguide 133 is coupled to the fourth adiabatic tapered optical waveguide 134 for propagation, until it reaches the ninth tapered optical waveguide 142. In this way, the transmission mode at the output of the optical beam splitter 100 is only the TE0 mode, so that subsequent devices only need to support a single polarization state, thereby reducing transmission cost and complexity.

[0072] Furthermore, since the widths of the eighth tapered optical waveguide 141 and the ninth tapered optical waveguide 142 are uniformly distributed and used only for transmitting the TE0 mode, the lengths of the eighth tapered optical waveguide 141 and the ninth tapered optical waveguide 142 can be set according to actual needs, and no specific limitation is made here. In one example, the lengths of the eighth tapered optical waveguide 141 and the ninth tapered optical waveguide 142 are both greater than or equal to 19 micrometers and less than or equal to 21 micrometers, such as 19 micrometers, 20 micrometers, 21 micrometers, etc. Preferably, the lengths of the eighth tapered optical waveguide 141 and the ninth tapered optical waveguide 142 are both 20 micrometers.

[0073] In one example, the lengths of the first adiabatic conical optical waveguide 131, the second adiabatic conical optical waveguide 132, the third adiabatic conical optical waveguide 133, and the fourth adiabatic conical optical waveguide 134 are equal, and the lengths of the first adiabatic conical optical waveguide 131, the second adiabatic conical optical waveguide 132, the third adiabatic conical optical waveguide 133, and the fourth adiabatic conical optical waveguide 134 all satisfy greater than or equal to 949 micrometers and less than or equal to 951 micrometers. Preferably, d1 = d2 = d3 = d4 = 950 micrometers to further improve transmission efficiency and extinction ratio.

[0074] Continue to refer to Figure 8 and Figure 9 Along the transmission direction Z of the incident light signal, the optical mode conversion waveguide assembly 110 may sequentially include a fifth adiabatic tapered optical waveguide 111, a sixth adiabatic tapered optical waveguide 112, and a seventh adiabatic tapered optical waveguide 113. The input end of the fifth adiabatic tapered optical waveguide 111 can be connected to a single-mode optical waveguide to ensure that the incident light signal includes both TE0 and TMO modes. The output end of the fifth adiabatic tapered optical waveguide 111 is connected to the input end of the sixth adiabatic tapered optical waveguide 112, the output end of the sixth adiabatic tapered optical waveguide 112 is connected to the input end of the seventh adiabatic tapered optical waveguide 113, and the output end of the seventh adiabatic tapered optical waveguide 113 is connected to the first waveguide branch 121 and the second waveguide branch 122.

[0075] Among them, the widths of the fifth, sixth, and seventh adiabatic tapered optical waveguides gradually increase in width along the transmission direction Z of the incident light signal. Furthermore, the width d7 of the output end of the fifth adiabatic tapered optical waveguide is equal to the width d8 of the input end of the sixth adiabatic tapered optical waveguide; the width d9 of the output end of the sixth adiabatic tapered optical waveguide is equal to the width d10 of the input end of the seventh adiabatic tapered optical waveguide; and the width d11 of the output end of the seventh adiabatic tapered optical waveguide is greater than or equal to the sum of the widths W7 of the input end of the first waveguide branch 121 and W8 of the input end of the second waveguide branch 122 (reference). Figures 4 to 7 ).

[0076] It is understandable that the widths of the fifth, sixth, and seventh adiabatic tapered optical waveguides 111, 112, and 113 change slowly to meet the insulation requirements. The sixth adiabatic tapered optical waveguide 112 is mainly used for mode conversion, so that a portion of the TM0 mode (i.e., the first part of the optical signal) is converted to the TE1 mode, while the TE0 mode maintains its original transmission mode. The seventh adiabatic tapered optical waveguide 113 is connected to the optical mode separation component 120 (e.g., an asymmetric Y-branch structure) to separate the TE0 mode and the TE1 mode.

[0077] It should be noted that, in order to obtain higher mode conversion efficiency, the width of the input end of the fifth adiabatic tapered optical waveguide 111 satisfies 0.8 μm ≤ d12 ≤ 1.0 μm (e.g., 0.8 μm, 0.9 μm, 1.0 μm, etc., preferably, d12 = 0.9 μm); the width of the output end of the fifth adiabatic tapered optical waveguide 111 (i.e., the input end of the sixth adiabatic tapered optical waveguide 112) satisfies 1.3 μm ≤ d7 (d8) ≤ 1.5 μm (e.g., 1.3 μm, 1.4 μm, 1.5 μm, etc., preferably, d7 = d8). The width of the output end of the sixth adiabatic conical optical waveguide 112 (i.e., the input end of the seventh adiabatic conical optical waveguide 113) satisfies 1.9 μm ≤ d9(d10) ≤ 2.1 μm (e.g., 1.9 μm, 2.0 μm, 2.1 μm, etc., preferably, d9 = d10 = 2.0 μm); the width of the output end of the seventh adiabatic conical optical waveguide 113 satisfies 2.5 μm ≤ d11 ≤ 2.7 μm (e.g., 2.5 μm, 2.6 μm, 2.7 μm, etc., preferably, d11 = 2.6 μm). To meet the insulation requirements and achieve high transmission efficiency, the length of the fifth insulated tapered optical waveguide 111 satisfies 34 μm ≤ d13 ≤ 36 μm (e.g., 34 μm, 35 μm, 36 μm, etc., preferably d13 = 35 μm); the length d14 of the sixth insulated tapered optical waveguide 112 satisfies 184.6 μm ≤ d14 ≤ 186.6 μm (e.g., 184.6 μm, 185.6 μm, 186.6 μm, etc., preferably d14 = 185.6 μm); and the length d15 of the seventh insulated tapered optical waveguide 113 satisfies 19 μm ≤ d15 ≤ 21 μm (e.g., 19 μm, 20 μm, 21 μm, etc., preferably d15 = 20 μm).

[0078] The following is combined Figures 9 to 13 An embodiment of the optical beam splitter 100 provided in this application is described, wherein the incident optical signal includes a TMO mode and a TEO mode.

[0079] The optical beam splitter assembly 100 may include an optical mode conversion waveguide assembly 110, an optical mode separation assembly 120, and an optical signal filtering assembly 130. The optical mode conversion waveguide assembly 110 may be a three-segment adiabatic tapered structure, comprising a fifth adiabatic tapered optical waveguide 111, a sixth adiabatic tapered optical waveguide 112, and a seventh adiabatic tapered optical waveguide 113. This three-segment adiabatic tapered structure can be used to convert a portion of the TM0 mode in the incident optical signal into a TE1 mode, with the TE0 mode transmitting using its original transmission characteristics. Specifically, the fifth adiabatic tapered optical waveguide 111, the sixth adiabatic tapered optical waveguide 112, and the seventh adiabatic tapered optical waveguide 113 are all partially etched ridge waveguides, with the ridge waveguide width gradually increasing from narrow to wide. By optimizing the width of the optical waveguide, a mode hybridization region of TM0 mode and TE1 mode exists in the three-segment adiabatic tapered structure. The selection of the initial width and the width difference at the end of each adiabatic tapered optical waveguide must meet the process tolerance requirements. The length of each adiabatic tapered optical waveguide should be as efficient as possible to ensure mode conversion, so as to improve the conversion efficiency of TM0 mode.

[0080] The optical mode separation component 120 can be an asymmetric Y-branch structure, comprising a first waveguide branch 121 of uniform width (i.e., the wide arm of the asymmetric Y-branch) and a second waveguide branch 122 of uniform width (i.e., the narrow arm of the asymmetric Y-branch). The asymmetric Y-branch structure is connected to the output end of the seventh adiabatic tapered optical waveguide 113. The wide arm of the asymmetric Y-branch is used to convert the input TE0 mode into the TE0 mode, and the narrow arm of the asymmetric Y-branch is used to convert the input TE1 mode into the TE0 mode.

[0081] The optical signal filtering component 130 can be an asymmetric DC filtering structure, comprising a first adiabatic tapered optical waveguide 131, a second adiabatic tapered optical waveguide 132, an eighth adiabatic tapered optical waveguide 141, a third adiabatic tapered optical waveguide 133, a fourth adiabatic tapered optical waveguide 134, and a ninth tapered optical waveguide 142. The first and third adiabatic tapered optical waveguides 131 and 133 are both tapered waveguides that gradually narrow, while the second and fourth adiabatic tapered optical waveguides 132 and 134 are both tapered waveguides that gradually widen. Furthermore, there exists a first position where the width of the third adiabatic tapered optical waveguide 133 is equal to the width of the fourth adiabatic tapered optical waveguide 134, so that the TE0 mode satisfies the phase matching condition.

[0082] The first adiabatic tapered waveguide 131 and the second adiabatic tapered waveguide 132 constitute the first filtering structure (i.e., the first coupling region), used to filter out the TM0 mode output from the wide arm of the asymmetric Y-branch. The third adiabatic tapered waveguide 133 and the fourth adiabatic tapered waveguide 134 constitute the second filtering structure (i.e., the second coupling region), used to filter out the TE1 mode output from the narrow arm of the asymmetric Y-branch.

[0083] It should be noted that the reference Figures 11 to 14The three-segment adiabatic tapered structure employs a partially etched ridge waveguide. The vertical asymmetry enhances the hybridization of the modes. Using a finite-difference (FDE) solver, different propagation modes within the ridge waveguide, such as the TE, TM0, and TE1 modes, are obtained. The effective refractive index curves as a function of the ridge waveguide width reveal a hybrid mode of TM0 and TE1 near a width of 1.8 μm, where the polarization states are indistinguishable. As the waveguide width gradually increases, a slow change in ridge waveguide width allows for an adiabatic transition from the TM0 mode to the TE1 mode. The effective refractive index curves of the TE0, TM0, and TE1 modes in the partially etched ridge waveguide of the asymmetric Y-branch structure are obtained using the FDE solver and are related to the width of the strip waveguide (i.e., the first and second waveguide branches). Figure 11 It can be seen that after the TE0 and TE1 modes pass through the asymmetric Y-branch structure (α≥30°) which functions as a mode sorter, the input modes will evolve into output arm modes with the closest effective index. This means that different input modes (e.g., TE0 and TE1 modes) can evolve into TE0 modes in the wide arm and narrow arm of the asymmetric Y-branch, respectively. Furthermore, the curve showing the change in the width of the effective refractive index waveguide indicates that the width of the output end of the seventh adiabatic tapered optical waveguide 113 is 2.6 μm. When the width of the narrow arm of the asymmetric Y-branch is 1.15 μm and the length is 411 μm, the evolution from TE1 mode to TE0 mode can be achieved in the narrow arm of the asymmetric Y-branch. When the width of the wide arm of the asymmetric Y-branch is 1.25 μm and the length is 411 μm, the evolution from TE0 mode to TE0 mode can be achieved in the wide arm of the asymmetric Y-branch. At the same time, the initial spacing between the wide arm and the narrow arm of the asymmetric Y-branch can be less than or equal to 200 nm (e.g., 200 nm) to meet the lithographic tolerance requirements. The etching depth of the first and second filtering regions is 200 nm, i.e., the ridge height is 200 nm, and the thickness of the partially etched waveguide plate 163 is 200 nm.

[0084] Uncertainties in manufacturing processes may lead to an increase in incompletely rotated TM0 modes and incompletely coupled TE1 modes, which will remain in the first adiabatic tapered waveguide 131 and the third adiabatic tapered waveguide 133. The first adiabatic tapered waveguide 131 has an initial width of 1.25 μm and an end width of 0.9 μm. The corresponding second adiabatic tapered waveguide 132 has an initial width of 0.9 μm, an end width of 1.25 μm, and a length of 950 μm. After the width of the eighth adiabatic tapered waveguide 141 is fixed at 1.25 μm, the residual TM0 and TE1 modes can be effectively filtered out, thereby improving the polarization extinction ratio. Simultaneously, the use of adiabatic... The asymmetric DC filter structure is beneficial for reducing wavelength sensitivity, thus facilitating the realization of the broadband characteristics of C+L. The third adiabatic tapered optical waveguide 133 has an initial width of 1.15 μm and an end width of 0.9 μm. The corresponding fourth adiabatic tapered optical waveguide 134 has an initial width of 0.9 μm, an end width of 1.15 μm, and a length of 950 μm. After the width of the fourth adiabatic tapered optical waveguide 134 is fixed at 1.15 μm, it can effectively filter out residual TM0 and TE1 modes, thereby improving the polarization extinction ratio. At the same time, the use of an adiabatic asymmetric DC filter structure is beneficial for reducing wavelength sensitivity, thus facilitating the realization of the broadband characteristics of C+L.

[0085] It should be noted that, for reference Figure 13 and Figure 16 The transmission efficiencies from the input transmission modes TE0 and TM0 to the two output ports in the C+L band were calculated using the EME solver. Figure 13 As shown, the polarization extinction ratio of both ports is greater than 38dB throughout the C+L band, which is beneficial for improving transmission distance and capacity.

[0086] refer to Figure 11 One embodiment of this application also provides an optical beamsplitter 160 (e.g., a polarization rotation beamsplitter), which includes an insulating layer 164 (e.g., may include a waveguide substrate 1641 and a base 1642), a first planar structure 163 located on the insulating layer 164, an optical beamsplitter assembly 162 (i.e., a waveguide layer) located on the first planar structure 163, and a cladding 161 located on the first planar structure 163 and the optical beamsplitter assembly 162. The optical beamsplitter assembly may include an optical mode conversion waveguide assembly, an optical mode separation assembly, and an optical signal filtering assembly as provided in the above embodiments, and will not be described in detail.

[0087] It should be noted that all optical waveguide structures in this application are partially etched ridge waveguides (see reference). Figure 10 The optical beam splitter 162 and the first planar structure 163 of the partially etched waveguide are made of thin-mode lithium niobate, the substrate 1642 is made of silicon, and the cladding 161 and the waveguide substrate 161 are made of silicon dioxide.

[0088] In practical applications, the optical beam splitter provided in this application can be implemented based on basic materials such as lithium niobate (LiNbO3) and integrated into an optical quantum computer. An optical quantum computer is a quantum computing device that uses photons (light particles) as qubits for information processing.

[0089] A quantum computer primarily consists of a single-photon source, a quantum chip, and a detection system. The single-photon source generates high-quality single photons, which serve as the carriers of qubits, through laser excitation of quantum dots or spontaneous parametric down-conversion (SPDC). The quantum processor is composed of optical components such as optical fibers, waveguides, beam splitters, phase modulators, and mirrors to achieve optical transmission and logical operations (e.g., Hadamard gates, CNOT gates). The detection system measures the final state of the photons (e.g., polarization or path) and outputs the calculation results. For detailed descriptions of the specific processing procedures of a quantum computer, please refer to the relevant technical descriptions; they will not be elaborated upon here.

[0090] In practical applications, the optical beam splitter provided in this application can relate to the optical beam splitter of the aforementioned optical quantum computer.

[0091] Therefore, the aforementioned optical beam splitters or optical quantum computers are also within the scope of protection of this application.

[0092] It is understood that in this application, directional descriptions such as "upper," "lower," "inner," and "outer" are relative rather than absolute. These directional terms may be applicable when the optical beam splitter provided in this application is positioned according to the orientation and location shown in the accompanying drawings.

[0093] It should be understood that although terms such as "first" or "second" may be used in this application to describe various elements (such as the first thermally adiabatic tapered optical waveguide and the second thermally adiabatic tapered optical waveguide), these elements are not defined by these terms, which are only used to distinguish one element from another.

[0094] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0095] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

[0096] The components and devices described in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the accompanying drawings. As those skilled in the art will recognize, these components and devices can be connected, arranged, and configured in any manner.

[0097] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An optical beam splitter assembly, characterized in that, include: An optical mode conversion waveguide assembly is configured to receive an incident optical signal containing multiple transmission modes, and to convert a first portion of the incident optical signal transmitted in a first type mode into an optical signal transmitted in a third type mode, while the optical signal transmitted in a second type mode in the incident optical signal maintains its original mode characteristics during transmission. An optical mode separation component is configured to receive and separate an optical signal transmitted in the third type mode and an optical signal transmitted in the second type mode from a second portion of the optical signal transmitted in the first type mode, and to convert the third portion of the optical signal transmitted in the third type mode into an optical signal transmitted in the fourth type mode. The optical signal transmitted in the fourth type mode and the optical signal transmitted in the second type mode are transmitted using the same transmission mode. The optical mode separation component includes a first waveguide branch with uniform width and a second waveguide branch with uniform width, wherein the width of the first waveguide branch is greater than the width of the second waveguide branch; The output end of the first waveguide branch is connected to the input end of the first adiabatic tapered optical waveguide, and the first waveguide branch is used to transmit optical signals transmitted in the second type mode; The output end of the second waveguide branch is connected to the input end of the first adiabatic tapered optical waveguide. The second waveguide branch is used to transmit the unconverted fourth part of the optical signal transmitted in the third type mode and the optical signal transmitted in the fourth type mode. An optical signal filtering component is configured to receive and filter out the unconverted second portion of the optical signal transmitted in the first type of mode after passing through the optical mode conversion waveguide component and the unconverted fourth portion of the optical signal transmitted in the third type of mode after passing through the optical mode separation component, thereby obtaining an optical signal transmitted in the second type of mode and an optical signal transmitted in the fourth type of mode, wherein... The optical signal filtering component includes a first thermally adiabatic tapered optical waveguide and a second thermally adiabatic tapered optical waveguide. The width of the first thermally adiabatic tapered optical waveguide gradually decreases along the transmission direction of the incident light signal, and the first thermally adiabatic tapered optical waveguide is connected to the optical mode separation component. The width of the second thermally adiabatic conical optical waveguide gradually increases along the transmission direction of the incident light signal, and the first thermally adiabatic conical optical waveguide and the second thermally adiabatic conical optical waveguide are arranged opposite to each other. In the first position, the width of the first thermally adiabatic tapered optical waveguide is equal to the width of the second thermally adiabatic tapered optical waveguide. The optical signal filtering component further includes: a third heat-insulated conical optical waveguide and a fourth heat-insulated conical optical waveguide; The input end of the third adiabatic tapered optical waveguide is connected to the output end of the second waveguide branch, and the width of the third adiabatic tapered optical waveguide gradually becomes thinner along the transmission direction of the incident light signal. The width of the fourth thermally adiabatic conical optical waveguide gradually increases along the transmission direction of the incident light signal, and the third thermally adiabatic conical optical waveguide and the fourth thermally adiabatic conical optical waveguide are arranged opposite to each other. In the second position, the width of the third adiabatic tapered optical waveguide is equal to the width of the fourth adiabatic tapered optical waveguide.

2. The optical beam splitter assembly according to claim 1, characterized in that, Along the transmission direction of the incident light signal, the lengths of the first thermally adiabatic conical optical waveguide and the second thermally adiabatic conical optical waveguide are equal.

3. The optical beam splitter assembly according to claim 1, characterized in that, The angle between the first waveguide branch and the second waveguide branch is greater than or equal to 30°.

4. The optical beam splitter assembly according to claim 1, characterized in that, Along the transmission direction of the incident light signal, the lengths of the third and fourth adiabatic conical optical waveguides are equal.

5. The optical beam splitter assembly according to claim 1, characterized in that, Along the transmission direction of the incident light signal, the optical mode conversion waveguide assembly sequentially includes a fifth adiabatic conical optical waveguide, a sixth adiabatic conical optical waveguide, and a seventh adiabatic conical optical waveguide. The output end of the fifth adiabatic tapered optical waveguide is connected to the input end of the sixth adiabatic tapered optical waveguide, the output end of the sixth adiabatic tapered optical waveguide is connected to the input end of the seventh adiabatic tapered optical waveguide, and the output end of the seventh adiabatic tapered optical waveguide is connected to the first waveguide branch and the second waveguide branch. The widths of the fifth, sixth, and seventh adiabatic conical optical waveguides gradually increase along the transmission direction of the incident light signal. Furthermore, the width of the output end of the fifth adiabatic tapered optical waveguide is equal to the width of the input end of the sixth adiabatic tapered optical waveguide, the width of the output end of the sixth adiabatic tapered optical waveguide is equal to the width of the input end of the seventh adiabatic tapered optical waveguide, and the width of the output end of the seventh adiabatic tapered optical waveguide is greater than or equal to the sum of the widths of the input ends of the first waveguide branch and the second waveguide branch.

6. The optical beam splitter assembly according to claim 1, characterized in that, The optical signal filtering component also includes an eighth tapered optical waveguide with uniform width and a ninth tapered optical waveguide with uniform width. The input end of the eighth tapered optical waveguide has the same width as the output end of the second adiabatic tapered optical waveguide, and the input end of the eighth tapered optical waveguide is connected to the output end of the second adiabatic tapered optical waveguide for transmitting optical signals transmitted in the second type of mode. The input end of the ninth tapered optical waveguide has the same width as the output end of the fourth adiabatic tapered optical waveguide, and the input end of the ninth tapered optical waveguide is connected to the output end of the fourth adiabatic tapered optical waveguide for transmitting optical signals transmitted in the fourth type mode.

7. An optical beam splitter, characterized in that, include: Insulation layer, The first flat plate structure is located on the insulating layer. An optical beam splitter assembly, located on the first planar structure, as described in any one of claims 1 to 6. The cladding is located on the first planar structure and the optical beam splitter assembly.

8. A quantum optical computer, characterized in that, The optical quantum computer includes the optical beam splitter, single-photon source, and single-photon detector as described in claim 7. The optical beam splitter is used to receive and perform calculations on the photons generated by the single-photon source, so that the single-photon detector can detect the final state of the photons and output the calculation results.

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