Polarization rotating beam splitter and electronic equipment

Abstract

This application provides a polarization rotation beamsplitter and electronic device, relating to the field of optical signal processing technology. The polarization rotation beamsplitter includes: a first waveguide comprising a mode evolution section, a mode matching section, and a first output section arranged sequentially; a second waveguide comprising a coupling section and a second output section arranged sequentially; in the signal transmission direction of the first waveguide, the mode matching section is disposed on one side of the coupling section, and the mode matching section and the coupling section form a coupler; the mode evolution section includes an asymmetric shallow etched region. By setting a corresponding asymmetric shallow etched region within the mode evolution section, the mode evolution function can be realized based on a simple etching process, performing polarization rotation conversion processing on different polarization modes, effectively reducing the waveguide length required for mode evolution, and reducing insertion loss caused by length, resulting in a small-volume, low-loss, high-bandwidth, and high-power polarization rotation beamsplitter, meeting the requirements for unified polarization mode processing in various scenarios.

Description

Technical Field

[0001] This application relates to the field of optical signal processing technology, and more specifically, to a polarization rotating beam splitter and electronic device. Background Technology

[0002] The next generation of information technologies driven by 5G, the Internet of Things, and artificial intelligence is continuously propelling optical communication systems towards higher capacity and lower power consumption. Against this backdrop, polarization multiplexing technology has become crucial for overcoming the bottleneck of single-channel transmission rates. At the heart of this technology, the polarization rotating beamsplitter unifies the polarization modes that the system needs to process by separating and rotating orthogonal polarization states, thereby simplifying subsequent operations.

[0003] Current mainstream on-chip implementation schemes are divided into two categories: mode coupling and mode evolution. Mode coupling structures utilize hybrid supermodes of TE / TM fundamental modes, which are compact but complex to design and difficult to fabricate. Mode evolution, on the other hand, is achieved through the conversion and separation of TM fundamental modes into higher-order TE modes. Although the device size is larger, it has greater manufacturing advantages due to its larger process tolerance.

[0004] The core of a mode evolution device is a polarization rotation unit and a coupling beam splitter unit. Polarization rotation relies on an asymmetric tapered waveguide to efficiently convert the TM fundamental mode into a higher-order TE mode through an adiabatic evolution process. This structure is easy to implement with wide bandwidth and large process tolerance; however, its evolution process typically requires waveguide lengths of hundreds of micrometers, accompanied by significant insertion loss. Therefore, existing polarization rotation beam splitters for mode evolution are large in size, narrow in bandwidth, and have high loss, resulting in poor practicality and failing to meet the current demand for unified polarization mode processing in various scenarios. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a polarization rotating beam splitter and electronic device to improve the problem of poor practicality of existing polarization rotating beam splitters.

[0006] To address the aforementioned issues, in a first aspect, embodiments of this application provide a polarization rotating beam splitter, which includes: a first waveguide and a second waveguide;

[0007] The first waveguide includes: a mode evolution segment, a mode matching segment, and a first output segment arranged sequentially;

[0008] The second waveguide includes: a coupling section and a second output section arranged sequentially;

[0009] In the signal transmission direction of the first waveguide, the mode matching segment is disposed on one side of the coupling segment, and the mode matching segment and the coupling segment form a coupler;

[0010] The pattern evolution segment includes an asymmetric shallow etched region.

[0011] In the above implementation process, polarization mode rotation conversion is achieved through the mode evolution segment set in the first waveguide. Mode matching and signal transfer are performed through a coupler formed by the mode matching segment in the first waveguide and the coupling segment in the second waveguide. Depending on the specific mode type of the input optical signal, the signal is output from either the first output segment of the first waveguide or the second output segment of the second waveguide. Furthermore, to reduce the waveguide length required for mode evolution through the adiabatic evolution process of the tapered waveguide, a corresponding asymmetric shallow etched region is set within the mode evolution segment. This allows for mode evolution within a shorter mode evolution segment using a simple etching process, enabling polarization rotation conversion for different polarization modes. This effectively reduces insertion loss caused by increased waveguide length. The combined effect of the asymmetric shallow etched region and the asymmetric directional coupler within the mode evolution segment results in a small-volume, low-loss, high-bandwidth, and high-power polarization rotation beamsplitter, improving its practicality and meeting the unified polarization mode processing requirements of various application scenarios.

[0012] Optionally, when a first signal of a non-target polarization mode is input into the first waveguide, the mode evolution segment is used to convert the first signal of the non-target polarization mode into a second signal of a higher-order target polarization mode.

[0013] The coupler is used to perform mode matching and coupling on the second signal to obtain a target signal with a target polarization mode, and the second output segment is used to output the target signal.

[0014] In the above implementation process, when the optical signal input to the first waveguide is a first signal of a non-target polarization mode, in order to output a signal of the target polarization mode, the mode evolution segment in the first waveguide can convert the first signal of the non-target polarization mode into a second signal of a higher-order mode of the target polarization mode through an adiabatic evolution process. However, considering that the second signal is a higher-order mode signal, in order to achieve the signal output of the fundamental mode, it is also necessary to work in conjunction with a coupler. The coupler performs mode matching and coupling on the second signal to obtain the target signal of the fundamental mode under the target polarization mode. Based on the coupler, the target signal is transferred from the first waveguide to the second waveguide for transmission. The second output segment of the second waveguide outputs the target signal, realizing mode conversion, coupling, signal transfer, and specified beam splitting output under the input of a non-target polarization mode.

[0015] Optionally, when a third signal of a target polarization mode is input into the first waveguide, the first waveguide is used to transmit the third signal, and the first output segment is used to output the third signal.

[0016] In the above implementation process, when the optical signal input to the first waveguide is the third signal of the target polarization mode, the third signal can be directly transmitted by the first waveguide without the need for multiple processing such as mode evolution, coupling, and signal transfer. The third signal is directly output by the first output segment of the first waveguide, realizing the specified beam splitting output under the input of the target polarization mode.

[0017] Optionally, in a vertical direction perpendicular to the signal transmission direction and parallel to the waveguide mounting plane, the asymmetric shallow etched region is configured as a target pattern with varying width.

[0018] In the above implementation process, considering that the adiabatic evolution process of the tapered waveguide requires a long waveguide length, in order to reduce the length of the mode evolution segment in the signal transmission direction, the asymmetric shallow etched region is set as a target pattern with varying width in the vertical direction perpendicular to the signal transmission direction and parallel to the waveguide setting plane. By changing the width in the vertical direction, the geometric symmetry of the waveguide in the mode evolution segment is broken, and polarization rotation can be completed within a shorter propagation length, thereby improving the efficiency of polarization mode evolution.

[0019] Optionally, the target shape is a triangle;

[0020] The first vertex of the triangle is one side endpoint of the beginning of the pattern evolution segment, the second vertex of the triangle is one side endpoint of the end of the pattern evolution segment, and the third vertex of the triangle is a point in the pattern evolution segment.

[0021] In the above implementation process, the target pattern can be set as a triangle with low pattern etching difficulty. The first and second vertices of the triangle are the endpoints of the start and end of the mode evolution segment on the same side, respectively. The third vertex is a point within the mode evolution segment. That is, the two vertices of the triangle are relatively fixed. The width of the target pattern in the vertical direction and the magnitude and trend of the horizontal direction can be adjusted by the position of the adjustable third vertex. Different asymmetric structures can be designed according to the actual situation to break the geometric symmetry of the waveguide within the mode evolution segment.

[0022] Optionally, the third vertex is determined by reverse design based on the simulation results of the input signal and the mode evolution efficiency requirements.

[0023] In the above implementation process, simulation can be performed based on the input signal to obtain simulation results. Combined with the mode evolution efficiency requirements for the mode evolution segment, the triangle can be reverse-engineered to determine the specific position of the third vertex within the mode evolution segment.

[0024] Optionally, in the signal transmission direction, the waveguide width of the mode evolution segment changes from narrow to wide, the waveguide width of the mode matching segment changes from wide to narrow, and the width of the coupling segment changes based on the simulation results of the input signal;

[0025] Wherein, the minimum width of the pattern matching segment is greater than the maximum width of the coupling segment.

[0026] In the above implementation process, in the signal transmission direction, the waveguide width of the mode evolution section in the first waveguide changes from narrow to wide to achieve mode evolution through an adiabatic evolution process. The waveguide width of the mode matching section changes from wide to narrow. Meanwhile, the width of the coupling section in the second waveguide changes slightly based on simulation results of the input signal, and the minimum width of the mode matching section is greater than the maximum width of the coupling section. This ensures that the propagation constants of the mode matching section and the coupling section are matched in the target polarization mode, guaranteeing efficient coupling and conversion from the target polarization higher-order mode of the mode matching section to the target polarization mode of the coupling section. Ultimately, this allows the optical signal converted from the non-target polarization mode to be output from the second output section in the target polarization mode. By coordinating the width changes of the mode matching section and the coupling section, the performance consistency of the mode matching section is ensured over a large wavelength range, thereby improving the overall operating bandwidth of the polarization rotating beam splitter.

[0027] Optionally, in the signal transmission direction, the length of the mode evolution segment is a first length, and the length of the mode matching segment is a second length;

[0028] The first length is determined based on the mode evolution efficiency requirements and loss requirements;

[0029] The second length is determined based on the same effective refractive index under different polarization modes.

[0030] In the above implementation process, the waveguide length affects performance in the signal transmission direction. The length of the mode evolution segment is the first length. Considering the impact of the first length on insertion loss, a suitable first length can be determined based on the required mode evolution efficiency and the required loss. The length of the mode matching segment is the second length. To achieve mode matching, coupling, and signal transfer, a suitable second length can be determined based on the same effective refractive index under different polarization modes, so that the coupler can process different polarization modes.

[0031] Optionally, the second output segment is configured as a bent segment that bends away from the first output segment;

[0032] And / or, the first output segment is configured to form a bent segment that bends away from the second output segment.

[0033] In the above implementation process, considering that the two output segments are prone to mutual interference when they are close to each other, the second output segment and the first output segment can be configured as bent segments that bend away from each other. By using the structure of the bent segments, the vertical distance between the first output segment and the second output segment can be increased, thereby reducing the adverse effects caused by the first output segment and the second output segment being too close.

[0034] Optionally, both the first waveguide and the second waveguide are ridge waveguides; wherein the ridge waveguide is fabricated by selective etching onto a silicon waveguide.

[0035] In the above implementation process, both the first waveguide and the second waveguide can be ridge waveguides prepared by selective etching on silicon waveguides, so as to realize and maintain single-mode transmission and improve coupling efficiency.

[0036] Optionally, the etching depth of the ridge waveguide is D1, and the etching depth of the asymmetric shallow etching region is D2; wherein, 0.3≤D2 / D1≤0.75.

[0037] In the above implementation process, the etching depth of the conventional ridge waveguides of the first and second waveguides is D1. In order to destroy the geometric symmetry structure of the mode evolution segment at the waveguide etching depth, the etching depth of the asymmetric shallow etching region in the mode evolution segment can be D2, which is different from D1, and D2 / D1 satisfies a preset ratio. This allows the asymmetric shallow etching region to be etched at a shallower etching depth in the mode evolution segment, and the mode evolution efficiency of the mode evolution segment can be optimized through the asymmetric shallow etching region.

[0038] Secondly, embodiments of this application also provide an electronic device, which includes the polarization rotating beam splitter described in any one of the first aspects above.

[0039] In summary, the embodiments of this application provide a polarization rotation beamsplitter and electronic device. By setting corresponding asymmetric shallow etching regions within the mode evolution segment, the mode evolution function can be realized based on a simple etching process. Different polarization modes are converted by polarization rotation, effectively reducing the waveguide length required for mode evolution and reducing the insertion loss caused by the length. This results in a small-volume, low-loss, high-bandwidth, and high-power polarization rotation beamsplitter that meets the requirements for unified polarization mode processing in various scenarios. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of the structure of a polarization rotating beam splitter provided in an embodiment of this application;

[0042] Figure 2 This is a schematic diagram of the specific structure of a polarization rotating beam splitter provided in an embodiment of this application.

[0043] Icons: 100 - Silicon waveguide; 110 - First waveguide; 120 - Second waveguide; 111 - Mode evolution section; 112 - Mode matching section; 113 - First output section; 121 - Coupler section; 122 - Second output section; 130 - Coupler; 140 - Asymmetric shallow etched region; 211 - Signal transmission direction; 212 - Vertical direction; 123 - Tapered section; 221 - First length; 222 - Second length. Detailed Implementation

[0044] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of the embodiments of this application.

[0045] The core of current mode evolution devices is a polarization rotation unit and a coupling beam splitter unit. Polarization rotation relies on an asymmetric tapered waveguide to efficiently convert the TM fundamental mode into a higher-order TE mode through an adiabatic evolution process. This structure is easy to implement with wide bandwidth and large process tolerance; however, its evolution process typically requires waveguide lengths of hundreds of micrometers, accompanied by significant insertion loss. Therefore, existing mode evolution polarization rotation beam splitters are large in size, narrow in bandwidth, and have high loss, resulting in poor practicality and failing to meet the current demand for unified polarization mode processing in various scenarios.

[0046] To address the aforementioned issues, this application provides a polarization rotation beamsplitter and electronic device. By setting corresponding asymmetric shallow etched regions within the mode evolution segment, the mode evolution function can be achieved based on a simple etching process. This allows for polarization rotation conversion processing of different polarization modes, effectively reducing the waveguide length required for mode evolution and minimizing insertion loss caused by length. The result is a small-volume, low-loss, high-bandwidth, and high-power polarization rotation beamsplitter that meets the requirements for unified polarization mode processing in various scenarios.

[0047] Optionally, the polarization rotating beam splitter provided in this application embodiment can be installed in various types of electronic devices, such as optical sensing and measurement devices, laser devices, optical communication and information processing devices, imaging and display devices, etc.

[0048] Please see Figure 1 , Figure 1 This is a schematic diagram of a polarization rotating beam splitter provided in an embodiment of this application. The polarization rotating beam splitter may include: a first waveguide 110 and a second waveguide 120.

[0049] The first waveguide 110 includes a mode evolution segment 111, a mode matching segment 112, and a first output segment 113 arranged in sequence, and the second waveguide 120 includes a coupling segment 121 and a second output segment 122 arranged in sequence.

[0050] It should be noted that the mode evolution segment 111, mode matching segment 112, and first output segment 113 are merely descriptive structures that distinguish different shaped regions of the first waveguide 110; the first waveguide 110 is essentially a continuously arranged, monolithic waveguide. Similarly, the coupling segment 121 and the second output segment 122 are merely descriptive structures that distinguish different shaped regions of the second waveguide 120; the second waveguide 120 is also essentially a continuously arranged, monolithic waveguide.

[0051] Optionally, in the signal transmission direction 211 of the first waveguide 110, a mode matching section 112 is disposed on one side of the coupling section 121, and the mode matching section 112 and the coupling section 121 form a coupler 130. Polarization mode rotation is performed through the mode evolution section 111 in the first waveguide 110, i.e., polarization mode conversion is achieved. Mode matching and signal transfer are performed through the coupler 130 formed by the mode matching section 112 in the first waveguide 110 and the coupling section 121 in the second waveguide 120, so that the signal is output by the first output section 113 of the first waveguide 110 or the second output section 122 of the second waveguide 120 according to the specific mode type of the input optical signal.

[0052] Optionally, in the signal transmission direction 211 of the first waveguide 110, the mode matching section 112 and the coupling section 121 are arranged adjacent to each other, such as... Figure 1 As shown, the pattern matching segment 112 and the coupling segment 121 can be set in parallel.

[0053] It should be noted that, in order to reduce the waveguide length required for mode evolution during the adiabatic evolution process of the tapered waveguide, the mode evolution segment 111 includes an asymmetric shallow etched region 140. The asymmetric shallow etched region 140 can be set based on a simple etching process to break the geometric symmetry structure of the mode evolution segment 111, thereby achieving mode evolution within a shorter segment and performing polarization rotation conversion for different polarization modes, effectively reducing the insertion loss caused by the increase in waveguide length. By combining the asymmetric shallow etched region 140 and the asymmetric directional coupler 130 within the mode evolution segment 111, a small-volume, low-loss, and high-power polarization rotation beamsplitter is obtained, improving its practicality and meeting the requirements for unified polarization mode processing in various application scenarios.

[0054] Optionally, different polarization modes can include different propagation modes, such as TE mode and TM mode, i.e., Transverse Electric mode, where the electric field vector is completely perpendicular to the propagation direction of the waveguide and parallel to the plane of the waveguide (usually horizontal), while the magnetic field has a component along the propagation direction; and Transverse Magnetic mode, where the magnetic field vector is completely perpendicular to the propagation direction of the waveguide, while the electric field has a component along the propagation direction.

[0055] Optionally, based on the actual polarization mode unification requirements, appropriate target and non-target polarization modes can be selected and set. Furthermore, to ensure the waveguide can meet single-mode transmission requirements and reduce the adverse effects of other higher-order modes, both the target and non-target polarization modes can be the fundamental modes of the polarization mode. This reduces severe crosstalk and performance degradation caused by optical power coupling into higher-order modes. For example, in applications where the polarization mode unification requirement is a unified output TE mode optical signal, the fundamental mode of the TE mode, i.e., the TE0 mode, can be used as the target polarization mode, and the fundamental mode of the TM mode, i.e., the TM0 mode, can be used as the non-target polarization mode.

[0056] It should be noted that when a first signal of a non-target polarization mode is input into the first waveguide 110, the mode evolution section 111 is used to convert the first signal of the non-target polarization mode into a second signal of a higher-order target polarization mode. The coupler 130 is used to perform mode matching and coupling on the second signal to obtain the target signal of the target polarization mode, and the second output section 122 is used to output the target signal. When the optical signal input to the first waveguide 110 is a first signal of a non-target polarization mode, in order to output a signal of the target polarization mode, the mode evolution segment 111 in the first waveguide 110 can convert the first signal of the non-target polarization mode into a second signal of a higher-order mode of the target polarization mode through an adiabatic evolution process. However, considering that the second signal is a signal of a higher-order mode, in order to achieve the signal output of the fundamental mode, it is also necessary to work in conjunction with the coupler 130. The coupler 130 performs mode matching and coupling on the second signal to obtain the target signal of the fundamental mode under the target polarization mode. Based on the coupler 130, the target signal is transferred from the first waveguide 110 to the second waveguide 120 for transmission. The second output segment 122 of the second waveguide 120 outputs the target signal, realizing mode conversion, coupling, signal transfer, and specified beam splitting output under the input of a non-target polarization mode.

[0057] It should be noted that, taking the TE0 mode as the target polarization mode and the TM0 mode as the non-target polarization mode as an example, when the first signal of TM0 is input into the first waveguide 110, since the TM0 mode is even-symmetric in the planar waveguide or channel waveguide, its main electric field component (Ez) is symmetric about the waveguide center in the vertical direction. To achieve efficient coupling between the two modes, they must have the same spatial symmetry. Both are even-symmetric modes, and under uniform or regular periodic perturbations, their coupling is very weak. The geometric symmetry of the mode evolution segment 111 in this application is disrupted by the asymmetric shallow etching region 140. Furthermore, considering that the effective refractive indices of TM0 and TE0 are usually quite different, and their propagation constants are also quite different, the target polarization higher-order mode (corresponding to the target polarization mode, in this embodiment, the TE1 mode) can be used as an intermediate mode during mode evolution. Since the TE1 mode is odd-symmetric, its electric field is antisymmetric about the waveguide center in the vertical direction. By using the "even → odd → even" transformation, the asymmetric and symmetric perturbations are utilized to bypass the obstacle of direct even-even coupling. This enables efficient evolution between modes within a shorter mode evolution segment 111, improving the feasibility and efficiency of the mode conversion process.

[0058] It should be noted that when the first waveguide 110 is input with a third signal of the target polarization mode, the first waveguide 110 is used to transmit the third signal, and the first output segment 113 is used to output the third signal. When the optical signal input to the first waveguide 110 is the third signal of the target polarization mode, the third signal can be directly transmitted by the first waveguide 110 without the need for multiple processing steps such as mode evolution, coupling, and signal transfer. The third signal is directly output by the first output segment 113 of the first waveguide 110, achieving the specified beam splitting output under the input of the target polarization mode.

[0059] It should be noted that, with the TE0 mode as the target polarization mode, when the third signal of TE0 is input into the first waveguide 110, the first waveguide 110 can directly transmit and output the third signal, and the transmission process of the third signal is not affected by the coupler 130 of the mode evolution section 111.

[0060] Optionally, please refer to Figure 2 , Figure 2 This is a schematic diagram of the specific structure of a polarization rotating beam splitter provided in an embodiment of this application.

[0061] Optionally, considering that the adiabatic evolution process of the tapered waveguide requires a relatively long waveguide length, in order to reduce the length of the mode evolution segment 111 in the signal transmission direction 211, the asymmetric shallow etched region 140 is set as a target pattern with varying width in the vertical direction 212, which is perpendicular to the signal transmission direction 211 and parallel to the waveguide setting plane. By changing the width of the target pattern in the vertical direction 212, the geometric symmetry of the waveguide in the mode evolution segment 111 is broken, and polarization rotation can be completed within a shorter propagation length, thereby improving the efficiency of polarization mode evolution.

[0062] For example, the target graphic may include various types of patterns that can produce width variations in the vertical direction 212, such as triangles, multi-wave shapes, and multi-zigzag shapes.

[0063] It should be noted that, in order to reduce the fabrication difficulty of the asymmetric shallow etched region 140, the target pattern can be set as a triangle with a relatively simple structure (such as...). Figure 2(As shown). The first vertex of the triangle is one side endpoint of the start of mode evolution segment 111, the second vertex is one side endpoint of the end of mode evolution segment 111, and the third vertex is a point within mode evolution segment 111. The first and second vertices of the triangle represent the start and end points of mode evolution segment 111 on the same side, respectively, while the third vertex is a point within mode evolution segment 111. That is, the two vertices of the triangle are relatively fixed, and the adjustable third vertex allows for adjustment of the target pattern's width variation in the vertical direction 212, as well as the variation amplitude and trend in the horizontal direction, i.e., the waveguide extension direction. This enables the design of different asymmetric structures based on actual conditions, thereby breaking the geometric symmetry of the waveguide within mode evolution segment 111.

[0064] Optionally, Figure 2 Only one feasible embodiment is shown in which the first and second vertices of the triangle are both located on the side of the mode evolution segment 111 away from the second waveguide 120. The structure in which the first and second vertices are both located on the side of the mode evolution segment 111 closer to the second waveguide 120 will not be described in detail.

[0065] Optionally, with the first and second vertices fixed, the third vertex determines the shape of the entire triangle, that is, it determines the magnitude and trend of the width variation of the target shape in the vertical direction 212. Different triangle shapes play different roles in the pattern evolution segment 111. Therefore, the third vertex is determined through reverse design based on the simulation results of the input signal and the pattern evolution efficiency requirements. Simulations can be performed based on the input signal to obtain simulation results. Combined with the pattern evolution efficiency requirements for the pattern evolution segment 111, the triangle can be reverse-designed to determine the specific position of the third vertex within the pattern evolution segment 111.

[0066] For example, the first or second vertex can be used as the origin of the coordinate system to determine the coordinate positions of multiple third vertices at different locations within the pattern evolution segment 111. Combining these coordinate positions, simulation processing is performed in the simulation software. The corresponding pattern evolution efficiency requirements (e.g., the pattern evolution efficiency must be greater than or equal to 98%) are used as constraints to obtain suitable positions of one or more third vertices that meet the pattern efficiency requirements. In the case of multiple suitable positions, a suitable position with a smaller target area can be selected as the final target position for subsequent etching preparation, further improving the preparation efficiency of the asymmetric shallow etched region 140.

[0067] Please continue reading. Figure 2In the signal transmission direction 211, the waveguide width of the mode evolution segment 111 changes from narrow to wide, the waveguide width of the mode matching segment 112 changes from wide to narrow, and the width of the coupling segment 121 changes based on the simulation results of the input signal. The minimum width of the mode matching segment 112 is greater than the maximum width of the coupling segment 121. In the first waveguide 110, the waveguide width of the mode evolution section 111 gradually widens to achieve mode evolution through an adiabatic evolution process. The waveguide width of the mode matching section 112 gradually narrows. Meanwhile, the width of the coupling section 121 in the second waveguide 120 varies slightly based on simulation results of the input signal, with the minimum width of the mode matching section 112 greater than the maximum width of the coupling section 121. This ensures that the propagation constants of the mode matching section 112 and the coupling section 121 are matched in the target polarization mode, guaranteeing efficient coupling and conversion from the target polarization higher-order mode of the mode matching section 112 to the target polarization mode of the coupling section 121. Ultimately, this allows the optical signal converted from the non-target polarization mode to be output from the second output section 122 in the target polarization mode. By coordinating the width variations of the mode matching section 112 and the coupling section 121, the performance consistency of the mode matching section 112 is ensured over a wider wavelength range, thereby improving the overall operating bandwidth of the polarization rotating beam splitter.

[0068] Optionally, the width of the coupling segment 121 can vary slightly based on the simulation results of the input signal. The range of width values ​​that achieves the highest coupling efficiency with the mode-matching segment 112 can be selected as the width variation range of the coupling segment 121 based on the simulation results. To further improve the coupling effect between the coupling segment 121 and the mode-matching segment 112, the waveguide width of the coupling segment 121 varies slightly from narrow to wide in the vertical direction. The first output segment 113 and the second output segment 122 can be set as equal-width segments with no change in waveguide width in the vertical direction 212, and the maximum width of the coupling segment 121 is consistent with the width of the second output segment 122. In the second waveguide 120, a corresponding tapered segment 123 can also be provided before the coupling segment 121. In the signal transmission direction 211, the width of the tapered segment 123 varies from narrow to wide to achieve thermal coupling.

[0069] Alternatively, the coupling segment 121 can also be set as a segment of equal width, with the width being the same as that of the second output segment 122.

[0070] It should be noted that the mode evolution segment 111 can gradually change the effective refractive index of the waveguide under different polarization modes by changing the width of the waveguide, thereby realizing the conversion of polarization modes, that is, realizing the adiabatic evolution process. This process is slow enough that energy will not leak into other unwanted polarization modes.

[0071] Optionally, within the mode matching section 112, the first waveguide 110 transitions from a wide to a narrow width through the tapered shape of the mode matching section 112, thus achieving low-loss mode field adaptation.

[0072] It should be noted that the pattern matching segment 112 is located on the side of the coupling segment 121 and can be parallel to the coupling segment 121. The pattern matching segment 112 and the coupling segment 121 located nearby form an asymmetrical directional coupler 130.

[0073] For example, in the vertical direction 212, the minimum width of the mode evolution segment 111 can be denoted as w1, the maximum width of the mode matching segment 112 is also the maximum width of the mode evolution segment 111, and can be denoted as w2, the minimum width of the mode matching segment 112 is also the waveguide width of the first output segment 113, and can be denoted as w3, and the maximum width of the coupling segment 121 on the second waveguide 120 is equal to the width of the second output segment 122, and is denoted as w4. In order for the waveguide to meet the single-mode transmission requirements and reduce the adverse effects caused by other higher-order modes, the range of w1 can be determined based on the fundamental mode under different polarization modes in the single-mode transmission requirements, combined with the achievable processing accuracy. The value range of w1 can be 0.4μm≤w1≤0.8μm, for example, w1=0.6μm, etc. Based on the width variation requirements needed for pattern evolution and the actual value of w1, simulation processing can be performed. Based on the simulation results, the range of w2 can be determined. The range of w2 can be 0.7μm ≤ w2 ≤ 1.1μm. For example, if w1 = 0.6μm, w2 = 0.78μm. w3 is less than w2, and the range of w3 can be 0.5μm ≤ w3 ≤ 1μm. Based on the actual pattern matching requirements and the values ​​of w2 and w3, the range of w4 can be determined. The range of w4 can be 0.2μm ≤ w4 ≤ 0.5μm to achieve the corresponding pattern matching function.

[0074] Please continue reading. Figure 2 In the signal transmission direction 211, the length of the mode evolution segment 111 is a first length 221, and the length of the mode matching segment 112 is a second length 222. The first length 221 is determined based on mode evolution efficiency requirements and loss requirements, while the second length 222 is determined based on the same effective refractive index under different polarization modes. Considering the impact of the first length 221 on insertion loss, a suitable first length 221 can be determined based on the corresponding mode evolution efficiency requirements and the corresponding loss requirements. To achieve mode matching, coupling, and signal transfer, a suitable second length 222 can be determined based on the same effective refractive index under different polarization modes, so that the coupler 130 can process different polarization modes.

[0075] Optionally, the width variation range of the mode evolution segment 111 can be determined based on the specific values ​​of w1 and w2, combined with the mode evolution efficiency requirements, such as limiting the mode evolution efficiency to be greater than or equal to 98%, thereby determining the first length 221 of the mode evolution segment 111.

[0076] Optionally, based on the specific values ​​of w2 and w3, and under the constraint of the same effective refractive index in different polarization modes, the width variation of the mode matching segment 112 can be determined so that the target polarization higher-order mode can be successfully coupled to the target polarization mode, thereby determining the second length 222 of the mode matching segment 112.

[0077] For example, since the mode conversion efficiency of the mode evolution segment 111 is low when the first length 221 is too short and the loss is too high when the first length 221 is too long, the value range of the first length 221 can be 30μm≤first length 221≤70μm, and the value range of the second length 222 can be 10μm≤second length 222≤100μm.

[0078] It should be noted that there is a corresponding spacing between the coupling section 121 and the mode matching section 112 in the vertical direction 212. This spacing can be the distance between the centers of the two waveguides in the vertical direction 212, or the distance between the edges of the two waveguides. This spacing can be denoted as 'd'. In the vertical direction, 'd' can be an equal distance or it can vary slightly; that is, the edges of the two waveguides can be parallel or non-parallel. The larger 'd' is, the longer the second length 222 of the mode matching section 112 is, i.e., the longer the required length of the coupler 130. The specific value of 'd' can be determined by considering the actual spatial requirements of the polarization rotating beam splitter in the vertical direction 212. The range of 'd' is 0.1 μm ≤ d ≤ 1.4 μm. The specific value of 'd' can be adjusted by changing the width of one side of the coupling section 121, thereby adjusting the oblique trapezoidal structure of the coupling section 121.

[0079] Please continue reading. Figure 2 Considering that two output segments are prone to mutual interference when they are close together, the second output segment 122 is configured as a bent segment that bends away from the first output segment 113, and / or the first output segment 113 is configured as a bent segment that bends away from the second output segment 122. This bent segment structure increases the vertical distance 212 between the first output segment 113 and the second output segment 122, thereby reducing the adverse effects caused by the first output segment 113 and the second output segment 122 being too close.

[0080] Optionally, the bend can be configured as a corresponding S-shaped waveguide. Figure 2Only one feasible embodiment of the second output segment 122 being a bent segment is shown in the figure; the structures of other bent segments will not be described in detail.

[0081] Optionally, in the vertical direction 212, the distance between the output ports of the first output segment 113 and the second output segment 122 is greater than or equal to the corresponding preset distance, so that there is sufficient distance between the two output segments, further reducing the adverse situation of mutual interference between the two output segments.

[0082] For example, the preset spacing can be set according to the actual spatial requirements of the polarization rotating beam splitter in the vertical direction 212, for example, it can be set to 20μm-30μm, etc.

[0083] It should be noted that both the first waveguide 110 and the second waveguide 120 are ridge waveguides; the ridge waveguides are fabricated by selective etching on the silicon waveguide 100 to facilitate and maintain single-mode transmission and improve coupling efficiency.

[0084] Optionally, the etching depth of the ridge waveguide is D1, and the etching depth of the asymmetric shallow etched region 140 is D2; wherein, 0.3≤D2 / D1≤0.75. The etching depth of the conventional ridge waveguides of the first waveguide 110 and the second waveguide 120 is D1. In order to disrupt the geometric symmetry structure of the mode evolution segment 111 at the waveguide etching depth, the etching depth of the asymmetric shallow etched region 140 in the mode evolution segment 111 can be D2, which is different from D1, and D2 / D1 satisfies a preset ratio. This allows the asymmetric shallow etched region 140 to be obtained by etching at a shallower depth in the mode evolution segment 111, and the mode evolution efficiency of the mode evolution segment 111 is optimized by the asymmetric shallow etched region 140.

[0085] For example, taking a conventional silicon waveguide structure with a depth of 3 μm as an example, the etching depth D1 of the ridge waveguide can be in the range of 210 nm ≤ D1 ≤ 220 nm. Correspondingly, the etching depth D2 of the asymmetric shallow etching region 140 can be in the range of 60 nm ≤ D2 ≤ 160 nm, so that the asymmetric shallow etching region 140 and other regions of the mode evolution segment 111 produce corresponding waveguide height changes.

[0086] Preferably, 66nm≤D2≤157.5nm can be set so that 0.3≤D2 / D1≤0.75.

[0087] Alternatively, an asymmetric deep region can be obtained in the opposite way on the ridge waveguide with a shallow etching depth. That is, the etching depth of the asymmetric deep region is higher than that of the ridge waveguide, so that the waveguide height changes are generated in the asymmetric deep etching region and other regions of the mode evolution segment 111, and the corresponding functions can be realized based on the waveguide height changes.

[0088] In summary, the embodiments of this application achieve efficient polarization rotation in a short size through the key structure of the asymmetric shallow etched region on the mode evolution segment of the second waveguide. Simultaneously, by synergistically optimizing the etch morphology and coupler waveguide width, the operating bandwidth of the polarization rotation beam splitter is effectively broadened. The entire device structure is compact and can be fabricated using only standard processes.

[0089] In addition, the components in the various embodiments of this application can be integrated together to form an independent part, or each component can exist independently, or two or more components can be integrated to form an independent part.

[0090] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0091] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes 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.

[0092] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, article, or apparatus that includes said element.

Claims

1. A polarization-rotating beamsplitter, characterized by, The polarization rotation beam splitter comprises a first waveguide and a second waveguide; The first waveguide comprises a mode evolution section, a mode matching section and a first output section arranged in sequence; The second waveguide comprises a coupling section and a second output section arranged in sequence; In the signal transmission direction of the first waveguide, the mode matching section is arranged on one side of the coupling section, and the mode matching section and the coupling section form a coupler; The mode evolution section comprises an asymmetric shallow etching region; In the case that the first waveguide is input with a first signal of a non-target polarization mode, the mode evolution section is configured to convert the first signal of the non-target polarization mode into a second signal of a target polarization high-order mode; the coupler is configured to perform mode matching and coupling on the second signal to obtain a target signal of a target polarization mode, and the second output section is configured to output the target signal; In a vertical direction perpendicular to the signal transmission direction and parallel to a waveguide arrangement plane, the asymmetric shallow etching region is arranged as a target pattern with a changing width; the target pattern is a triangle; a first vertex of the triangle is a side endpoint of a start end of the mode evolution section, a second vertex of the triangle is a side endpoint of an end of the mode evolution section, and a third vertex of the triangle is a point in the mode evolution section; In the signal transmission direction, the waveguide width of the mode evolution section changes from narrow to wide, the waveguide width of the mode matching section changes from wide to narrow, and the width of the coupling section changes based on simulation results of an input signal; the minimum width of the mode matching section is greater than the maximum width of the coupling section.

2. The polarization-rotating beamsplitter of claim 1, wherein, In the case that the first waveguide is input with a third signal of a target polarization mode, the first waveguide is configured to transmit the third signal, and the first output section is configured to output the third signal.

3. The polarization-rotating beamsplitter of claim 1, wherein, The third vertex is determined by reverse design based on simulation results of an input signal and mode evolution efficiency requirements. In the signal transmission direction, the length of the mode evolution section is a first length, and the length of the mode matching section is a second length; 4. The polarization-rotating beamsplitter of any one of claims 1-2, wherein, The first length is determined based on mode evolution efficiency requirements and loss requirements; The second length is determined based on the same effective refractive index under different polarization modes. The second output section is configured as a bending section that bends away from the first output section; 5. The polarization-rotating beamsplitter of any one of claims 1-2, wherein, And / or, the first output section is configured as a bending section that bends away from the second output section. The first waveguide and the second waveguide are both ridge waveguides; the ridge waveguide is prepared by selective etching on a silicon waveguide.

6. The polarization-rotating beamsplitter of any one of claims 1-2, wherein, The etching depth of the ridge waveguide is D1, and the etching depth of the asymmetric shallow etching region is D2; 0.3≤D2 / D1≤0.

75.

7. The polarization-rotating beamsplitter of claim 6, wherein, The electronic device comprises the polarization rotation beam splitter of any one of claims 1-7.

8. An electronic device, comprising: ​

Images