Bent waveguide and related apparatus

Abstract

This application provides a curved waveguide and related equipment. The curved waveguide includes a first straight region, a curved region, and a second straight region connected end-to-end. The curved region includes a first arc-shaped waveguide, a second arc-shaped waveguide, and a third arc-shaped waveguide. The first and third arc-shaped waveguides are symmetrical about the centerline of the second arc-shaped waveguide, and the first and second straight regions are also symmetrical about the centerline of the second arc-shaped waveguide. The curvature k of the first and third arc-shaped waveguides satisfies the formula: where s represents the transmission distance corresponding to the curvature k; Rc represents the radius of curvature of the second arc-shaped waveguide; represents the angle between the tangent shared by the first and second arc-shaped waveguides at the connection point and the horizontal line; is a constant greater than 0 and less than , where represents the total curvature angle of the curved region. This can significantly reduce the overall transmission loss of the curved waveguide.

Description

Technical Field

[0001] This application relates to the field of waveguides, and more specifically, to a curved waveguide and related equipment. Background Technology

[0002] Bending is an extremely important and indispensable feature in waveguides. To achieve complex functions, save space, and enable interconnections between devices, bending is unavoidable. Current waveguide bending typically employs an "Euler-circle" technique, where Euler bends with curvature that linearly varies with transmission distance connect the straight and curved regions of the waveguide to reduce mode mismatch loss. However, waveguide loss is significant at the boundary between the straight and curved regions. Summary of the Invention

[0003] The purpose of this application is to provide a curved waveguide and related equipment to solve the problem that existing curved waveguides have high waveguide loss at the junction of the straight and curved regions.

[0004] This application provides a curved waveguide, comprising a first straight region, a curved region, and a second straight region connected end to end. The curved region includes a first arc-shaped waveguide, a second arc-shaped waveguide, and a third arc-shaped waveguide. The first and third arc-shaped waveguides are symmetrical about the centerline of the second arc-shaped waveguide, and the first and second straight regions are also symmetrical about the centerline of the second arc-shaped waveguide. The centerline of the second arc-shaped waveguide is the line connecting the center of the second arc-shaped waveguide to the center of the circle of the second arc-shaped waveguide. The first and third arc-shaped waveguides have the same curvature k, and both satisfy the formula:

[0005] Where s represents the arc length of the first arc waveguide; R c The radius of curvature characterizing the second arc-shaped waveguide. The angle between the tangent shared by the first and second arc-shaped waveguides at their connection point and the horizontal line; greater than 0 and less than The constant, where, The total bending angle of the bending region is characterized.

[0006] In the above implementation process, since the curvature k of both the first arc-shaped waveguide and the third arc-shaped waveguide satisfies the formula: .

[0007] Thus, even at the boundary between the straight region (first straight region / second straight region) and the curved region, the curvature k is continuous with respect to the corresponding transmission distance s and its first derivative, without abrupt changes, achieving a smooth and gradual transition of the curved waveguide region from zero. This makes the change in the eigenmode field distribution throughout the curved waveguide sufficiently smooth, reducing the radiation of the optical field outward from the waveguide while altering the direction of optical field propagation. This effectively reduces the loss caused by eigenmode field mismatch and significantly lowers the overall transmission loss of the curved waveguide.

[0008] Optionally, the The target constant is to minimize the bending loss in the bending region.

[0009] In the above implementation method, because The target constant is to minimize the transmission loss in the curved region, thus reducing the transmission loss of the curved waveguide to the greatest extent possible.

[0010] Optionally, the first straight region, the curved region, and the second straight region each include: silicon substrate; A buried oxide layer is disposed on the silicon substrate; A silicon flat plate layer is disposed on the side of the buried oxide layer opposite to the silicon substrate; A silicon waveguide is disposed on the side of the silicon planar layer opposite to the buried oxide layer; The projection of the silicon planar layer onto the buried oxide layer is greater than and covers the projection of the silicon waveguide onto the buried oxide layer.

[0011] In the above embodiment, a silicon planar plate layer is disposed on the side of the buried oxide layer facing away from the silicon substrate, and the projection of the silicon planar plate layer on the buried oxide layer covers and is larger than the projection of the silicon waveguide. Given that existing buried oxide layers are typically composed of silicon dioxide, and silicon has significantly better thermal conductivity than silicon dioxide, introducing a silicon planar plate layer can effectively improve the local thermal conductivity of the bent waveguide, thereby facilitating the use of the thermal effect of current to control the operating temperature of the bent waveguide.

[0012] Optionally, the dimension of the silicon waveguide perpendicular to the silicon substrate is greater than or equal to 2.5 μm and less than or equal to 3.5 μm, and the dimension of the silicon waveguide parallel to the silicon substrate is greater than or equal to 1.8 μm and less than or equal to 3.0 μm.

[0013] In the above implementation, the dimension of the silicon waveguide perpendicular to the silicon substrate is limited to greater than or equal to 2.5 μm and less than or equal to 3.5 μm, and the dimension of the silicon waveguide parallel to the silicon substrate is limited to greater than or equal to 1.8 μm and less than or equal to 3.0 μm. Thus, compared to existing silicon waveguides, not only are the dimensions of the silicon waveguide perpendicular to the silicon substrate increased, but also the dimensions of the silicon waveguide parallel to the silicon substrate are increased, thereby providing stronger mode field confinement capability.

[0014] Optionally, the dimension of the buried oxide layer in the direction perpendicular to the silicon substrate is greater than or equal to 0.1 μm and less than or equal to 1.5 μm.

[0015] In the above implementation, by limiting the size of the buried oxide layer in the direction perpendicular to the silicon substrate to greater than or equal to 0.1 μm and less than or equal to 1.5 μm, it is possible to effectively suppress the surge in parasitic capacitance caused by an excessively thin buried oxide layer, while utilizing the thinner buried oxide layer to quickly dissipate heat, thereby improving the overall reliability and operational stability of the bent waveguide.

[0016] Optionally, the thickness of the silicon plate layer is greater than or equal to 0.1 μm and less than or equal to 0.6 μm.

[0017] In the above implementation, by limiting the lower limit of the silicon plate layer thickness to 0.1 μm, the silicon plate layer has a sufficient cross-sectional area to form an effective heat conduction path. This allows for the full utilization of silicon's high thermal conductivity to quickly conduct away the heat generated during the use of the bent waveguide. Furthermore, by limiting the upper limit of the silicon plate layer thickness to 0.6 μm, the influence of the silicon plate layer on the intrinsic mode field can be kept within a negligible range.

[0018] Secondly, this application provides an SOI photonic chip, including the aforementioned bent waveguide.

[0019] Thirdly, this application provides a resonator including the aforementioned bent waveguide.

[0020] Fourthly, this application provides an optical waveguide splitter, including the aforementioned bent waveguide.

[0021] Fifthly, this application provides an on-chip external cavity laser, including the aforementioned curved waveguide. Attached Figure Description

[0022] 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.

[0023] Figure 1(a) is a schematic diagram of a bent waveguide provided in an embodiment of this application; Figure 1(b) is a schematic diagram of a bent waveguide provided in an embodiment of this application; Figure 2 This is a schematic diagram showing the curve of curvature K' of an existing curved waveguide as a function of transmission distance S'. Figure 3 This is a schematic diagram of the curvature K of the bent waveguide as a function of transmission distance S in an embodiment of this application; Figure 4 This is a schematic diagram of an existing waveguide structure; Figure 5 This application provides a schematic diagram of a waveguide structure; Figure 6(a) is Figure 5 A schematic diagram of the electric field intensity distribution of the waveguide structure in TM0 mode; Figure 6(b) is Figure 5 The diagram shows the electric field intensity distribution of the waveguide structure in TE0 mode. Detailed Implementation

[0024] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0025] Example 1 Bending is an extremely important and essential form of optical waveguide. In order to achieve complex functions, save space, and realize interconnection between devices, bending is unavoidable. Current bent waveguide designs usually adopt the "Euler-circle" bending technology, that is, between straight waveguides and circular arc waveguides, Euler bending with curvature that changes linearly with the transmission distance is used to reduce mode field mismatch loss.

[0026] The curved waveguide may include a first straight region L1, a curved region, and a second straight region L2 connected end to end in sequence. The curved region includes a first arc waveguide HOP1, a second arc waveguide CIR, and a third arc waveguide HOP2. The first arc waveguide HOP1 and the third arc waveguide HOP2 are symmetrical about the centerline of the second arc waveguide CIR, and the first straight region L1 and the second straight region L2 are also symmetrical about the centerline of the second arc waveguide CIR. The centerline of the second arc waveguide CIR is the line connecting the center of the second arc waveguide CIR and the center of the circle of the second arc waveguide CIR.

[0027] For example, a schematic diagram of a bent waveguide can be shown in Figures 1(a)-1(b).

[0028] If the first arc waveguide HOP1 and the third arc waveguide HOP2 are waveguides that satisfy the "Eulerian-circle" property, then the curvature k' of both of them satisfies the following formula:

[0029] Where K' represents the curvature of the waveguide bend, S' represents the transmission distance corresponding to the current curvature K', R0 represents the initial bending radius of the first arc waveguide HOP1 and the third arc waveguide HOP2, and R c The curvature k' represents the bending radius at the ends of the first arc-shaped waveguide HOP1 and the third arc-shaped waveguide HOP2, and L represents the total length of the first arc-shaped waveguide HOP1 and the third arc-shaped waveguide HOP2. From this formula, it can be seen that the curvature k' changes linearly with the transmission distance s'. When R0 is 1500 μm, R... c When L' is 150µm and L' is 50µm, the curve of curvature K' as a function of transmission distance S' is as follows: Figure 2 As shown.

[0030] based on Figure 2 It can be seen that at the junction of the first arc-shaped waveguide HOP1 and the first straight region L1 (curvature of 0), and at the junction of the third arc-shaped waveguide HOP2 and the second straight region L2, the first arc-shaped waveguide HOP1 and the second arc-shaped waveguide CIR (curvature of 1 / R) are located at... c The junction of the third arc waveguide HOP2 and the second arc waveguide CIR (with a curvature of 1 / R) c At the boundary between the waveguide and the transmission distance S', the first derivative of curvature K' with respect to the transmission distance S', dk' / ds', undergoes a sudden change. This leads to a mismatch in the eigenmode field of the waveguide at the boundary, thereby introducing a significant loss.

[0031] To make the mode field transition smoother and reduce waveguide loss, a curved waveguide is provided in this embodiment.

[0032] Based on the curved waveguides shown in Figure 1(a) and / or Figure 1(b), the first curved waveguide HOP1 and the third curved waveguide HOP2 have the same curvature k, and both satisfy the following formula:

[0033] Where s represents the transmission distance corresponding to the curvature k; R c The radius of curvature characterizing the second arc-shaped waveguide. The angle between the tangent and the horizontal line shared by the first and second arc waveguides at the connection point; greater than 0 and less than The constant, The total bending angle of the curved region.

[0034] In the embodiments of this application, It can be the target constant that minimizes the transmission loss in the curved region.

[0035] In this embodiment of the application, if the total bending radius of the bent waveguide is 30 μm and the bending angle is 180°, When the curvature is 72°, the curve of curvature K changing with transmission distance S can be shown as follows: Figure 3 As shown.

[0036] It is evident that even at the boundary between the straight region (first straight region / second straight region) and the curved region, the curvature k is continuous with respect to the corresponding transmission distance s and its first derivative, without any abrupt changes, achieving a smooth and gradual transition of the curved waveguide region from zero. This ensures that the change in the eigenmode field distribution throughout the curved waveguide is sufficiently smooth, reducing the radiation of the optical field outwards while altering the propagation direction. This effectively reduces losses caused by eigenmode field mismatch and significantly lowers the overall transmission loss of the curved waveguide.

[0037] For example, the total bending angle in a known bending region Given the total bending radius R0 and waveguide width W, the bending region can be drawn in the following way.

[0038] because greater than 0 and less than The constant is therefore the total bending angle in the known bending region. In this case, it can be determined The range of values ​​for is (0, ...). ).

[0039] It can take values ​​in the range (0, ... Within a certain range, a constant is obtained at a preset interval as... For each Each can be calculated in the following ways The corresponding alternative bending areas.

[0040] Formula 1: ; x 0 is used to characterize the x-coordinate of the center of the second arc-shaped waveguide. y 0 is used to characterize the ordinate of the center of the second arc waveguide.

[0041] Formula 2: ; Formula 3: ; Formula 4: This formula is used to characterize the bending angle of the first and / or third arc-shaped waveguides. θ The functional relationship between waveguide length s and waveguide length s.

[0042] Formula 2 ( ) and formula 3 ( Substitute into formula 1 ( Formula 5 can be obtained from this: .

[0043] Since Formula 4 can characterize the bending angle The functional relationship between the waveguide length s and the waveguide length s, and and Given this, we can solve Equation 5 to obtain R. c The numerical solution. In this embodiment, the numerical solution function in numerical computing software can be used to solve Equation 5. R c That is, the radius of the second arc-shaped waveguide. Since the center of the second arc-shaped waveguide is at the total bending angle... Therefore, given Rc, the position of the center of the second arc waveguide can also be determined on the angle bisector.

[0044] Let the length of the first arc-shaped waveguide in the candidate curved region to be solved be L, then Substitute Calculation yields .

[0045] N linear vectors s can be generated within the interval [0, L]. Substituting the values ​​of the N vectors s into formula 6: This allows us to solve for the N coordinate points of the center curve of the first arc waveguide.

[0046] according to By mirroring the angle bisector of the first arc waveguide with respect to N coordinate points, the center curve coordinates of the third arc waveguide are obtained. The endpoints of the center curve coordinates of the first arc waveguide and the center curve coordinates of the third arc waveguide are connected by an arc of radius Rc, thus obtaining the center curve coordinates of the curved region.

[0047] Substitute the coordinates of the center curve of the curved region into Formula 7: This allows for radial translation of the curved coordinates. Substituting the waveguide half-width W / 2, the boundary coordinates of the curved region can be obtained. Importing this into graphics drawing software yields candidate curved regions.

[0048] In obtaining each After identifying the corresponding candidate bending regions, the transmission loss of each bending region can be calculated. In this embodiment, the transmission loss of each bending region can be calculated using electromagnetic simulation software, and the candidate bending region with the lowest transmission loss can be determined as the target bending region.

[0049] Correspondingly, the curved waveguide is composed of a first straight region, a target curved region, and a second straight region connected in sequence.

[0050] Under the constraint that the bending loss and polarization-dependent loss of a bent waveguide are less than 0.05 dB, the equivalent bending radius of the waveguide obtained by the "Euler-circle" technique is still 150 μm. This severely limits the integration density of polarization-insensitive photonic chips, making it difficult to achieve ultra-large-scale integration of photonic devices. However, the technical solution provided in this application can reduce the equivalent bending radius of the waveguide to 30 μm, thereby significantly improving the integration density of photonic devices.

[0051] Example 2 Current waveguide structures include Figure 4 As shown, it includes a silicon substrate 101, a buried oxide layer 102, and a silicon waveguide 103. The silicon waveguide width W is 500 nm, the silicon waveguide height h is 220 nm, and the buried oxide layer thickness h... b The refractive index is 2µm. This waveguide structure design inherently exhibits polarization sensitivity; that is, light polarized parallel to the chip plane and light polarized perpendicular to the chip plane have significantly different effective refractive indices in the waveguide, which increases the complexity of optical chip system design. Simultaneously, this waveguide structure has insufficient mode field confinement, resulting in a high-intensity evanescent field distributed on the waveguide surface. Limited by the sidewall roughness level of current etching processes, the waveguide transmission loss exceeds 1dB / cm.

[0052] To make curved waveguides insensitive to polarization and enhance their mode field confinement capability, this application provides a schematic diagram of a waveguide structure. (Combined with...) Figure 5 As shown, the waveguide structures of the first straight region, the curved region, and the second straight region in the embodiments of this application can all be as follows: Figure 5As shown. In other words, the first straight region, the curved region, and the second straight region in the embodiments of this application can each include: a silicon substrate 101; a buried oxide layer 102 disposed on the silicon substrate 101; a silicon flat plate layer 104 disposed on the side of the buried oxide layer 102 away from the silicon substrate 101; and a silicon waveguide 103 disposed on the side of the silicon flat plate layer 104 away from the buried oxide layer 102. The projection of the silicon planar layer 104 onto the buried oxide layer 102 is greater than and covers the projection of the silicon waveguide 103 onto the buried oxide layer 102.

[0053] In the waveguide structure provided in this application embodiment, a silicon planar layer is disposed on the side of the buried oxide layer facing away from the silicon substrate, and the projection of the silicon planar layer on the buried oxide layer covers and is larger than the projection of the silicon waveguide. Given that existing buried oxide layers are typically composed of silicon dioxide, and silicon has significantly better thermal conductivity than silicon dioxide, introducing a silicon planar layer can effectively improve the local thermal conductivity of the bent waveguide, thereby facilitating the use of the thermal effect of current to control the operating temperature of the bent waveguide.

[0054] In one optional implementation of this application embodiment, the silicon planar layer 104 may cover the side of the buried oxide layer 102 facing away from the silicon substrate 101. Alternatively, the silicon planar layer 104 may not cover the side of the buried oxide layer 102 facing away from the silicon substrate 101, but only the projection of the silicon planar layer 104 on the buried oxide layer 102 is greater than and covers the projection of the silicon waveguide 103 on the buried oxide layer 102.

[0055] For example, in combination Figure 5 In the waveguide structure shown, the closest distance d between the projected boundary of the silicon planar layer 104 on the buried oxide layer 102 and the projected boundary of the silicon waveguide 103 on the buried oxide layer 102 can be greater than or equal to 4 μm and less than or equal to 12 μm.

[0056] In this embodiment, the region of the silicon planar layer 104 that does not overlap with the silicon waveguide 103 may also include doped ions, such as phosphorus ions, boron ions, or arsenic ions. Thus, the silicon planar layer 104 can be connected to the metal electrode via doped ions, thereby generating current in the silicon waveguide 103 to achieve modulation.

[0057] The dimension h of the silicon waveguide 103 in the direction perpendicular to the silicon substrate 101 can be greater than or equal to 2.5 μm and less than or equal to 3.5 μm, and the dimension w of the silicon waveguide 103 in the direction parallel to the silicon substrate 101 can be greater than or equal to 1.8 μm and less than or equal to 3.0 μm. Thus, compared to existing silicon waveguides, not only can the dimension of the silicon waveguide in the direction perpendicular to the silicon substrate be increased, but also the dimension of the silicon waveguide in the direction parallel to the silicon substrate can be increased, thereby providing stronger mode field confinement capability.

[0058] The buried oxide layer 102 is perpendicular to the silicon substrate 101 in the direction h.b The size can be greater than or equal to 0.1 μm and less than or equal to 1.5 μm. In this way, while effectively suppressing the surge in parasitic capacitance caused by an excessively thin buried oxide layer, heat can be quickly dissipated using a thinner buried oxide layer, thereby improving the overall reliability and operational stability of the bent waveguide.

[0059] The thickness h of silicon flat layer 104 s The thickness can be greater than or equal to 0.16 μm and less than or equal to 0.6 μm. By limiting the lower limit of the silicon plate layer thickness to 0.1 μm, the silicon plate layer has a sufficient cross-sectional area to form an effective heat conduction path. This allows the high thermal conductivity of silicon to be fully utilized to quickly conduct away the heat generated during the use of the bent waveguide. By limiting the upper limit of the silicon plate layer thickness to 0.6 μm, the slowing down of heating and cooling rates due to excessive heat capacity can be effectively avoided.

[0060] The buried oxide layer 102 may be made of silicon dioxide. The silicon substrate 101, the silicon planar layer 104, and the silicon waveguide 103 may all be made of monocrystalline silicon.

[0061] For example, the buried oxide layer 102 is perpendicular to the silicon substrate 101 in the direction h. b The dimensions can be 0.1μm, 0.2μm, or 1.5μm. The thickness h of the silicon substrate layer 104 is... s The dimensions can be 0.1 μm, 0.2 μm, or 0.6 μm. The dimension h of the silicon waveguide 103 in the direction perpendicular to the silicon substrate 101 can be 2.5 μm, 2.8 μm, or 3.5 μm. The dimension w of the silicon waveguide 103 in the direction parallel to the silicon substrate 101 can be 1.8 μm, 2 μm, or 3.0 μm. In this way, the intensity distribution of the two mutually orthogonal polarization states in the curved waveguide can be made to be consistent, thereby making the propagation constants of the two modes consistent, achieving the effect of the curved waveguide being insensitive to polarization states.

[0062] Combining Figure 6(a) and Figure 6(b), based on Figure 5 The diagram shows the mode field distribution of the waveguide structure under different polarization states. Figure 6(a) is... Figure 5 The diagram shows the electric field intensity distribution of the waveguide structure in TM0 mode. Figure 6(b) is... Figure 5 The diagram shows the electric field intensity distribution of the waveguide structure in TE0 mode. The horizontal axis in Figures 6(a) and 6(b) both represent... Figure 5 The horizontal direction of the waveguide cross-section schematic diagram, with the waveguide center at x=0, and the unit is micrometers (microns). The vertical axis of Figures 6(a) and 6(b) both represent... Figure 5 The vertical direction of the waveguide cross-section schematic diagram shows the lower boundary coordinate of the silicon slab layer at z=0, in micrometers. The black lines in Figures 6(a) and 6(b) represent... Figure 5 The outer contours of the silicon waveguide layer and the silicon flat plate layer in the waveguide structure shown.

[0063] visible, Figure 5 The waveguide structure shown has the same mode field distribution in both TE0 and TM0 modes, and Figure 5 The waveguide structure shown has an effective refractive index of 3.447 in TM0 mode. Figure 5 The waveguide structure shown has an effective refractive index of 3.445 in the TE0 mode, a difference of only about 0.05%, which indicates that... Figure 5 The waveguide structure shown is insensitive to polarization state.

[0064] TM is an abbreviation for Transverse Magnetic. It represents a transverse magnetic wave in which the magnetic field component is zero along the direction of light propagation in the waveguide, and the magnetic field vector is completely distributed on the cross-section perpendicular to the propagation direction. In other words, TM represents a transverse magnetic wave in which the electric field has a component in the propagation direction, while the magnetic field component in the propagation direction is zero. TM0 represents the fundamental mode in the TM polarization state, whose electric field energy distribution on the waveguide cross-section exhibits a single peak shape with no zero point. It is the TM mode with the most concentrated energy and the easiest to excite.

[0065] TE is an abbreviation for Transverse Electric. In the direction of light propagation along the waveguide, the electric field component is zero, and the electric field vector is completely distributed across a cross-section perpendicular to the propagation direction. In other words, TE characterizes the polarization state of the electric field parallel to the plane. TE0 characterizes the base film in the TE polarization state, where the electric field intensity distribution exhibits a single peak without zero points; it is the most energy-concentrated and easily excited TE mode.

[0066] Example 3: Based on the same inventive concept, this embodiment provides an SOI photonic chip, including the bent waveguide of the above embodiment.

[0067] SOI photonic chips are widely used in optical communication modules in data centers, primarily because they overcome the physical bottlenecks in data transmission bandwidth and speed inherent in traditional electrical interconnect technologies. However, with the rapid popularization of artificial intelligence technology, modern data centers are placing more stringent demands on computing power and data communication capabilities. Existing waveguide structures exhibit polarization sensitivity; that is, the polarization states of light parallel to and perpendicular to the chip plane show a significant difference in effective refractive index within the waveguide. This greatly increases the complexity of the overall optical chip design and the difficulty of debugging.

[0068] However, since the SOI chip in this application embodiment innovatively integrates the bent waveguide in the above embodiments, and the bent waveguide in the above embodiments is insensitive to polarization state, the design complexity of the SOI chip in this application embodiment can be significantly reduced compared to existing SOI chips.

[0069] In addition, since the curved waveguide in the above embodiments has a strong optical field confinement capability, it can maintain excellent optical performance with a very small bending radius. Therefore, it can support higher density optical path integration, which is conducive to reducing the overall size of SOI chip. This significantly reduces manufacturing costs and power consumption while achieving higher bandwidth density optical signal processing and transmission, ultimately strongly supporting the stringent requirements of data centers for computing power and data communication capabilities in the era of artificial intelligence.

[0070] Based on the same inventive concept, this embodiment provides a resonator, including the bent waveguide of the above embodiment.

[0071] Based on the same inventive concept, this application provides an optical waveguide splitter, including the curved waveguide of the above embodiment.

[0072] Based on the same inventive concept, this application provides an on-chip external cavity laser, including the curved waveguide of the above embodiments.

[0073] In this embodiment, the passive filtering module of the on-chip external cavity laser may include the bent waveguide described in the above embodiment.

[0074] In this document, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, without necessarily requiring or implying any such actual relationship or order between these entities or operations.

[0075] In this article, "multiple" refers to two or more.

[0076] 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.

Claims

1. A curved waveguide, characterized by, The system comprises a first straight region, a curved region, and a second straight region connected end to end. The curved region includes a first arc-shaped waveguide, a second arc-shaped waveguide, and a third arc-shaped waveguide. The first and third arc-shaped waveguides are symmetrical about the centerline of the second arc-shaped waveguide, and the first and second straight regions are also symmetrical about the centerline of the second arc-shaped waveguide. The centerline of the second arc-shaped waveguide is the line connecting the center of the second arc-shaped waveguide to the center of the circle of the second arc-shaped waveguide. The first and third arc-shaped waveguides have the same curvature k, and both satisfy the formula: Where s represents the transmission distance corresponding to the curvature k; Rc represents the radius of curvature of the second arc-shaped waveguide. The angle between the tangent shared by the first and second arc-shaped waveguides at their connection point and the horizontal line; greater than 0 and less than The constant, where, The total bending angle of the bending region is characterized.

2. The curved waveguide of claim 1, wherein, The Target constant for minimizing the transmission loss of the bending region.

3. The curved waveguide of claim 1, wherein, The first straight region, the curved region, and the second straight region all include: silicon substrate; A buried oxide layer is disposed on the silicon substrate; A silicon flat plate layer is disposed on the side of the buried oxide layer opposite to the silicon substrate; A silicon waveguide is disposed on the side of the silicon planar layer opposite to the buried oxide layer; The projection of the silicon planar layer onto the buried oxide layer is greater than and covers the projection of the silicon waveguide onto the buried oxide layer.

4. The curved waveguide of claim 3, wherein, The dimension of the silicon waveguide perpendicular to the silicon substrate is greater than or equal to 2.5 μm and less than or equal to 3.5 μm, and the dimension of the silicon waveguide parallel to the silicon substrate is greater than or equal to 1.8 μm and less than or equal to 3.0 μm.

5. The curved waveguide of claim 3, wherein, The buried oxide layer has a dimension in the direction perpendicular to the silicon substrate that is greater than or equal to 0.1 μm and less than or equal to 1.5 μm.

6. The curved waveguide of claim 3, wherein, The thickness of the silicon flat layer is greater than or equal to 0.1 μm and less than or equal to 0.6 μm.

7. An SOI photonic chip, characterized by Includes the curved waveguide as described in any one of claims 1 to 6.

8. A resonator characterized by, Includes the curved waveguide as described in any one of claims 1 to 6.

9. An optical waveguide optical power splitter, characterized by Includes the curved waveguide as described in any one of claims 1 to 6.

10. An on-chip external cavity laser, characterized in that, Includes the curved waveguide as described in any one of claims 1 to 6.

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