Bent waveguide, optical chip and quantum light source
By employing several arc-shaped waveguide segments in a curved waveguide, the direction of optical wave propagation is adjusted, solving the problems of high loss and large size in existing technologies, and achieving low loss and good single-mode retention.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- TURINGQ CO LTD
- Filing Date
- 2025-09-29
- Publication Date
- 2026-08-04
AI Technical Summary
In the existing technology, it is difficult to achieve both low loss and good single-mode retention in the design of bent waveguides, and the size of bent waveguides is difficult to reduce.
By employing several sequentially connected arc-shaped waveguide segments, the optical wave propagation direction is gradually adjusted to reduce optical wave loss and improve single-mode retention. The specific dimensions and positions of each arc-shaped waveguide segment are determined through calculation.
It effectively reduces the loss of light waves during propagation, improves single-mode retention, and can reduce the size of curved waveguides.
Smart Images
Figure CN224594871U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of semiconductor optoelectronics, and in particular to a curved waveguide, an optical chip, and a quantum light source. Background Technology
[0002] In the design of integrated photonic circuits, bending waveguides can cause significant coupling between different modes. Specifically, only the fundamental mode exists in the straight waveguide at the front end of the bending waveguide. After transmission through the bending waveguide, higher-order modes are usually excited at the output end of the bending waveguide. The greater the curvature of the bending waveguide, the more severe the excitation of higher-order modes.
[0003] Currently, bent waveguides need to have low loss and good single-mode retention, but it is difficult to reduce their size. Utility Model Content
[0004] The technical problem to be solved by this utility model is to overcome the above-mentioned defects in the prior art and provide a curved waveguide, an optical chip and a quantum light source.
[0005] The present invention solves the above-mentioned technical problems through the following technical solution:
[0006] A bent waveguide, the bent waveguide comprising:
[0007] At the input terminal, light waves are incident on the input terminal along a first direction;
[0008] A plurality of arc-shaped waveguide segments are connected sequentially. After passing through the input end, the light wave enters the arc-shaped waveguide segments. The plurality of arc-shaped waveguide segments are used to adjust the propagation direction of the light wave to a second direction.
[0009] At the output end, the light wave enters the output end after passing through the arc-shaped waveguide segment, and then exits through the output end.
[0010] In this scheme, by adopting the above structure, by setting the curved waveguide as a series of sequentially connected arc-shaped waveguide segments, and by gradually adjusting the propagation direction of the light wave using these arc-shaped waveguide segments, the loss of the light wave during propagation can be effectively reduced, the single-mode retention of the light wave can be improved, and the size of the light wave can be reduced.
[0011] Preferably, the number of the arc-shaped waveguide segments is i, where i is a natural number not less than 1; the angle between the first direction and the second direction is θ; and the center of the circle corresponding to the i-th arc-shaped waveguide segment is O. i-1 The starting and ending points of the arc-shaped waveguide segment described in segment i are B. i-1 and B iThe coordinates of the first arc-shaped waveguide segment are set as follows: O0 = (0,0), B0 = (0,R0), B1 = (R0sinθ,R0cosθ); the coordinates of the remaining arc-shaped waveguide segments are as follows:
[0012] B i =(O i-1,x +R i-1 sin(iθ), O i-1,y +R i-1 cos(iθ));
[0013] O i = (B i,x -R i sin(iθ),B i,y -R i cos(iθ)).
[0014] In this scheme, by adopting the above structure and through the above calculations, the specific size and position of each arc-shaped waveguide segment can be accurately obtained, thereby better reducing the loss of optical waves and reducing the size of the curved waveguide.
[0015] Preferably, the arc-shaped waveguide segments are smoothly connected.
[0016] In this scheme, by adopting the above structure, the smoothly connected arc-shaped waveguide segment can enable light waves to propagate smoothly and reduce light wave loss.
[0017] Preferably, the angle between the first direction and the second direction is in the range of 45°-180°.
[0018] In this scheme, by adopting the above structure, the application range of the curved waveguide can be improved.
[0019] Preferably, the shape of the arc-shaped waveguide segments is an arc, and the central angle of each arc-shaped waveguide segment is equal.
[0020] In this scheme, by adopting the above structure, several arcs with equal central angles can reduce the calculation difficulty of the arc waveguide and facilitate the fabrication of the arc segment waveguide.
[0021] Preferably, the cross-section of the curved waveguide is ridge-shaped.
[0022] Preferably, the material of the bent waveguide includes lithium niobate or lithium tantalate.
[0023] Preferably, the loss of each arc-shaped waveguide segment is lower than the loss corresponding to the waveguide with the minimum bending radius of the threshold.
[0024] In this scheme, by adopting the above structure, the loss of light waves in the curved waveguide can be further reduced.
[0025] An optical chip includes a substrate layer, a buried oxide layer, a waveguide layer, and a cladding layer, wherein the waveguide layer includes a bent waveguide as described above.
[0026] In this solution, by adopting the above structure, the optical chip can effectively reduce the loss of light waves during propagation, improve the single-mode retention of light waves, and reduce the size of the optical chip.
[0027] A quantum light source comprising a bent waveguide as described above.
[0028] In this scheme, by adopting the above structure, the quantum light source can effectively reduce the loss of light waves during propagation, improve the single-mode retention of light waves, and reduce the size of the optical chip.
[0029] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of this utility model.
[0030] The positive and progressive effects of this utility model are as follows:
[0031] This invention, by setting the curved waveguide as a series of sequentially connected arc-shaped waveguide segments and gradually adjusting the propagation direction of the light wave using these arc-shaped waveguide segments, can effectively reduce the loss of the light wave during propagation, improve the single-mode retention of the light wave, and reduce the size of the light wave. Attached Figure Description
[0032] Figure 1 This is a top view of the curved waveguide in an embodiment of the present invention.
[0033] Figure 2 for Figure 1 A schematic diagram of the cross-section of a curved waveguide.
[0034] Figure 3 for Figure 1 A schematic diagram of the cross-section of a curved waveguide from another perspective.
[0035] Figure 4 This is a schematic diagram of the Y-axis angle and effective refraction of a bent waveguide made of lithium niobate.
[0036] Figure 5 for Figure 1 Schematic diagram of optical field changes in a curved waveguide.
[0037] Figure 6 This is a flowchart of the curved waveguide design method in this embodiment of the present invention.
[0038] Explanation of reference numerals in the attached figures:
[0039] Bending waveguide 100
[0040] Input terminal 11
[0041] Arc-shaped waveguide 12
[0042] Output terminal 13
[0043] Bottom 21
[0044] Buried oxygen layer 22
[0045] Waveguide layer 23
[0046] Cladding 24 Detailed Implementation
[0047] The present invention will be described more clearly and completely below by way of embodiments and in conjunction with the accompanying drawings, but the present invention is not limited to the scope of the embodiments.
[0048] like Figures 1-6 As shown, this embodiment includes a bent waveguide 100, an optical chip, and a quantum light source, as well as a bent waveguide design method. The optical chip and quantum light source utilize the bent waveguide 100, and the bent waveguide design method can design the bent waveguide 100.
[0049] The curved waveguide 100 includes an input end 11, a plurality of arc-shaped waveguide segments 12, and an output end 13. Light waves enter the input end 11 along a first direction; the plurality of arc-shaped waveguide segments 12 are sequentially connected, and the light waves enter the arc-shaped waveguide segments 12 after passing through the input end 11. The plurality of arc-shaped waveguide segments 12 are used to adjust the propagation direction of the light waves to a second direction; the light waves enter the output end 13 after passing through the arc-shaped waveguide segments 12, and exit through the output end 13. By configuring the curved waveguide 100 to include a plurality of sequentially connected arc-shaped waveguide segments 12, and gradually adjusting the propagation direction of the light waves using the plurality of arc-shaped waveguide segments 12, the loss of light waves during propagation can be effectively reduced, the single-mode retention of light waves can be improved, and the size of light waves can be reduced.
[0050] exist Figure 1 In the diagram, the number of arc-shaped waveguide segments 12 is i, where i is a natural number not less than 1; the angle between the first direction and the second direction is θ; and the center of the circle corresponding to the i-th arc-shaped waveguide segment 12 is O. i-1 The starting and ending points of the i-th arc-shaped waveguide segment 12 are B. i-1 and B i The coordinates of the first arc-shaped waveguide 12 are set as follows: O0 = (0,0), B0 = (0,R0), B1 = (R0sinθ,R0cosθ); the coordinates of the remaining arc-shaped waveguide 12 are as follows:
[0051] B i =(O i-1,x +Ri-1 sin(iθ), O i-1,y +R i-1 cos(iθ));
[0052] O i = (B i,x -R i sin(iθ),B i,y -R i cos(iθ)).
[0053] Through the above calculations, the specific dimensions and positions of each arc-shaped waveguide 12 can be accurately obtained, thereby better reducing the loss of light waves and reducing the size of the curved waveguide 100.
[0054] Understandable. Figure 1 The curved waveguide 100 is not fully shown in the figure; B2 and B are omitted. i-1 The curved waveguide 100 segment can be curved in shape as a whole. The input end 11 and the output end 13 of the curved waveguide 100 face different directions. Several curved waveguide segments 12 are disposed between the input end 11 and the output end 13.
[0055] In this embodiment, the two ends of the arc-shaped waveguide 12 are the input end 11 and the output end 13, respectively. In other embodiments, the input end 11 and the output end 13 can also be straight waveguide segments.
[0056] Several arc-shaped waveguide segments 12 are smoothly connected. The smooth connection of the arc-shaped waveguide segments 12 allows light waves to propagate smoothly and reduces light wave loss.
[0057] The angle between the first and second directions ranges from 45° to 180°. This can improve the application range of the curved waveguide 100. Specifically, the angle between the first and second directions can be 60°, 90°, 120°, 135°, 150°, or other values.
[0058] In this example, the several arc-shaped waveguide segments 12 are circular arcs, and the central angle of each arc-shaped waveguide segment 12 is equal in size. Having several circular arcs with equal central angles reduces the computational complexity of the arc-shaped waveguide and facilitates its fabrication. In other examples, the central angle of each arc-shaped waveguide segment 12 can be different.
[0059] The loss of each curved waveguide segment 12 is lower than the loss corresponding to the minimum bending radius of the waveguide at the threshold. This can further reduce the loss of light waves in the curved waveguide 100. As a general implementation, the loss of the curved waveguide 100 can be set to no more than 0.1 dB.
[0060] The cross-section of the curved waveguide 100 can be either ridge-shaped or rectangular.
[0061] The bent waveguide 100 is made of lithium niobate or lithium tantalate, or other doped lithium niobate materials.
[0062] Lithium niobate has a relatively small refractive index difference, approximately 0.7. If a circular arc waveguide with a fixed radius of curvature is used to achieve a 90° deflection of light, the radius of the arc needs to be tens of micrometers to meet the conditions for lossless transmission; for transverse magnetic waves (TM) and other higher-order modes, the bending radius often needs to reach more than one hundred micrometers.
[0063] As one specific implementation, the parameters of the bent waveguide 100 can be as follows:
[0064] The lithium niobate wafer is X-cut, with a thickness of 600 nm and an etching depth of 300 nm; the buried oxide layer 22 has a thickness of 4.7 μm; and the cladding layer 24 is air.
[0065] The lithium niobate waveguide has a top width of 1µm and the input light mode is transverse magnetic wave (TM). Its refractive index varies with the propagation direction as follows: Figure 4 As shown. In Figure 4 In the diagram, the vertical axis represents the effective refractive index, and the horizontal axis represents the angle with the Y-axis of the lithium niobate crystal. It can be seen that as the angle increases, the effective refractive index decreases.
[0066] The initial propagation direction of the curved waveguide 100 is X-tangent Y-propagation, that is, it enters the curved waveguide 100 along the X-axis and then exits the curved waveguide 100 along the Y-axis. The rotation angle θ is 90° and the number of segments i = 9.
[0067] The radii of each arc-shaped waveguide segment 12 are as follows: R0 = 42 μm, R1 = 50 μm, R2 = 60 μm, R3 = 80 μm, R4 = 90 μm, R5 = 90 μm, R6 = 95 μm, R7 = 105 μm, R8 = 105 μm.
[0068] The optical field transmission variation of the above parameters in the bent waveguide 100 is as follows: Figure 5 As shown, the brightness of the light waves can be balanced, and the propagation angle can be gradually changed.
[0069] The overall dimensions of the curved waveguide 100 are 70um*89um, and the transmission efficiency is 99.6%. Its loss is equivalent to a 90° arc radius with a radius of 90um and an overall size of 90um*90um. Compared with ordinary arc waveguides, the curved waveguide 100 has more flexible design and a more compact size.
[0070] In other embodiments, the number of segmented waveguides 12, the radius of the arc, and the center angle of the arc in the curved waveguide 100 can be set as needed, in combination with the loss threshold, waveguide material, and usage environment.
[0071] This embodiment also includes an optical chip, which includes a substrate layer 21, a buried oxide layer 22, a waveguide layer 23, and a cladding layer 24. The waveguide layer 23 includes the bent waveguide 100 as described above. The optical chip can effectively reduce the loss of light waves during propagation, improve the single-mode retention of light waves, and reduce the size of the optical chip.
[0072] The cladding 24 may include, but is not limited to, optical cladding materials such as air, silicon dioxide, silicon oxynitride, and polymers.
[0073] Waveguide layer 23 may include, but is not limited to, anisotropic materials such as lithium niobate crystal, various doped lithium niobate, and lithium tantalate; the thickness of waveguide layer 23 may include, but is not limited to, 200 nm-900 nm; the shape of the waveguide may include ridge waveguides and strip waveguides, and the etching depth may include, but is not limited to, 200 nm-900 nm; the waveguide width is typically in the range of hundreds of nanometers to micrometers depending on the operating wavelength; the waveguide length may be in the range of tens to hundreds of micrometers depending on actual requirements. A bent waveguide 100 may be part of waveguide layer 23.
[0074] The material of the buried oxide layer 22 can be silicon dioxide, and the thickness can range from 1000um to 5000um.
[0075] The substrate 21 is made of materials including but not limited to silicon, quartz, lithium niobate, etc.
[0076] This embodiment also includes a quantum light source, which includes the bent waveguide 100 as described above. The quantum light source can effectively reduce light wave loss during propagation, improve the single-mode retention of light waves, and reduce the size of optical chips.
[0077] like Figure 6 As shown, the design method for curved waveguides can be as follows.
[0078] S10: Set the rotation angle θ between the first and second directions of the curved waveguide 100, set the number i of the arc segment waveguide 12, and set the preset insertion loss IL of the curved waveguide 100.
[0079] S20: The minimum bending radius at which the loss of the lithium niobate waveguide is below a threshold when the direction of light propagation is perpendicular to the Y-axis of the lithium niobate waveguide, calculated using MODE or other FDE algorithm software.
[0080] S30: Calculate and optimize the overall curved waveguide 100 using FDTD or other FDTD algorithm software to obtain the total loss IL of the curved waveguide 100. m .
[0081] S40: If the total loss ILm is not greater than the preset loss IL, the design ends; if the total loss ILm is greater than the preset loss IL, return to S10 and set the number of arc segment waveguides 12 to i+1, repeat steps S20-S40 until the total loss ILm is greater than the preset loss IL.
[0082] The bent waveguide design method can quickly design a suitable bent waveguide 100 that meets loss requirements and has a more compact size.
[0083] As one implementation method, the preset loss IL range can include 0-1dB or other values required in practical applications.
[0084] The number i of the arc-shaped waveguide segments 12 can be no less than 5. The rotation angle θ can be 90°.
[0085] In S20, MODE (Ansys Lumerical MODE) is a software that uses the FDE algorithm to solve optical waveguide modes. It can be applied to modal analysis of structures such as waveguides and couplers.
[0086] In S30, FDTD stands for Ansys Lumerical FDTD. ANSYS Lumerical FDTD is a photonics design software that integrates FDTD (Finite-Difference Time-Domain), RCWA (Reflectance Coefficient Calculation Method), and a stack solver, supporting the modeling and optimization of complex photonic devices within a single design environment. This software can be used for precise, multifunctional, and high-performance simulation design of photonic products. It can also accurately and rigorously solve 3D vector Maxwell's equations.
[0087] While specific embodiments of this utility model have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of this utility model is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of this utility model, but all such changes and modifications fall within the scope of protection of this utility model.
Claims
1. A curved waveguide, characterized in that, The bent waveguide includes: At the input terminal, light waves are incident on the input terminal along a first direction; A plurality of arc-shaped waveguide segments are connected sequentially. After passing through the input end, the light wave enters the arc-shaped waveguide segments. The plurality of arc-shaped waveguide segments are used to adjust the propagation direction of the light wave to a second direction. At the output end, the light wave enters the output end after passing through the arc-shaped waveguide segment, and then exits through the output end.
2. The bent waveguide as described in claim 1, characterized in that, The number of arc-shaped waveguide segments is i, where i is a natural number not less than 1; the angle between the first direction and the second direction is θ; the center of the circle corresponding to the i-th arc-shaped waveguide segment is O. i-1 The starting and ending points of the arc-shaped waveguide segment described in segment i are B. i-1 and B i The coordinates of the first arc-shaped waveguide segment are set as follows: O0 = (0,0), B0 = (0,R0), B1 = (R0sinθ,R0cosθ); the coordinates of the remaining arc-shaped waveguide segments are as follows: B i =(O i-1,x +R i-1 sin(iθ),O i-1,y +R i-1 cos(iθ)); O i =(B i,x -R i sin(iθ),B i,y -R i cos(iθ))。 3. The bent waveguide as described in claim 1, characterized in that, The arc-shaped waveguide segments are smoothly connected.
4. The bent waveguide as described in claim 1, characterized in that, The angle between the first direction and the second direction ranges from 45° to 180°.
5. The bent waveguide as described in claim 1, characterized in that, The shape of several of the arc-shaped waveguide segments is an arc, and the central angle of each arc-shaped waveguide segment is equal.
6. The bent waveguide as described in claim 1, characterized in that, The cross-section of the curved waveguide is ridge-shaped.
7. The bent waveguide as described in claim 1, characterized in that, The material of the curved waveguide includes lithium niobate or lithium tantalate.
8. The curved waveguide as described in any one of claims 1-7, characterized in that, The loss of each arc-shaped waveguide segment is lower than the loss corresponding to the minimum bending radius of the waveguide at the threshold.
9. An optical chip, characterized in that, The optical chip includes a substrate layer, a buried oxide layer, a waveguide layer, and a cladding layer, wherein the waveguide layer includes a flexural waveguide as described in any one of claims 1-8.
10. A quantum light source, characterized in that, The quantum light source includes a curved waveguide as described in any one of claims 1-8.