Waveguide reflector utilizing multimode interference and photon integrated loop
By introducing a multi-mode interference module into the photon integration loop, the optical wave loss problem caused by the overlap of optical waveguides at the reflector is solved, and a more efficient optical waveguide design is achieved.
Patent Information
- Application Number
- CN202323560608.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-26
- Publication Date
- 2025-03-11
- Estimated Expiration
- 2033-12-26
AI Technical Summary
In the photon integration loop, partial overlap of the input and output optical waveguides at the mirror results in light wave loss.
A multi-mode interference module is adopted to connect the input and output optical waveguides to the first end of the multi-mode interference module, and the mirror is located at the second end of the multi-mode interference module, thereby avoiding overlap of the optical waveguides.
By adding a multi-mode interference module, partial overlap of optical waveguides at the reflector is effectively avoided, optical wave loss is reduced, and the performance of photon integrated circuit is improved.
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Figure CN222599885U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of integrated photon devices, in particular to a waveguide reflector and a photon integrated circuit utilizing multi-mode interference. Background Art
[0002] In the design of photonic integrated circuits, it is often necessary to emit light. However, because photonic integrated circuits mostly use optical waveguides, the input optical waveguide 1 and the output optical waveguide 2 will partially overlap 4 at the reflection surface (mirror) 3, such as Figure 1 The limiting and guiding function of the optical waveguide on the light wave will fail in this overlapping area, resulting in a certain loss of the light wave reflected to the output waveguide relative to the input light wave. Utility Model Content
[0003] In order to solve at least part of the above problems in the prior art, the utility model provides a waveguide reflector using multi-mode interference, comprising:
[0004] A multi-mode interference module, comprising a first end and a second end opposite to the first end;
[0005] An input waveguide connected to a first end of the multimode interference module;
[0006] an output waveguide connected to the first end of the multimode interference module; and
[0007] A reflecting mirror is located at the second end of the multi-mode interference module.
[0008] Furthermore, both the input waveguide and the output waveguide are curved waveguides.
[0009] Furthermore, the multimode interference module is half of a 2x2 multimode interferometer.
[0010] Further, the reflector is a reflection-enhancing dielectric coating formed on the polished surface after the waveguide end face is polished; or
[0011] The reflector is a metal coating formed on the polished surface after the waveguide end face is polished.
[0012] Further, the input waveguide and the output waveguide are interchangeable.
[0013] Furthermore, the outlet of the input waveguide is an imaging point of the multimode interference module, and the inlet of the output waveguide is another imaging point of the multimode interference module.
[0014] Further, the multi-mode interference module is a quadrilateral waveguide section surrounded by the first end, the second end, a first side and a second side, wherein the first side is opposite to the second side;
[0015] The two ends of the quadrilateral waveguide section are edges along the Y axis of the three-dimensional space, and the two side portions are edges along the X axis of the three-dimensional space. The waveguide section has a restriction on the light wave along the Z axis, and can form a planar waveguide mode. The two side portions can form a restriction on the light wave in the Y direction, and the X direction is the propagation direction of the light wave of the waveguide section of the multi-mode interference module;
[0016] The width W of the multimode interference module M M I Wide enough so that there are multiple transverse modes in the waveguide of the quadrilateral waveguide section in the Y direction, and the transverse modes propagate along the X direction, where the width W of the multimode interference module is M M I is the distance between the first side and the second side.
[0017] Furthermore, the length L of the multimode interference module M M I is 3*Lπ, length L M M I is the distance between the first end and the second end, wherein Lπ is π / (β0-β1), wherein β0 is the propagation constant of the lowest-order transverse mode of the waveguide of the waveguide section along the X-axis, and β1 is the propagation constant of the second-lowest-order transverse mode of the waveguide of the waveguide section along the X-axis.
[0018] Furthermore, the outlet width of the input waveguide is the same as the inlet width of the output waveguide, the outlet of the input waveguide is where the input waveguide is connected to the multimode interference module, and the inlet of the output waveguide is where the output waveguide is connected to the multimode interference module.
[0019] Furthermore, the outlet width of the input waveguide is the same as the inlet width of the output waveguide, the outlet of the input waveguide is where the input waveguide is connected to the multimode interference module, and the inlet of the output waveguide is where the output waveguide is connected to the multimode interference module.
[0020] The utility model also provides a photon integrated circuit, comprising the waveguide reflector.
[0021] The utility model has at least the following beneficial effects: the waveguide reflector using multimode interference disclosed by the utility model adds a multimode interference module between the input waveguide, the output waveguide and the reflector to avoid the problem of partial overlap of the input waveguide and the output waveguide at the reflector. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] In order to further illustrate the above and other advantages and features of various embodiments of the present invention, a more specific description of various embodiments of the present invention will be presented with reference to the accompanying drawings. It will be understood that these drawings only depict typical embodiments of the present invention and are therefore not to be considered as limiting the scope thereof. In the accompanying drawings, for clarity, identical or corresponding parts will be represented by identical or similar reference numerals.
[0023] Figure 1 A schematic diagram showing that the existing input and output optical waveguides partially overlap at the reflection surface;
[0024] Figure 2 A schematic structural diagram of a waveguide reflector using multi-mode interference according to an embodiment of the utility model is shown;
[0025] Figure 3 A schematic diagram showing the propagation of an incident light spot in a multimode interference waveguide according to an embodiment of the utility model; and
[0026] Figure 4 A schematic structural diagram of a 2X2 multi-mode interferometer according to an embodiment of the utility model is shown. DETAILED DESCRIPTION
[0027] It should be noted that various components in the various drawings may be shown exaggeratedly for illustrative purposes and are not necessarily correct to scale.
[0028] In the present invention, each embodiment is only intended to illustrate the solution of the present invention and should not be understood as limiting.
[0029] In the present invention, unless otherwise specified, the quantifiers "a", "an" and "an" do not exclude the presence of multiple elements.
[0030] It should also be pointed out that in the embodiments of the present invention, for the sake of clarity and simplicity, only a portion of the parts or components may be shown, but a person of ordinary skill in the art will understand that, under the guidance of the present invention, required parts or components may be added according to the needs of specific scenarios.
[0031] It should also be pointed out that within the scope of the present invention, the terms "same", "equal", "equal to" and the like do not mean that the two values are absolutely equal, but allow a certain reasonable error, that is, the terms also cover "substantially the same", "substantially equal", and "substantially equal to".
[0032] It should also be pointed out that in the description of the present invention, the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than explicitly or implicitly indicating that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as explicitly or implicitly indicating relative importance.
[0033] In addition, the embodiments of the present invention describe the process steps in a specific order, but this is only for the convenience of distinguishing the steps, and does not limit the order of the steps. In different embodiments of the present invention, the order of the steps can be adjusted according to the adjustment of the process.
[0034] Figure 2 A schematic structural diagram of a waveguide reflector using multi-mode interference according to an embodiment of the utility model is shown.
[0035] like Figure 2 As shown, a waveguide reflector using multi-mode interference includes an input waveguide 10, a multi-mode interference module 11, a reflector 12 and an output waveguide 13.
[0036] The multimode interference module 11 has a first end, a second end opposite to the first end, a first side portion and a second side portion connecting the first end and the second end, and the first side portion and the second side portion are opposite to each other. The first end portion and the second end portion are the ends in the long side direction of the multimode interference module 11. The multimode interference module 11 is cut from a complete 2x2 multimode interferometer.
[0037] The multimode interference module 11 is a quadrilateral waveguide segment surrounded by a first end and a second end and a first side and a second side. The two ends of the quadrilateral waveguide segment are edges along one axis of the three-dimensional space (assuming the Y axis), and the two sides are edges along another axis of the three-dimensional space (assuming the X axis). The quadrilateral waveguide segment has restrictions on light waves along the Z axis, and can form a planar waveguide mode. The two sides can form restrictions on light waves in the Y direction, and the X direction is the propagation direction of light waves of the multimode interference module 11.
[0038] The width W of the multimode interference module 11 M M I is the distance between the first side portion and the second side portion. The width W of the multi-mode interference module 11 M M Iis wide enough so that there are multiple transverse modes in the waveguide of the waveguide section in the Y direction, and the modes propagate along the X direction, wherein the width W of the multimode interference module M M I is the distance between the first side and the second side.
[0039] The length L of the multimode interference module 11 M M I is the distance between the first end and the second end, and the length L M M I It is 3*Lπ, where Lπ is π / (β0-β1), where β0 is the propagation constant of the lowest-order transverse mode of the waveguide of the multimode interference module along the X-axis, and β1 is the propagation constant of the second-lowest-order transverse mode of the waveguide of the multimode interference module along the X-axis.
[0040] The input waveguide 10 and the output waveguide 13 are connected to the first end of the multimode interference module 11. The input waveguide 10 and the output waveguide 13 are curved waveguides to eliminate the coupling between the waveguides as quickly as possible. The input waveguide 10 is used to introduce input light. The output waveguide 13 is used to receive reflected light. The input waveguide 10 and the output waveguide 13 can be interchanged, the input waveguide 10 receives reflected light, and the output waveguide 13 introduces input light.
[0041] The exit width W of the input waveguide 10 is g and the entrance width W of the output waveguide 13 g Same, width W g Should be smaller than the multimode interference module width W MMI The W g It should be larger than the transverse peak width of the highest order mode of the transverse mode contained in the waveguide section of the multimode interference module (i.e., the mode sub-spot width). The outlet of the input waveguide 10 is where the input waveguide 10 is connected to the multimode interference module 11, and the input light enters the multimode interference module 11 through the outlet of the input waveguide 10. The inlet of the output waveguide 13 is where the output waveguide 13 is connected to the multimode interference module 11, and the reflected light enters the output waveguide 13 from the multimode interference module 11 through the inlet of the output waveguide 13.
[0042] The vertical distance W between the entrance of the input waveguide 10 and the exit of the output waveguide 13 is s It should be approximately taken as W MMI / 6; here W s It is the distance between the center of the entrance of the input waveguide 10 and the center of the exit of the output waveguide 13; the "approximately" depends on the strength of the restriction of the waveguide section of the multimode interference module on the light wave in the Y direction.
[0043] The reflector 12 is located at the second end of the multimode interference module 11. The reflector 12 is used to reflect light and reflect the input light. In one embodiment of the utility model, the reflector is formed by polishing the end face of the multimode interference module 10 and performing a reflective dielectric coating. In another embodiment of the utility model, the reflector is formed by polishing the end face of the multimode interference module 10 and performing a metal coating.
[0044] Figure 3 A schematic diagram showing the propagation of an incident light spot in a multimode interference waveguide according to an embodiment of the utility model is shown.
[0045] The input waveguide and the output waveguide are located at two imaging points of the multimode interference waveguide (2x2 multimode interferometer). When the incident light wave enters the multimode interference waveguide from the input waveguide, which is an imaging point of the multimode interference waveguide, multimode interference will occur in the multimode interference waveguide, that is, the incident light spot excites multiple waveguide modes in the multimode interference waveguide. The propagation constants of these modes are different, generating interference patterns. When the multimode interference waveguide is long enough, the above-mentioned incident light field will appear periodically along the direction of the multimode interference waveguide (from left to right), such as Figure 3 shown.
[0046] like Figure 3 As shown, the incident light spot is at Z=0, and the incident light spot is located at the lower part of the multimode interference waveguide, close to the first side. After a length of 3*Lπ, the image identical to the incident light spot will appear at the upper part of the waveguide, close to the second side. At this time, the light spot position is mirror-symmetrical with the incident position (at Z=0) along the central axis of the waveguide, and the central axis of the waveguide is the transverse axis between the first side and the second side. After another length of 3*Lπ, a light spot identical to the incident light spot will appear at the same position as the incident position, and the above position refers to the position along the Y axis.
[0047] If a reflector is placed at the position of Z=1 / 2*3*Lπ to transmit the light wave back, according to the reverse transmission theory, the imaging spot will appear at a position that is mirror-symmetrical to the spot at Z=3*Lπ with respect to the Y-axis, which is the position of the reflected spot in the required waveguide reflector.
[0048] Notice, Figure 3 The incident light spot and Figure 2 The positions of the input waveguides in the vertical direction (Y direction) are opposite, that is, Figure 2 Input in the top, Figure 3 The input is at the bottom. The positions of the input waveguide and the output waveguide can be swapped, the input can be used as output, and the output can be used as input.
[0049] Figure 4 A schematic structural diagram of a 2X2 multi-mode interferometer according to an embodiment of the utility model is shown.
[0050] The preparation method of the waveguide reflector using multimode interference is as follows:
[0051] Waveguide reflectors that utilize multimode interference can be obtained by precisely controlling the position of the polished end face. Figure 4 The structure shown is a long multimode interference waveguide 20, with an input waveguide 21 and an output waveguide 22 placed at both ends. The chip is then cut from the middle (AA), and the cut surfaces are polished to form two left and right devices.
[0052] During polishing, the control of the polishing position can be achieved by coupling the optical wave signal to the waveguide reflector during the polishing operation, and judging whether the polishing reaches the ideal position by observing the intensity of the optical wave output from the reflected waveguide. The method of monitoring the optical signal to control the polishing process can be performed through a control loop with a data acquisition system and a host computer.
[0053] In one embodiment of the present invention, the reflector is formed by polishing the end surface of the cut multimode interference waveguide and performing a reflection-enhancing dielectric coating. In another embodiment of the present invention, the reflector is formed by polishing the end surface of the cut multimode interference waveguide and performing a metal coating.
[0054] The complete multimode interference waveguide 20 is a 2x2 multimode interferometer. After being cut in the middle, a reflector is formed on the end face. The reflector is then located at half the length of the 2x2 multimode interferometer.
[0055] Although some embodiments of the present invention have been described in this application document, it will be understood by those skilled in the art that these embodiments are only shown as examples. Under the guidance of the present invention, those skilled in the art can think of numerous variations, alternatives and improvements without exceeding the scope of the present invention. The attached claims are intended to define the scope of the present invention and thereby cover methods and structures within the scope of these claims themselves and their equivalents.
Claims
1. A waveguide reflector utilizing multimode interference, characterized in that: include: The multimode interference module has a first end and a second end opposite to the first end; the length L of the multimode interference module MMI is 3*Lπ, length L MMI is the distance between the first end and the second end, wherein Lπ is π / (β0-β1), wherein β0 is the propagation constant of the lowest-order transverse mode of the waveguide of the multimode interference module along the X-axis, and β1 is the propagation constant of the second-lowest-order transverse mode of the waveguide of the multimode interference module along the X-axis; An input waveguide connected to a first end of the multimode interference module; an output waveguide connected to the first end of the multimode interference module; and A reflecting mirror is located at the second end of the multi-mode interference module.
2. The waveguide reflector according to claim 1, characterized in that The input waveguide and the output waveguide are both bent waveguides.
3. The waveguide reflector according to claim 1, characterized in that The multimode interference module is half of a 2x2 multimode interferometer.
4. The waveguide reflector according to claim 1, characterized in that: The reflector is a reflection-enhancing dielectric coating formed on the polished surface after the waveguide end face is polished; or The reflector is a metal coating formed on the polished surface after the waveguide end face is polished.
5. The waveguide reflector according to claim 1, characterized in that The input waveguide and the output waveguide are interchangeable.
6. The waveguide reflector according to claim 1, characterized in that The outlet of the input waveguide is an imaging point of the multi-mode interference module, and the inlet of the output waveguide is another imaging point of the multi-mode interference module.
7. The waveguide reflector according to claim 1, characterized in that The multi-mode interference module is a quadrilateral waveguide section surrounded by the first end, the second end, a first side and a second side, wherein the first side is opposite to the second side; The two ends of the quadrilateral waveguide section are edges along the Y axis of the three-dimensional space, and the two side portions are edges along the X axis of the three-dimensional space. The waveguide section has a restriction on the light wave along the Z axis, and can form a planar waveguide mode. The two side portions can form a restriction on the light wave in the Y direction, and the X direction is the propagation direction of the light wave of the waveguide section of the multi-mode interference module; The width W of the multimode interference module MMI Wide enough so that there are multiple transverse modes in the waveguide of the quadrilateral waveguide section in the Y direction, and the transverse modes propagate along the X direction, where the width W of the multimode interference module is MMI is the distance between the first side and the second side.
8. The waveguide reflector according to claim 1, characterized in that The outlet width of the input waveguide is the same as the inlet width of the output waveguide. The outlet of the input waveguide is where the input waveguide is connected to the multimode interference module, and the inlet of the output waveguide is where the output waveguide is connected to the multimode interference module.
9. A photonic integrated circuit, characterized in that: A waveguide reflector comprising any one of claims 1 to 8.