CN116094647A - Wavelength division multiplexer - Google Patents
Wavelength division multiplexer Download PDFInfo
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- CN116094647A CN116094647A CN202310056462.4A CN202310056462A CN116094647A CN 116094647 A CN116094647 A CN 116094647A CN 202310056462 A CN202310056462 A CN 202310056462A CN 116094647 A CN116094647 A CN 116094647A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0201—Add-and-drop multiplexing
- H04J14/0215—Architecture aspects
- H04J14/0217—Multi-degree architectures, e.g. having a connection degree greater than two
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
- G02B6/29379—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means characterised by the function or use of the complete device
- G02B6/2938—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means characterised by the function or use of the complete device for multiplexing or demultiplexing, i.e. combining or separating wavelengths, e.g. 1xN, NxM
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0224—Irregular wavelength spacing, e.g. to accommodate interference to all wavelengths
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Abstract
The present disclosure provides a wavelength division multiplexer, comprising: an input optical waveguide for inputting an optical signal containing a plurality of wavelengths to be processed; a mach-zehnder interferometer module comprising: the input port of the first Mach-Zehnder interferometer is connected with the first output port of the first Mach-Zehnder interferometer; the input port of the third Mach-Zehnder interferometer is connected with the second output port of the first Mach-Zehnder interferometer; an output waveguide module including a plurality of output optical waveguides; the first Mach-Zehnder interferometer, the second Mach-Zehnder interferometer and the third Mach-Zehnder interferometer comprise a first multimode waveguide and a second multimode waveguide, the length of the first multimode waveguide is larger than that of the second multimode waveguide, and the Mach-Zehnder interferometer module is of a two-stage filter cascade structure so that optical signals containing multiple wavelengths interfere and are output from multiple output optical waveguides respectively, so that wavelength division multiplexing is realized.
Description
Technical Field
The present disclosure relates to the field of optical communications, and more particularly, to a wavelength division multiplexer.
Background
The wavelength division multiplexing (Wavelength Division Multiplexing, WDM) technology is widely applied in the field of optical communication nowadays, and has important significance for improving the communication capacity and the data transmission speed.
Currently, common wavelength division multiplexers include mach-zehnder interferometers, arrayed waveguide gratings (Arrayed Waveguide Grating, AWG), waveguide bragg gratings, and the like. The number of wavelength division multiplexer channels based on Mach-Zehnder interferometers is small, but the passband is flatter, the size is small, the insertion loss and crosstalk are low, and the wavelength division multiplexer is commonly used for short-distance optical interconnection of data centers and the like. The traditional wavelength division multiplexer based on the cascade Mach-Zehnder interferometer mostly adopts a structure with unequal arm length or unequal arm width, and the central wavelength position is very sensitive to the manufacturing process and the working temperature, so that the industrial actual requirements are difficult to meet.
Disclosure of Invention
To solve at least one technical problem of the foregoing and other aspects of the present disclosure, the present disclosure provides a wavelength division multiplexer, which includes a first mach-zehnder interferometer, a second mach-zehnder interferometer, and a third mach-zehnder interferometer, each of which includes a first multimode waveguide and a second multimode waveguide, a length of the first multimode waveguide is greater than a length of the second multimode waveguide, and a mach-zehnder interferometer module is a cascade structure of a second filter to cause optical signals including a plurality of wavelengths to interfere and output from a plurality of output optical waveguides, respectively, so as to implement wavelength division multiplexing.
Embodiments of the present disclosure provide a wavelength division multiplexer including: an input optical waveguide for inputting an optical signal containing a plurality of wavelengths to be processed; a mach-zehnder interferometer module comprising: the input port of the first Mach-Zehnder interferometer is connected with the first output port of the first Mach-Zehnder interferometer; the input port of the third Mach-Zehnder interferometer is connected with the second output port of the first Mach-Zehnder interferometer; an output waveguide module including a plurality of output optical waveguides; the first Mach-Zehnder interferometer, the second Mach-Zehnder interferometer and the third Mach-Zehnder interferometer comprise a first multimode waveguide and a second multimode waveguide, the length of the first multimode waveguide is longer than that of the second multimode waveguide, and the Mach-Zehnder interferometer module is of a two-stage filter cascade structure so that the optical signals with multiple wavelengths interfere and are output from the output optical waveguides respectively, so that wavelength division multiplexing is realized.
According to some embodiments of the present disclosure, the lengths of the first multimode waveguide and the second multimode waveguide are related to a free spectral range of the wavelength division multiplexer, wherein values of the free spectral ranges of the first mach-zehnder interferometer, the second mach-zehnder interferometer, and the third mach-zehnder interferometer are respectively changed in response to changes in the lengths of the first multimode waveguide and the second multimode waveguide.
According to some embodiments of the present disclosure, the first, second, and third mach-zehnder interferometers further each include: a first phase shift arm including a first mode converter, a second mode converter, and the first multimode waveguide connected in this order, wherein the optical signal is converted from a fundamental mode to a first-order mode through the first mode converter in the first phase shift arm, and the optical signal is converted from the first-order mode to the fundamental mode through the second mode converter in the first phase shift arm, so that the optical signal is transmitted in the first multimode waveguide in the fundamental mode; and a second phase shift arm including a third mode converter, the second multimode waveguide, and a fourth mode converter connected in this order, wherein the optical signal is converted from the fundamental mode to the first mode through the third mode converter in the second phase shift arm so that the optical signal is transmitted in the first mode through the second multimode waveguide, and the optical signal is converted from the first mode to the fundamental mode through the fourth mode converter.
According to some embodiments of the present disclosure, the first, second, and third mach-zehnder interferometers further each include: a first curved directional coupler connected to the first phase shift arm and the second phase shift arm via a wired single-mode waveguide; and a second curved directional coupler connected to the first phase shift arm and the second phase shift arm through the wired single-mode waveguide; wherein the first curved directional coupler and the second curved directional coupler are configured to combine and interfere the optical signals.
According to some embodiments of the present disclosure, the first curved directional coupler and the second curved directional coupler each include two input ports, two concentric arc structural waveguides, and two output ports, wherein arc centers of the two concentric arc structural waveguides of the first curved directional coupler and arc centers of the two concentric arc structural waveguides of the second curved directional coupler are symmetrical with respect to a horizontal direction, and a splitting ratio of the first curved directional coupler and the second curved directional coupler is 50:50, so as to implement a process tolerance.
According to some embodiments of the present disclosure, the first mode converter and the second mode converter are disposed with a connection point of the first mode converter and the second mode converter as a center mirror image, and each of the first mode converter, the second mode converter, the third mode converter, and the fourth mode converter includes an input single mode waveguide and an output multimode waveguide, the input single mode waveguide and the output multimode waveguide form a waveguide coupling region for mode conversion of the optical signal, wherein a width of the input single mode waveguide is equal to a width of the wiring single mode waveguide, and a width of the output multimode waveguide is equal to a width of the first multimode waveguide and the second multimode waveguide.
According to some embodiments of the present disclosure, the first phase shift arm further includes a first tapered waveguide connected between the second mode converter and the first multimode waveguide and a second tapered waveguide connected between the first multimode waveguide and the single-mode wire waveguide, the second phase shift arm further includes a third tapered waveguide and a fourth tapered waveguide connected between the fourth mode converter and the single-mode wire waveguide, the third tapered waveguide and the fourth tapered waveguide are sequentially connected, and the first tapered waveguide, the second tapered waveguide, the third tapered waveguide and the fourth tapered waveguide are all isosceles trapezoid structures, wherein a width of an upper base of the isosceles trapezoid structures is equal to a width of the single-mode wire waveguide, and a width of a lower base of the isosceles trapezoid structures is equal to a width of the first multimode waveguide and a width of the second multimode waveguide so as to realize adiabatic change.
According to some embodiments of the present disclosure, a total length of the wired single-mode waveguide of the first phase shift arm is equal to a total length of the wired single-mode waveguide of the second phase shift arm.
According to some embodiments of the disclosure, the first multimode waveguide and the second multimode waveguide have equal widths.
According to some embodiments of the disclosure, the output multimode waveguides of the first mode converter, the second mode converter, the third mode converter, and the fourth mode converter are rectangular or trapezoidal.
According to the wavelength division multiplexer provided by the disclosure, the wavelength division multiplexer comprises a first Mach-Zehnder interferometer, a second Mach-Zehnder interferometer and a third Mach-Zehnder interferometer, wherein the first Mach-Zehnder interferometer, the second Mach-Zehnder interferometer and the third Mach-Zehnder interferometer comprise a first multimode waveguide and a second multimode waveguide, the length of the first multimode waveguide is greater than that of the second multimode waveguide, and the Mach-Zehnder interferometer module is of a cascade structure of a second filter so that optical signals containing a plurality of wavelengths are interfered and then output from a plurality of output optical waveguides respectively, so that the wavelength division multiplexing is realized.
Drawings
FIG. 1 is a block diagram of a wavelength division multiplexer according to an exemplary embodiment of the present disclosure;
FIG. 2 is a block diagram of a portion of a Mach-Zehnder interferometer module of the wavelength division multiplexer of the illustrative embodiment shown in FIG. 1;
FIG. 3 is a block diagram of a first curved directional coupler of the Mach-Zehnder interferometer module of the illustrative embodiment shown in FIG. 2;
FIG. 4 is a block diagram of a first mode converter of the exemplary embodiment shown in FIG. 2;
FIG. 5 is a block diagram of a first mode converter of another exemplary embodiment shown in FIG. 2;
in the drawings, the reference numerals have the following meanings:
100. an input optical waveguide;
200. a Mach-Zehnder interferometer module;
210. a first Mach-Zehnder interferometer;
211. an input port;
212. a first curved directional coupler;
213. a first phase shift arm;
214. a second phase shift arm;
215. a second curved directional coupler;
216. a first output port;
217. a second output port;
31. wiring the single-mode waveguide;
32. a first mode converter;
33. a second mode converter;
34. a first tapered waveguide;
35. a first multimode waveguide;
36. a second tapered waveguide;
41. a third mode converter;
42. a second multimode waveguide;
43. a fourth mode converter;
44. a third tapered waveguide;
45. a fourth tapered waveguide;
51. bending the waveguide coupling region;
52. an output port;
61. inputting a single-mode waveguide;
62. a waveguide coupling region;
63. outputting a multimode waveguide;
220. a second Mach-Zehnder interferometer;
230. a third Mach-Zehnder interferometer;
300. an output waveguide module;
301. a first output optical waveguide;
302. a second output optical waveguide;
303. a third output optical waveguide;
304. and a fourth output optical waveguide.
Detailed Description
For the purposes of promoting an understanding of the principles and advantages of the disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and/or the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.
All terms, including technical and scientific terms, used herein have the meaning commonly understood by one of ordinary skill in the art unless otherwise defined. It should be noted that the terms used herein should be construed to have meanings consistent with the context of the present specification and should not be construed in an idealized or overly formal manner.
Where expressions like at least one of "A, B and C, etc. are used, the expression" system having at least one of A, B and C "shall be construed, for example, in general, in accordance with the meaning of the expression as commonly understood by those skilled in the art, and shall include, but not be limited to, systems having a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B, C together, etc. Where a formulation similar to at least one of "A, B or C, etc." is used, such as "a system having at least one of A, B or C" shall be interpreted in the sense one having ordinary skill in the art would understand the formulation generally, for example, including but not limited to systems having a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B, C together, etc.
For the purposes of promoting an understanding of the principles and advantages of the disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same.
Fig. 1 is a block diagram of a wavelength division multiplexer according to an exemplary embodiment of the present disclosure.
The wavelength division multiplexer provided according to the embodiment of the present disclosure, as shown in fig. 1, includes an input optical waveguide 100, a mach-zehnder interferometer module 200, and an output waveguide module 300, wherein the input optical waveguide 100 is used for inputting an optical signal to be processed including a plurality of wavelengths, the mach-zehnder interferometer module 200 includes a first mach-zehnder interferometer 210, a second mach-zehnder interferometer 220, and a third mach-zehnder interferometer 230, an input port of the second mach-zehnder interferometer 220 is connected with a first output port 216 of the first mach-zehnder interferometer 210 and an input port of the third mach-zehnder interferometer 230 is connected with a second output port 217 of the first mach-zehnder interferometer 210, the output waveguide module 300 includes a plurality of output optical waveguides, where the first mach-zehnder interferometer 210, the second mach-zehnder interferometer 220, and the third mach-zehnder interferometer 230 each include a first multimode waveguide 35 and a second multimode waveguide 42, and the length of the first multimode waveguide 35 is greater than that of the second multimode waveguide 42, and the mach-zehnder interferometer module 200 is a two-stage filter cascade structure so that optical signals including a plurality of wavelengths interfere and are output from the plurality of output optical waveguides, respectively, to implement wavelength division multiplexing.
According to an embodiment of the present disclosure, the first multimode waveguide 35 and the second multimode waveguide 42 are equal in width.
According to an embodiment of the present disclosure, the input optical waveguide 100 inputs an optical signal containing a plurality of wavelengths to be processed into the first mach-zehnder interferometer 210 through the input port 211.
According to an embodiment of the present disclosure, output waveguide module 300 includes a plurality of output optical waveguides, first output optical waveguide 301, second output optical waveguide 302, third output optical waveguide 303, and fourth output optical waveguide 304, respectively.
The wavelength division multiplexer provided by the embodiment of the disclosure can realize low loss and crosstalk, is insensitive to temperature and has large process tolerance by utilizing the cascade structure of the three Mach-Zehnder interferometers.
According to an embodiment of the present disclosure, the lengths of the first multimode waveguide 35 and the second multimode waveguide 42 are related to the free spectral range of the wavelength division multiplexer, wherein the values of the free spectral range of the first mach-zehnder interferometer 210, the second mach-zehnder interferometer 220, and the third mach-zehnder interferometer 230 change in response to changes in the lengths of the first multimode waveguide 35 and the second multimode waveguide 42, respectively.
According to embodiments of the present disclosure, the free spectral range of a wavelength division multiplexer may be expressed specifically as:
wherein FSR represents the free spectral range, lambda represents the center wavelength, n g1 Representing the group index of refraction, n, of the first multimode waveguide 35 g2 The group refractive index of the second multimode waveguide 42 is represented, L1 represents the length of the first multimode waveguide 35, and L2 represents the length of the second multimode waveguide 42.
Meanwhile, to achieve high process tolerance, the lengths of the first multimode waveguide 35 and the second multimode waveguide 42 also need to satisfy:
wherein n is 1 Indicating the effective refractive index, n, of the first multimode waveguide 35 2 Representing the effective refractive index of the second multimode waveguide 42, W1 represents the waveguide width of the first multimode waveguide 35, and W2 represents the waveguide width of the second multimode waveguide 42.
Fig. 2 is a block diagram of a portion of a mach-zehnder interferometer module 200 of the wavelength division multiplexer of the illustrative embodiment shown in fig. 1.
According to an embodiment of the present disclosure, as shown in fig. 2, the first mach-zehnder interferometer 210, the second mach-zehnder interferometer 220, and the third mach-zehnder interferometer 230 each further comprise: a first phase shift arm 213 including a first mode converter 32, a second mode converter 33, and a first multimode waveguide 35 connected in this order, wherein an optical signal is converted from a fundamental mode to a first-order mode through the first mode converter 32 in the first phase shift arm 213, and an optical signal is converted from the first-order mode to a fundamental mode through the second mode converter 33 in the first phase shift arm 213, so that the optical signal is transmitted in the first multimode waveguide 35 in the fundamental mode; and a second phase shift arm 214 including a third mode converter 41, a second multimode waveguide 42, and a fourth mode converter 43 connected in this order, wherein the optical signal is converted from the fundamental mode to the first mode by the third mode converter 41 in the second phase shift arm 214, so that the optical signal is transmitted in the second multimode waveguide 42 in the first mode, and the optical signal is converted from the first mode to the fundamental mode by the fourth mode converter 43.
According to embodiments of the present disclosure, using the difference in effective refractive index of the fundamental mode and the first-order mode as a function of waveguide width, it is possible to achieve an offset of the center wavelength of near zero due to the variation of waveguide width, i.e., with high process tolerance.
According to the embodiment of the present disclosure, the first mode converter 32 and the second mode converter 33 of the first phase shift arm 213 are identical in structure to the third mode converter 41 and the fourth mode converter 43 of the second phase shift arm 214 in order to cancel the phase difference caused by the introduction of the mode converters, ensuring that the phase difference of the first phase shift arm 213 and the second phase shift arm 214 is determined only by the first multimode waveguide 35 and the second multimode waveguide 42.
According to an embodiment of the present disclosure, wavelength division multiplexing with high process tolerance is achieved by generating a phase difference in the first phase shift arm 213 and the second phase shift arm 214 using a fundamental mode and a first order mode, respectively.
According to an embodiment of the present disclosure, the first mach-zehnder interferometer 210, the second mach-zehnder interferometer 220, and the third mach-zehnder interferometer 230 each further comprise: a first curved directional coupler 212 connected to the first phase shift arm 213 and the second phase shift arm 214 through a wired single-mode waveguide 31; and a second curved directional coupler 215 connected to the first phase shift arm 213 and the second phase shift arm 214 through a wired single-mode waveguide 31; wherein the first curved directional coupler 212 and the second curved directional coupler 215 are used to combine and interfere the optical signals.
According to the embodiment of the disclosure, the first curved directional coupler 212 and the second curved directional coupler 215 are adopted as 3dB optical splitters, so that the process insensitivity and the wavelength insensitivity of the devices are realized, the process tolerance of the devices is further improved, and the insertion loss and the crosstalk of the devices are reduced.
According to the embodiment of the present disclosure, the first phase shift arm 213 further includes a first tapered waveguide 34 connected between the second mode converter 33 and the first multimode waveguide 35 and a second tapered waveguide 36 connected between the first multimode waveguide 35 and the wiring single mode waveguide 31, the second phase shift arm 214 further includes a third tapered waveguide 44 and a fourth tapered waveguide 45 connected between the fourth mode converter 43 and the wiring single mode waveguide 31, the third tapered waveguide 44 and the fourth tapered waveguide 45 are sequentially connected, and each of the first tapered waveguide 34, the second tapered waveguide 36, the third tapered waveguide 44 and the fourth tapered waveguide 45 is an isosceles trapezoid structure having an upper base width equal to the width of the wiring single mode waveguide 31 and a lower base width equal to the widths of the first multimode waveguide 35 and the second multimode waveguide 42 to realize adiabatic change.
According to an embodiment of the present disclosure, the total length of the wired single-mode waveguide 31 of the first phase shift arm 213 is equal to the total length of the wired single-mode waveguide 31 of the second phase shift arm 214.
According to an embodiment of the present disclosure, the FSR of the first Mach-Zehnder interferometer 210 is 40nm, and the FSRs of the second Mach-Zehnder interferometer 220 and the third Mach-Zehnder interferometer 230 are 80nm. Optical signals with four wavelengths of 1271nm, 1291nm, 1311nm and 1331nm are input from the input optical waveguide 100, two beams of light after passing through the first bending directional coupler 212 are subjected to phase difference between the first phase shift arm 213 and the second phase shift arm 214, then are combined and interfered through the second bending directional coupler 215, optical signals with the wavelengths of 1271nm and 1311nm are output from the first output port 216 of the first Mach-Zehnder interferometer 210 and enter the second Mach-Zehnder interferometer 220, optical signals with the wavelengths of 1271nm are output from the first output optical waveguide 301, optical signals with the wavelengths of 1311nm are output from the second output optical waveguide 302, optical signals with the wavelengths of 1291nm and 1331nm are output from the second output port 217 of the first Mach-Zehnder interferometer 210 and enter the third Mach-Zehnder interferometer 230, optical signals with the wavelengths of 1291nm are output from the third output optical waveguide 303 and optical signals with the wavelengths of 1331nm are output from the fourth output optical waveguide 304 through a similar process.
According to the embodiment of the disclosure, the three Mach-Zehnder interferometer cascade structures can be utilized to realize low loss and crosstalk, insensitivity to temperature and large process tolerance, and wavelength division multiplexing is realized on the premise of realizing high process tolerance, namely, optical signals containing a plurality of wavelengths are respectively output from different output optical waveguides.
Fig. 3 is a block diagram of a first curved directional coupler 212 of the mach-zehnder interferometer module 200 of the exemplary embodiment shown in fig. 2.
According to an embodiment of the present disclosure, as shown in fig. 3, each of the first curved directional coupler 212 and the second curved directional coupler 215 includes two input ports 211, two concentric arc structural waveguides, and two output ports 52, wherein the arc centers of the two concentric arc structural waveguides of the first curved directional coupler 212 and the arc centers of the two concentric arc structural waveguides of the second curved directional coupler 215 are symmetrical with respect to a horizontal direction, and the split ratio of the first curved directional coupler 212 and the second curved directional coupler 215 is 50:50, so as to implement process tolerance.
According to an embodiment of the present disclosure, the split ratio of the first curved directional coupler 212 and the second curved directional coupler 215 is 50:50, and remains unchanged over a wide spectral range, which at least includes a range from a minimum wavelength to a maximum wavelength of four wavelengths of the optical signal to be processed by the wavelength division multiplexer, with high process tolerance characteristics. Two bands, the O band (1260 nm to 1360 nm) and the C band (1530 nm to 1565 nm), which are commonly used in the field of optical communications are also possible.
According to embodiments of the present disclosure, the bending radii of the bending waveguide coupling regions 51 of the first and second bending directional couplers 212 and 215 should be large enough and the input port 211 and the output port 52 are connected using an S-shaped bending waveguide to reduce bending losses, and by adjusting the bending radii and bending angles, a 50:50 splitting ratio in a wide spectral range can be achieved.
According to an embodiment of the present disclosure, the inner arc radius of the two concentric arc structure waveguides is R1, the outer arc radius is R2, the distance between the inner arc structure waveguide and the outer arc structure waveguide is G, and the waveguide width of the inner arc structure waveguide is F, r2=r1+f+g.
Fig. 4 is a block diagram of the first mode converter 32 of one exemplary embodiment shown in fig. 2, and fig. 5 is a block diagram of the first mode converter 32 of another exemplary embodiment shown in fig. 2.
According to an embodiment of the present disclosure, as shown in fig. 2 and 4, the first mode converter 32 and the second mode converter 33 are disposed with the connection point of the first mode converter 32 and the second mode converter 33 as a mirror image, and each of the first mode converter 32, the second mode converter 33, the third mode converter 41, and the fourth mode converter 43 includes an input single mode waveguide 61 and an output multimode waveguide 63, the input single mode waveguide 61 and the output multimode waveguide 63 forming a waveguide coupling region 62, the waveguide coupling region 62 being used for mode conversion of an optical signal, wherein the width of the input single mode waveguide 61 is equal to the width of the wiring single mode waveguide 31, and the output multimode waveguide 63 is equal to the width of the first multimode waveguide 35 and the second multimode waveguide 42.
According to the embodiment of the present disclosure, the input single mode waveguide 61 and the output multimode waveguide 63 are placed in parallel at a certain interval, and the width of the input single mode waveguide 61 and the width of the output multimode waveguide 63 satisfy the phase matching condition.
According to an embodiment of the present disclosure, as shown in fig. 4 and 5, the output multimode waveguides 63 of the first, second, third and fourth mode converters 32, 33, 41 and 43 are rectangular or trapezoidal.
According to the embodiment of the present disclosure, the output multimode waveguides 63 of the first mode converter 32, the second mode converter 33, the third mode converter 41, and the fourth mode converter 43 have higher process tolerances when they are trapezoidal.
According to the embodiment of the present disclosure, when the output multimode waveguides 63 of the first mode converter 32, the second mode converter 33, the third mode converter 41, and the fourth mode converter 43 are rectangular, since the waveguide widths of the output multimode waveguides 63 are different from those of the input multimode waveguides 61, it may be defined as an asymmetric directional coupler, and when the output multimode waveguides 63 of the first mode converter 32, the second mode converter 33, the third mode converter 41, and the fourth mode converter 43 are trapezoidal, the portion of the input multimode waveguides 61 at the waveguide coupling region 62 is rectangular, since the shapes of the input multimode waveguides 61 and the output multimode waveguides 63 at the position of the waveguide coupling region 62 are different, it may also be defined as an asymmetric directional coupler.
According to the embodiment of the disclosure, the structure of the asymmetric directional coupler is adopted to realize the mutual conversion of the fundamental mode and the first-order mode.
It should be further noted that, the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "rear", "left", "right", etc., are only referring to the directions of the drawings, and are not intended to limit the scope of the present disclosure. Like elements are denoted by like or similar reference numerals throughout the drawings. Conventional structures or constructions will be omitted when they may cause confusion in understanding the present disclosure.
The embodiments of the present disclosure are described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the embodiments cannot be used advantageously in combination. The scope of the disclosure is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be made by those skilled in the art without departing from the scope of the disclosure, and such alternatives and modifications are intended to fall within the scope of the disclosure.
Claims (10)
1. A wavelength division multiplexer, comprising:
an input optical waveguide for inputting an optical signal containing a plurality of wavelengths to be processed;
a mach-zehnder interferometer module comprising:
a first mach-zehnder interferometer is provided,
the input port of the second Mach-Zehnder interferometer is connected with the first output port of the first Mach-Zehnder interferometer; and
the input port of the third Mach-Zehnder interferometer is connected with the second output port of the first Mach-Zehnder interferometer;
an output waveguide module including a plurality of output optical waveguides;
the first Mach-Zehnder interferometer, the second Mach-Zehnder interferometer and the third Mach-Zehnder interferometer comprise a first multimode waveguide and a second multimode waveguide, the length of the first multimode waveguide is larger than that of the second multimode waveguide, and the Mach-Zehnder interferometer module is of a two-stage filter cascade structure so that optical signals containing multiple wavelengths interfere and are output from multiple output optical waveguides respectively, so that wavelength division multiplexing is achieved.
2. The wavelength division multiplexer of claim 1 wherein the lengths of the first multimode waveguide and the second multimode waveguide are related to a free spectral range of the wavelength division multiplexer, wherein the values of the free spectral range of the first mach-zehnder interferometer, the second mach-zehnder interferometer, and the third mach-zehnder interferometer change in response to changes in the lengths of the first multimode waveguide and the second multimode waveguide, respectively.
3. The wavelength division multiplexer of claim 1 wherein the first, second, and third mach-zehnder interferometers each further comprise:
a first phase shift arm including a first mode converter, a second mode converter, and the first multimode waveguide connected in sequence, wherein the optical signal is converted from a fundamental mode to a first-order mode through the first mode converter in the first phase shift arm, and the optical signal is converted from the first-order mode to the fundamental mode through the second mode converter in the first phase shift arm, so that the optical signal is transmitted in the first multimode waveguide in the fundamental mode; and
the second phase shift arm comprises a third mode converter, the second multimode waveguide and a fourth mode converter which are sequentially connected, wherein the optical signal is converted from the fundamental mode to the first mode through the third mode converter in the second phase shift arm so that the optical signal is transmitted in the first mode in the second multimode waveguide, and the optical signal is converted from the first mode to the fundamental mode through the fourth mode converter.
4. The wavelength division multiplexer of claim 3 wherein the first, second, and third mach-zehnder interferometers each further comprise:
a first curved directional coupler connected to the first phase shift arm and the second phase shift arm through a wired single-mode waveguide; and
a second curved directional coupler connected to the first and second phase shift arms through the wired single-mode waveguide;
wherein the first curved directional coupler and the second curved directional coupler are configured to combine and interfere the optical signals.
5. The wavelength division multiplexer of claim 4 wherein the first curved directional coupler and the second curved directional coupler each comprise two input ports, two concentric circular arc structured waveguides, and two output ports, wherein the arc centers of the two concentric circular arc structured waveguides of the first curved directional coupler and the arc centers of the two concentric circular arc structured waveguides of the second curved directional coupler are symmetrical about a horizontal direction, and wherein the split ratio of the first curved directional coupler and the second curved directional coupler is 50:50, achieving process tolerance.
6. The wavelength division multiplexer of claim 4 wherein the first mode converter and the second mode converter are disposed in mirror image about a junction of the first mode converter and the second mode converter, each of the first mode converter, the second mode converter, the third mode converter, and the fourth mode converter including an input single mode waveguide and an output multimode waveguide, the input single mode waveguide and the output multimode waveguide forming a waveguide coupling region for mode conversion of the optical signal, wherein a width of the input single mode waveguide is equal to a width of the routing single mode waveguide, and a width of the output multimode waveguide is equal to a width of the first multimode waveguide and the second multimode waveguide.
7. The wavelength division multiplexer of claim 4 wherein the first phase shift arm further comprises a first tapered waveguide connected between the second mode converter and the first multimode waveguide and a second tapered waveguide connected between the first multimode waveguide and the single mode wire waveguide, the second phase shift arm further comprises a third tapered waveguide and a fourth tapered waveguide connected between the fourth mode converter and the single mode wire waveguide, the third tapered waveguide and the fourth tapered waveguide are sequentially connected, the first tapered waveguide, the second tapered waveguide, the third tapered waveguide and the fourth tapered waveguide are all isosceles trapezoid structures, the upper base widths of the isosceles trapezoid structures are equal to the widths of the single mode wire waveguides, and the lower base widths of the isosceles trapezoid structures are equal to the widths of the first multimode waveguide and the second multimode waveguide to achieve adiabatic changes.
8. The wavelength division multiplexer of claim 4 wherein a total length of the routed single-mode waveguides of the first phase shift arm is equal to a total length of the routed single-mode waveguides of the second phase shift arm.
9. The wavelength division multiplexer of claim 4 wherein the first multimode waveguide and the second multimode waveguide are equal in width.
10. The wavelength division multiplexer of claim 6 wherein the output multimode waveguides of the first, second, third and fourth mode converters are rectangular or trapezoidal.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117055156A (en) * | 2023-08-30 | 2023-11-14 | 广州铌奥光电子有限公司 | Bending directional coupler with large process tolerance and design method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117055156A (en) * | 2023-08-30 | 2023-11-14 | 广州铌奥光电子有限公司 | Bending directional coupler with large process tolerance and design method |
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