CN117092836A

CN117092836A - Electro-optical switch

Info

Publication number: CN117092836A
Application number: CN202311114193.9A
Authority: CN
Inventors: 罗先刚; 崔鸽; 陈开鑫; 马小霞; 吴子静
Original assignee: Tianfu Xinglong Lake Laboratory
Current assignee: Tianfu Xinglong Lake Laboratory
Priority date: 2023-08-31
Filing date: 2023-08-31
Publication date: 2023-11-21

Abstract

The embodiment of the application provides an electro-optical switch, and relates to the technical field of optical communication. The electro-optical switch is made based on electro-optical materials and comprises a substrate, a single-mode input waveguide, an interference arm waveguide, a single-mode output waveguide and a beam splitter with an adjustable beam splitting ratio. The beam splitter adopts a multimode interference coupler or a dual-mode interferometer structure, and utilizes the electro-optic effect of the electro-optic material to adjust the beam splitting proportion of an input optical signal to 1:1 in a mode of applying an electric field, so that the high extinction ratio of the electro-optic switch is realized. In addition, the beam splitter made of the material with the electro-optic effect can realize adjustable beam splitting ratio without carrying out ion doping treatment on the waveguide core of the beam splitter, so that the waveguide loss is small. Meanwhile, the adopted multimode interference coupler or dual-mode interferometer structure does not need to manufacture waveguide coupling intervals of hundreds of nanometers, and an expensive deep ultraviolet photoetching machine is not needed in the processing process, so that the manufacturing cost is reduced.

Description

Electro-optical switch

Technical Field

The application relates to the technical field of optical communication, in particular to an electro-optical switch.

Background

With the continuous development of information society fields such as electronic commerce, electronic government affairs, 5G, cloud computing, artificial intelligence and the like, electro-optical devices become the key of the optical communication field. Among them, the electro-optical switch for directly switching the optical path, wavelength or optical mode of the optical signal is particularly important, and the electro-optical switch with low crosstalk is an essential component for constructing high-performance optical communication, optical signal processing and microwave photon systems. For electro-optical switches, the higher the extinction ratio means the smaller the inter-channel crosstalk, the lower the communication error rate, so how to realize high extinction ratio is the primary consideration when designing electro-optical switches for application requirements.

In the prior art, a high-performance optical switch is mainly realized by adopting a Mach-Zehnder interferometer, and according to the working principle of the Mach-Zehnder interferometer, the beam splitting ratio of the 3dB beam splitter is required to be 1:1 to realize a large extinction ratio. Currently, optical switches are mostly implemented by using materials such as silicon, silicon nitride, lithium niobate, etc., where silicon materials do not have an electro-optical effect. The 3dB beam splitter of the silicon-based optical switch mostly adopts a multimode interferometer structure, PN junctions are manufactured by doping in multimode interference areas, the phase relation of light waves in the multimode interference areas is changed based on the plasma dispersion effect of injected carriers, and finally the tunable characteristic of the beam splitting ratio of the beam splitter is realized. In order to realize the plasma dispersion effect, the waveguide core needs to be doped, and meanwhile, carriers need to be injected into the waveguide core during tuning, however, the process of doping the carriers is complex, the insertion loss is increased, and the injected carriers cause a thermal effect, so that the tuning of the beam splitting ratio is influenced. Because silicon nitride does not have a thermo-optic effect, the silicon nitride-based optical switch can realize the tuning of the beam splitting ratio, so that the extinction ratio is improved, and the silicon nitride-based optical switch can only utilize the thermo-optic effect and is realized by adopting a cascade Mach-Zehnder interferometer in structure.

Disclosure of Invention

In order to overcome at least the above-mentioned shortcomings in the prior art, an object of the present application is to provide an electro-optical switch, which is made of electro-optical material, and includes a substrate, a single-mode input waveguide, an interference arm waveguide, a single-mode output waveguide, and a beam splitter with an adjustable beam splitting ratio. The interference arm waveguide comprises a first interference arm waveguide and a second interference arm waveguide, the beam splitter comprises a first beam splitter and a second beam splitter, and the first beam splitter and the second beam splitter adopt a multimode interference coupler structure or a dual-mode interferometer structure.

The output end of the single-mode input waveguide is connected with the input end of the first beam splitter, the output end of the first beam splitter is connected with the input ends of the first interference arm waveguide and the second interference arm waveguide, the output ends of the first interference arm waveguide and the second interference arm waveguide are connected with the input end of the second beam splitter, the output end of the second beam splitter is connected with the input end of the single-mode output waveguide, and the beam splitting ratio of the beam splitter to an input optical signal is tuned through an electro-optic effect.

In one possible implementation, the beam splitter includes a substrate, a buffer layer, a waveguide core, a cladding layer, and a tuning electrode. The buffer layer is directly located above the substrate, the waveguide core is directly located above the buffer layer, the waveguide core is made of a material with an electro-optical effect, the cladding is directly located above the waveguide core, and the tuning electrode is directly located above the cladding.

In one possible implementation, the waveguide core is made of a lithium niobate thin film, and the shape of the waveguide core is rectangular or ridge-shaped protrusion.

In one possible implementation, the buffer layer, the cladding layer, and the waveguide core together form an optical waveguide structure, and the buffer layer and the cladding material are silica or other materials that together form an optical waveguide with the waveguide core material.

In one possible implementation, the tuning electrode includes a first tuning electrode and a second tuning electrode, the first tuning electrode being disposed opposite the second tuning electrode.

The opposite arrangement direction of the first tuning electrode and the second tuning electrode is perpendicular to the extending direction of the waveguide core.

In one possible implementation, the input optical signal excites a plurality of modes in the beam splitter, the excitation in the beam splitter producing a fundamental mode signal and a first order mode signal, wherein the power ratio of the fundamental mode signal and the first order mode signal is 1:1.

in one possible implementation, the electro-optical switch further comprises push-pull electrodes. The first interference arm waveguide and the second interference arm waveguide are arranged in the push-pull electrode, and the push-pull electrode is used for controlling the phase difference between the optical signals transmitted by the first interference arm waveguide and the optical signals transmitted by the second interference arm waveguide.

In one possible implementation, the beam splitter includes a 1 x 2 type beam splitter and a 2 x 2 type beam splitter.

In one possible implementation, the single-mode input waveguide includes a first single-mode input waveguide and a second single-mode input waveguide, and the single-mode output waveguide includes a first single-mode output waveguide and a second single-mode output waveguide.

The first single-mode input waveguide and the second single-mode input waveguide are connected with the input end of the first beam splitter, and the first single-mode output waveguide and the second single-mode output waveguide are connected with the output end of the second beam splitter.

In one possible implementation, the single-mode input waveguide, the interference arm waveguide, and the single-mode output waveguide are made of lithium niobate thin films.

Based on any one of the above aspects, an embodiment of the present application provides an electro-optical switch, where the electro-optical switch includes a substrate, a single-mode input waveguide, an interference arm waveguide, a single-mode output waveguide, and a beam splitter having an electro-optical effect. The beam splitter adopts a multimode interference coupler or a dual-mode interferometer structure, and utilizes the electro-optic effect of the beam splitter, and the beam splitting proportion of the optical signal can be adjusted to be 1:1 by applying an electric field, so that the high extinction ratio of the electro-optic switch is realized. In addition, the use of the beam splitter having an electro-optical effect eliminates the need for ion doping of the waveguide core of the beam splitter 150, and reduces waveguide loss. Meanwhile, the waveguide coupling interval of hundreds of nanometers is not required to be manufactured, and an expensive deep ultraviolet photoetching machine is not required to be used in the processing process, so that the manufacturing cost is reduced.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following description will briefly explain the drawings required for the embodiments, it being understood that the following drawings illustrate only some embodiments of the present application and are therefore not to be considered limiting of the scope, and that other related drawings may be obtained according to these drawings without the inventive effort of a person skilled in the art.

Fig. 1 is a schematic diagram of one possible configuration of an electro-optical switch according to an embodiment of the present application;

fig. 2 is a schematic diagram of a possible partial structure of an electro-optical switch according to an embodiment of the present application;

fig. 3 is a schematic diagram showing a possible partial structure of an electro-optical switch according to an embodiment of the present application;

fig. 4 is a schematic diagram of a second possible configuration of an electro-optical switch according to an embodiment of the present application;

fig. 5 is a schematic diagram of a possible configuration of an electro-optical switch according to an embodiment of the present application.

Icon:

100-electro-optical switches; 110-a substrate; 120-single mode input waveguide; 121-a first single-mode input waveguide; 122-a second single-mode input waveguide; 130-an interference arm waveguide; 131-a first interference arm waveguide; 132-a second interference arm waveguide; 140-single mode output waveguide; 141-a first single-mode output waveguide; 142-a second single-mode output waveguide; 150-beam splitter; 150A-a first beam splitter; 150B-a second beam splitter; 160-push-pull electrode; 151-a substrate; 152-a buffer layer; 153-waveguide core; 154-cladding; 155-tuning the electrodes; 1551-a first tuning electrode; 1552-second tuning electrode.

Description of the embodiments

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. The components of the embodiments of the present application generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the application, as presented in the figures, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.

In the description of the present application, it should be noted that, the azimuth or positional relationship indicated by the terms "upper", "lower", etc. are based on the azimuth or positional relationship shown in the drawings, or the azimuth or positional relationship that is commonly put in use of the product of the application, are merely for convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element to be referred to must have a specific azimuth, be configured and operated in a specific azimuth, and therefore should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like, are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.

In the description of the present application, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art in specific cases.

It should be noted that, in the case of no conflict, different features in the embodiments of the present application may be combined with each other.

Referring to fig. 1, an electro-optical switch 100 according to an embodiment of the present application includes a substrate 110, a single-mode input waveguide 120, an interference arm waveguide 130, a single-mode output waveguide 140, and a beam splitter 150 having an electro-optical effect. The interference arm waveguide 130 includes a first interference arm waveguide 131 and a second interference arm waveguide 132, and the beam splitter 150 includes a first beam splitter 150A and a second beam splitter 150B.

The output end of the single-mode input waveguide 120 is connected to the input end of the first beam splitter 150A, the output end of the first beam splitter 150A is connected to the input ends of the first interference arm waveguide 131 and the second interference arm waveguide 132, the output ends of the first interference arm waveguide 131 and the second interference arm waveguide 132 are connected to the input end of the second beam splitter 150B, and the output end of the second beam splitter 150B is connected to the input end of the single-mode output waveguide 140. Wherein the beam splitter 150 adjusts the beam splitting ratio of the received optical signal by the electro-optical effect of the beam splitter 150.

In this embodiment, the electro-optical effect of the beam splitter 150 is utilized, and the beam splitting ratio of the optical signal can be adjusted to be 1:1 by applying an electric field, so as to achieve a high extinction ratio of the electro-optical switch 100. In addition, the beam splitter 150 having the electro-optical effect is adopted, and the waveguide core of the beam splitter 150 is not required to be subjected to treatment such as ion doping, so that the waveguide loss is small. Meanwhile, the waveguide coupling interval of hundreds of nanometers is not required to be manufactured, and an expensive deep ultraviolet photoetching machine is not required to be used in the processing process, so that the production cost is reduced.

Referring to fig. 2, in one possible embodiment, beam splitter 150 includes a base 151, a buffer layer 152, a waveguide core 153, a cladding layer 154, and a tuning electrode 155.

The buffer layer 152 is directly above the base 151, the waveguide core 153 is directly above the buffer layer 152, the waveguide core 153 is made of a material having an electro-optical effect, the cladding layer 154 is directly above the waveguide core 153, and the tuning electrode 155 is directly above the cladding layer 154.

In the above-described structure, the waveguide core 153 having the electro-optical effect is used in cooperation with the tuning electrode 155, tuning of the beam splitting ratio can be achieved by applying an electric field, and the beam splitting ratio is tuned by the electro-optical effect without performing a process such as doping of the waveguide core 153, so that the waveguide loss is small.

Further, referring again to fig. 2, the waveguide core 153 is made of a lithium niobate thin film, and in addition, the waveguide core 153 may be rectangular or ridge-shaped. Preferably, the waveguide core 153 is in the shape of a ridge protrusion, which is a lithium niobate thin film ridge waveguide with a small transmission loss.

Further, the buffer layer 152 and the cladding layer 154 are both silicon dioxide layers, wherein the thickness of the silicon dioxide buffer layer 152 may be 3-5 μm, so as to prevent the evanescent field of the light wave in the waveguide core 153 from extending to the substrate 151, thereby increasing the transmission loss. Correspondingly, the cladding 154 may separate the waveguide core 153 from the tuning electrode 155, avoiding absorption losses of the optical wave by the metal tuning electrode 155.

In one possible implementation, referring again to fig. 2, tuning electrode 155 includes a first tuning electrode 1551 and a second tuning electrode 1552, which may be made of metal. The first tuning electrode 1551 is disposed opposite to the second tuning electrode 1552, and the opposite direction of the first tuning electrode 1551 and the second tuning electrode 1552 is perpendicular to the extending direction of the waveguide core 153.

Referring to fig. 3, the first tuning electrode 1551 and the second tuning electrode 1552 may be disposed asymmetrically at the ridge-shaped protrusion of the waveguide core 153, and the lengths of the first tuning electrode 1551 and the second tuning electrode 1552 along the waveguide direction are the same but the widths of the first tuning electrode 1551 and the second tuning electrode 1552 perpendicular to the waveguide direction are different. At this time, when an appropriate positive or negative voltage is applied between the two tuning electrodes, the beam splitting ratio of the beam splitter 150 in the present embodiment may be adjusted to 1:1.

Further, the beam splitter 150 splits the received optical signal into a fundamental mode signal and a first order mode signal, wherein a splitting ratio of the fundamental mode signal and the first order mode signal is 1:1.

specifically, the first beam splitter 150A excites the optical signal from the single-mode input waveguide 120 into a fundamental mode signal and a first-order mode signal of equal power, which will propagate along the first beam splitter 150A at different speeds, and interfere at the junction of the first beam splitter 150A and the interference arm waveguide 130, equally distributing the optical signal to the first interference arm waveguide 131 and the second interference arm waveguide 132. Similarly, the second beam splitter 150B excites the optical signals from the first interference arm waveguide 131 and the second interference arm waveguide 132 into a fundamental mode signal and a first-order mode signal with equal power, and the fundamental mode signal and the first-order mode signal will be transmitted along the second beam splitter 150B at different speeds, and interference occurs at the connection between the second beam splitter 150B and the single-mode output waveguide 140, and whether the optical signal interference cancellation of the first interference arm waveguide 131 and the second interference arm waveguide 132 will completely determine the extinction ratio of the electro-optical switch 100 provided in this embodiment.

In the above process, the voltage applied to the tuning electrode 155 on the corresponding beam splitter 150 can be controlled, and the phase difference between the fundamental mode signal and the first-order mode signal is adjusted to pi/2 by the tuning electric field of a certain intensity, thereby achieving the purpose of a beam splitting ratio of 1:1. It can be understood that when the beam splitter 150 is used as a 3dB beam splitter, only the phase difference between the fundamental mode signal and the first-order mode signal needs to be controlled, the phase relationship between the mode signals does not need to be considered, more interference of higher-order modes can be avoided, the electro-optical tuning efficiency is easier to improve, and the analysis and design of the beam splitter 150 are easier.

Further analysis shows that the performance of the electro-optical switch 100 provided by the embodiment of the present application is not only related to the transmission characteristic of the beam splitter 150, but also related to the phase difference between the optical signals of the first interference arm waveguide 131 and the second interference arm waveguide 132, and whether the optical powers of the first interference arm waveguide 131 and the second interference arm waveguide 132 are equal determines whether the optical signals of the two interference arm waveguides 130 interfere with each other.

For this purpose, referring to fig. 4, the electro-optical switch 100 further includes push-pull electrodes. The first interference arm waveguide 131 and the second interference arm waveguide 132 are disposed in a push-pull electrode, and the push-pull electrode is used for controlling a phase difference between an optical signal transmitted by the first interference arm waveguide 131 and an optical signal transmitted by the second interference arm waveguide 132, and the phase difference and a transmission characteristic of the second beam splitter 150B jointly determine the performance of the electro-optical switch 100 provided by the embodiment of the present application. In addition, the push-pull electrode can adjust the optical power of the first interference arm waveguide 131 and the second interference arm waveguide 132 to be equal, and according to the working principle of the mach-zehnder interferometer, the optical signal transmitted by the first interference arm waveguide 131 and the optical signal transmitted by the second interference arm waveguide 132 can be completely cancelled by interference in the second beam splitter 150B, so as to achieve the purpose of high extinction ratio.

In one possible implementation, the beam splitter 150 may include a 1 x 2 type beam splitter 150 and a 2 x 2 type beam splitter 150. Preferably, the beam splitter 150 may be a 2 x 2 type beam splitter 150, i.e. comprising two inputs and two outputs.

Further, the inlet ports of the first beam splitter 150A and the second beam splitter 150B are tapered structures, so that loss caused by mode conversion between the single-mode waveguide and the dual-mode waveguide can be reduced.

Still further, referring to fig. 5, the single-mode input waveguide 120 includes a first single-mode input waveguide 121 and a second single-mode input waveguide 122, and the single-mode output waveguide 140 includes a first single-mode output waveguide 141 and a second single-mode output waveguide 142. The first single-mode input waveguide 121 and the second single-mode input waveguide 122 are connected to an input end of the first beam splitter 150A, and an optical signal may be transmitted from the first single-mode input waveguide 121 and/or the second single-mode input waveguide 122 to the first beam splitter 150A. The first single-mode output waveguide 141 and the second single-mode output waveguide 142 are connected to the output end of the second beam splitter 150B, and the phase difference between the optical signal transmitted by the first interference arm waveguide 131 and the optical signal transmitted by the second interference arm waveguide 132 determines the output waveguide of the optical signal after interference in the second beam splitter 150B. When the phase difference is 0, the optical signal inputted from the single-mode waveguide 121 is outputted from the second single-mode waveguide 142, and when the phase difference is p, the optical signal inputted from the single-mode waveguide 121 is outputted from the first single-mode waveguide 141, thereby realizing the switching function.

In one possible implementation, the single-mode input waveguide 120, the interference arm waveguide 130, and the single-mode output waveguide 140 may be made of lithium niobate thin films with small transmission loss.

In summary, the embodiment of the application provides an electro-optical switch, which includes a substrate, a single-mode input waveguide, an interference arm waveguide, a single-mode output waveguide, and a beam splitter having an electro-optical effect. The beam splitter adopts a multimode interference coupler or a dual-mode interferometer structure, and utilizes the electro-optic effect of the waveguide core material, and the beam splitting proportion of the optical signal can be adjusted to be 1:1 by applying an electric field, so that the high extinction ratio of the electro-optic switch is realized. In addition, the beam splitter is made of a material with an electro-optical effect, so that the waveguide core of the beam splitter 150 does not need to be subjected to ion doping and the like, and the waveguide loss is small. Meanwhile, the waveguide coupling interval of hundreds of nanometers is not required to be manufactured, and an expensive deep ultraviolet photoetching machine is not required to be used in the processing process, so that the manufacturing cost is reduced.

The above description is only of the preferred embodiments of the present application and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. The electro-optical switch is characterized by being manufactured based on electro-optical materials and comprising a substrate, a single-mode input waveguide, an interference arm waveguide, a single-mode output waveguide and a beam splitting ratio adjustable beam splitter, wherein the interference arm waveguide comprises a first interference arm waveguide and a second interference arm waveguide, the beam splitter comprises a first beam splitter and a second beam splitter, and the first beam splitter and the second beam splitter adopt a multimode interference coupler structure or a dual-mode interferometer structure;

2. The electro-optic switch of claim 1, wherein the beam splitter comprises a substrate, a buffer layer, a waveguide core, a cladding layer, and a tuning electrode;

the buffer layer is directly positioned above the substrate;

the waveguide core is directly positioned above the buffer layer and is made of a material with an electro-optic effect;

the cladding is directly over the waveguide core;

the tuning electrode is located directly above the cladding layer.

3. The electro-optical switch of claim 2, wherein the waveguide core is made of a lithium niobate thin film;

the waveguide core is rectangular or ridge-shaped.

4. An electro-optic switch as claimed in claim 3, wherein the buffer layer, the cladding layer and the waveguide core together form an optical waveguide structure, the buffer layer and the cladding layer material being silica or other material which together with the waveguide core material forms an optical waveguide.

5. An electro-optical switch as claimed in claim 3, wherein the tuning electrode comprises a first tuning electrode and a second tuning electrode, the first tuning electrode being disposed opposite the second tuning electrode;

6. An electro-optical switch as claimed in claim 3, wherein an input optical signal excites a plurality of modes in the beam splitter, excitation in the beam splitter producing a fundamental mode signal and a first order mode signal, wherein the power ratio of the fundamental mode signal to the first order mode signal is 1:1.

7. the electro-optic switch of claim 1, wherein the electro-optic open loop further comprises a push-pull electrode;

the first interference arm waveguide and the second interference arm waveguide are arranged in the push-pull electrode, and the push-pull electrode is used for controlling the phase difference between the optical signals transmitted by the first interference arm waveguide and the optical signals transmitted by the second interference arm waveguide.

8. An electro-optic switch as claimed in claim 7, wherein the beam splitters comprise a 1 x 2 type beam splitter and a 2 x 2 type beam splitter.

9. The electro-optic switch of claim 8, wherein the single-mode input waveguide comprises a first single-mode input waveguide and a second single-mode input waveguide, the single-mode output waveguide comprising a first single-mode output waveguide and a second single-mode output waveguide;

10. An electro-optic switch as claimed in claim 9, wherein the single mode input waveguide, the interference arm waveguide and the single mode output waveguide are made of electro-optic material such as lithium niobate film.