CN113892053A

CN113892053A - Electro-optical modulator, optical device and optical module

Info

Publication number: CN113892053A
Application number: CN201980096201.7A
Authority: CN
Inventors: 陈宏民; 邵海峰
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2019-05-20
Filing date: 2019-05-20
Publication date: 2022-01-04
Also published as: WO2020245618A3; WO2020245618A2

Abstract

The application provides an electro-optical modulator, which can reduce the resistance value of the electro-optical modulator to improve the modulation efficiency. The electro-optical modulator comprises a bottom lining, a grounding electrode, a signal electrode, a P-type structure, a first phase shift arm and a second phase shift arm; the grounding electrode, the signal electrode and the P-type structure are arranged on one surface of the bottom lining; the first phase shifting arm and the second phase shifting arm are arranged on the surface of the P-type structure far away from the bottom lining; along the direction of keeping away from the end liner, the part that first phase shift arm is located the modulation zone includes the P type doping layer, waveguide core layer, heavily dope N type doping layer, N type contact layer and the first metal electrode that stack gradually, and the part that the second phase shift arm is located the modulation zone includes the P type doping layer, waveguide core layer, heavily dope N type doping layer, N type contact layer and the second metal electrode that stack gradually, and first metal electrode passes through the metal air bridge with signal electrode and is connected, and the second metal electrode passes through the metal air bridge with earthing electrode and is connected.

Description

Electro-optical modulator, optical device and optical module

Electro-optical modulator, optical device and optical module technical field

The application relates to the field of photoelectric technology, in particular to an electro-optical modulator, an optical device and an optical module.

Background

With the rapid development of optical communication technology, Mach-Zehnder (MZ) electro-optic modulator structures based on indium phosphide (InP) material systems are widely used due to their advantages of high bandwidth, high modulation efficiency, small size, low power consumption, and the like. Fig. 1 is a schematic cross-sectional view of a waveguide structure of a modulation region of a common electro-optic modulator, which includes a semi-insulating substrate 101, a signal electrode 102, a ground electrode 103, a first electrode 104, a second electrode 105, a P-type contact layer 106, a P-type doped layer 107, a waveguide core layer 108, and an N-type doped layer 109. The signal electrode 102 is connected to the first electrode 104 via a metal air bridge 111, and the ground electrode 103 is connected to the second electrode 105 via the metal air bridge 111. An optical signal is confined to be transmitted in the waveguide core layer 108, and when a high-frequency signal is applied between the signal electrode 102 and the ground electrode 103, the high-frequency signal is applied to the waveguide core layer through the first electrode 104 and the second electrode 105 to modulate the optical signal.

The modulation bandwidth of the electro-optical modulator depends on the loss of the high-frequency signal transmitted by the traveling wave electrode, and the lower the loss, the larger the modulation bandwidth. The loss is strongly related to the magnitude of the resistance and capacitance of the electro-optical modulator, and the larger the resistance and capacitance, the larger the transmission loss of the high-frequency signal. The resistance of the equivalent circuit of the electro-optical modulator is generally composed of a P-type contact resistance generated by the contact of the first electrode 104 and the second electrode 105 with the P-type contact layer 106, a resistance of the P-type doped layer 107, and a resistance of the N-type doped layer 109 in series. Therefore, it is a problem how to increase the modulation bandwidth by lowering the resistance value of the electro-optical modulator.

Disclosure of Invention

The application provides an electro-optical modulator, which can reduce resistance to improve the modulation bandwidth of the electro-optical modulator. In addition, the application also provides a corresponding optical device and an optical module.

In a first aspect, the present application provides an electro-optic modulator comprising a substrate, a ground electrode, a signal electrode, a P-type structure, a first phase shift arm, and a second phase shift arm; the grounding electrode, the signal electrode and the P-type structure are arranged on one surface of the bottom lining, the P-type structure is positioned between the grounding electrode and the signal electrode, and the P-type structure comprises at least two P-type materials with different doping concentrations; the first phase shifting arm and the second phase shifting arm are arranged on the surface, far away from the substrate, of the P-type structure, the first phase shifting arm is closer to the signal electrode relative to the second phase shifting arm, and the second phase shifting arm is closer to the grounding electrode relative to the first phase shifting arm; the part of the first phase shift arm, which is positioned in the modulation region, comprises a P-type doped layer, a waveguide core layer, a highly doped N-type doped layer, an N-type contact layer and a first metal electrode which are sequentially stacked along the direction far away from the substrate, wherein the first metal electrode is connected with the signal electrode through a metal air bridge; the part of the second phase shift arm, which is positioned in the modulation region, comprises a P-type doped layer, a waveguide core layer, a highly doped N-type doped layer, an N-type contact layer and a second metal electrode which are sequentially stacked along the direction far away from the bottom lining, and the second metal electrode is connected with the grounding electrode through a metal air bridge.

In the electro-optical modulator provided by the application, the N-type contact layer is in contact with the first metal electrode and the second metal electrode, so that the contact resistance generated by the electro-optical modulator in the process of modulating the optical signal is the N-type contact resistance. Since the conductivity of N-type materials tends to be at least one order of magnitude greater than the conductivity of P-type materials, the N-type resistance tends to be at least one order of magnitude less than the P-type resistance. Therefore, the N-type contact resistance value of the electro-optical modulator provided by the application is reduced by at least one order of magnitude compared with the P-type contact resistance value of an electro-optical modulator (for example, the electro-optical modulator shown in fig. 1) in which the metal electrode is in contact with the P-type contact layer in the prior art, so that the modulation bandwidth is improved.

In one possible design, the N-type contact layer is a highly doped N-type contact layer.

In this possible design, the conductivity of the N-type contact layer is increased by increasing the doping concentration of the dopant ions of the N-type contact layer, so that the resistance of the N-type contact layer and the N-type contact resistance are further reduced, and the modulation bandwidth is further increased.

In one possible design, the P-type structure comprises a highly doped P-type layer and a highly doped P-type contact layer which are stacked, the highly doped P-type layer is arranged on one surface of the substrate, and the highly doped P-type contact layer is arranged on the surface of the highly doped P-type layer far away from the substrate; the doping concentration of the high-doping P type layer is greater than that of the high-doping P type contact layer, and the doping concentration of the high-doping P type contact layer is greater than that of the P type doping layer.

In one possible design, the P-type structure comprises two P-type doping layers, a more highly doped P-type layer and a highly doped P-type contact layer, the two P-type doping layers and the more highly doped P-type layer are positioned between the highly doped P-type contact layer and the bottom lining, the two P-type doping layers and the more highly doped P-type layer are both arranged on one surface of the bottom lining, and the more highly doped P-type layer is sandwiched between the two P-type doping layers; the width of the higher doped P type layer is smaller than the distance between two opposite side surfaces of the first phase shifting arm and the second phase shifting arm, the doping concentration of the higher doped P type layer is larger than that of the high doped P type contact layer, and the doping concentration of the high doped P type contact layer is larger than that of the P type doping layer.

Based on the two possible designs, the thickness of the P-type material is increased by designing the P-type structure so as to ensure the optical transmission loss. And since the P-type structure is designed, the P-type doped layer can be a thin layer, for example, the P-type doped layer with the thickness of 300 nanometers (nm). The 300nm P-doped layer provides only a small resistance compared to the existing thick P-doped layer. In addition, the resistance of the P-type structure is determined by the doping concentration of the P-type material and the distance between the two opposite sides of the first phase shift arm and the second phase shift arm. Therefore, the resistance value of the P-type structure can be reduced by reducing the distance between the two opposite side surfaces of the first phase shift arm and the second phase shift arm and increasing the doping concentration of the P-type material under the condition of ensuring the optical transmission loss.

In one possible embodiment, an insulating layer is provided between the ground electrode and a surface of the substrate, and/or an insulating layer is provided between the signal electrode and a surface of the substrate.

In this possible design, the insulating effect between the ground electrode and/or the signal electrode and the surface of the substrate is ensured by providing an insulating layer. And the insulating layer is arranged, so that the positions of the grounding electrode and/or the signal electrode are heightened, and the manufacturing difficulty of the electro-optical modulator is reduced.

In one possible design, the electro-optic modulator includes a plurality of modulation regions and a plurality of non-modulation regions, the plurality of modulation regions and the plurality of non-modulation regions being alternately distributed along the optical transmission direction.

In one possible design, the non-modulation region includes a P-type doped layer, a waveguide core layer, and an isolation layer stacked in this order along a direction away from the substrate.

In a second aspect, the present application provides an electro-optical modulator, including a substrate, on one surface of which a signal electrode, a first phase shift arm substrate, a second phase shift arm substrate, and a ground electrode are sequentially disposed along a direction perpendicular to an optical transmission direction; a first phase shift arm is arranged on the surface, far away from the substrate, of the first phase shift arm substrate, and the first phase shift arm comprises a first P-type doped layer, a waveguide core layer, a first N-type doped layer, a first N-type contact layer and a third metal electrode which are sequentially stacked along the direction far away from the substrate; a second phase shift arm is arranged on the surface, far away from the substrate, of the second phase shift arm substrate, and the second phase shift arm comprises a first P-type doped layer, a waveguide core layer, a first N-type doped layer, a first N-type contact layer and a fourth metal electrode which are sequentially stacked along the direction far away from the substrate; the third metal electrode and the fourth metal electrode extend along the light transmission direction and are connected through a plurality of mutually spaced metal air bridges; a fifth metal electrode is arranged at one end, close to the signal electrode, of the surface, far away from the bottom lining, of the first phase shift arm substrate, and the fifth metal electrode is connected with the signal electrode through a metal air bridge; and a sixth metal electrode is arranged at one end, close to the grounding electrode, of the surface, far away from the bottom lining, of the second phase shift arm substrate, and the sixth metal electrode is connected with the grounding electrode through a metal air bridge.

In the electro-optical modulator provided by the application, the first N-type contact layer is in contact with the third metal electrode and the fourth metal electrode, so that in the process of modulating an optical signal by the electro-optical modulator, the contact resistance generated by the two phase shift arms is the first N-type contact resistance. Since the conductivity of N-type materials tends to be at least an order of magnitude greater than that of P-type materials, therefore,

the N-type resistance tends to be at least one order of magnitude less than the P-type resistance. Therefore, the first N-type contact resistance value of the electro-optical modulator provided by the present application is reduced by at least one order of magnitude compared to the P-type contact resistance value of an electro-optical modulator (e.g., the electro-optical modulator shown in fig. 1) in which the metal electrode is in contact with the P-type contact layer in the prior art, thereby improving the modulation bandwidth.

In one possible design, the first N-type contact layer is a highly doped N-type contact layer.

In this possible design, the conductivity of the first N-type contact layer is increased by increasing the doping concentration of the dopant ions of the first N-type contact layer, thereby further reducing the resistance of the first N-type contact layer and the N-type contact resistance to further increase the modulation bandwidth.

In one possible design, the electro-optic modulator includes a plurality of modulation regions and a plurality of non-modulation regions, the plurality of modulation regions and the plurality of non-modulation regions being alternately distributed along the optical transmission direction; the fifth metal electrode is arranged on the part of the first phase shift arm substrate belonging to the modulation region; the sixth metal electrode is disposed on a portion of the second phase shift arm substrate belonging to the modulation region.

In one possible design, along the direction away from the substrate, the portion of the first phase shift arm substrate or the second phase shift arm substrate located in the modulation region includes an undoped layer and a second P-type doped layer which are sequentially stacked; along the direction far away from the substrate, the part of the first phase shift arm substrate or the second phase shift arm substrate, which is positioned in the non-modulation region, comprises a non-doped layer and a second N-type doped layer which are sequentially stacked.

In one possible design, a portion of the first phase shift arm substrate or the second phase shift arm substrate located in the modulation region along a direction away from the substrate includes an undoped layer, a second P-type doped layer, and a P-type contact layer, which are stacked in sequence; along the direction far away from the substrate, the part of the first phase shift arm substrate or the second phase shift arm substrate, which is positioned in the non-modulation region, comprises a non-doped layer, a second N-type doped layer and a second N-type contact layer which are sequentially stacked.

Based on the two possible designs, on one hand, the P-type material is used as a modulation area, and the N-type material is used as a non-modulation area, so that the P-type material and the N-type material are contacted with each other to form a PNP structure, and the electrical isolation between different units is realized.

On the other hand, in the process of modulating the optical signal by the electro-optical modulator, the contact between the fifth metal electrode and the P-type contact layer and the contact between the sixth metal electrode and the P-type contact layer generate a P-type contact resistance. Since the contact area between the fifth metal electrode (or the sixth metal electrode) and the P-type contact layer is not limited by the specification of the waveguide core layer, the P-type contact resistance value can be reduced by enlarging the contact area between the fifth metal electrode (or the sixth metal electrode) and the P-type contact layer based on the principle that the larger the contact area is, the smaller the resistance is. In contrast, in the conventional electro-optical modulator, the contact area between the metal electrode in the phase shift arm and the P-type contact layer is generally small due to the limitation of the specification of the waveguide core layer, and thus adjustment cannot be performed. Therefore, the P-type contact resistance of the electro-optical modulator based on the design can be reduced by several times compared with the P-type contact resistance of the existing electro-optical modulator.

In one possible design, along the direction away from the substrate, the portion of the first phase shift arm substrate or the second phase shift arm substrate located in the modulation region includes an undoped layer and a second N-type doped layer which are sequentially stacked; along the direction far away from the substrate, the part of the first phase shift arm substrate or the second phase shift arm substrate, which is positioned in the non-modulation region, comprises a non-doped layer and a second P-type doped layer which are sequentially stacked. In one possible design, along the direction away from the substrate, the portion of the first phase shift arm substrate or the second phase shift arm substrate located in the modulation region includes a non-doped layer, a second N-type doped layer, and a second N-type contact layer, which are stacked in sequence; along the direction far away from the substrate, the part of the first phase shift arm substrate or the second phase shift arm substrate, which is positioned in the non-modulation region, comprises a non-doped layer, a second P-type doped layer and a P-type contact layer which are sequentially stacked.

Based on the two possible designs, on one hand, the P-type material is used as a non-modulation region, and the N-type material is used as a modulation region, so that the P-type material and the N-type material are contacted with each other to form a PNP structure, and the electrical isolation between different units is realized.

On the other hand, in the process of modulating the optical signal by the electro-optical modulator, the contact between the fifth metal electrode and the sixth metal electrode and the second N-type contact layer generates a second N-type contact resistance. And the N-type contact resistance value is reduced by at least one order of magnitude compared to the P-type contact resistance value. Therefore, the contact resistance of the electro-optical modulator based on the design is also far smaller than that of the existing electro-optical modulator, and the modulation bandwidth is improved.

In one possible design, the electro-optic modulator further includes a first dc-biased electrode and a second dc-biased electrode; the first direct current bias electrode and the second direct current bias electrode are arranged on one surface of the substrate and are positioned at two ends of the signal electrode along the light transmission direction, and the first direct current bias electrode and the second direct current bias electrode are respectively connected with the third metal electrode through metal air bridges; or the first direct current bias electrode and the second direct current bias electrode are arranged on one surface of the substrate and are positioned at two ends of the grounding electrode along the light transmission direction, and the first direct current bias electrode and the second direct current bias electrode are respectively connected with the fourth metal electrode through the metal air bridge.

In this possible design, the electro-optic modulator is capable of providing two modes of operation. One is to turn on the signal electrode and the ground electrode, and to turn off the first DC bias electrode and the second DC bias electrode, and the electro-optical modulator operates in a normal mode. And the other is that the signal electrode and the grounding electrode are powered off, the first direct current bias electrode and the second direct current bias electrode are powered on, and the electro-optical modulator works in a direct current bias mode.

In one possible design, an insulating layer is provided between the first dc-biased electrode and a surface of the substrate and/or an insulating layer is provided between the second dc-biased electrode and a surface of the substrate.

In a third aspect, the present application provides an optical device comprising the electro-optic modulator of the first aspect, any of the alternative designs of the first aspect, the second aspect, or any of the alternative designs of the second aspect.

In a third aspect, the present application provides a light module comprising the light device according to the third aspect.

Drawings

FIG. 1A is a schematic cross-sectional view of a waveguide structure of a modulation region of a prior art electro-optic modulator;

FIG. 1B is a block diagram of an electro-optic modulator provided herein;

FIG. 2 is a first schematic diagram illustrating an embodiment of an electro-optic modulator according to the present application;

FIG. 3 is a schematic diagram II of an electro-optic modulator according to an embodiment of the present disclosure;

FIG. 4 is a schematic diagram III of an electro-optic modulator according to an embodiment of the present application;

FIG. 5 is a fourth schematic structural diagram of an embodiment of an electro-optic modulator provided herein;

FIG. 6 is a first top view of an electro-optic modulator provided herein;

FIG. 7 is a fifth block diagram illustrating an embodiment of an electro-optic modulator provided herein, and FIG. 8 is a sixth block diagram illustrating an embodiment of an electro-optic modulator provided herein; FIG. 9 is a second top view of an electro-optic modulator according to the present application;

FIG. 10 is a seventh schematic structural diagram illustrating an embodiment of an electro-optic modulator according to the present application;

FIG. 11 is a block diagram eight of one embodiment of an electro-optic modulator provided herein;

FIG. 12 is a first process flow diagram of an electro-optic modulator provided herein;

FIG. 13 is a second process flow diagram of an electro-optic modulator according to the present application;

FIG. 14 is a third schematic process flow diagram of an electro-optic modulator provided herein;

FIG. 15 is a fourth schematic process flow diagram of an electro-optic modulator according to the present application;

FIG. 16 is a nine schematic structural diagram of one embodiment of an electro-optic modulator provided herein;

FIG. 17 is a block diagram ten illustrating an embodiment of an electro-optic modulator provided herein;

fig. 18 is an eleventh structural schematic diagram of an embodiment of an electro-optic modulator provided in the present application.

Detailed Description

First, when ordinal terms such as "first," "second," "third," or "fourth" are referred to below, they should be understood as being used for distinguishing only, unless they are actually used to express an order in context.

The words "exemplary" or "such as" are used hereinafter to mean serving as an example, instance, or illustration. Any embodiment or design described herein as "exemplary" or "e.g.," is not necessarily to be construed as preferred or advantageous over other embodiments or designs. Rather, use of the word "exemplary" or "such as" is intended to present concepts related in a concrete fashion.

Unless otherwise indicated, "/" herein generally indicates that the former and latter associated objects are in an "or" relationship, e.g., a/B may represent a or B. The term "and/or" is merely an associative relationship that describes an associated object, meaning that three relationships may exist, e.g., a and/or B, may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the present application, "a plurality" means two or more.

Before describing the technical solution provided in the present application, please refer to fig. 1B, which shows a structural diagram of an electro-optical modulator. It should be noted that the electro-optical modulators mentioned in the present application are all Mach-Zehnder (MZ) electro-optical modulators. As shown in fig. 1B, the electro-optic modulator includes a beam splitter 10 and a beam combiner 20. The beam splitter 20 is configured to split the received light beam into two paths, and the beam combiner 20 is configured to combine the two paths into one path. The electro-optical modulator also includes a first phase shift arm 30, a second phase shift arm 40, a ground electrode 91, and a signal electrode 92. The first phase shift arm 30 and the second phase shift arm 40 are both located between the ground electrode 91 and the signal electrode 92. Further, as shown in fig. 1B, the electro-optical modulator further includes a matching resistor 50, one end of the matching resistor 50 is connected to the ground electrode 91, and the other end is connected to the signal electrode 92. It should be understood that the ground electrode 91 and the signal electrode 92 can be loaded with the high frequency signal 60 simultaneously (or together). in addition, as shown in fig. 1B, the electro-optical modulator includes a non-modulation region 70 and a modulation region 80, and with regard to their structures, a more detailed description will be given in the following embodiments of the present application, which will not be described herein for a while. It should be appreciated that the electro-optic modulator also includes a dc bias electrode (not shown in fig. 1B) for operating the electro-optic modulator in a reverse biased state.

Fig. 2 is a schematic structural diagram of an embodiment of an electro-optical modulator according to the present application. The electro-optic modulator includes a substrate 201, a ground electrode 202, a signal electrode 203, a P-type structure 204, a first phase shift arm 205, and a second phase shift arm 206. The ground electrode 202, the signal electrode 203, and the P-type structure 204 are disposed on the same side of the substrate 201, with the P-type structure 204 being disposed between the ground electrode 202 and the signal electrode 203.

A first phase shift arm 205 and a second phase shift arm 206 are disposed on the surface of the P-type structure 204 away from the substrate 201, with the first phase shift arm 205 being closer to the signal electrode 203 than the second phase shift arm 206, and the second phase shift arm 206 being closer to the ground electrode 202 than the first phase shift arm 205.

The first phase shift arm 205 and the second phase shift arm 206 are each a multilayer structure. In this example, the portion of the first phase shift arm 205 located in the modulation region includes a P-type doped layer 207, a waveguide core layer 208, an N-type doped layer 209, an N-type contact layer 210, and a first metal electrode 211, which are sequentially stacked along a direction away from the substrate 201, and the first metal electrode 211 is electrically connected to the signal electrode 203.

Optionally, the first metal electrode 211 and the signal electrode 203 may be electrically connected through a metal air bridge 212. It should be noted that, in the present application, when electrical connection between any two electrodes is required, the electrical connection may be achieved through a metal air bridge, or may be achieved through other methods (for example, a direct contact method). When a metal air bridge connection is used, it should be understood that this is only an exemplary description and is not intended to be limiting as far as electrical connections can be made in this manner.

The portion of the second phase shift arm 206 located in the modulation region includes a P-type doped layer 207, a waveguide core layer 208, an N-type doped layer 209, an N-type contact layer 210, and a second metal electrode 213, which are sequentially stacked in a direction away from the substrate 201, and the second metal electrode 213 and the ground electrode 202 are connected by a metal air bridge 212.

The first phase shift arm 205 and the second phase shift arm 206 may be generated by an etching process, for example, a deep etching process or a shallow etching process. Illustratively, a P-type structure 204, a P-type doped layer 207, a waveguide core layer 208, an N-type doped layer 209, and an N-type contact layer 210 may be sequentially grown on one surface of the substrate 201 in a direction away from the substrate 201. Then, the N-type contact layer 210, the N-type doped layer 209, the waveguide core layer 208, and the P-type doped layer 207 are etched in this order from the N-type contact layer 210 to form two ridge shapes as the first phase shift arm 205 and the second phase shift arm 206. The multi-concentration P-shaped structure 204 is then etched down to the substrate 201, resulting in the shape shown in fig. 2.

After the P-type structure 204 is etched, two symmetrical wide electrodes are disposed at two ends of the P-type structure 204, and the two wide electrodes extend along the light transmission direction and are parallel to the plane where the projection of the substrate 201 is located, so as to form a traveling wave electrode structure. Then, one of the two symmetrical wide electrodes is used as a signal electrode 203, and the other is used as a ground electrode 202. The signal electrode 203 and the ground electrode 202 are provided on the surface of the substrate 201, and may be provided in such a manner that the signal electrode 203 and the ground electrode 202 are in direct contact with the surface of the substrate 201 (i.e., in the configuration shown in fig. 2), or may be provided by first growing an insulating layer 214 on the surface of the substrate 201 at corresponding positions and then providing the signal electrode 203 and the ground electrode 202 on the insulating layer 214. That is, one possible arrangement is to provide an insulating layer 214 between the ground electrode 202 and the surface of the substrate 201, and/or to provide an insulating layer 214 between the signal electrode 203 and the surface of the substrate 201. For example, as shown in fig. 3, insulating layers 214 are provided between the ground electrode 202 and the surface of the substrate 201 and between the signal electrode 203 and the surface of the substrate 201.

The material of the insulating layer 214 may be silicon dioxide (Si 02), benzocyclobutene (BCB), or the like.

In general, an electro-optic modulator generally includes a modulation region, which is a region where an optical signal interacts with an electrical signal to achieve modulation when propagating in the waveguide core layer 208. Therefore, it is necessary for the first phase shift arm 205 to dispose the first metal electrode 211 on the upper surface of the N-type contact layer 210 at the portion located in the modulation region, and to connect the first metal electrode 211 with the signal electrode 203 through the metal air bridge 212. Similarly, it is also necessary for the second phase shift arm 206 to dispose a second metal electrode 213 on the upper surface of the N-type contact layer 210 at the portion located in the modulation region, and to connect the second metal electrode 213 to the ground electrode 202 via the metal air bridge 212. The upper surface of the N-type contact layer 210 refers to the surface of the N-type contact layer 210 away from the substrate 201.

Then, when a high-frequency signal is applied between the signal electrode 203 and the ground electrode 202, an equivalent circuit path of the modulation region of the electro-optical modulator may be from the signal electrode 203 to the ground electrode 202 through a metal air bridge 212 (between the signal electrode 203 and the first metal electrode 211), the first metal electrode 211, the N-type contact layer 210 in the first phase shift arm 205, the N-type doped layer 209, the waveguide core layer 208, the P-type doped layer 207, the P-type structure 204, the P-type doped layer 207 in the second phase shift arm 206, the waveguide core layer 208, the N-type doped layer 209, the N-type contact layer 210, the second metal electrode 213, and the metal air bridge 212 (between the signal electrode 202 and the second metal electrode 213).

In the process of modulating the optical signal, the contact between the metal electrode (whether the first metal electrode 211 or the second metal electrode 213) in the phase shift arm and the N-type contact layer 210 generates an N-type contact resistance. Therefore, the resistance value of the equivalent circuit of the electro-optical modulator provided by the present application (i.e., the resistance value from the signal electrode 203 to the ground electrode 205) can be understood as the series resistance value of the N-type contact resistance, the resistance of the N-type contact layer 210, the resistance of the N-type doped layer 209, the resistance of the P-type doped layer 207, and the resistance of the P-type structure 204.

Since the conductivity of N-type materials tends to be at least one order of magnitude greater than the conductivity of P-type materials, the N-type resistance value tends to be at least one order of magnitude less than the P-type resistance value. In addition, the contact resistance of the N-type material to the metal is an order of magnitude smaller than that of the P-type material to the metal. Therefore, the N-type contact resistance value of the electro-optical modulator provided by the application is reduced by at least one order of magnitude compared with the P-type contact resistance value of the electro-optical modulator (for example, the electro-optical modulator shown in fig. 1) in which the metal electrode is in contact with the P-type contact layer, so that the modulation bandwidth is improved.

Alternatively, the N-type contact layer 210 may be a highly doped N-type contact layer. The conductivity of the N-type contact layer 210 can be increased by increasing the doping concentration of the dopant ions of the N-type contact layer 210, so as to further reduce the resistance of the N-type contact layer 210 and the N-type contact resistance, thereby further increasing the modulation bandwidth.

In addition, in order to ensure the light transmission loss, the P-type doped layer of the conventional electro-optical modulator often needs to have a certain thickness to increase the distance between the optical field and the first electrode 104, the second electrode 105 and the P-type contact layer 106 (see fig. 1) so as to reduce the light transmission loss. Meanwhile, the width of the waveguide core layer is generally determined by the impedance matching and bandwidth requirements of the traveling wave electrode and cannot be changed. Therefore, the resistance value of the P-type doped layer of the conventional electro-optical modulator is large and cannot be reduced. And in the present application, however,

the P-type structure 204 is located below the waveguide core layer 208, on one hand, the optical transmission loss is reduced by designing the concentration of the P-type structure 204, on the other hand, the resistance is reduced by increasing the thickness of the P-type structure 204, and meanwhile, the thickness of the P-type doped layer 207 may be small, for example, the thickness of the P-type doped layer 207 may be 300 nm. The 300nm P-doped layer 207 provides only a small resistance compared to the thickness of the P-doped layer 107 of the prior structure. P-type structure of P-type structure

The P-type structure 204 is used to connect and conduct the first phase shift arm 205 and the second phase shift arm 206. The P-type structure 204 may be a highly doped P-type layer 215, a more highly doped P-type layer 217, or may be composed of at least two P-type materials with different doping concentrations.

Therefore, the resistance of the P-type structure 204 is determined by the doping concentration of the P-type material and the distance between the two opposing sides of the first phase shifting arm 205 and the second phase shifting arm 206. Therefore, the resistance value of the P-type structure can be reduced by reducing the distance between the two opposing sides of the first phase shift arm 205 and the second phase shift arm 206 and increasing the doping concentration of the P-type material while ensuring the optical transmission loss.

The control of the distance between the two opposing sides of the first phase shift arm 205 and the second phase shift arm 206 may be achieved by an etching process, for example, the distance between the two opposing sides of the first phase shift arm 205 and the second phase shift arm 206 is set to 8 micrometers (um), or less than 8 um.

When the P-type structure 204 includes at least two P materials with different doping concentrations, various design approaches may be used. Illustratively, one possible design is that the P-type structure 204 includes a highly doped P-type layer 215 and a highly doped P-type contact layer 216, as shown in fig. 4. A highly doped P-type layer 215 is disposed on one surface of the substrate 201 and a highly doped P-type contact layer 216 is disposed on a surface of the highly doped P-type layer 215 remote from the substrate 201.

The doping concentration of the highly doped P-type layer 215 is greater than or equal to that of the highly doped P-type contact layer 216, and the doping concentration of the highly doped P-type contact layer 216 is greater than or equal to that of the P-type doping layer 207. The highly doped P-type layer 215 is far from the waveguide core layer 208, and thus can be set to a high concentration, and thus has a low resistance.

Illustratively, the highly doped P-type layer 215 may be an indium gallium arsenide (InGaAs) layer, and the doping concentration of the dopant ions may be lel8 (where e represents the power of 10, i.e., lel8 represents the power of 18 of 1 times 10) per cubic centimeter. The highly doped P-type layer 215 may be an indium potassium arsenic phosphorous (InGaAsP) layer or an indium aluminum arsenic (InAlAs) layer, etc., and the doping concentration of the dopant ions may be 10el8 per cubic centimeter. The doping ions may Be beryllium (Be), copper (Cu), or zinc (Zn) plasma.

Alternatively, another possible design is that the P-type structure 204 includes two P-doped layers 207, a more highly doped P-type layer 217, and a highly doped P-type contact layer 216, as shown in fig. 5. Two P-doped layers 207 and a more highly doped P-type layer 217 are disposed on one surface of the substrate 201, the more highly doped P-type layer 217 being sandwiched between the two P-doped layers 207. Two P-doped layers 207 and a more highly doped P-type layer 217 are located between the highly doped P-contact layer 216 and the substrate 201. The surfaces of the two P-doped layers 207 and the more highly doped P-type layer 217 away from the substrate may form a plane.

The width of the higher doped P-type layer 217 is smaller than the distance between two opposite sides of the first phase shift arm 205 and the second phase shift arm 206, the doping concentration of the higher doped P-type layer 217 is greater than that of the high doped P-type contact layer 216, and the doping concentration of the high doped P-type contact layer 216 is greater than that of the P-type doped layer 207.

Since the higher doped P-type layer 217 is located between the two P-type doped layers 207 and is further away from the waveguide core layer 208, the doping concentration of the higher doped P-type layer 217 does not affect the optical transmission loss, so that a higher doping concentration can be set. Then the higher doped P-type layer 217 may have a higher doping concentration than the highly doped P-type layer 215 in the first possible design. For example, the more highly doped P-type layer 217 may be an InGaAs layer, an InAlAs layer, an InGaAsP layer, or the like, and the doping concentration may be 20el8 per cubic centimeter or 5el9 per cubic centimeter.

Fig. 6 is a top view of an electro-optic modulator provided herein, and fig. 2-5 above may be schematic diagrams of cross-sections taken along the line V-V shown in fig. 6. As shown in fig. 6, the electro-optic modulator includes a plurality of modulation regions and a plurality of non-modulation regions, which are alternately distributed along the optical transmission direction. The non-modulation region does not need to carry out interaction between an electric signal and an optical signal, and only completes transmission of the optical signal. Therefore, the first metal electrode 211 and the second metal electrode 213 are not required to be disposed in the non-modulation region. That is, in this example, the first metal electrode 211 and the second metal electrode 213 are periodic electrodes, and the distribution rule of the first metal electrode 211 and the second metal electrode 213 is the same as the distribution rule of the modulation regions. That is, a plurality of first metal electrodes 211 are disposed in the first phase shift arm 205 according to the distribution rule of the modulation regions, and each first metal electrode 211 is connected to the signal electrode 203 through a metal air bridge 212. A plurality of metal air bridges 212 are arranged in the second phase shift arm 206 according to the distribution rule of the modulation regions, and each second metal electrode 213 is also connected with the grounding electrode 202 through one metal air bridge 212

It is worth mentioning that the electro-optical modulator consists of periodic cells (sections), each cell comprising a modulation region and non-modulation regions located in each half of both sides of the modulation region. By controlling the proportion of the modulation region in one unit, for example, 90% of the modulation region and 10% of the non-modulation region in one unit, the characteristic impedance required for photoelectric speed matching and modulation can be realized. In addition, the electro-optical modulator provided by the application can be compatible with a current mainstream differential driver (driver).

During operation of the modulator, it is necessary to electrically isolate the periodic cells (sections). Illustratively, please refer to fig. 7, which shows a schematic structure of a non-modulation region including a first phase shift arm 205 and a second phase shift arm 206, wherein fig. 7 is a cross-sectional view taken along the V '-V' line shown in fig. 6.

As shown in fig. 7, the layer structure of the non-modulation region includes a P-type doped layer 207, a waveguide core layer 208 and an isolation layer 218 in sequence along the direction away from the P-type structure 204. The isolation layer 218 may be formed by various schemes, such as etching away (e.g., wet etching away) the N-type contact layer 210 and then implanting helium (He +) ions into the N-type doped layer 209 to form the isolation layer 218. Alternatively, the N-doped layer 209 and the N-contact layer 210 may be etched away, and an undoped layer may be grown on the waveguide core layer 208 to serve as the spacer 218.

Fig. 8 is a schematic structural diagram of another embodiment of an electro-optic modulator according to the present application. The electro-optical modulator includes a substrate 801 (in which the substrate 801 is semi-insulating), and on one surface of the substrate 801, a signal electrode 802, a first phase shift arm substrate 803, a second phase shift arm substrate 804, and a ground electrode 805 are provided in this order in a direction perpendicular to an optical transmission direction. Wherein a first phase shift arm substrate 803 and a second phase shift arm substrate 804 are disposed between the signal electrode 802 and the ground electrode 805, the first phase shift arm substrate 803 being closer to the signal electrode 802 than the second phase shift arm substrate 804, the second phase shift arm substrate 804 being closer to the ground electrode 805 than the first phase shift arm substrate 803.

A first phase shift arm 806 is disposed on a surface of the first phase shift arm substrate 803 away from the substrate 801, and the first phase shift arm 806 includes a first P-type doped layer 807, a waveguide core layer 808, a first N-type doped layer 809, a first N-type contact layer 810, and a third metal electrode 811 stacked in this order along a direction away from the substrate 801.

A second phase shift arm 812 is disposed on a surface of the second phase shift arm base 804 away from the substrate 801, and the second phase shift arm 812 includes a first P-type doped layer 807, a waveguide core layer 808, a first N-type doped layer 809, a first N-type contact layer 810, and a fourth metal electrode 813 sequentially stacked in a direction away from the substrate 801.

The third metal electrode 811 and the fourth metal electrode 813 extend along the light transmission direction, and the third metal electrode 811 and the fourth metal electrode 813 are connected by a plurality of metal air bridges 814 spaced apart from each other.

A fifth metal electrode 815 is further disposed on a surface of the first phase shift arm substrate 803 away from the substrate 801, and the fifth metal electrode 815 is electrically connected to the signal electrode 802. The fifth metal electrode 815 is closer to the signal electrode 802 than the first phase shift arm 806. It should be noted that the electrical connection may be realized by a metal air bridge 814.

A sixth metal electrode 816 is further disposed on the surface of the second phase shift arm base 804 away from the substrate 801, and the sixth metal electrode 816 is connected to the ground electrode 805 through a metal air bridge 814. In other words, the sixth metal electrode 816 is closer to the ground electrode 805 than the second phase shifting arm 812.

Fig. 9 is a top view of an electro-optic modulator provided herein, and fig. 8 may be a cross-sectional view taken along line V-V of fig. 9. As shown in fig. 9, the electro-optical modulator includes a plurality of modulation regions and a plurality of non-modulation regions, which are alternately distributed along the optical transmission direction. A fifth metal electrode 815 is disposed on a portion of the first phase shift arm substrate 803 belonging to the modulation region. That is, a plurality of fifth metal electrodes 815 are disposed on the surface of the first phase shift arm substrate 803 away from the substrate 801, the distribution of the fifth metal electrodes 815 is the same as the distribution of the modulation regions, each modulation region has a fifth metal electrode 815 disposed therein, and each fifth metal electrode 815 is connected to the signal electrode 802 through a metal air bridge 814. A plurality of sixth metal electrodes 816 are disposed on the surface of the second phase shift arm substrate 804 away from the substrate 801, the distribution of the sixth metal electrodes 816 is the same as that of the modulation regions, one sixth metal electrode 816 is disposed in each modulation region, and each sixth metal electrode 816 is connected to the ground electrode 805 through a metal air bridge 814.

As shown in fig. 9, in this example, the signal electrode 802, the ground electrode 805, the third metal electrode 811 and the fourth metal electrode 813 extend along the light transmission direction and are parallel to the plane on which the projection of the substrate 801 is located.

It is worth mentioning that the electro-optical modulator consists of periodic cells (sections), and each cell comprises a modulation region and non-modulation regions located at both sides of the modulation region. By controlling the proportion of the modulation region in one cell, for example, 90% of the modulation region and 10% of the non-modulation region in one cell, the characteristic impedance required for photoelectric speed matching and modulation can be realized. In addition, the electro-optical modulator provided by the application can be compatible with a current mainstream differential driver (driver).

In one possible design, as shown in fig. 10, the portions of the first and second phase

shift arm bases

803 and 804 located in the modulation region along the direction away from the substrate 801 include a second P-doped layer 818 and a P-contact layer 819, which are stacked in this order. Referring to fig. 11, which is a cross-sectional view of the substrate 801 cut along the V '-V' line shown in fig. 9, the portions of the first phase shift arm base 803 and the second phase shift arm base 804 located in the non-modulation region include a second N-type doped layer 820 and a second N-type contact layer 822 sequentially stacked.

For the non-modulation region, along the direction away from the substrate 801, the first phase shift arm 806 includes a third P-type doped layer 827, a waveguide core layer 808, a first N-type doped layer 809, a first N-type contact layer 810, and a third metal electrode 811 stacked in this order. The second phase shift arm 812 includes a third P-type doped layer 827, a waveguide core 808, a first N-type doped layer 809, a first N-type contact layer 810, and a fourth metal electrode 813 stacked in this order. I.e., in the modulation region, between the waveguide core 808 and the phase shift arm substrate is a first P-doped layer 807, while in the non-modulation region, between the waveguide core 808 and the phase shift arm substrate is a third P-doped layer 827.

In this design, P-type materials (including the second P-type doped layer 818 and the P-type contact layer 819) serve as modulation regions, N-type materials (including the second N-type doped layer 820 and the second N-type contact layer 822) serve as non-modulation regions, and the P-type materials and the N-type materials are in contact with each other to form a PNP structure, so that electrical isolation between different units is achieved.

Then, when a high-frequency signal is applied between the signal electrode 802 and the ground electrode 805, an equivalent circuit path of the modulation region of the electro-optical modulator may sequentially pass through the metal air bridge 814 (between the signal electrode 802 and the fifth metal electrode 815), the fifth metal electrode 815, the P-type contact layer 819, the first P-type doped layer 807 in the first phase shift arm 806, the waveguide core layer 808, the first N-type doped layer 809, the first N-type contact layer 810, the third metal electrode 811, the metal air bridge 814 (between the third metal electrode 811 and the fourth metal electrode 813), the fourth metal electrode 813 in the second phase shift arm 812, the first N-type contact layer 810, the first N-type doped layer 809, the waveguide core layer 808, the second N-type doped layer 813, First P-doped layer 807, P-contact 819, sixth metal electrode 816, metal air bridge 814 (between sixth metal electrode 816 and ground electrode 805), to ground electrode 805.

When a high-frequency signal is loaded between the signal electrode 802 and the grounding electrode 805 and the modulation area of the electro-optical modulator modulates the optical signal, the contact between the third metal electrode 811 and the fourth metal electrode 813 and the first N-type contact layer 810 generates a first N-type contact resistance. The contact of fifth metal electrode 815 and sixth metal electrode 816 with P-type contact layer 819 creates a P-type contact resistance. The metal air bridge 814 between the third metal electrode 811 and the fourth metal electrode 813 creates a resistance. Therefore, based on this design, the resistance value of the electro-optical modulator (i.e., the resistance value of the equivalent circuit from the signal electrode 802 to the ground electrode 805) can be approximated by the series resistance value of the first N-type contact resistance value, the resistance value of the N-type contact layer 810, the resistance value of the N-type doping layer 809, the resistance value of the first P-type doping layer 807, the resistance between the first P-type doping layer 807 to the fifth metal electrode 815, the contact resistance between the fifth metal electrode 815 and the first phase shift arm substrate 803 (P-type contact resistance value), the resistance between the first P-type doping layer 807 to the sixth metal electrode 816, and the contact resistance between the sixth metal electrode 816 and the second phase shift arm substrate 804 (P-type contact resistance value).

Then, based on the design, the contact resistance of the electro-optic modulator includes a first N-type contact resistance and a P-type contact resistance. Wherein the first N-type contact resistance is reduced by at least one order of magnitude compared to the P-type contact resistance value of the metal electrode in the phase shift arm in contact with the P-type contact layer (e.g., the P-type contact resistance value of the first electrode 104 (or the second electrode 105) in contact with the P-type contact layer 106 in fig. 1). On the other hand, for the P-type contact resistance generated by the contact between the fifth metal electrode 815 (or the sixth metal electrode 816) and the P-type contact layer 819, since the contact area between the fifth metal electrode 815 (or the sixth metal electrode 816) and the P-type contact layer 819 is not limited by the size of the waveguide core layer, based on the principle that the larger the contact area is, the smaller the resistance is, the P-type contact resistance value can be reduced by enlarging the contact area between the fifth metal electrode 815 (or the sixth metal electrode 816) and the P-type contact layer 819. In contrast, in the conventional electro-optical modulator, the contact area between the metal electrode in the phase shift arm and the P-type contact layer is generally small due to the limitation of the size of the waveguide core layer, and thus adjustment cannot be performed. Therefore, the P-type contact resistance of the electro-optical modulator based on the design can be reduced by several times compared with the P-type contact resistance of the existing electro-optical modulator. Therefore, the contact resistance of the electro-optical modulator based on the design is far smaller than that of the existing electro-optical modulator, and the modulation bandwidth is improved.

Optionally, the first N-type contact layer 809 may be a highly doped N-type contact layer, and the contact resistance of the first N-type contact layer 810 may be reduced by increasing the doping concentration of the dopant ions of the first N-type contact layer 809. In addition, by increasing the doping concentration of the doping ions of the first N-type contact doping layer 809, the conductivity of the first N-type contact doping layer 809 can be increased, so that the resistance value of the first N-type contact layer 809 and the resistance value of the first N-type contact can be further reduced, and the modulation bandwidth can be further increased. Secondly, for the resistance from the first P-type doped layer 807 to the fifth metal electrode 815 in the first phase shift arm 806 and the resistance from the first P-type doped layer 807 to the sixth metal electrode 816 in the second phase shift arm 812, the resistance from the first P-type doped layer 807 to the fifth metal electrode 815 in the first phase shift arm 806 and the resistance from the first P-type doped layer 807 to the sixth metal electrode 816 in the second phase shift arm 812 can be reduced by reducing the thickness of the first P-type doped layer 807, increasing the thickness of the waveguide core 808 of the first N-type doped layer 809 and the first P-type doped layer 807 in the first phase shift arm 806, reducing the distance between the fifth metal electrode 815 and the first P-type doped layer 807 in the first phase shift arm 806, and reducing the distance between the sixth metal electrode 816 and the first P-type doped layer 807 in the second phase shift arm 812, to boost the modulation bandwidth.

Alternatively, the modulation region and the non-modulation region may not include contact layers (the P-type contact layer 819 in fig. 10 and the second N-type contact layer 822 in fig. 11). That is, along the direction away from the substrate 801, the portions of the first phase shift arm base 803 and the second phase shift arm base 804 in the modulation region include the second P-doped layer 818 stacked in sequence, and the fifth metal electrode 815 may be in direct contact with the second P-doped layer 818. The portions of the first phase shift arm base 803 and the second phase shift arm base 804 in the non-modulation region along the direction away from the substrate 801 include a second N-doped layer 820 sequentially stacked.

Based on the design, the process flow of the electro-optic modulator may include an etching process and a diffusion process. Illustratively, first, as shown in fig. 12 (a), an undoped layer 817 is grown on one surface of the substrate 801, for example, the undoped layer 817 may be an InP layer. If the modulated and non-modulated regions are provided with contact layers, then continued growth of the non-doped contact layer 823 may be performed on the surface of the non-doped layer 817 away from the substrate 801, for example, the non-doped contact layer 823 may be an InGaAs layer.

Then, a diffusion process is used to obtain each layer material required for the layer structure of the first phase shift arm substrate 803 and the second phase shift arm substrate 804. For example, a part of the region is P-type diffused (P-type diffusion) according to the modulation region and the non-modulation region divided in advance, and as shown in fig. 12 (b), a second P-type doped layer 818 and a P-type contact layer 819 of the modulation region are obtained. And performing N-type diffusion (N-type diffusion) on the other partial region, as shown in fig. 12 (c), to obtain a second N-type doped layer 820 and a second N-type contact layer 822 in the non-modulation region.

When the undoped layer 817 is diffused P-type or N-type, the undoped layer 817 at the corresponding position may be fully diffused as P-type or N-type, that is, after the diffusion is completed, the substrate 810 is provided with the second N-type doped layer 820 and the second P-type doped layer 818. Alternatively, as shown in FIG. 12, an undoped layer 817 may remain on the substrate 810.

After the phase shift arm substrate diffusion is completed, each layer of material required for the multilayer structure of the first phase shift arm 806 and the second phase shift arm 812 can be sequentially grown on the multilayer structure of the phase shift arm substrate in a direction away from the substrate 801. Illustratively, as shown in fig. 13 (a), a first P-type doped layer 807, a waveguide core layer 808, a first N-type doped layer 809, and a first N-type contact layer 810 are sequentially grown on a P-type contact layer 818 of the modulation region in a direction away from the substrate 801. As shown in fig. 13 (b), a third N-type doped layer 827, a waveguide core layer 808, a first N-type doped layer 809, and a first N-type contact layer 810 are sequentially grown on the second N-type contact layer 822 in the non-modulation region in a direction away from the substrate 801.

A first etch is then performed to etch the shape of the first phase shift arm 806 and the second phase shift arm 812. That is, for the modulation region, from the first N-type contact layer 810, designated portions of the first N-type contact layer 810, the first N-type doped layer 809, the waveguide core layer 808, and the first P-type doped layer 807 are etched in this order, resulting in the shapes of the first phase shift arm 803 and the second phase shift arm 812. For the non-modulation region, from the first N-type contact layer 810, designated portions of the first N-type contact layer 810, the first N-type doping layer 809, the waveguide core layer 808, and the third N-type doping layer 827 are etched in this order, resulting in the shapes of the first phase shift arm 803 and the second phase shift arm 812. Here, as shown in fig. 14 (a), for the modulation region, the first N-type contact layer 810 is etched to the P-type contact layer 819. As shown in fig. 14 (b), for the non-modulation region, the etching starts from the first N-type contact layer 810 until the second N-type contact layer 822.

Then, a second etching step is performed to etch the first phase shift arm substrate 803 and the second phase shift arm substrate 804. For the portions of the first phase-shift arm base 803 and the second phase-shift arm base 804 located in the modulation region, as shown in fig. 15 (a), the P-contact layer 819, the second P-doped layer 818, and the specified portions of the undoped layer 817 on the substrate 801 are etched away, starting with the P-contact layer 819, resulting in the first phase-shift arm base 803 and the second phase-shift arm base 804. For the portions of the first phase shift arm base 803 and the second phase shift arm base 804 located in the non-modulation region, as shown in fig. 15 (b), the second N-type contact layer 822, the second N-type doped layer 820, and the specified portion of the non-doped layer 817 on the substrate 801 are etched away from the second N-type contact layer 822, resulting in the first phase shift arm base 803 and the second phase shift arm base 804.

After the etching of the first phase shift arm substrate 803 and the second phase shift arm substrate 804 is completed, two mutually symmetrical wide electrodes are disposed at the designated positions of the substrate 801, and the two wide electrodes extend along the light transmission direction and are parallel to the plane where the projection of the substrate 201 is located, so as to form a traveling wave electrode structure. Then, either one of the two symmetrical wide electrodes is used as a signal electrode 802, and the other is used as a ground electrode 805. The signal electrode 802 and the ground electrode 805 may be provided on the surface of the substrate 801 in such a manner that the signal electrode 802 and the ground electrode 805 are in direct contact with the surface of the substrate 801 (i.e., the structure shown in fig. 8). Alternatively, an insulating layer 824 may be grown at a predetermined position on the surface of the substrate 801, and then the signal electrode 802 and the ground electrode 805 may be provided on the insulating layer 824. That is, one possible arrangement is to provide an insulating layer 824 between the ground electrode 805 and the surface of the substrate 801 and/or to provide an insulating layer 824 between the signal electrode 802 and the surface of the substrate 801. For example, as shown in fig. 16, insulating layers 824 are provided between the ground electrode 805 and the surface of the substrate 801 and between the signal electrode 502 and the surface of the substrate 801.

Wherein the material of the insulating layer can be 824, which can be Si0₂Or BCB, etc.

Finally, a third metal electrode 811, a fourth metal electrode 813, a fifth metal electrode 815, a sixth metal electrode 816 and a metal air bridge 814 are provided. That is, the third metal electrode 811 is disposed on the surface of the first N-type contact layer 810 of the first phase shift arm 803 remote from the substrate 801, the metal electrode 813 is disposed on the surface of the first N-type contact layer 810 of the second phase shift arm 812 remote from the substrate 801, and the third metal electrode 811 and the fourth metal electrode 813 are connected by disposing a plurality of metal air bridges 814 (see fig. 9) spaced apart from each other. The distribution rule of the metal electrode 814 connecting the third metal electrode 811 and the fourth metal electrode 813 may be the same as or different from the distribution rule of the modulation region.

As shown in fig. 16 (a), in each portion of the first phase shift arm substrate 803 located in the modulation region, a fifth metal electrode 815 is disposed on the surface of the second P-type doped layer 818 away from the substrate 801, and a metal air bridge 814 is disposed to connect the fifth metal electrode 815 and the signal electrode 802. Similarly, in each portion of the modulation region where the second phase shift arm substrate 804 is located, a sixth metal electrode 816 is disposed on the surface of the second P-doped layer 818 away from the substrate 801, and a metal air bridge 814 is disposed to connect the sixth metal electrode 816 and the ground electrode 805. And finishing the manufacture of the electro-optical modulator. A schematic cross-sectional view of the non-modulation region corresponding to the modulation region shown in fig. 16 (a) may be as shown in fig. 16 (b).

In another possible design, a P-type material (including the second P-type doped layer 818 and the P-type contact layer 819) may be used as the non-modulation region, and an N-type material (including the second N-type doped layer 820 and the second N-type contact layer 822) may be used as the modulation region, and the P-type material and the N-type material are in contact with each other to form a PNP structure, so as to achieve electrical isolation between different cells. That is, as shown in fig. 17 (a), the portions of the first phase shift arm bases 803 and the second phase shift arm bases 804 located in the modulation region along the direction away from the substrate 801 include a non-doped layer 817, a second N-doped layer 820, and a second N-contact layer 822 sequentially stacked. As shown in FIG. 17 (b), the portions of the first phase-shifting arm bases 803 and the second phase-shifting arm bases 804 located in the non-modulation region along the direction away from the substrate 801 include an undoped layer 817, a second P-type doped layer 818, a first N-type doped layer 817 and a second N-type doped layer 817 sequentially stacked in this order,

A P-type contact layer 819.

Accordingly, as shown in fig. 17 (b), the first phase shift arm 806 includes a third P-type doped layer 827, a waveguide core layer 808, a first N-type doped layer 809, a first N-type contact layer 810, and a third metal electrode 811 stacked in this order in a direction away from the substrate 801 in the non-modulation region. The second phase shift arm 812 includes a third P-type doped layer 827, a waveguide core 808, a first N-type doped layer 809, a first N-type contact layer 810, and a fourth metal electrode 813 stacked in this order. I.e., in the modulation region, between the waveguide core 808 and the phase shift arm substrate is a first P-doped layer 807, while in the non-modulation region, between the waveguide core 808 and the phase shift arm substrate is a third P-doped layer 827.

Then, when the signal electrode 802 and the ground electrode 805 are electrically connected, a current path of an equivalent circuit of the modulation region of the electro-optical modulator may sequentially pass through the metal air bridge 814 (between the signal electrode 802 and the fifth metal electrode 815), the fifth metal electrode 815, the second N-type contact layer 822, the first P-type doped layer 807 in the first phase shift arm 806, the waveguide core layer 808, the first N-type doped layer 809, the first N-type contact layer 810, the third metal electrode 811, the metal air bridge 814 (between the third metal electrode 811 and the fourth metal electrode 813), the fourth metal electrode 813 in the second phase shift arm 812, the first N-type contact layer 810, the first N-type doped layer 809, the waveguide core layer 808, the metal air bridge 814, First P-doped layer 807, second N-contact 822, sixth metal electrode 816, metal air bridge 814 (between sixth metal electrode 816 and ground electrode 805), to ground electrode 805.

When the signal electrode 802 and the grounding electrode 805 are electrified, and the modulation area of the electro-optical modulator modulates the optical signal, the contact between the third metal electrode 811 and the fourth metal electrode 813 and the first N-type contact layer 810 generates a first N-type contact resistance. The contact of fifth metal electrode 815 and sixth metal electrode 816 with second N-type contact layer 822 creates a second N-type contact resistance. The metal air bridge between the third metal electrode 811 and the fourth metal electrode 813 creates a resistance. Therefore, the resistance value of the electro-optic modulator based on this design can be approximated to the first N-type contact resistance value, the resistance value of the N-type contact layer 810, and,

The resistance of the N-type doped layer 809, the resistance of the first P-type doped layer 807, and the resistance of the second N-type contact in series.

Unlike the previous alternative design (i.e., a design with P-type material as the modulating region and N-type material as the non-modulating region), the contact resistance of the electro-optic modulator in this design includes a first N-type contact resistance and a second N-type contact resistance. And the resistance of the N-type contact is reduced by at least one order of magnitude compared with the resistance of the P-type contact. Therefore, the contact resistance of the electro-optical modulator based on the design is also far smaller than that of the existing electro-optical modulator, and the modulation bandwidth is improved.

Alternatively, in this design, the modulation region and the non-modulation region may not include a contact layer (e.g., the second N-type contact layer 822 in fig. 17 (a) and the P-type contact layer 819 in fig. 17 (b)), that is, along the direction away from the substrate 801, the portions of the first phase-shift arm substrate 803 and the second phase-shift arm substrate 804 in the modulation region include the non-doped layer 817 and the second N-doped layer 820, which are sequentially stacked, and the fifth metal electrode 815 may directly contact the second N-doped layer 820. The portions of the first phase shift arm base 803 and the second phase shift arm base 804 located in the non-modulation region in the direction away from the substrate 801 include an undoped layer 817 and a second P-type doped layer 818 which are sequentially stacked, and the sixth metal electrode 816 may be in direct contact with the second P-type doped layer 818.

Referring to fig. 18, a dc bias structure of an electro-optical modulator according to any one of fig. 8 to 17 is provided in the present application. It is noted that the dc bias arrangement does not include a matching resistor, which in fact needs to be placed between the signal electrode 802 and the ground electrode 805 to terminate the high frequency signal. The dc bias structure of the electro-optic modulator further includes a first dc bias electrode 825 and a second dc bias electrode 826, and the first dc bias electrode 825 and the second dc bias electrode 826 may be disposed at two ends of the signal electrode 802, or disposed at two ends of the ground electrode 805, and finally may be connected to the same dc voltage source.

For example, a first dc bias electrode 825 and a second dc bias electrode 826 are disposed on the surface of the substrate 801 and located at two ends of the signal electrode 802 along the light transmission direction, and the first dc bias electrode 825 and the second dc bias electrode 826 are respectively connected to the third metal electrode 811 through the metal air bridge 814.

Alternatively, the first dc bias electrode 825 and the second dc bias electrode 826 are disposed on the surface of the substrate 801 and located at both ends of the ground electrode 805 along the light transmission direction, and the first dc bias electrode 825 and the second dc bias electrode 826 are respectively connected to the fourth metal electrode 813 through the metal air bridge 814.

The first dc bias electrode 825 and the second dc bias electrode 826 may be provided on the surface of the substrate 801, and the first dc bias electrode 825 and the second dc bias electrode 826 may be provided in direct contact with the surface of the substrate 801. Alternatively, an insulating layer 824 may be grown at a predetermined position on the surface of the substrate 801, and then the first dc bias electrode 825 and the second dc bias electrode 826 may be provided on the insulating layer 824. An insulating layer 824 is provided between the first dc bias electrode 825 and the surface of the substrate 801 and/or between the second dc bias electrode 826 and the surface of the substrate 801.

Taking as an example that the first dc bias electrode 825 and the second dc bias electrode 826 may be disposed at both ends of the ground electrode 805. FIG. 18 (a) is a plan view showing a DC bias structure of the electro-optic modulator, and FIG. 18 (b) is a view taken along FIG. 18 (a)¹The cross-section of the V-V line is shown schematically. Based on this example, when the electro-optic modulator operates, a dc bias signal is applied to the waveguide core 808 through the first dc bias electrode 825 and the second dc bias 826 to provide a reverse bias operation state for the modulator, and then a high frequency signal is applied through the signal electrode 802 and the ground electrode 805 to complete modulation of the optical signal.

The present application also provides an optical device comprising an electro-optic modulator provided herein (e.g., the electro-optic modulator described in any of fig. 2-18 in the embodiments described above). The optical device may be CDM, CFP, etc.

The application also provides an optical module, which comprises the optical device provided by the application.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the present application, and all such changes or substitutions are included in the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

Claims book

1. An electro-optical modulator is characterized by comprising a bottom lining, a grounding electrode, a signal electrode, a P-type structure, a first phase shift arm and a second phase shift arm;

the grounding electrode, the signal electrode and the P-type structure are arranged on the same side of the bottom lining, and the P-type structure is positioned between the grounding electrode and the signal electrode;

the first phase shift arm and the second phase shift arm are arranged on the surface of the P-type structure far away from the substrate, the first phase shift arm is closer to the signal electrode relative to the second phase shift arm, and the second phase shift arm is closer to the grounding electrode relative to the first phase shift arm;

the part of the first phase shift arm, which is positioned in the modulation region, comprises a P-type doped layer, a waveguide core layer, a highly doped N-type doped layer, an N-type contact layer and a first metal electrode which are sequentially stacked along the direction far away from the substrate, wherein the first metal electrode is electrically connected with the signal electrode;

the part of the second phase shift arm, which is positioned in the modulation region, comprises a P-type doped layer, a waveguide core layer, a highly doped N-type doped layer, an N-type contact layer and a second metal electrode which are sequentially stacked along the direction far away from the bottom lining, and the second metal electrode is electrically connected with the grounding electrode.

2. The electro-optic modulator of claim 1, wherein the N-type contact layer is a highly doped N-type contact layer.

3. The electro-optic modulator of claim 1 or 2, wherein the P-type structure comprises a highly doped P-type layer and a highly doped P-type contact layer, which are stacked, the highly doped P-type layer being disposed on one surface of the substrate, the highly doped P-type contact layer being disposed on a surface of the highly doped P-type layer away from the substrate; the doping concentration of the high-doping P type layer is greater than that of the high-doping P type contact layer, and the doping concentration of the high-doping P type contact layer is greater than that of the P type doping layer.

4. The electro-optic modulator of any of claims 1-3, wherein the P-type structure comprises two P-doped layers, a more highly doped P-type layer, and a highly doped P-type contact layer, the two P-doped layers and the more highly doped P-type layer being located between the highly doped P-type contact layer and the substrate, the two P-doped layers and the more highly doped P-type layer being disposed on one surface of the substrate, and the more highly doped P-type layer being sandwiched between the two P-doped layers;

the width of the higher doped P type layer is smaller than or equal to the distance between two opposite side faces of the first phase shifting arm and the second phase shifting arm, the doping concentration of the higher doped P type layer is larger than or equal to that of the high doped P type contact layer, and the doping concentration of the high doped P type contact layer is larger than or equal to that of the P type doping layer.

5. An electro-optic modulator according to any of claims 1-4 wherein an insulating layer is provided between the ground electrode and the one surface and/or an insulating layer is provided between the signal electrode and the one surface.

6. An electro-optic modulator according to any of claims 1-5 comprising a plurality of modulating regions and a plurality of non-modulating regions, the plurality of modulating regions and the plurality of non-modulating regions being alternately distributed along the direction of optical transmission.

7. The electro-optic modulator of claim 6, wherein the non-modulation region comprises a P-doped layer, a waveguide core layer, and an isolation layer stacked in that order in a direction away from the substrate.

8. An electro-optical modulator is characterized by comprising a substrate, wherein a signal electrode, a first phase shift arm substrate, a second phase shift arm substrate and a ground electrode are sequentially arranged on one surface of the substrate along a direction perpendicular to an optical transmission direction;

a first phase shift arm is arranged on the surface, far away from the substrate, of the first phase shift arm substrate, and the first phase shift arm comprises a first P-type doped layer, a waveguide core layer, a first N-type doped layer, a first N-type contact layer and a third metal electrode which are sequentially stacked along the direction far away from the substrate;

a second phase shift arm is arranged on the surface, far away from the substrate, of the second phase shift arm substrate, and the second phase shift arm comprises a first P-type doped layer, a waveguide core layer, a first N-type doped layer, a first N-type contact layer and a fourth metal electrode which are sequentially stacked along the direction far away from the substrate;

the third metal electrode and the fourth metal electrode extend along the light transmission direction, and are connected by a plurality of mutually spaced connection portions;

a fifth metal electrode is arranged at one end, close to the signal electrode, of the surface, far away from the bottom lining, of the first phase shift arm substrate, and the fifth metal electrode is electrically connected with the signal electrode;

and a sixth metal electrode is arranged at one end, close to the grounding electrode, of the surface, far away from the bottom lining, of the second phase shift arm substrate, and the sixth metal electrode is electrically connected with the grounding electrode.

9. The electro-optic modulator of claim 8, wherein the first N-type contact layer is a highly doped N-type contact layer.

10. The electro-optic modulator of claim 8 or 9, wherein the electro-optic modulator comprises a plurality of modulation regions and a plurality of non-modulation regions, the plurality of modulation regions and the plurality of non-modulation regions being alternately distributed along a light transmission direction;

the fifth metal electrode is arranged on the part of the first phase shift arm substrate belonging to the modulation region;

the sixth metal electrode is arranged on the part of the second phase shift arm substrate belonging to the modulation region.

11. The electro-optic modulator of claim 10, wherein a portion of the first phase shift arm substrate or the second phase shift arm substrate located at the modulation region in a direction away from the substrate comprises a second P-type doped layer; along a direction away from the substrate, a portion of the first phase shift arm base or the second phase shift arm base located in the unmodulated region includes a second N-type doped layer.

12. The electro-optic modulator of claim 10, wherein the portion of the first phase shift arm substrate or the second phase shift arm substrate located in the modulation region in a direction away from the substrate comprises a second P-type doped layer and a P-type contact layer sequentially stacked;

and along the direction far away from the substrate, the part of the first phase shift arm substrate or the second phase shift arm substrate, which is positioned in the non-modulation region, comprises a second N-type doped layer and a second N-type contact layer which are sequentially stacked.

13. The electro-optic modulator of claim 10, wherein the portion of the first phase shift arm substrate or the second phase shift arm substrate located in the modulation region in a direction away from the substrate comprises a second N-doped layer sequentially stacked;

and along the direction far away from the substrate, the part of the first phase shift arm substrate or the second phase shift arm substrate, which is positioned in the non-modulation region, comprises second P-type doped layers which are sequentially stacked.

14. The electro-optic modulator of claim 10, wherein the portion of the first phase shift arm substrate or the second phase shift arm substrate located in the modulation region along the direction away from the substrate comprises a second N-doped layer, a second N-contact layer, which are sequentially stacked;

along the direction far away from the substrate, the part of the first phase shift arm substrate or the second phase shift arm substrate, which is located in the non-modulation region, comprises a second P-type doped layer and a P-type contact layer which are sequentially stacked.

15. The electro-optic modulator of any of claims 10-14, wherein the first phase-shifting arm comprises a third N-doped layer, a waveguide core layer, a first N-doped layer, a first N-contact layer, and a third metal electrode, which are sequentially stacked in a direction away from the substrate, at a portion located in the non-modulation region; the second phase shift arm comprises a third N-type doped layer, a waveguide core layer, a first N-type doped layer, a first N-type contact layer and a fourth metal electrode which are sequentially stacked.

16. An electro-optic modulator according to any of claims 8-15 wherein an insulating layer is provided between the ground electrode and the one surface and/or an insulating layer is provided between the signal electrode and the one surface.

17. The electro-optic modulator of any of claims 8-16, further comprising a first dc bias electrode and a second dc bias electrode;

the first direct current bias electrode and the second direct current bias electrode are arranged on the one surface and located at two ends of the signal electrode along the light transmission direction, and the first direct current bias electrode and the second direct current bias electrode are respectively connected with the third metal electrode through connecting parts; alternatively, the first and second electrodes may be,

the first and second dc bias electrodes are disposed on the one surface and located at both ends of the ground electrode along the light transmission direction, and the first and second dc bias electrodes are connected to the fourth metal electrode through connection portions, respectively.

18. An electro-optic modulator according to claim 17 wherein an insulating layer is provided between the first dc-biased electrode and the one surface and/or an insulating layer is provided between the second dc-biased electrode and the one surface.

19. An optical device comprising an electro-optic modulator according to any of claims 1 to 18.

20. A light module comprising the light device of claim 19.