WO2023217153A1

WO2023217153A1 - Phase shifter

Info

Publication number: WO2023217153A1
Application number: PCT/CN2023/093068
Authority: WO
Inventors: 李毅
Original assignee: 北京万集科技股份有限公司
Priority date: 2022-05-09
Filing date: 2023-05-09
Publication date: 2023-11-16
Also published as: CN117075364A

Abstract

A phase shifter, comprising a substrate (10), a buried oxide layer (20), a silicon waveguide layer (40), a silicon nitride waveguide layer (30) and a refractive index change structure (50), wherein the silicon waveguide layer (40) and the silicon nitride waveguide layer (30) are both buried in the buried oxide layer (20), and the silicon waveguide layer (40) and the silicon nitride waveguide layer (30) are spaced by a preset distance; transmission mode coupling can occur between the silicon waveguide layer (40) and the silicon nitride waveguide layer (30); and the refractive index change structure (50) at least acts on the silicon waveguide layer (40). By means of increasing an effective refractive index of a transmission mode in the silicon waveguide layer (40), an effective refractive index of a transmission mode in the silicon nitride waveguide layer (30) is increased. When a set form of energy is applied to the phase shifter by means of a refractive index change structure (50), a carrier concentration of a silicon waveguide layer (40) is changed, thus causing a change in an effective refractive index of a transmission mode in a silicon nitride waveguide layer (30), such that the change in the effective refractive index of the transmission mode in the silicon nitride waveguide layer (30) is caused by means of changing the refractive index of the silicon waveguide layer (40) near the silicon nitride waveguide layer (30), without directly changing the refractive index of the silicon nitride waveguide layer (30).

Description

a phase shifter

This application claims priority to the invention patent application filed with the Patent Office of the State Intellectual Property Office on May 9, 2022, with the application number 202210499689.1 and the invention title "A Phase Shifter", the entire content of which is incorporated by reference. in this application.

Technical field

The present application belongs to the technical field of electronic devices, and more specifically, relates to a phase shifter.

Background technique

In silicon electro-optical modulators using the plasmon dispersion effect, the refractive index of silicon is related to the carrier concentration. Among them, the higher the concentration of carriers, the smaller the refractive index of silicon. The change in the refractive index of silicon can cause a corresponding change in the phase of light, thereby achieving modulation of light intensity, forming the working principle of a silicon electro-optical modulator.

Silicon nitride is a common compound of silicon. On the one hand, silicon nitride has the characteristics of no two-photon absorption effect in the C-band. On the other hand, when light is transmitted in the silicon nitride waveguide layer, the loss of light is low, which can It is compatible with CMOS technology and is widely used in optical chips.

However, since silicon nitride has an inversion symmetry center and does not have a linear electro-optical effect, and the thermo-optical coefficient of silicon nitride is an order of magnitude lower than that of silicon, thermo-optical modulators based on silicon nitride consume more power and have difficult heat dissipation problems. Solution: In addition, silicon nitride is difficult to dope, and electro-optical modulators based on the plasma dispersion effect cannot be produced. Therefore, there is an urgent need for high-performance silicon nitride modulators in the field of optical chips.

technical problem

The purpose of the embodiments of the present application is to provide a phase shifter that can meet the urgent demand for high-performance silicon nitride modulators in the field of optical chips.

Technical solutions

In order to achieve the above purpose, the technical solution adopted in this application is:

The phase shifter includes a substrate, a buried oxide layer, a silicon waveguide layer, a silicon nitride waveguide layer, and a refractive index changing structure;

The silicon waveguide layer and the silicon nitride waveguide layer are both buried in the buried oxide layer, and the silicon waveguide layer and the silicon nitride waveguide layer are separated by a preset distance; the silicon waveguide layer and the Transmission mode coupling can occur between silicon nitride waveguide layers;

The refractive index changing structure at least acts on the silicon waveguide layer to increase the effective refractive index of the transmission mode in the silicon nitride waveguide layer by increasing the effective refractive index of the transmission mode in the silicon nitride waveguide layer.

In one embodiment, the energy of light transmitted by the silicon waveguide layer accounts for 0.00000000000000001%~10% of the total energy of light transmitted by the phase shifter.

In one embodiment, the phase shifter is an electro-optical phase shifter, and the refractive index changing structure includes positive and negative electrodes, and the positive and negative electrodes are applied on the silicon waveguide layer to increase transmission within the silicon waveguide layer. The effective refractive index of the mode is increased to increase the effective refractive index of the transmission mode within the silicon nitride waveguide layer.

In one embodiment, the silicon waveguide layer is a silicon waveguide, and the shape of the silicon waveguide is a ridge waveguide. Both sides of the ridge waveguide are p-type doping regions and n-type doping regions respectively. The positive and negative electrodes are in contact with the p-type doped region and the n-type doped region respectively.

In one embodiment, the phase shifter is a thermo-optical phase shifter. The refractive index changing structure includes positive and negative electrodes and a resistor. The positive and negative electrodes are connected to the resistor. The resistor causes the silicon The temperature of the waveguide layer and the silicon nitride waveguide layer increases.

In one embodiment, the resistor is a titanium nitride resistor, the resistor is buried in the buried oxide layer, and the silicon nitride waveguide layer is located between the resistor and the silicon waveguide layer.

In one embodiment, the phase shifter is a piezoelectric phase shifter, the refractive index changing structure includes a deformation material, the silicon waveguide layer is a silicon waveguide, and the silicon nitride waveguide layer is a silicon nitride waveguide, so The deformation material acts on the buried oxide layer, so that the buried oxide layer is subjected to downward and perpendicular forces to the extending direction of the waveguide.

In one embodiment, the deformation material is lead zirconate titanate, the refractive index changing structure further includes an upper metal electrode and a lower metal electrode, and the lead zirconate titanate is coated on the outer surface of the piezoelectric phase shifter, so After the above metal electrode and the lower metal electrode are energized, a voltage is applied to the deformation material to increase the effective refractive index of the transmission mode in the silicon waveguide layer, so as to increase the effective refraction of the transmission mode in the silicon nitride waveguide layer. Rate;

In one embodiment, the deformation material is lead zirconate titanate, and the refractive index changing structure further includes an upper metal electrode and a lower metal electrode. When the piezoelectric phase shifter is a phase shifter in a chip, the Lead zirconate titanate is coated on the outer surface of the chip. After the upper metal electrode and the lower metal electrode are energized, a voltage is applied to the deformation material to increase the effective refractive index of the transmission mode in the silicon waveguide layer. The effective refractive index of the transmission mode within the silicon nitride waveguide layer.

In one embodiment, the phase shifter is an acousto-optic phase shifter, and the refractive index changing structure includes an acoustic wave forming material. The acoustic wave forming material generates acoustic waves and transmits the acoustic waves to the silicon waveguide layer and silicon nitride. waveguide layer.

In one embodiment, the acoustic wave forming material is aluminum nitride, the refractive index changing structure further includes upper and lower metal electrodes, the upper and lower metal electrodes and the silicon waveguide layer are only provided in the acousto-optic phase shifter area, A radio frequency signal source is added to both ends of the upper and lower metal electrodes, and sound waves are generated in the aluminum nitride and transmitted to the silicon nitride waveguide and the silicon waveguide layer.

In one embodiment, the phase shifter is a linear electro-optical phase shifter, and the refractive index changing structure includes positive and negative electrodes and a linear electro-optical effect material, and the positive and negative electrodes apply bias voltage to the linear electro-optical effect material, so that The effective refractive index of the transmission mode in the linear electro-optical effect material is increased, thereby increasing the effective refractive index of the transmission mode in the silicon waveguide layer to increase the effective refractive index of the transmission mode in the silicon nitride waveguide layer.

In one embodiment, at least one of the silicon nitride waveguide layer and the silicon waveguide layer is provided with a coating, so as to isolate the two with zero interference through the coating.

In one embodiment, the silicon nitride waveguide layer and the silicon waveguide layer are spaced apart, both the silicon nitride waveguide layer and the silicon waveguide layer are filled with silicon dioxide, and the silicon nitride waveguide layer and The silicon waveguide layers achieve zero interference through physical distance, and when the carrier concentration in the silicon waveguide layer changes, the effective refractive index of the transmission mode in the silicon nitride waveguide layer will occur. Variety.

In one embodiment, the silicon waveguide layer is a silicon-based waveguide layer, a lithium niobate waveguide layer or a silicon ridge waveguide layer.

beneficial effects

Compared with the prior art, the phase shifter provided by this application includes a substrate, a buried oxide layer, a silicon waveguide layer, a silicon nitride waveguide layer, and a refractive index changing structure. Among them, the silicon waveguide layer and the silicon nitride waveguide layer are both buried in the buried oxide layer, and the silicon waveguide layer and the silicon nitride waveguide layer are separated by a preset distance. Transmission mode coupling can occur between the silicon waveguide layer and the silicon nitride waveguide layer. . The refractive index changing structure at least acts on the silicon waveguide layer to increase the effective refractive index of the transmission mode in the silicon nitride waveguide layer by increasing the effective refractive index of the transmission mode in the silicon nitride waveguide layer.

In the phase shifter provided by this application, when a set form energy is applied to the phase shifter through the refractive index changing structure, due to the introduction of the set form energy, the carrier concentration in the silicon waveguide layer will change, and due to the nitrogen The material of the silicon nitride waveguide layer is different from that of the silicon waveguide layer. The carrier concentration in the silicon nitride waveguide layer also changes, which will cause the effective refractive index of the transmission mode in the silicon nitride waveguide layer to change, thereby achieving different results. The refractive index of the silicon nitride waveguide layer is directly changed, but the effective refractive index of the transmission mode in the silicon nitride waveguide layer is changed by changing the refractive index of the silicon waveguide layer near the silicon nitride waveguide layer.

Since the effective refractive index of the transmission mode in the silicon nitride waveguide layer is changed by changing the refractive index of the silicon waveguide layer near the silicon nitride waveguide layer, only a small part of the energy is located inside the silicon waveguide layer and is free to carry current. The loss introduced by sub-absorption is smaller because the phase shifter provided by this application has lower insertion loss. Compared with the existing thermo-optical phase shifter, the phase shifter provided by this application has low power consumption, fast modulation speed, and wide bandwidth. It can reach above 1GHz, which can meet the urgent demand for high-performance silicon nitride modulators in the field of optical chips.

Description of the drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments or exemplary technologies will be briefly introduced below. Obviously, the drawings in the following description are only for the purpose of the present application. For some embodiments, for those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting creative efforts.

Figure 1 is a cross-sectional view along the length direction of a phase shifter provided by an embodiment of the present application;

Figure 2 is a cross-sectional view along the width direction of a phase shifter provided by an embodiment of the present application;

Figure 3 is a projection view along the height direction of the phase shifter shown in Figure 2;

Figure 4 is a cross-sectional view along the width direction of a phase shifter provided by an embodiment of the present application;

Figure 5 is a cross-sectional view along the length direction of the phase shifter shown in Figure 4;

Figure 6 is a cross-sectional view along the width direction of a phase shifter provided by an embodiment of the present application;

Figure 7 is a cross-sectional view along the length direction of the phase shifter shown in Figure 6;

Figure 8 is a cross-sectional view along the width direction of a phase shifter provided by an embodiment of the present application;

Figure 9 is a projection view along the height direction of the phase shifter shown in Figure 8;

Figure 10 is an energy distribution diagram of the silicon waveguide layer provided in an embodiment of the present application;

Figure 11 is an energy distribution diagram of a silicon waveguide layer provided in an embodiment of the present application.

Among them, each figure in the figure is marked with:

10. Substrate; 20. Buried oxide layer; 30. Silicon nitride waveguide layer; 40. Silicon waveguide layer; 50. Refractive index changing structure; 60. Resistance; 70. Deformation material; 80. Acoustic wave forming material; 90. Linear Electro-optical effect materials.

Embodiments of the invention

In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clear, this application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present application and are not used to limit the present application.

It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

It should be understood that the terms "length", "width", "top", "bottom", "front", "back", "left", "right", "vertical", "horizontal", "top" The orientations or positional relationships indicated by , "bottom", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply what is meant. Devices or elements must have a specific orientation, be constructed and operate in a specific orientation and therefore are not to be construed as limiting.

In addition, the terms “first” and “second” are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of indicated technical features. Therefore, features defined as "first" and "second" may explicitly or implicitly include one or more of these features. In the description of this application, "plurality" means two or more than two, unless otherwise explicitly and specifically limited.

The phase shifter provided in the embodiment of the present application will now be described.

Referring to FIGS. 1 to 11 , the phase shifter provided by the embodiment of the present application includes a substrate 10 , a buried oxide layer 20 , a silicon nitride waveguide layer 30 and a silicon waveguide layer 40 , and a refractive index changing structure 50 .

Wherein, the silicon nitride waveguide layer 30 and the silicon nitride waveguide layer 40 are both buried in the buried oxide layer 20 , and the silicon waveguide layer 40 and the silicon nitride waveguide layer 30 are separated by a preset distance. The silicon waveguide layer 40 and the silicon nitride waveguide layer 30 Transmission mode coupling can occur between them. The refractive index changing structure 50 at least acts on the silicon waveguide layer 40 to increase the effective refractive index of the transmission mode in the silicon waveguide layer 40 to increase the effective refractive index of the transmission mode in the silicon nitride waveguide layer 30 .

Compared with the prior art, in the phase shifter provided by the embodiment of the present application, when a set form energy is applied to the phase shifter through the refractive index changing structure 50, due to the introduction of the set form energy, the energy in the silicon waveguide layer 40 is The carrier concentration will change, and because the materials of the silicon waveguide layer 40 and the silicon nitride waveguide layer 30 are different, the carrier concentration in the silicon waveguide layer 40 will change, which will cause transmission in the silicon nitride waveguide layer. The effective refractive index of the mode changes, thereby not directly changing the refractive index of the silicon nitride waveguide layer, but by changing the refractive index of the silicon waveguide layer 40 near the silicon nitride waveguide layer, causing transmission within the silicon nitride waveguide layer. The effective refractive index of the mode changes.

Since the effective refractive index of the transmission mode in the silicon nitride waveguide layer is changed by changing the refractive index of the silicon waveguide layer 40 near the silicon nitride waveguide layer, the loss introduced by free carrier absorption is smaller, because the application provides The phase shifter has lower insertion loss. Compared with the existing thermo-optical phase shifter, the phase shifter provided by this application has low power consumption, fast modulation speed, and a bandwidth of more than 1GHz, which can meet the requirements in the field of optical chips. There is an urgent need for high-performance silicon nitride modulators.

Among them, it should be noted that the effective refractive index of the transmission mode in the waveguide layer not only depends on the refractive index of the waveguide layer itself and the cross-sectional size of the waveguide layer itself, but also depends on the refractive index of the outer cladding of the waveguide layer and the waveguide layer. The cross-sectional dimensions of the outer cladding.

For example, considering only the difference in refractive index of the outer cladding of the waveguide layer, for a single-mode silicon waveguide layer with height dimensions and width dimensions of 220nm and 500nm respectively, and the outer cladding is air, the TE mode transverse electromagnetic wave (TEM mode) in the transmission line ), transverse electric wave (TE mode), and transverse magnetic wave (TM mode), the effective refractive index of the three guided wave forms is 2.35. When the outer cladding is silicon dioxide, the effective refractive index of the three guided wave forms of the TE mode in the transmission line is 2.45: transverse electromagnetic wave (TEM mode), transverse electric wave (TE mode), and transverse magnetic wave (TM mode). Therefore, the effective refractive index of the transmission mode in the waveguide layer can be indirectly affected by changing the refractive index of the outer cladding of the waveguide layer.

In the embodiment of the present application, the silicon nitride waveguide layer 30 is equivalent to the waveguide layer itself, and the silicon waveguide layer 40 is equivalent to the outer cladding of the silicon nitride waveguide layer 30, and the materials of the two are different. When the carrier concentration in the silicon waveguide layer 40 changes, because the materials of the silicon waveguide layer 40 and the silicon nitride waveguide layer 30 are different, and the silicon nitride waveguide layer 30 is a silicon nitride waveguide layer, the silicon waveguide Changes in the carrier concentration in layer 40 will cause changes in the effective refractive index of the transmission mode in the silicon nitride waveguide layer, thereby achieving the goal of not directly changing the refractive index of the silicon nitride waveguide layer, but by changing the silicon nitride The refractive index of the silicon waveguide layer 40 near the waveguide layer causes the effective refractive index of the transmission mode in the silicon nitride waveguide layer to change.

In this application, the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are spaced apart, and can be filled with silicon dioxide. There is a certain physical distance between them to achieve no mutual interference, and when the silicon waveguide layer 40 When the carrier concentration in the silicon nitride waveguide layer changes, the effective refractive index of the transmission mode in the silicon nitride waveguide layer changes. Of course, in some embodiments, the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 may be interference isolated by a coating on at least one of them.

In the embodiment of the present application, the silicon waveguide layer 40 may be a silicon-based waveguide layer, a lithium niobate waveguide layer, or a silicon ridge waveguide layer.

As shown in FIG. 1 , in a specific embodiment, the phase shifter includes a silicon substrate 10 and a buried oxide layer 20 stacked on the silicon substrate 10 . For example, the buried oxide layer 20 can be a silicon dioxide layer. The length dimension of the silicon substrate 10 is consistent with the length dimension of the buried oxide layer 20 , and the height dimension of the buried oxide layer 20 is greater than the height dimension of the silicon substrate 10 .

The silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are both buried in the buried oxide layer 20, and the silicon waveguide layer 40 is a silicon-based waveguide layer. Among them, the silicon waveguide layer 40 is arranged parallel and spaced directly above the silicon substrate 10, the silicon nitride waveguide layer 30 is parallel and spaced directly above the silicon waveguide layer 40, the silicon substrate 10, the buried oxide layer 20, and the nitride waveguide layer 40. The length directions of the silicon waveguide layer 30 and the silicon waveguide layer 40 are consistent. The length dimension of the silicon waveguide layer 40 is smaller than the length dimension of the silicon substrate 10 , and the length dimension of the silicon nitride waveguide layer 30 is smaller than the length dimension of the silicon waveguide layer 40 . In a middle region of the side of the silicon waveguide layer 40 facing the silicon nitride waveguide layer 30 , the silicon waveguide layer 40 is provided with a protruding portion protruding toward the silicon nitride waveguide layer 30 .

Wherein, the refractive index changing structure 50 includes positive and negative electrodes, the positive and negative electrodes are applied on the silicon waveguide layer 40, the refractive index changing structure 50 is spaced along the length direction of the silicon buried oxide layer 20, the length direction of the positive and negative electrodes and the buried oxide layer 20 have the same height direction, the upper ends of the positive and negative electrodes are exposed outside the buried oxide layer 20 , and the lower ends of the positive and negative electrodes opposite to the upper ends are electrically connected to both ends of the silicon waveguide layer 40 in the length direction respectively. It should be noted that the positive and negative electrodes include a positive electrode and a negative electrode. The positive electrode and the negative electrode are generally used in pairs. The positive and negative electrodes in the embodiment of the present application include a positive electrode and a negative electrode used in pairs.

In this embodiment, the upper end of the refractive index changing structure 50 is exposed in the air to facilitate electrical contact and provide voltage signals to the silicon waveguide layer 40 , and other parts of the refractive index changing structure 50 are buried in the silicon dioxide layer. The silicon nitride waveguide layer and the silicon ridge waveguide layer are not in contact with each other, but are separated by a certain physical distance. The silicon nitride waveguide layer and the silicon ridge waveguide layer are filled with a silicon dioxide layer. When a bias voltage is applied to the positive and negative electrodes of the refractive index changing structure 50, the carrier concentration in the silicon ridge waveguide layer changes, that is, the refractive index of silicon is changed, thereby changing the transmission mode in the silicon nitride waveguide layer. The effective refractive index changes the phase of the light transmitted by the phase shifter.

In the preferred embodiment, the silicon waveguide layer 40 is a silicon waveguide. The shape of the silicon waveguide is a ridge waveguide. Both sides of the ridge waveguide are p-type doped areas and n-type doped areas respectively. The positive and negative electrodes are respectively connected with the p-type doped areas. in contact with the n-type doped region.

As shown in FIGS. 2 and 3 , in a specific embodiment, the phase shifter includes a silicon substrate 10 and a buried oxide layer 20 stacked on the silicon substrate 10 . For example, the buried oxide layer 20 can be a silicon dioxide layer. The refractive index changing structure 50 includes positive and negative electrodes and a resistor 60. The positive and negative electrodes are connected to the resistor 60. The resistor 60 increases the temperature of the silicon waveguide layer 40 and the silicon nitride waveguide layer 30 after being energized. The length dimension of the silicon substrate 10 is consistent with the length dimension of the buried oxide layer 20 , and the height dimension of the buried oxide layer 20 is greater than the height dimension of the silicon substrate 10 so as to provide a certain space in the height direction of the buried oxide layer 20 . , the silicon nitride waveguide layer 30, the silicon waveguide layer 40 and the refractive index changing structure 50 can be configured, wherein the refractive index changing structure 50 includes positive and negative electrodes and a resistor 60.

The resistor 60 , the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are all buried in the buried oxide layer 20 . The silicon waveguide layer 40 is a silicon-based waveguide layer, and the resistor 60 is a titanium nitride layer. The silicon waveguide layer 40 is parallel and spaced directly above the silicon substrate 10 , the silicon nitride waveguide layer 30 is parallel and spaced directly above the silicon waveguide layer 40 , and the resistor 60 is parallel and spaced apart from the silicon nitride waveguide layer. Directly above 30 , the length directions of the silicon substrate 10 , the buried oxide layer 20 , the resistor 60 , the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are all consistent. That is to say, the resistor 60, the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are arranged in parallel and spaced apart in sequence. The other end of the refractive index changing structure 50 is electrically connected to both ends of the length of the resistor 60. The silicon nitride waveguide layer 30 The silicon waveguide layer 40 is provided on the side of the resistor 60 away from the refractive index changing structure 50 .

Wherein, the length dimension of the silicon waveguide layer 40 is smaller than the length dimension of the resistor 60 , the length dimension of the resistor 60 is smaller than the length dimension of the silicon nitride waveguide layer 30 , and the length dimension of the silicon nitride waveguide layer 30 is consistent with the length dimension of the buried oxide layer 20 . The width dimension of the silicon waveguide layer 40 is smaller than the width dimension of the silicon nitride waveguide layer 30 , the width dimension of the silicon waveguide layer 40 is smaller than the width dimension of the resistor 60 , the width dimension of the resistor 60 is smaller than the width dimension of the buried oxide layer 20 , and the resistor 60 , The height dimensions of the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 tend to be consistent.

The positive and negative electrodes are spaced apart along the length direction of the silicon buried oxide layer 20 . The length direction of the positive and negative electrodes is consistent with the height direction of the buried oxide layer 20 . The upper ends of the positive and negative electrodes are exposed to the outside of the buried oxide layer 20 . The lower end opposite to the upper end is electrically connected to both ends of the resistor 60 in the length direction.

In this embodiment, the phase shifter is specifically a thermo-optical phase shifter. As shown in Figures 2 and 3, when a bias voltage is applied to both exposed ends of the refractive index changing structure 50 of the phase shifter, the TiN resistor 60 is heated. , causing the temperature of the silicon nitride waveguide layer and the silicon-based waveguide layer located below to rise. At this time, the refractive index of the silicon-based waveguide layer increases, which causes the effective refractive index of the transmission mode in the silicon nitride waveguide layer to increase.

In this embodiment, since a small part of the transmission mode in the silicon nitride waveguide layer is coupled into the silicon-based waveguide layer, the increase in the refractive index of the silicon-based waveguide layer will further increase the effective refraction of the transmission mode in the silicon nitride waveguide layer. Rate. In this embodiment, since the thermo-optical coefficient of silicon nitride is small, the thermo-optical phase shifter based on silicon nitride consumes a large amount of π phase shift power, taking advantage of the fact that the thermo-optical coefficient of silicon is one order of magnitude higher than that of silicon nitride. , place the silicon-based waveguide layer next to the silicon nitride waveguide layer to ensure that only a small number of modes are coupled from the silicon nitride waveguide layer to the silicon-based waveguide layer. This will increase the silicon-based refractive index as the temperature rises. It will further increase the effective refractive index of the transmission mode in the silicon nitride waveguide, thereby reducing the π phase shift power consumption of the silicon nitride-based thermo-optical phase shifter.

As shown in FIGS. 4 and 5 , in a specific embodiment, the phase shifter includes a silicon substrate 10 and a buried oxide layer 20 stacked on the silicon substrate 10 . For example, the buried oxide layer 20 can be a silicon dioxide layer. The refractive index changing structure 50 includes a deformation material 70 , wherein the length dimension of the silicon substrate 10 is consistent with the length dimension of the buried oxide layer 20 , and the height dimension of the buried oxide layer 20 is greater than the height dimension of the silicon substrate 10 .

Among them, the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are both buried in the buried oxide layer 20. The silicon waveguide layer 40 is a silicon-based waveguide layer, and the deformation material 70 is a lead zirconate titanate layer. The deformation material 70 acts on the buried oxide layer 20. , so that the buried oxide layer 20 is subjected to downward and perpendicular force to the extending direction of the waveguide.

More specifically, the deformation material 70 , the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are arranged in parallel and at intervals in sequence. The silicon waveguide layer 40 is parallel and spaced directly above the silicon substrate 10 , the silicon nitride waveguide layer 30 is parallel and spaced directly above the silicon waveguide layer 40 , and the deformation material 70 is parallel and spaced apart from the silicon nitride waveguide. Directly above the layer 30 and directly above the buried oxide layer 20, the length directions of the silicon substrate 10, the buried oxide layer 20, the piezoelectric ceramic bottom layer, the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are all consistent.

Among them, the length dimension of the silicon waveguide layer 40 is smaller than the length dimension of the silicon nitride waveguide layer 30. The length dimension of the silicon nitride waveguide layer 30 and the length dimension of the deformation material 70 tend to be consistent. The length dimension of the deformation material 70 is consistent with the length dimension of the buried oxide layer. 20's length is the same size. Wherein, the width dimension of the silicon waveguide layer 40 is smaller than the width dimension of the silicon nitride waveguide layer 30 , the width dimension of the silicon waveguide layer 40 is smaller than the width dimension of the deformation material 70 , and the width dimension of the deformation material 70 is consistent with the width dimension of the buried oxide layer 20 , and the height dimensions of the deformation material 70, the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 tend to be consistent.

In this embodiment, one of the refractive index changing structures 50 is stacked on the upper surface of the buried oxide layer 20 , the deformation material 70 is stacked on the refractive index changing structure 50 , and the other of the two refractive index changing structures 50 is stacked on the upper surface of the buried oxide layer 20 . One is laminated on the deformation material 70 .

More specifically, the refractive index changing structure 50 also includes an upper metal electrode and a lower metal electrode. Lead zirconate titanate is coated on the outer surface of the piezoelectric phase shifter. After the upper metal electrode and the lower metal electrode are energized, the deformation material 70 A voltage is applied to increase the effective refractive index of the transmission mode in the silicon waveguide layer 40 to increase the effective refractive index of the transmission mode in the silicon nitride waveguide layer 30 .

Alternatively, when the piezoelectric phase shifter is a phase shifter in a chip, lead zirconate titanate is coated on the outer surface of the chip. After the upper metal electrode and the lower metal electrode are energized, a voltage is applied to the deformation material 70 to increase the silicon content. The effective refractive index of the transmission mode in the waveguide layer 40 is increased to increase the effective refractive index of the transmission mode in the silicon nitride waveguide layer 30 .

In this embodiment, the phase shifter is a piezoelectric phase shifter. As shown in Figures 5 and 6, the silicon nitride waveguide layer extends from left to right. After passing through the piezoelectric phase shifter, the phase changes. Specifically, when a bias voltage is applied to the exposed ends of the refractive index changing structure 50, an electric field parallel to the thickness direction of the deformation material 70 is generated, thereby causing a piezoelectric effect, that is, the deformation material 70 becomes thicker and the width direction becomes narrower. Dimensional changes in both directions of thickness and width can cause compressive stress inside the silicon nitride waveguide layer and the silicon-based waveguide layer, thereby increasing the refractive index. The increase in the refractive index of the silicon-based waveguide layer causes the effective refractive index of the transmission mode in the silicon nitride waveguide layer to increase. Since a small part of the energy in the transmission mode in the silicon nitride waveguide layer is coupled into the silicon-based waveguide layer, the increase in the refractive index of the silicon-based waveguide layer will further increase the effective refractive index of the transmission mode in the silicon nitride waveguide layer. This can reduce the π phase shift power consumption of the piezoelectric phase shifter.

As shown in FIGS. 6 and 7 , in a specific embodiment, the phase shifter includes a silicon substrate 10 and a buried oxide layer 20 stacked on the silicon substrate 10 . For example, the buried oxide layer 20 can be a silicon dioxide layer. The refractive index changing structure 50 includes an acoustic wave forming material 80 that generates acoustic waves and transmits the acoustic waves to the silicon waveguide layer 40 and the silicon nitride waveguide layer 30 , wherein the length dimension of the silicon substrate 10 and the length of the buried oxide layer 20 The length dimensions are consistent, and the height dimension of the buried oxide layer 20 is greater than the height dimension of the silicon substrate 10 .

Among them, the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are both buried in the buried oxide layer 20, the silicon waveguide layer 40 is a silicon-based waveguide layer, the sound wave forming material 80 is an aluminum nitride layer, the sound wave forming material 80, the silicon nitride waveguide Layer 30 and silicon waveguide layer 40 are arranged parallel and spaced apart in sequence. Wherein, the silicon waveguide layer 40 is arranged parallel and spaced directly above the silicon substrate 10 , the silicon nitride waveguide layer 30 is parallel and spaced directly above the silicon waveguide layer 40 , and the acoustic wave forming material 80 is parallel and spaced apart from the silicon nitride. Directly above the waveguide layer 30 and directly above the buried oxide layer 20 , the length directions of the silicon substrate 10 , the buried oxide layer 20 , the acoustic wave forming material 80 , the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are all consistent.

Among them, the length dimension of the silicon waveguide layer 40 is smaller than the length dimension of the silicon nitride waveguide layer 30 , the length dimension of the silicon nitride waveguide layer 30 is consistent with the length dimension of the buried oxide layer 20 , and the length dimension of the acoustic wave forming material 80 is consistent with the length dimension of the buried oxide layer 20 . 20's length is the same size. Wherein, the width dimension of the silicon waveguide layer 40 is smaller than the width dimension of the silicon nitride waveguide layer 30 , the width dimension of the silicon waveguide layer 40 is smaller than the width dimension of the buried oxide layer 20 , and the width dimension of the acoustic wave forming material 80 is smaller than the width dimension of the buried oxide layer 20 size, and the height dimensions of the acoustic wave forming material 80, the silicon nitride waveguide layer 30, and the silicon waveguide layer 40 tend to be consistent.

In this embodiment, the refractive index changing structure 50 also includes upper and lower metal electrodes. The upper and lower metal electrodes and the silicon waveguide layer 30 are only located in the acousto-optic phase shifter area. A radio frequency signal source is added to both ends of the upper and lower metal electrodes. Sound waves are generated and transmitted to the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 . Structurally, one of the refractive index changing structures 50 is stacked on the upper surface of the buried oxide layer 20 , the acoustic wave forming material 80 is stacked on the refractive index changing structure 50 , and the other of the two refractive index changing structures 50 is stacked on the upper surface of the buried oxide layer 20 . One is laminated on the sound wave forming material 80 .

In this embodiment, the phase shifter is an acousto-optic phase shifter. As shown in Figures 7 and 8, the silicon nitride waveguide layer extends from left to right. After passing through the acousto-optic phase shifter, the phase changes. Specifically, when radio frequency signals are applied to both ends of the two metal refractive index changing structures 50, sound waves are generated in the sound wave forming material 80 and transmitted to the silicon nitride waveguide layer and the silicon-based waveguide layer. The acoustic wave introduces mechanical stress into the silicon nitride waveguide layer and the silicon-based waveguide layer. The stress changes the refractive index of the two waveguides, which in turn causes the effective refractive index of the transmission mode in the silicon nitride waveguide to change.

In this embodiment, since a small part of the energy in the transmission mode in the silicon nitride waveguide layer is coupled into the silicon-based waveguide layer, coupled with the existence of tensile stress, the refraction of the silicon nitride waveguide layer and the silicon-based waveguide layer will be The refractive index decreases, and the compressive stress will increase the refractive index of the silicon nitride waveguide layer and the silicon-based waveguide layer. Therefore, the change in the refractive index of the silicon-based waveguide layer will further increase the effective refractive index of the transmission mode in the silicon nitride waveguide layer. changes rather than canceling each other out, thereby reducing the π phase shift power consumption of the acousto-optic phase shifter.

As shown in FIGS. 8 and 9 , in a specific embodiment, the phase shifter includes a silicon substrate 10 and a buried oxide layer 20 stacked on the silicon substrate 10 . For example, the buried oxide layer 20 can be a silicon dioxide layer. The refractive index changing structure 50 includes positive and negative electrodes and a linear electro-optical effect material 90. The positive and negative electrodes apply a bias voltage to the linear electro-optical effect material 90, so that the effective refractive index of the transmission mode in the linear electro-optical effect material 90 is increased. The length dimension of the silicon substrate 10 is consistent with the length dimension of the buried oxide layer 20 , and the height dimension of the buried oxide layer 20 is slightly smaller than the height dimension of the silicon substrate 10 .

Among them, the silicon nitride waveguide layer 30 is buried in the buried oxide layer 20 , the linear electro-optical effect material 90 is stacked on the silicon nitride waveguide layer 30 , and the length dimension of the silicon nitride waveguide layer 30 is consistent with the length dimension of the buried oxide layer 20 , the width dimension of the silicon nitride waveguide layer 30 is much smaller than the width dimension of the linear electro-optical effect material 90 and the buried oxide layer 20. The width dimension of the linear electro-optical effect material 90 is consistent with the width dimension of the buried oxide layer 20. The silicon nitride waveguide layer 30 The bottom surface of the silicon nitride waveguide layer 30 is in contact with the buried oxide layer 20 , and the top surface of the silicon nitride waveguide layer 30 and the opposite sides along the width direction are covered by the linear electro-optical effect material 90 .

The silicon waveguide layer 40 is stacked on the linear electro-optical effect material 90, and the length dimension of the silicon waveguide layer 40 is smaller than the length dimension of the buried oxide layer 20, and the width dimension of the silicon waveguide layer 40 is smaller than the width dimension of the buried oxide layer 20. The size difference between the length dimension of the silicon waveguide layer 40 and the length dimension of the buried oxide layer 20 tends to be consistent with the size difference between the width dimension of the silicon waveguide layer 40 and the width dimension of the buried oxide layer 20 . The positive and negative electrodes are respectively stacked on the upper surfaces of the two ends of the silicon waveguide layer 40 in the length direction, and the length dimensions of the positive and negative electrodes are both smaller than the length dimension of the silicon waveguide layer 40 , and the upper surface of the silicon waveguide layer 40 is The middle area is provided with a protruding portion protruding upward, and both sides of the protruding portion in the width direction are spaced apart from the positive and negative electrodes. In this embodiment, the linear electro-optical effect material 90 is a benzocyclobutene layer, and the silicon waveguide layer 40 is a lithium niobate waveguide layer.

In the embodiments of the present application, the extension dimensions of any different layer structures in any direction can be adaptively set according to specific needs, and can be consistent or greatly different. The embodiments of the present application are designed to make each implementation provided The example is more specific and clear. The extension dimensions between the layer structures are compared and illustrated according to the accompanying drawings. In fact, the embodiments of the present application do not impose any restrictions or comparisons on the dimensions between the layer structures in any direction. Each different layer structure can be Design based on actual processes and needs.

In this embodiment, the phase shifter is specifically a linear electro-optical phase shifter. As shown in Figures 9 and 10, the silicon nitride waveguide layer extends from left to right. After passing through the linear electro-optical phase shifter, the phase changes. In this embodiment, most of the chip surface area is silicon dioxide, and the silicon dioxide covers the optical device based on the silicon nitride waveguide layer. The refractive index changing structure 50 and the lithium niobate waveguide are only present in the linear electro-optical phase shifter area. When a bias voltage is applied to both ends of the refractive index changing structure 50, under the action of the electric field, a linear electro-optical effect will be generated in the lithium niobate waveguide layer, and its refractive index will change.

In this embodiment, since a small part of the energy in the transmission mode within the silicon nitride waveguide layer is coupled into the lithium niobate waveguide layer, the refractive index of the lithium niobate waveguide layer changes, thereby changing the transmission within the silicon nitride waveguide layer. The effective refractive index of the mode, thereby changing the phase of the propagating mode within the silicon nitride waveguide.

As shown in Figures 10 and 11, in the phase shifter provided in the above embodiments, the energy contained in the silicon nitride waveguide layer 30 is greater than the energy contained in the buried oxide layer 20, and the energy contained in the buried oxide layer 20 is greater than The energy contained in the silicon waveguide layer 40. Preferably, the energy percentage in the silicon-based waveguide layer ranges from 0.00000000000000001% to 10%. Since a small part of the energy in the transmission mode in the silicon nitride waveguide layer is coupled into the silicon-based waveguide layer, the refractive index of the silicon-based waveguide layer changes, thereby changing the effective refractive index of the transmission mode in the silicon nitride waveguide layer, thereby changing the phase of the transmission mode in the silicon nitride waveguide layer.

The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the protection of the present application. within the range.

Claims

A phase shifter characterized by:

Including a substrate (10), a buried oxide layer (20), a silicon waveguide layer (40), a silicon nitride waveguide layer (30), and a refractive index changing structure (50);

The silicon waveguide layer (40) and the silicon nitride waveguide layer (30) are both buried in the buried oxide layer (20), and the silicon waveguide layer (40) and the silicon nitride waveguide layer (20) 30) Separate by a preset distance; transmission mode coupling can occur between the silicon waveguide layer (40) and the silicon nitride waveguide layer (30);

The refractive index changing structure (50) at least acts on the silicon waveguide layer (40) by increasing the effective refractive index of the transmission mode in the silicon waveguide layer (40) to increase the silicon nitride waveguide layer (30). ) the effective refractive index of the transmission mode.
The phase shifter according to claim 1, characterized in that the energy of light transmitted by the silicon waveguide layer (40) accounts for 0.000000000000000001%~10% of the total energy of light transmitted by the phase shifter.
The phase shifter according to claim 1 or 2, characterized in that the phase shifter is an electro-optical phase shifter, and the refractive index changing structure (50) includes positive and negative electrodes, and the positive and negative electrodes are applied on the on the silicon waveguide layer (40) to increase the effective refractive index of the transmission mode in the silicon waveguide layer (40), and to increase the effective refractive index of the transmission mode in the silicon nitride waveguide layer (30).
The phase shifter according to any one of claims 1 to 3, characterized in that the silicon waveguide layer (40) is a silicon waveguide, the shape of the silicon waveguide is a ridge waveguide, and both sides of the ridge waveguide They are p-type doped regions and n-type doped regions respectively, and the positive and negative electrodes are in contact with the p-type doped region and the n-type doped region respectively.
The phase shifter according to any one of claims 1 to 4, characterized in that the phase shifter is a thermo-optical phase shifter, and the refractive index changing structure (50) includes positive and negative electrodes and a resistor (60 ), the positive and negative electrodes are connected to the resistor (60), and the resistor (60) increases the temperature of the silicon waveguide layer (40) and the silicon nitride waveguide layer (30) after being energized.
The phase shifter according to claim 5, characterized in that the resistor (60) is a titanium nitride resistor, the resistor (60) is buried in the buried oxide layer (20), and the silicon nitride waveguide A layer (30) is located between the resistor (60) and the silicon waveguide layer (40).
The phase shifter according to any one of claims 1 to 4, characterized in that the phase shifter is a piezoelectric phase shifter, the refractive index changing structure (50) includes a deformation material (70), The silicon waveguide layer (40) is a silicon waveguide, the silicon nitride waveguide layer (30) is a silicon nitride waveguide, and the deformation material (70) acts on the buried oxide layer (20), so that the buried oxide layer (20) is The oxygen layer (20) is subjected to a force downward and perpendicular to the direction of the waveguide extension.
The phase shifter according to claim 7, wherein the deformation material (70) is lead zirconate titanate, the refractive index changing structure (50) further includes an upper metal electrode and a lower metal electrode, and the zirconium titanate Lead titanate is coated on the outer surface of the piezoelectric phase shifter. After the upper metal electrode and the lower metal electrode are energized, a voltage is applied to the deformation material (70) to increase the internal content of the silicon waveguide layer (40). The effective refractive index of the transmission mode is increased to increase the effective refractive index of the transmission mode in the silicon nitride waveguide layer (30).
The phase shifter according to claim 7, characterized in that:

The deformation material (70) is lead zirconate titanate, and the refractive index changing structure (50) also includes an upper metal electrode and a lower metal electrode. When the piezoelectric phase shifter is a phase shifter in a chip, the The lead zirconate titanate is coated on the outer surface of the chip. After the upper metal electrode and the lower metal electrode are energized, a voltage is applied to the deformation material (70) to increase the transmission mode in the silicon waveguide layer (40). The effective refractive index is to increase the effective refractive index of the transmission mode in the silicon nitride waveguide layer (30).
The phase shifter according to any one of claims 1 to 4, characterized in that the phase shifter is an acousto-optic phase shifter, and the refractive index changing structure (50) includes an acoustic wave forming material (80), The sound wave forming material (80) generates sound waves and transmits the sound waves to the silicon waveguide layer (40) and the silicon nitride waveguide layer (30).
The phase shifter according to claim 10, characterized in that the sound wave forming material (80) is aluminum nitride, the refractive index changing structure (50) further includes upper and lower metal electrodes, the upper and lower metal electrodes and the The silicon waveguide layer (30) is only provided in the acousto-optic phase shifter area. A radio frequency signal source is added to both ends of the upper and lower metal electrodes. Sound waves are generated in the aluminum nitride and transmitted to the silicon nitride. waveguide layer (30) and the silicon waveguide layer (40).
The phase shifter according to any one of claims 1 to 4, characterized in that the phase shifter is a linear electro-optical phase shifter, and the refractive index changing structure (50) includes positive and negative electrodes and a linear electro-optical effect Material (90), the positive and negative electrodes apply a bias voltage to the linear electro-optical effect material (90), so that the effective refractive index of the transmission mode in the linear electro-optical effect material (90) is increased, and then by increasing the silicon The effective refractive index of the transmission mode in the waveguide layer (40) is increased to increase the effective refractive index of the transmission mode in the silicon nitride waveguide layer (30).
The phase shifter according to any one of claims 1 to 12, characterized in that at least one of the silicon nitride waveguide layer (30) and the silicon waveguide layer (40) is provided with coating to provide zero interference isolation between the two via said coating.
The phase shifter according to any one of claims 1 to 12, characterized in that the silicon nitride waveguide layer (30) and the silicon waveguide layer (40) are arranged at intervals, and the silicon nitride waveguide layer (30) and the silicon waveguide layer (40) are both filled with silicon dioxide to achieve zero interference through physical distance.
The phase shifter according to claim 13 or 14, characterized in that the silicon waveguide layer (40) is a silicon-based waveguide layer, a lithium niobate waveguide layer or a silicon ridge waveguide layer.