CN117075364A

CN117075364A - Phase shifter

Info

Publication number: CN117075364A
Application number: CN202210499689.1A
Authority: CN
Inventors: 李毅
Original assignee: Beijing Wanji Technology Co Ltd
Current assignee: Wuhan Wanji Photoelectric Technology Co Ltd
Priority date: 2022-05-09
Filing date: 2022-05-09
Publication date: 2023-11-17
Also published as: WO2023217153A1

Abstract

The application provides a phase shifter, which comprises a substrate, an oxygen-buried layer, a silicon waveguide layer, a silicon nitride waveguide layer and a refractive index changing structure, wherein the oxygen-buried layer is arranged on the substrate; the silicon waveguide layer and the silicon nitride waveguide layer are buried in the buried oxide layer, and a preset distance is reserved between the silicon waveguide layer and the silicon nitride waveguide layer; transmission mode coupling may occur between the silicon waveguide layer and the silicon nitride waveguide layer; the refractive index changing structure acts on at least the silicon waveguide layer to increase the effective refractive index of the transmission mode in the silicon waveguide layer by increasing the effective refractive index of the transmission mode in the silicon waveguide layer. When the set form energy is applied to the phase shifter through the refractive index changing structure, the carrier concentration of the silicon waveguide layer changes, which causes the effective refractive index of the transmission mode in the silicon nitride waveguide layer to change, thereby realizing that the refractive index of the silicon nitride waveguide layer is not directly changed, but the effective refractive index of the transmission mode in the silicon nitride waveguide layer is caused to change by changing the refractive index of the silicon waveguide layer near the silicon nitride waveguide layer.

Description

Phase shifter

Technical Field

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

Background

In silicon electro-optic modulators employing the plasma dispersion effect, the refractive index of silicon is related to the carrier concentration. Wherein the higher the concentration of carriers, the smaller the refractive index of silicon. The change of the refractive index of the silicon can cause the corresponding change of the phase of the light, so that the modulation of the light intensity is realized, and the working principle of the silicon electro-optical modulator is further formed.

Silicon nitride is a common compound of silicon, on the one hand, silicon nitride has the characteristic of no two-photon absorption effect in the C-band, and on the other hand, light loss is low when light is transmitted in a silicon nitride waveguide layer, and it is compatible with CMOS process and is widely used in optical chips.

However, since silicon nitride has an inversion symmetry center, does not have a linear electro-optic effect, and the thermo-optic coefficient of silicon nitride is an order of magnitude lower than that of silicon, the power consumption of a thermo-optic modulator based on silicon nitride is larger, the heat dissipation problem is difficult to solve, and the silicon nitride is difficult to dope, so that an electro-optic modulator based on a plasma dispersion effect cannot be manufactured. Therefore, there is an urgent need in the art of optical chips for high performance silicon nitride modulators.

Disclosure of Invention

It is an aim of embodiments of the present application to provide a phase shifter which satisfies the urgent need for high performance silicon nitride modulators in the field of optical chips.

In order to achieve the above purpose, the application adopts the following technical scheme:

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

the silicon waveguide layer and the silicon nitride waveguide layer are buried in the buried oxide layer, and a preset distance is reserved between the silicon waveguide layer and the silicon nitride waveguide layer; transmission mode coupling may occur between the silicon waveguide layer and the silicon nitride waveguide layer;

the refractive index changing structure acts at least 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 waveguide layer.

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

In one embodiment, the phase shifter is an electro-optic phase shifter, and the refractive index changing structure includes positive and negative electrodes applied to the silicon waveguide layer to increase an effective refractive index of the transmission mode in the silicon waveguide layer, and further to increase an effective refractive index of the transmission mode in the silicon nitride waveguide layer.

In an embodiment, the silicon waveguide layer is a silicon waveguide, the shape of the silicon waveguide is a ridge waveguide, two sides of the ridge waveguide are respectively a p-type doped region and an n-type doped region, and the positive electrode and the negative electrode are respectively in contact with the p-type doped region and the n-type doped region.

In an embodiment, the phase shifter is a thermo-optic phase shifter, the refractive index changing structure includes a positive electrode and a negative electrode, the positive electrode and the negative electrode are connected to the resistor, and the resistor increases the temperature of the silicon waveguide layer and the silicon nitride waveguide layer after being electrified.

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 an 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, the silicon nitride waveguide layer is a silicon nitride waveguide, and the deformation material acts on the buried layer, so that the buried layer is subjected to a force downward and perpendicular to an extending direction of the waveguide.

In an embodiment, the deformation material is lead zirconate titanate, the refractive index changing structure further includes an upper metal electrode and a lower metal electrode, the lead zirconate titanate is coated on the outer surface of the piezoelectric phase shifter, and after the upper metal electrode and the lower metal electrode are electrified, 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 refractive index of the transmission mode in the silicon nitride waveguide layer;

or 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, and after the upper metal electrode and the lower metal electrode are electrified, voltage is applied to the deformation material so as to increase the effective refractive index of the transmission mode in the silicon waveguide layer, and further increase the effective refractive index of the transmission mode in 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 that generates an acoustic wave and transmits the acoustic wave to the silicon waveguide layer and the silicon nitride waveguide layer.

In an 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 disposed in the acousto-optic phase shifter region, a radio frequency signal source is added to two ends of the upper and lower metal electrodes, and acoustic waves are generated in the aluminum nitride and transferred to the silicon nitride waveguide and the silicon waveguide layer.

In an embodiment, the phase shifter is a linear electro-optic phase shifter, and the refractive index changing structure includes a positive electrode, a negative electrode and a linear electro-optic effect material, where the positive electrode and the negative electrode apply a bias voltage to the linear electro-optic effect material, so that an effective refractive index of a transmission mode in the linear electro-optic effect material is increased, and further by increasing an effective refractive index of a transmission mode in the silicon waveguide layer, an effective refractive index of a transmission mode in the silicon nitride waveguide layer is increased.

The phase shifter provided by the application has the beneficial effects that:

compared with the prior art, the phase shifter provided by the application comprises a substrate, a buried oxide layer, a silicon waveguide layer, a silicon nitride waveguide layer and a refractive index changing structure. Wherein the silicon waveguide layer and the silicon nitride waveguide layer are buried in the buried oxide layer, and a predetermined distance is spaced between the silicon waveguide layer and the silicon nitride waveguide layer, and 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 waveguide layer by increasing the effective refractive index of the transmission mode in the silicon waveguide layer.

When the phase shifter provided by the application is applied with the energy in the set form through the refractive index changing structure, the carrier concentration in the silicon waveguide layer can be changed due to the input of the energy in the set form, and the effective refractive index of a transmission mode in the silicon nitride waveguide layer can be changed due to the fact that the material of the silicon nitride waveguide layer is different from that of the silicon waveguide layer, so that 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 without directly changing the refractive index of the silicon nitride waveguide layer.

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, so that only a small part of energy is positioned in the silicon waveguide layer, and the loss introduced by free carrier absorption is small.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a cross-sectional view of a phase shifter along a length direction according to an embodiment of the present application;

fig. 2 is a cross-sectional view of a phase shifter according to an embodiment of the present application along a width direction;

fig. 3 is a perspective view of the phase shifter shown in fig. 2 in a height direction;

FIG. 4 is a cross-sectional view of a phase shifter along a width direction according to an embodiment of the present application;

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

fig. 6 is a cross-sectional view of a phase shifter according to an embodiment of the present application;

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

fig. 8 is a cross-sectional view of a phase shifter according to an embodiment of the present application;

fig. 9 is a perspective view of the phase shifter shown in fig. 8 in a height direction;

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

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

Wherein, each reference sign in the figure:

10. a substrate; 20. an oxygen burying layer; 30. a silicon nitride waveguide layer; 40. a silicon waveguide layer; 50. refractive index changing structure; 60. a resistor; 70. a deformable material; 80. an acoustic wave forming material; 90. linear electro-optic effect material.

Detailed Description

In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.

It will be understood that when an element is referred to as being "mounted" or "disposed" on another element, it can be directly on the other element or be 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 be indirectly connected to the other element.

It is to be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are merely for convenience in describing and simplifying the description based on the orientation or positional relationship shown in the drawings, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be construed as limiting the application.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present application, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

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

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

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

Compared with the prior art, when the phase shifter provided by the embodiment of the application applies the energy in the set form to the phase shifter through the refractive index changing structure 50, the carrier concentration in the silicon waveguide layer 40 changes due to the input of the energy in the set form, and the effective refractive index of the transmission mode in the silicon nitride waveguide layer changes due to the fact that the material of the silicon waveguide layer 40 is different from the material of the silicon nitride waveguide layer 30, so that the refractive index of the silicon nitride waveguide layer is not changed directly, and the effective refractive index of the transmission mode in the silicon nitride waveguide layer changes due to the change of the refractive index of the silicon waveguide layer 40 near the silicon nitride waveguide layer.

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, so that the loss introduced by free carrier absorption is smaller.

The effective refractive index of the transmission mode in the waveguide layer depends not only on the refractive index of the waveguide layer itself and the cross-sectional dimension of the waveguide layer itself, but also on the refractive index of the waveguide layer outer cladding and the cross-sectional dimension of the waveguide layer outer cladding.

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

In the embodiment of the present application, the silicon nitride waveguide layer 30 corresponds to the waveguide layer itself, the silicon waveguide layer 40 corresponds to the outer cladding layer of the silicon nitride waveguide layer 30, and the materials of the two layers are different. When the carrier concentration in the silicon waveguide layer 40 changes, the material of the silicon waveguide layer 40 is different from the material of the silicon nitride waveguide layer 30, and the silicon nitride waveguide layer 30 is a silicon nitride waveguide layer, the change of the carrier concentration in the silicon waveguide layer 40 causes the change of the effective refractive index of the transmission mode in the silicon nitride waveguide layer, so that the refractive index of the silicon nitride waveguide layer is not directly changed, but the change of the effective refractive index of the transmission mode in the silicon nitride waveguide layer is caused by changing the refractive index of the silicon waveguide layer 40 near the silicon nitride waveguide layer.

In the present application, the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are spaced apart, and filled with silicon dioxide, so that no mutual interference is realized between the two layers through a certain physical distance, and when the carrier concentration in the silicon waveguide layer 40 changes, the effective refractive index of the transmission mode in the silicon nitride waveguide layer is changed. Of course, in some embodiments, silicon nitride waveguide layer 30 and silicon waveguide layer 40 may be interferometrically isolated by a coating on at least one of the two.

In embodiments 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 one embodiment, the phase shifter includes a silicon substrate 10 and an oxygen-buried layer 20 stacked on the silicon substrate 10, for example, the oxygen-buried layer 20 may be a silicon dioxide layer. Wherein the length dimension of the silicon substrate 10 is identical to the length dimension of the buried oxide layer 20, and the height dimension of the buried oxide layer 20 is larger than the height dimension of the silicon substrate 10.

Both the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are buried in the buried oxide layer 20, and the silicon waveguide layer 40 is a silicon-based waveguide layer. The silicon waveguide layer 40 is disposed in parallel and spaced apart from and directly above the silicon substrate 10, the silicon nitride waveguide layer 30 is disposed in parallel and spaced apart from and directly above the silicon waveguide layer 40, and the length directions of the silicon substrate 10, the oxygen-buried layer 20, the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are all identical. Wherein 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 Yu Guibo waveguide layer 40. In an intermediate region of a side of the silicon waveguide layer 40 facing the silicon nitride waveguide layer 30, the silicon waveguide layer 40 is provided with a convex portion protruding toward the silicon nitride waveguide layer 30.

The refractive index changing structure 50 includes positive and negative electrodes applied on the silicon waveguide layer 40, the refractive index changing structure 50 is disposed at intervals 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 outside the buried oxide layer 20, and the lower ends of the positive and negative electrodes opposite to the upper ends are respectively electrically connected to two ends of the silicon waveguide layer 40 in the length direction.

In this embodiment, the upper end of the refractive index changing structure 50 is exposed to air so as to be in electrical contact with the silicon waveguide layer 40 for providing a voltage signal, and the other portions 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 but are spaced apart by a physical distance, and 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 exposed two ends 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, and the effective refractive index of the transmission mode in the silicon nitride waveguide layer is changed, so that the phase of light transmitted by the phase shifter is changed.

In a preferred embodiment, the silicon waveguide layer 40 is a silicon waveguide, the silicon waveguide is in the shape of a ridge waveguide, two sides of the ridge waveguide are respectively a p-type doped region and an n-type doped region, and the positive electrode and the negative electrode are respectively in contact with the p-type doped region and the n-type doped region.

As shown in fig. 2 and 3, in one embodiment, the phase shifter includes a silicon substrate 10 and an oxygen-buried layer 20 stacked on the silicon substrate 10, for example, the oxygen-buried layer 20 may 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 being connected to the resistor 60, the resistor 60 causing the temperatures of the silicon waveguide layer 40 and the silicon nitride waveguide layer 30 to rise upon energization. Wherein the length dimension of the silicon substrate 10 is identical to the length dimension of the buried oxide layer 20, and the height dimension of the buried oxide layer 20 is larger than the height dimension of the silicon substrate 10.

Resistor 60, silicon nitride waveguide layer 30 and silicon waveguide layer 40 are all buried in buried oxide layer 20, silicon waveguide layer 40 is a silicon-based waveguide layer, and resistor 60 is a titanium nitride layer. The silicon waveguide layer 40 is parallel and arranged above the silicon substrate 10 at intervals, the silicon nitride waveguide layer 30 is parallel and arranged above the silicon waveguide layer 40 at intervals, the resistor 60 is parallel and arranged above the silicon nitride waveguide layer 30 at intervals, and the length directions of the silicon substrate 10, the oxygen-buried layer 20, the resistor 60, the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are all consistent. That is, the resistor 60, the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are sequentially parallel and spaced apart, the other end of the refractive index changing structure 50 is electrically connected to two ends of the length of the resistor 60, and the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are disposed on one side of the resistor 60 facing 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 height dimensions of the resistor 60, the silicon nitride waveguide layer 30, and the silicon waveguide layer 40 tend to be uniform.

The positive and negative electrodes are arranged at intervals along the length direction of the silicon oxygen-buried layer 20, the length direction of the positive and negative electrodes is consistent with the height direction of the oxygen-buried layer 20, the upper ends of the positive and negative electrodes are exposed out of the oxygen-buried layer 20, and the lower ends of the positive and negative electrodes opposite to the upper ends are respectively and electrically connected with two ends of the resistor 60 in the length direction.

In this embodiment, the phase shifter is specifically a thermo-optic phase shifter, as shown in fig. 2 and 3, when a bias voltage is applied to the exposed two ends of the refractive index changing structure 50 of the phase shifter, the TiN resistor 60 is heated, resulting in an increase in the temperature of the underlying silicon nitride waveguide layer and the silicon fundamental waveguide layer, and at this time, the refractive index of the silicon fundamental waveguide layer increases, thereby increasing the effective refractive index of the transmission mode in the silicon nitride waveguide layer.

In this embodiment, since a small portion of the transmission modes in the silicon nitride waveguide layer are coupled into the silicon-based waveguide layer, an increase in the refractive index of the silicon fundamental waveguide layer further increases the effective refractive index of the transmission modes in the silicon nitride waveguide layer. In this embodiment, since the thermo-optic coefficient of silicon nitride is smaller, pi phase shift power consumption of the thermo-optic phase shifter based on silicon nitride is larger, and the silicon-based waveguide layer is disposed beside the silicon nitride waveguide layer by utilizing the characteristic that the thermo-optic coefficient of silicon is higher than that of silicon nitride by one order of magnitude, so that only a small portion of modes are coupled from the silicon nitride waveguide layer to the silicon-based waveguide layer, and thus the effective refractive index of the transmission mode in the silicon nitride waveguide is further increased due to the increase of the refractive index of the silicon-based waveguide caused by the increase of temperature, and pi phase shift power consumption of the thermo-optic phase shifter based on silicon nitride can be reduced.

As shown in fig. 4 and 5, in one embodiment, the phase shifter includes a silicon substrate 10 and an oxygen-buried layer 20 stacked on the silicon substrate 10, for example, the oxygen-buried layer 20 may be a silicon dioxide layer. The refractive index changing structure 50 includes a deformation material 70 in which the length dimension of the silicon substrate 10 and the length dimension of the buried oxide layer 20 are identical, and the height dimension of the buried oxide layer 20 is larger 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, the silicon waveguide layer 40 is a silicon fundamental waveguide layer, the deformation material 70 is a lead zirconate titanate layer, and the deformation material 70 acts on the buried layer 20, so that the buried layer 20 is subjected to a force downward and perpendicular 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 sequentially arranged in parallel and at intervals. The silicon waveguide layer 40 is parallel and arranged right above the silicon substrate 10 at intervals, the silicon nitride waveguide layer 30 is parallel and arranged right above the silicon waveguide layer 40 at intervals, the deformation material 70 is parallel and arranged right above the silicon nitride waveguide layer 30 at intervals, and is positioned right above the oxygen-buried layer 20, and the length directions of the silicon substrate 10, the oxygen-buried layer 20, the piezoelectric Tao Deceng, the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are all consistent.

Wherein 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 uniform, and the length dimension of the deformation material 70 and the length dimension of the buried oxide layer 20 are uniform. 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, the width dimension of the deformation material 70 and the width dimension of the buried oxide layer 20 are consistent, 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 the present embodiment, one of the refractive index changing structures 50 is laminated on the upper surface of the buried oxide layer 20, the deformation material 70 is laminated on the refractive index changing structure 50, and the other of the two refractive index changing structures 50 is laminated on the deformation material 70.

More specifically, the refractive index changing structure 50 further includes an upper metal electrode and a lower metal electrode, and lead zirconate titanate is coated on the outer surface of the piezoelectric phase shifter, and after the upper metal electrode and the lower metal electrode are energized, a voltage is applied to the deformation material 70 to increase the effective refractive index of the transmission mode in the silicon waveguide layer 40, and thus 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, and after the upper metal electrode and the lower metal electrode are energized, a voltage is applied to the deformation material 70 to increase the effective refractive index of the transmission mode in the silicon waveguide layer 40, and thus 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, and as shown in fig. 5 and 6, the silicon nitride waveguide layer extends from left to right, and after passing through the piezoelectric phase shifter, the phase is changed. Specifically, when a bias voltage is applied to the exposed two ends of the refractive index changing structure 50, an electric field parallel to the thickness direction of the deformation material 70 is generated, so that a piezoelectric effect is caused, that is, the deformation material 70 becomes thicker and narrower in the width direction, and the dimensional changes in both the thickness and the width directions can cause compressive stress to be generated inside the silicon nitride waveguide layer and the silicon-based waveguide layer, so that the refractive index of the silicon nitride waveguide layer and the silicon-based waveguide layer is increased. The increase in the refractive index of the silicon fundamental waveguide layer causes an increase in the effective refractive index of the transmission mode within the silicon nitride waveguide layer. Since a small portion of the energy in the transmission mode in the silicon nitride waveguide layer is coupled into the silicon-based waveguide layer, an increase in the refractive index of the silicon fundamental waveguide layer further increases the effective refractive index of the transmission mode in the silicon nitride waveguide layer, which can reduce the pi-phase shift power consumption of the piezoelectric phase shifter.

As shown in fig. 6 and 7, in one embodiment, the phase shifter includes a silicon substrate 10 and an oxygen-buried layer 20 stacked on the silicon substrate 10, for example, the oxygen-buried layer 20 may be a silicon dioxide layer. The refractive index changing structure 50 includes an acoustic wave forming material 80, the acoustic wave forming material 80 generating an acoustic wave and transmitting the acoustic wave to the silicon waveguide layer 40 and the silicon nitride waveguide layer 30, wherein a length dimension of the silicon substrate 10 and a length dimension of the oxygen buried layer 20 are identical, and a height dimension of the oxygen buried layer 20 is larger than a height dimension of the silicon substrate 10.

The silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are both buried in the oxygen-buried layer 20, the silicon waveguide layer 40 is a silicon-based waveguide layer, the acoustic wave forming material 80 is an aluminum nitride layer, and the acoustic wave forming material 80, the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are sequentially parallel and spaced apart. The silicon waveguide layer 40 is parallel and arranged right above the silicon substrate 10 at intervals, the silicon nitride waveguide layer 30 is parallel and arranged right above the silicon waveguide layer 40 at intervals, the acoustic wave forming material 80 is parallel and arranged right above the silicon nitride waveguide layer 30 at intervals, and is positioned right above the oxygen-buried layer 20, and the length directions of the silicon substrate 10, the oxygen-buried layer 20, the acoustic wave forming material 80, the silicon nitride waveguide layer 30 and the silicon waveguide layer 40 are all consistent.

Wherein 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 identical to the length dimension of the buried oxide layer 20, and the length dimension of the acoustic wave forming material 80 is identical to the length dimension of the buried oxide layer 20. 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, the width dimension of the acoustic wave forming material 80 is smaller than the width dimension of the buried oxide layer 20, 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 uniform.

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

In this embodiment, the phase shifter is an acousto-optic phase shifter, and as shown in fig. 7 and 8, the silicon nitride waveguide layer extends from left to right, and after passing through the acousto-optic phase shifter, the phase is changed. Specifically, when radio frequency signals are applied to both end portions of the two metal refractive index changing structures 50, acoustic waves are generated in the acoustic wave forming material 80 and transferred to the silicon nitride waveguide layer and the silicon fundamental waveguide layer. The acoustic wave introduces mechanical stress into the silicon nitride waveguide layer and the silicon-based waveguide layer, and the stress changes the refractive indexes of the two waveguides, so that the effective refractive index of a transmission mode in the silicon nitride waveguide is changed.

In this embodiment, since a small portion of energy in the transmission mode in the silicon nitride waveguide layer is coupled into the silicon substrate waveguide layer, and the existence of tensile stress reduces the refractive indexes of the silicon nitride waveguide layer and the silicon fundamental waveguide layer, and compressive stress increases the refractive indexes of the silicon nitride waveguide layer and the silicon fundamental waveguide layer, the change of the refractive index of the silicon fundamental waveguide layer further increases the change of the effective refractive index of the transmission mode in the silicon nitride waveguide layer, instead of canceling each other, so that pi phase shift power consumption of the acousto-optic phase shifter can be reduced.

As shown in fig. 8 and 9, in one embodiment, the phase shifter includes a silicon substrate 10 and an oxygen-buried layer 20 stacked on the silicon substrate 10, for example, the oxygen-buried layer 20 may be a silicon dioxide layer. The refractive index changing structure 50 includes positive and negative electrodes and a linear electro-optic effect material 90, the positive and negative electrodes applying a bias to the linear electro-optic effect material 90 such that the effective refractive index of the transmission mode within the linear electro-optic effect material 90 increases. 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 slightly smaller than the height dimension of the silicon substrate 10.

The silicon nitride waveguide layer 30 is buried in the oxygen-buried layer 20, the linear electro-optic effect material 90 is stacked on the silicon nitride waveguide layer 30, the length dimension of the silicon nitride waveguide layer 30 is identical to the length dimension of the oxygen-buried layer 20, the width dimension of the silicon nitride waveguide layer 30 is far smaller than the width dimensions of the linear electro-optic effect material 90 and the oxygen-buried layer 20, the width dimension of the linear electro-optic effect material 90 is identical to the width dimension of the oxygen-buried layer 20, the bottom surface of the silicon nitride waveguide layer 30 is in contact with the oxygen-buried 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-optic effect material 90.

The silicon waveguide layer 40 is laminated on the linear electro-optic 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, the width dimension of the silicon waveguide layer 40 is smaller than the width dimension of the buried oxide layer 20, and the dimension difference between the length dimension of the silicon waveguide layer 40 and the length dimension of the buried oxide layer 20 and the dimension difference between the width dimension of the silicon waveguide layer 40 and the width dimension of the buried oxide layer 20 tend to coincide. Positive and negative electrodes are respectively stacked on the upper surfaces of both ends of the silicon waveguide layer 40 in the length direction, the length dimensions of the positive and negative electrodes are both smaller than the length dimensions of the Yu Guibo waveguide layer 40, and a convex portion protruding upward is provided in the middle area of the upper surface of the silicon waveguide layer 40, and both sides of the convex portion in the width direction and the positive and negative electrodes are respectively arranged at intervals. In this embodiment, the linear electro-optic effect material 90 is a benzocyclobutene layer and the silicon waveguide layer 40 is a lithium niobate waveguide layer.

In this embodiment, the phase shifter is specifically a linear electro-optic phase shifter, and as shown in fig. 9 and 10, the silicon nitride waveguide layer extends from left to right, and after passing through the linear electro-optic phase shifter, the phase is changed. In this embodiment, the majority of the chip surface area is silicon dioxide, which covers the silicon nitride waveguide layer based optics, and the index changing structure 50 and lithium niobate waveguide are only present in the linear electro-optic phase shifter region. When a bias voltage is applied to both ends of the refractive index changing structure 50, a linear electro-optic effect is generated in the lithium niobate waveguide layer under the action of an electric field, and the refractive index of the lithium niobate waveguide layer is changed.

In this embodiment, since a small portion of the energy in the transmission mode in the silicon nitride waveguide layer is coupled into the lithium niobate waveguide layer, the refractive index of the lithium niobate waveguide layer is changed, and thus the effective refractive index of the transmission mode in the silicon nitride waveguide layer is changed, so that the phase of the transmission mode in the silicon nitride waveguide layer can be changed.

As shown in fig. 10 and 11, in the phase shifter provided in the above embodiment, the energy contained in the silicon nitride waveguide layer 30 is larger than the energy contained in the buried oxide layer 20, and the energy contained in the buried oxide layer 20 is larger than the energy contained in the silicon waveguide layer 40. Preferably, the percentage of energy in the silicon fundamental waveguide layer ranges from 0.00000000000000001% to 10%, and since a small fraction of the energy in the transmission mode in the silicon nitride waveguide layer is coupled into the silicon based waveguide layer, the change in refractive index of the silicon fundamental waveguide layer, and hence the effective refractive index of the transmission mode in the silicon nitride waveguide layer, changes the phase of the transmission mode in the silicon nitride waveguide.

The foregoing description of the preferred embodiments of the application is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the application.

Claims

1. A phase shifter, characterized by:

comprises a substrate (10), a buried oxide layer (20), a silicon waveguide layer (40) and 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 buried in the buried oxide layer (20), and the silicon waveguide layer (40) and the silicon nitride waveguide layer (30) are spaced apart by a preset distance; transmission mode coupling may occur between the silicon waveguide layer (40) and the silicon nitride waveguide layer (30);

the refractive index changing structure (50) acts at least on the silicon waveguide layer (40) to increase the effective refractive index of the transmission mode in the silicon nitride waveguide layer (30) by increasing the effective refractive index of the transmission mode in the silicon waveguide layer (40).

2. The phase shifter according to claim 1, characterized in that the energy of the light transmitted by the silicon waveguide layer (40) accounts for 0.00000000000000001% -10% of the total energy of the light transmitted by the phase shifter.

3. The phase shifter of claim 1, wherein the phase shifter is an electro-optic phase shifter and the refractive index changing structure (50) comprises positive and negative electrodes applied to the silicon waveguide layer (40) to increase the effective refractive index of the transmission mode in the silicon waveguide layer (40) and thereby the effective refractive index of the transmission mode in the silicon nitride waveguide layer (30).

4. A phase shifter according to claim 3, characterized in that the silicon waveguide layer (40) is a silicon waveguide in the shape of a ridge waveguide, the ridge waveguide being flanked by p-type doped regions and n-type doped regions, respectively, the positive and negative electrodes being in contact with the p-type doped regions and the n-type doped regions, respectively.

5. The phase shifter according to claim 1, characterized in that the phase shifter is a thermo-optic phase shifter, the refractive index changing structure (50) comprises positive and negative electrodes and a resistor (60), the positive and negative electrodes being connected to the resistor (60), the resistor (60) causing an increase in temperature of the silicon waveguide layer (40) and the silicon nitride waveguide layer (30) upon energizing.

6. The phase shifter of claim 5, wherein the resistor (60) is a titanium nitride resistor, the resistor (60) being buried in the buried oxide layer (20), the silicon nitride waveguide layer (30) being located between the resistor (60) and the silicon waveguide layer (40).

7. The phase shifter according to claim 1, characterized in that the phase shifter is a piezoelectric phase shifter, the refractive index changing structure (50) comprises a deformation material (70), the silicon waveguide layer (40) is a silicon waveguide, the silicon nitride waveguide layer (30) is a silicon nitride waveguide, the deformation material (70) acts on the buried layer (20) such that the buried layer (20) is subjected to a force downwards and perpendicular to the direction in which the waveguide extends.

8. The phase shifter of claim 7, wherein the deformation material (70) is lead zirconate titanate, the refractive index changing structure (50) further comprises an upper metal electrode and a lower metal electrode, the lead zirconate titanate is coated on the outer surface of the piezoelectric phase shifter, and a voltage is applied to the deformation material (70) after the upper metal electrode and the lower metal electrode are energized to increase the effective refractive index of the transmission mode in the silicon waveguide layer (40) and further to increase the effective refractive index of the transmission mode in the silicon nitride waveguide layer (30);

or 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, and after the upper metal electrode and the lower metal electrode are electrified, voltage is applied to the deformation material (70) so as to increase the effective refractive index of the transmission mode in the silicon waveguide layer (40) and further increase the effective refractive index of the transmission mode in the silicon nitride waveguide layer (30).

9. The phase shifter of claim 1, wherein the phase shifter is an acousto-optic phase shifter, the refractive index changing structure (50) comprises an acoustic wave forming material (80), the acoustic wave forming material (80) generating acoustic waves and transmitting the acoustic waves to the silicon waveguide layer (40) and silicon nitride waveguide layer (30).

10. The phase shifter according to claim 9, wherein the acoustic wave forming material (80) is aluminum nitride, the refractive index changing structure (50) further comprises upper and lower metal electrodes, the upper and lower metal electrodes and the silicon waveguide layer (30) are provided only in the acousto-optic phase shifter region, a radio frequency signal source is provided at both ends of the upper and lower metal electrodes, and an acoustic wave is generated in the aluminum nitride and transferred to the silicon nitride waveguide (30) and the silicon waveguide layer (40).

11. The phase shifter of claim 1, wherein the phase shifter is a linear electro-optic phase shifter, the refractive index changing structure (50) comprising positive and negative electrodes and a linear electro-optic effect material (90), the positive and negative electrodes biasing the linear electro-optic effect material (90) such that an effective refractive index of a transmission mode within the linear electro-optic effect material (90) is increased, thereby increasing an effective refractive index of a transmission mode within the silicon waveguide layer (40) by increasing the effective refractive index of the transmission mode within the silicon nitride waveguide layer (30).