PHASE SHIFTER, ELECTRO-OPTICAL DEVICE, OPTICAL COMMUNICATION SYSTEM, AND METHOD FOR MANUFACTURING PHASE SHIFTER

Abstract

A phase shifter, an electro-optical device, an optical communication system, and a method for manufacturing a phase shifter are disclosed. The phase shifter includes a substrate (100), an optical waveguide (104), an electrode, and a transition structure. The optical waveguide (104) is disposed on the substrate (100). Electrodes are disposed on both sides of the optical waveguide (104) in a direction perpendicular to the extension direction of the optical waveguide (104). The transition structure is located between the optical waveguide (104) and the electrode. The refractive index of the end of the substrate (100) closer to the optical waveguide (104) is lower than the refractive index of the optical waveguide (104), and the dielectric constant of the transition structure is higher than the dielectric constant of the optical waveguide (104). Therefore, when a voltage is applied to the optical waveguide (104) by the electrode, the voltage shared by the material between the electrode and the optical waveguide (104) is reduced, and the voltage applied to the optical waveguide (104) by the electrode can be increased. This can reduce the modulation voltage required by the phase shifter when the size of the phase shifter is the same. It can also be satisfied that the size of the phase shifter can be reduced under the same modulation voltage.

Description

[Technical field]

[0001] This application relates to the field of electro-optical technology, and in particular to phase shifters, electro-optical devices, and methods for manufacturing phase shifters. [Background technology]

[0002] With the continuous emergence and popularity of emerging services, such as 5G, Internet of Things, big data, and cloud computing, the rapidly increasing data transmission volume imposes higher and higher requirements on the performance of optical communication systems. For example, in an optical communication system including a transmitter, a transmission medium, and a receiver, the transmitter converts an electrical signal into an optical signal and outputs the optical signal, the optical signal is propagated in the transmission medium, and the receiver receives the optical signal and converts the optical signal into an electrical signal. A modulator in the transmitter is responsible for the conversion from an electrical signal to an optical signal. A phase shifter in the modulator applies a voltage to the waveguide through an electrode to modulate the intensity or phase of the optical signal, thereby improving the efficiency and bandwidth in the conversion process.

[0003] Generally, the waveguide is covered with a cladding layer, so that most of the voltage applied by the electrodes is shared by the cladding layer of the phase shifter, and as a result, the electric field applied to the waveguide by the electrodes is weak, and the modulation efficiency of the phase shifter is low. Summary of the Invention

[0004] In view of this, this application provides a phase shifter, an electro-optical device, an optical communication system, and a method for manufacturing the phase shifter to improve the modulation efficiency of the phase shifter.

[0005] According to a first aspect of the embodiment of this application, a phase shifter is provided, including a substrate, an optical waveguide, an electrode, and a transition structure. The optical waveguide is disposed on the substrate. In a direction perpendicular to the extension direction of the optical waveguide, electrodes are disposed on both sides of the optical waveguide. The transition structure is located between the optical waveguide and the electrode. The refractive index of the end of the substrate closer to the optical waveguide is lower than that of the optical waveguide, and the dielectric constant of the transition structure is higher than that of the optical waveguide. Therefore, when a voltage is applied to the optical waveguide by the electrode, the voltage shared by the material between the electrode and the optical waveguide is reduced, and the voltage applied to the optical waveguide by the electrode can be increased. This improves the modulation efficiency of the phase shifter. This can reduce the modulation voltage required by the phase shifter when the size of the phase shifter is the same. It can also be satisfied that the size of the phase shifter can be reduced under the same modulation voltage.

[0006] In one possible implementation, the transition structure includes a first transition structure and a second transition structure, and the electrode includes a first electrode and a second electrode. The first electrode and the second electrode are located on both sides of the optical waveguide in a direction perpendicular to the extension direction of the optical waveguide. The first transition structure is located between the optical waveguide and the first electrode, and the second transition structure is located between the optical waveguide and the second electrode. The refractive index of the end of the substrate closer to the optical waveguide is lower than the refractive index of the optical waveguide, and the dielectric constant of the first transition structure and the second transition structure is higher than the dielectric constant of the optical waveguide. When a voltage is applied to the ridge structure by the first electrode and the second electrode, the voltage shared by the material between the first electrode, the second electrode, and the ridge structure is reduced, ensuring that the voltage shared by the first transition structure and the second transition structure is small, and the voltage applied to the ridge structure by the first electrode and the second electrode can be increased. This can reduce the modulation voltage required by the phase shifter for the same size of the phase shifter.

[0007] In one possible implementation, the optical waveguide includes an interconnected body structure and a ridge structure, the ridge structure protruding from the body structure toward a side away from the substrate. The ridge structure is positioned to provide a lower loss than that of a strip waveguide. The first transition structure and the second transition structure are spaced apart from the ridge structure to prevent the transition structures from contacting the optical waveguide and affecting light propagation in the optical waveguide, e.g., increasing loss.

[0008] In one possible implementation, in a direction perpendicular to the extension direction of the optical waveguide, the first electrode and the second electrode are located on either side of the ridge structure and are separately disposed on the body structure, and the first transition structure and the second transition structure are separately disposed on the body structure, the first transition structure is located between the ridge structure and the first electrode, and the second transition structure is located between the ridge structure and the second electrode. In this way, the first electrode and the second electrode are located on either side of the ridge structure, respectively, and the first transition structure and the second transition structure are located on either side of the ridge structure, respectively, to ensure increasing the voltage applied to the ridge structure.

[0009] In one possible implementation, the first electrode is disposed on the first transition structure and the second electrode is disposed on the second transition structure, the first transition structure and the second transition structure being separately disposed on the body structure, with the first electrode and the second electrode located on either side of the ridge structure.

[0010] In one possible implementation, the first electrode and the second electrode are separately disposed on a substrate, and the first transition structure and the second transition structure are separately disposed on the substrate, thus reducing the overall thickness of the phase shifter and increasing the voltage on the plate structures.

[0011] In one possible implementation, the first electrode is disposed on a first transition structure, the second electrode is disposed on a second transition structure, and the first transition structure and the second transition structure are separately disposed on a substrate.

[0012] In one possible implementation, the phase shifter further includes an insulating layer disposed between the first electrode and the body structure and between the second electrode and the body structure to improve device operational reliability.

[0013] In one possible implementation, an insulating layer is further disposed between the first transition structure and the body structure and between the second transition structure and the body structure.

[0014] In one possible implementation, the substrate includes a substrate layer and a first cladding layer, the first cladding layer is disposed on the substrate layer, the optical waveguide is disposed on a side of the first cladding layer away from the substrate layer, and the refractive index of the first cladding layer is lower than that of the optical waveguide. In this way, it is possible to ensure that the refractive index of the portion of the substrate close to the optical waveguide is lower than that of the optical waveguide, so that the light in the optical waveguide is propagated in a form of total internal reflection. The material of the first cladding layer may be silicon dioxide or silicon nitride, etc. The material of the substrate layer may be silicon, lithium niobate, silicon dioxide, quartz, silicon carbide, sapphire, etc.

[0015] In one possible implementation, the phase shifter further includes a second cladding layer covering a surface of the optical waveguide remote from the substrate, the second cladding layer having a lower refractive index than the optical waveguide, which improves the reliability of light propagation in the optical waveguide in a total internal reflection mode. The material of the second cladding layer may be silicon dioxide, silicon nitride, air, or vacuum.

[0016] In one possible implementation, a second cladding layer is filled between the first transition structure and the ridge structure and between the second transition structure and the ridge structure to prevent the transition structures from affecting light propagation in the optical waveguide.

[0017] In one possible implementation, the optical waveguide material is lithium niobate, an electro-optic polymer, or tantalum niobate.

[0018] In one possible implementation, the first transition structure material and / or the second transition structure material is barium titanate, titanium dioxide, aluminum oxide, magnesium oxide, LaF3, LaYO3, or LaAlO3.

[0019] According to a second aspect of an embodiment of the present application, there is provided an electro-optical device including a phase shifter according to any of the implementations described above.

[0020] In one possible implementation, the electro-optical device is an electro-optical modulator, an electro-optical switch, or an electric field sensor.

[0021] According to a third aspect of an embodiment of the present application, there is provided an optical communication system including the electro-optical device described above.

[0022] According to a fourth aspect of an embodiment of the present application, there is provided a phase shifter manufacturing method, the method including: preparing a substrate; forming an optical waveguide on a surface of the substrate, the refractive index of an end of the substrate closer to the optical waveguide being lower than the refractive index of the optical waveguide; forming a first electrode and a second electrode on both sides of the optical waveguide in a direction perpendicular to an extension direction of the optical waveguide; and forming a first transition structure and a second transition structure on both sides of the optical waveguide, the first transition structure being located between the optical waveguide and the first electrode, the second transition structure being located between the optical waveguide and the second electrode, and the dielectric constants of the first transition structure and the second transition structure being higher than the dielectric constant of the optical waveguide.

[0023] In one possible implementation, an electro-optic crystal film layer is formed on a surface of a substrate, the edge of the substrate closer to the electro-optic crystal film layer having a lower refractive index than the electro-optic crystal film layer, and the electro-optic crystal thin film is etched to form an optical waveguide.

[0024] In one possible implementation, the phase shifter manufacturing method further includes forming an insulating layer between the first electrode and the body structure and between the second electrode and the body structure.

[0025] In one possible implementation, the phase shifter manufacturing method further includes forming an insulating layer between the first transition structure and the body structure and between the second transition structure and the body structure.

[0026] In one possible implementation, preparing the substrate includes forming a first cladding layer on a substrate layer to obtain a substrate, the first cladding layer having a refractive index lower than the refractive index of the optical waveguide, and an electro-optic crystal film layer formed on a side of the first cladding layer away from the substrate layer.

[0027] In one possible implementation, the phase shifter manufacturing method further includes forming a second cladding layer on a surface of the optical waveguide away from the substrate, the second cladding layer having a refractive index lower than the refractive index of the optical waveguide.

[0028] For the specific structure of the phase shifter in the fourth embodiment and the positional relationship between the specific structures, please refer to the specific description of the phase shifter in the first embodiment. [Brief description of the drawings]

[0029] [Figure 1] FIG. 2 is a cross-sectional structure diagram of a phase shifter according to one embodiment of the present application. [Figure 2(a)] FIG. 2 is a cross-sectional structure diagram of a phase shifter according to one embodiment of the present application. [Figure 2(b)] FIG. 2 is a cross-sectional structure diagram of a phase shifter according to one embodiment of the present application. [Figure 2(c)] FIG. 2 is a cross-sectional structure diagram of a phase shifter according to one embodiment of the present application. [Figure 2(d)] FIG. 2 is a cross-sectional structure diagram of a phase shifter according to one embodiment of the present application. [Figure 2(e)] FIG. 2 is a cross-sectional structure diagram of a phase shifter according to one embodiment of the present application. [Diagram 3] FIG. 2 is an axonometric view of a phase shifter according to an embodiment of the present application. [Figure 4(a)] FIG. 2 is a diagram of an electro-optic modulator configuration according to one embodiment of the present application. [Figure 4(b)]FIG. 2 is a diagram of an electro-optic modulator configuration according to one embodiment of the present application. [Figure 4(c)] FIG. 2 is a diagram of an electro-optic modulator configuration according to one embodiment of the present application. [Figure 4(d)] FIG. 2 is a diagram of an electro-optic modulator configuration according to one embodiment of the present application. [Diagram 5] FIG. 1 is a diagram of a configuration of an optical communication system according to an embodiment of the present application. [Figure 6] 1 is a diagram of a method for manufacturing a phase shifter according to an embodiment of the present application. [Figure 7(a)] 1 is a cross-sectional view of a substrate according to an embodiment of the present application. [Figure 7(b)] 1 illustrates forming an optical waveguide on a surface of a substrate according to an embodiment of the present application. [Figure 7(c)] FIG. 2 illustrates forming an electrode on an optical waveguide according to one embodiment of the present application. [Figure 7(d)] 1 illustrates forming a transition structure on an optical waveguide according to an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Hereinafter, the technical solutions in the embodiments of this application will be described with reference to the accompanying drawings in the embodiments of this application.

[0031] In addition, all directions or positional relationships mentioned in the embodiments of this application are positional relationships based on the attached drawings, and are merely intended to facilitate and simplify the description of this application, and do not imply or mean a specific direction that a device or element needs to have, and should not be interpreted as a limitation on this application. In the description of this application, unless otherwise specified, "multiple" means two or more. The terms "first" and "second", etc. are merely used to facilitate distinction and description, and do not indicate a specific order or sequence. "A and / or B" in this application represents three different combination forms, A, B, or A+B. Here, A and B represent abbreviations of the corresponding structures in this application, and are merely examples for display. Specifically, it needs to be determined based on the features before and after "and / or" in this application.

[0032] A phase shifter is usually configured to modulate the phase and intensity of light. Specifically, a phase shifter usually includes a waveguide and an electrode. Light is propagated in the waveguide in a form of total internal reflection, and voltages are applied by electrodes on both sides of the waveguide to change the refractive index of the waveguide and further modulate the propagation of the optical signal in order to perform modulation of the phase and intensity of the light. By changing the magnitude of the applied voltage, the light can be modulated with different phases and intensities. In this application, application scenarios of the phase shifter may include electro-optical devices, such as electro-optical modulators, electro-optical switches, or electric field sensors, and other electro-optical devices that need to use optical phase modulation.

[0033] Light is typically input from one end of the phase shifter and output from the other end. The shape of the phase shifter is not limited here. The phase shifter is generally presented as a structure extending from one end to the other end, such as the structure shown in FIG. 3. In this application, the phase shifter may include a cladding layer, a substrate layer 103, an optical waveguide, an electrode, and a transition structure. Please refer to FIG. 1 and FIG. 2(a)-FIG. 2(e) for the positional relationship between different structures in the phase shifter. Note that the structures shown in FIG. 1 and FIG. 2(a)-FIG. 2(e) are cross-sectional views of the phase shifter in different embodiments.

[0034] The optical waveguide 104 is made of an electro-optical material that has a linear electro-optical effect. The material of the optical waveguide 104 can be lithium niobate, electro-optical polymer, tantalum niobate, barium titanate, or lead zirconate titanate. For example, the material of the optical waveguide 104 is lithium niobate, the Z crystal axis of the lithium niobate crystal is perpendicular to the extension direction of the optical waveguide, and the Z axis of the lithium niobate crystal is the rotational symmetry axis of the lithium niobate crystal. Light is propagated in the optical waveguide in the form of total internal reflection.

[0035] The material of the substrate layer 103 may be silicon, lithium niobate, silicon dioxide, quartz, silicon carbide, or sapphire, etc. Certainly, the material of the substrate layer may alternatively be other elemental or compound semiconductor materials. The substrate layer 103 may provide mechanical support, for example for the cladding layers.

[0036] The refractive index of the cladding layer is lower than that of the optical waveguide 104, and is mainly used to confine the light in the optical waveguide 104, so that the optical field is propagated in the optical waveguide 104 in the form of total internal reflection. The cladding layer may partially or completely cover the surface of the optical waveguide 104. In this application, the cladding layer may include a first cladding layer 102 and a second cladding layer 101. The first cladding layer 102 is located between the substrate layer 103 and the optical waveguide 104. The material of the first cladding layer 102 may be silicon dioxide or silicon nitride, etc. The second cladding layer 101 covers the surface of the optical waveguide 104 away from the substrate layer 103, and the material of the second cladding layer 101 may be air, vacuum, silicon dioxide, silicon nitride, etc. Optionally, the substrate layer 103 and a part of the cladding layer may jointly function as the substrate 100. For example, a first cladding layer 102 may be bonded onto a substrate layer 103, which together function as the substrate 100. In general, however, it must be satisfied that the refractive index of the portion of the substrate 100 close to the optical waveguide 104 is lower than the refractive index of the optical waveguide 104.

[0037] The dielectric constant of the transition structure is higher than 8. Optionally, the dielectric constant of the transition structure is higher than the dielectric constant of the optical waveguide 104. For example, the material of the transition structure may be barium titanate, titanium dioxide, aluminum oxide, magnesium oxide, LaF3, LaYO3, or LaAlO3. The transition structure is mainly used to reduce the contribution of the voltage applied by the electrodes and increase the voltage applied to the optical waveguide 104. Optionally, the refractive index of the transition structure is lower than the refractive index of the optical waveguide 104. In this application, the different transition structures may be described as a first transition structure and a second transition structure, respectively. The materials of the different transition structures may be the same or different.

[0038] FIG. 1 is a cross-sectional view of a phase shifter according to an embodiment of this application. The phase shifter includes an optical waveguide 104, a first electrode 105, a second electrode 106, a first cladding layer 102, a second cladding layer 101, and a substrate 103. The optical waveguide 104 includes a ridge structure and a body structure. The first electrode 105 and the second electrode 106 are separately disposed on the body structure. In a direction perpendicular to the extension direction of the optical waveguide, the first electrode 105 and the second electrode 106 are located on both sides of the ridge structure, respectively. The optical waveguide 104 is disposed between the first cladding layer 102 and the second cladding layer 101. The first cladding layer 102 is disposed on the substrate 103. The second cladding layer 101 covers the first electrode 105, the second electrode 10, and the end of the optical waveguide 10 remote from the first cladding layer 102. The refractive index of the first cladding layer 102 and the refractive index of the second cladding layer 101 are lower than that of the optical waveguide 104, such that the optical field is propagated in the optical waveguide 104 in a total internal reflection manner.

[0039] When a voltage is applied to the optical waveguide 104 by the first electrode 105 and the second electrode 106, the linear electro-optic effect of the electro-optic material changes the refractive index of the optical waveguide 104, which results in a change in the propagation characteristics of the optical signal in the optical waveguide 104, such as the phase of the optical signal. Thus, the optical signal can be modulated. However, the dielectric constants of the first cladding layer 102 and the second cladding layer 101 are lower than that of the optical waveguide 104. For example, the dielectric constant of air is 1, and the dielectric constant of lithium niobate in the Z crystal axis direction is 28. As a result, most of the voltage applied by the first electrode 105 and the second electrode 106 is distributed in the second cladding layer 101, the electric field distributed inside the optical waveguide 104 is weak, and the optical signal is mainly distributed in the optical waveguide 104. As a result, the efficiency of modulating the optical field in the optical waveguide 104 is low.

[0040] An embodiment of this application further provides a phase shifter. Figures 2(a)-2(e) show cross-sectional views of five different forms of phase shifters, each including a substrate 100, an optical waveguide 104, an electrode, and a transition structure. The optical waveguide 104 is disposed on the substrate 100. Electrodes are disposed on both sides of the optical waveguide 104 in a direction perpendicular to the extension direction of the optical waveguide 104. The transition structure is located between the optical waveguide 104 and the electrode. The refractive index of the end of the substrate 100 closer to the optical waveguide 104 is lower than that of the optical waveguide 104.

[0041] In the embodiment of this application, the cross-sectional shape of the optical waveguide 104 may be presented as a rectangle or a "T" shape. Here, the "T" shape is used as an example for illustration. The optical waveguide 104 includes a body structure and a ridge structure that are interconnected. Specifically, the middle position of the body structure is connected to the ridge structure, so that the body structure and the ridge structure as a whole are presented as a "T" structure. Here, the ridge structure protrudes from the body structure toward the side away from the substrate 100, or the two opposite ends of the body structure protrude from the two opposite side surfaces of the ridge structure. Generally, the height of the body structure is 1 μm or less, the height of the ridge structure is 1.5 μm or less, and the width of the ridge structure is 5 μm or less. As shown in FIG. 3, the direction indicated by the arrow of the light input or light output in the figure is the extension direction of the optical waveguide.

[0042] In some examples, as shown in Figures 2(a) and 2(b), the electrodes can be disposed on the optical waveguide 104, specifically on the body structure, and are located on the face of the body structure away from the substrate 100. As shown in Figures 2(c)-2(e), the electrodes can instead be disposed on the substrate 100 or the transition structure, and are located on the same side of the substrate 100 as the optical waveguide 104. Here, in one example, the electrodes include a first electrode 105 and a second electrode 106. The first electrode 105 and the second electrode 106 are located on both sides of the optical waveguide 104 in a direction perpendicular to the extension direction of the optical waveguide 104, respectively. A voltage is applied to the optical waveguide 104 by the cooperating first electrode 105 and second electrode 106. In general, the positions of the first electrode 105 and the second electrode 106 are the same and are arranged symmetrically with respect to the ridge structure.

[0043] In some examples, as shown in Figures 2(a) and 2(b), the transition structure can be disposed on the optical waveguide 104, specifically, on the body structure and located on the face of the body structure away from the substrate 100. As shown in Figures 2(c)-2(e), the transition structure can instead be disposed on the substrate 100 and / or the transition structure and located on the same side of the substrate 100 as the optical waveguide 104. As shown in Figure 2(c), when the transition structure is disposed on both the substrate 100 and the transition structure, the transition structure can be partially connected to the substrate 100 and partially connected to the optical waveguide 104. Here, the transition structure is disposed between each electrode and the waveguide ridge. In one example, the transition structure can include a first transition structure 107 and a second transition structure 108. A first transition structure 107 is located between the optical waveguide 104 and the first electrode 105 , and a second transition structure 108 is located between the optical waveguide 104 and the second electrode 106 .

[0044] A transition structure is disposed on each side of the ridge structure. The dielectric constant of the transition structure is higher than 8. Therefore, when a voltage is applied to the ridge structure by the electrode, the voltage shared by the material between the electrode and the ridge structure is reduced, and the voltage applied to the ridge structure by the electrode can be increased. This improves the modulation efficiency of the phase shifter. This can reduce the modulation voltage required by the phase shifter when the size of the phase shifter is the same. It can also be satisfied that the size of the phase shifter can be reduced under the same modulation voltage.

[0045] In some examples, the first electrode 105, the second electrode 106, the first transition structure 107, the second transition structure 108, and the ridge structure are all located on the same side of the body structure, as shown in Figures 2(a), 2(b), and 2(d). In some examples, the first electrode 105, the second electrode 106, the first transition structure 107, the second transition structure 108, and the optical waveguide 104 are all located on the same side of the first cladding layer 102 or the same side of the substrate 100, as shown in Figures 2(c) and 2(e). The first electrode 105 and the second electrode 106 are located on either side of the ridge structure, respectively, with the first transition structure 107 located between the ridge structure and the first electrode 105, and the second transition structure 108 located between the ridge structure and the second electrode 106.

[0046] 2(b), in a direction perpendicular to the extending direction of the optical waveguide 104, the first electrode 105 and the second electrode 106 are separately disposed on the body structure and located on both sides of the ridge structure. The first transition structure 107 and the second transition structure 108 are separately disposed on the body structure, the first transition structure 107 is located between the ridge structure and the first electrode 105, and the second transition structure 108 is located between the ridge structure and the second electrode 106. In this way, the transition structures are respectively disposed on both sides of the ridge structure, ensuring that the voltage applied to the ridge structure is increased.

[0047] 2(c), the first electrode 105 and the second electrode 106 are separately disposed on the substrate 100, and the first transition structure 107 and the second transition structure 108 are separately disposed on the substrate 100. In other words, both the ridge structure and the body structure are located between the first transition structure 107 and the second transition structure 108, allowing the voltages applied by the electrodes to the ridge structure and the body structure to be increased simultaneously.

[0048] In one example, as shown in FIG. 2(d), the first electrode 105 is disposed on the first transition structure 107, and the second electrode 106 is disposed on the second transition structure 108, and the first transition structure 107 and the second transition structure 108 are separately disposed on the body structure, with the first electrode 105 and the second electrode 106 located on either side of the ridge structure, respectively.

[0049] 2(e), the first electrode 105 is disposed on the first transition structure 107 and the second electrode 106 is disposed on the second transition structure 108. The first transition structure 107 and the second transition structure 108 are separately disposed on the substrate 100 or the second cladding layer 102.

[0050] In this embodiment of the application, the phase shifter may further include an insulating layer (not shown). An insulating layer is disposed between the first electrode 105 and the body structure, between the second electrode 106 and the body structure, between the first transition structure 107 and the body structure, and between the second transition structure 108 and the body structure to improve reliability. The insulating layer may be a transparent or opaque material, and the refractive index of the insulating layer may be less than that of the optical waveguide, such as silicon oxide.

[0051] 2(b)-2(e), in some examples, the substrate 100 includes a substrate layer 103 and a first clad layer 102, the first clad layer 102 is disposed on the substrate layer 103, the optical waveguide 104 is disposed on the first clad layer 102, and the refractive index of the first clad layer 102 is lower than the refractive index of the optical waveguide 104. In this way, the refractive index of the portion of the substrate 100 close to the optical waveguide 104 is lower than the refractive index of the optical waveguide 104, and as a result, it can be ensured that the light in the optical waveguide 104 is propagated in the form of total internal reflection.

[0052] In some examples, as shown in Figures 2(a)-2(c), the phase shifter further includes a second cladding layer 101. The second cladding layer 101 covers the surface of the optical waveguide 104 away from the substrate 100. The refractive index of the second cladding layer 101 is lower than that of the optical waveguide 104. The second cladding layer 101 is mainly used for reinforcement and mechanical protection. If reinforcement is not considered, the second cladding layer 101 may be a vacuum or air. Optionally, the second cladding layer 101 further covers the surfaces of the first electrode 105, the second electrode 106, and the first transition structure 107 and the second transition structure 108 away from the substrate 100 or substrate layer 103 to reinforce the entire structure.

[0053] In this embodiment of the application, the first transition structure 107 and the second transition structure 108 are spaced apart from the ridge structure to prevent the transition structures from contacting the optical waveguide 104 and affecting the light propagation in the optical waveguide 104, e.g., increasing losses. Optionally, a second cladding layer 101 is filled between the first transition structure 107 and the ridge structure and between the second transition structure 108 and the ridge structure.

[0054] An embodiment of the present application further provides an electro-optic modulator, which includes one or more of the phase shifters described in the above embodiments, as shown in Figures 4(a)-4(d), where "multiple" means at least two.

[0055] In one example, the electro-optic modulator includes two phase shifters, as shown in FIG. 4(a). After the light passes through the beam splitter, the beam splitter can split the light into multiple light beams, and different lights are modulated separately through different phase shifters. Here, different phase shifters can modulate different lights to the same phase or different phases. After the modulation is completed, the different lights pass through a beam combiner and are converged into an output light beam.

[0056] In one example, as shown in Figure 4(b), the electro-optic modulator includes a microring resonant cavity in which a phase shifter is disposed, where light emitted by the coupler passes through the microring resonant cavity and enters the coupler at , and the phase shifter in the microring resonant cavity can modulate the intensity and phase of the light.

[0057] In one example, as shown in FIG. 4(c), the electro-optical modulator includes at least two electro-optical modulators shown in FIG. 4(a). A beam splitter can split the light beam into multiple light beams, and each of the multiple light beams enters a different electro-optical modulator shown in FIG. 4(a). The light emitted by the different electro-optical modulators shown in FIG. 4(a) can be converged into a light beam after passing through a beam combiner again for output. The electro-optical modulator shown in FIG. 4(c) further includes at least one phase shifter. When the light beam is output from the electro-optical modulator shown in FIG. 4(a), the light beam can pass through the phase shifter again.

[0058] In one example, the electro-optic modulator includes a phase shifter and a partial reflector, as shown in Figure 4(d), where after passing through the phase shifter, the light emitted through one partial reflector enters and then exits through another partial reflector.

[0059] An embodiment of this application provides an optical communication system including the electro-optical modulator, phase shifter, or electro-optical device described in the above embodiment. Here, the electro-optical modulator is used as an example for illustration. As shown in FIG. 5, the optical communication system may include a transmitter for electrical-to-optical conversion and a receiver for optical-to-electrical conversion. The transmitter and the receiver are connected via an optical fiber. The transmitter may include an electric chip, a laser generator, and an electro-optical modulator. Different laser generators may be configured to output continuous light of different wavelengths. Driven by the electric chip, the electro-optical modulator modulates the intensity and phase of the continuous light based on the input electric signal to perform the conversion from the electric signal to the optical signal. Different electro-optical modulators may modulate the continuous light of different wavelengths respectively. The transmitter may further include a wavelength division multiplexer, which is configured to converge the optical signals of different wavelengths. The receiver may include a wavelength division demultiplexer. A wavelength division demultiplexer separates the light input by the transmitter into optical signals of different wavelengths and outputs the optical signals to different photodetectors, which are configured to convert the optical signals into electrical signals.

[0060] An embodiment of this application further provides a method for manufacturing a phase shifter, as shown in Figure 6, the method includes the following steps:

[0061] Step S601: As shown in FIG. 7(a), a substrate 100 is prepared.

[0062] 7(a), providing the substrate includes forming a first cladding layer 102 on a substrate layer 103 to obtain a substrate 100. In one example, the refractive index of an end of the substrate closer to the optical waveguide 104 is lower than the refractive index of the optical waveguide 104.

[0063] Step S602: As shown in FIG. 7(b), an optical waveguide is formed on the surface of a substrate, and the refractive index of the end of the substrate closer to the optical waveguide is lower than the refractive index of the optical waveguide.

[0064] In one example, an electro-optic crystal film layer is formed on the surface of the substrate 100, and the refractive index of the end of the substrate 100 closer to the electro-optic crystal film layer is lower than that of the electro-optic crystal film layer. The electro-optic crystal thin film is etched to form the optical waveguide 104. Here, the etching may include partial etching or complete etching, and the optical waveguide 104 including the plate structure and the ridge structure may be formed through partial etching. In the case of complete etching, a ridge structure may be formed, and the ridge structure is used as the optical waveguide 104. It should be noted that the electro-optic crystal film layer may be formed on the surface of the substrate 100 by bonding or adhesion. In one example, a plate structure may be formed on the surface of the substrate 100 first, and then a ridge structure may be formed on the plate structure to form the optical waveguide including the plate structure and the ridge structure. In one example, the surface of the substrate 100 includes a material for manufacturing a waveguide, such as an electro-optic crystal film layer.

[0065] Step S603: As shown in FIG. 7(c), electrodes are formed on both sides of the optical waveguide 104 in a direction perpendicular to the extending direction of the optical waveguide 104.

[0066] Here, a first electrode and a second electrode may be formed on either side of the optical waveguide 104. In one example, the first electrode may be a signal electrode configured to apply a voltage, and the second electrode may be a ground electrode. In one example, the first electrode may be a ground electrode, and the second electrode may be a signal electrode configured to apply a voltage.

[0067] It should be noted that the material of the first electrode and / or the material of the second electrode may be gold, copper, aluminum, etc. The first electrode and the second electrode may be formed on both sides of the optical waveguide 104, respectively, by using a process such as photoetching, metal sputtering, or metal peeling.

[0068] Step S604: As shown in FIG. 7(d), a transition structure is formed on each side of the optical waveguide 104, and the dielectric constant of the transition structure is higher than 8.

[0069] Here, the transition structure may include a first transition structure 107 and a second transition structure 108. The first transition structure 107 is located between the optical waveguide 104 and the first electrode 105, and the second transition structure 108 is located between the optical waveguide 104 and the second electrode 106.

[0070] The transition structure may be formed by using processes such as chemical vapor deposition (CVD), sputtering, or peeling. As shown in FIG. 2(a)-FIG. 2(e), the transition structure may be formed on the surface of the substrate 100, the first cladding layer 102, or the body structure. Specifically, forming the transition structure on each side of the optical waveguide 104 includes forming a photoresist layer on the ends of the optical waveguide and the electrodes away from the substrate 100, removing the photoresist layer where the transition structure area needs to be formed, forming a transition structure layer on the photoresist layer and the ends of the transition structure area away from the substrate 100, and removing the remaining photoresist layer to form the transition structure. The transition structure area is the area where the transition structure is formed on the optical waveguide.

[0071] It should be noted that the order of step S603 and step S604 is determined based on a specific case. In one example, to obtain the phase shifters shown in Figures 2(a)-2(c), step S603 may be performed before step S604, or step S604 may be performed before step S603. In one example, to obtain the phase shifters shown in Figures 2(d) and 2(e), step S604 is performed before step S603.

[0072] Optionally, the phase shifter manufacturing method further includes forming insulating layers between the first electrode 105 and the body structure, between the second electrode 106 and the body structure, between the first transition structure 107 and the body structure, and between the second transition structure 108 and the body structure to improve the long-term stability of the device.

[0073] Optionally, the phase shifter manufacturing method further includes forming a second cladding layer 101 on the side of the optical waveguide 104 away from the substrate 100. The second cladding layer 101 may be silicon dioxide or silicon nitride, etc. The second cladding layer 101 may be formed in a manner of chemical vapor deposition. If the second cladding layer 101 is air or vacuum, this step may be omitted.

[0074] In this embodiment of the application, for the specific structures of the phase shifter and the positional relationship between the specific structures in the phase shifter manufacturing method, please refer to the description of the specific embodiment of the phase shifter.

[0075] The above provides a specific implementation of this application. It should be understood that the above embodiments are merely intended to describe the technical solutions of this application, and are not intended to limit this application. Although this application is described in detail with reference to the above embodiments, those skilled in the art should understand that, without departing from the scope of the technical solutions of the embodiments of this application, modifications can still be made to the technical solutions described in the above embodiments, or equivalent replacements can be made for some technical features thereof.

Claims

1. A phase shifter having a substrate, an optical waveguide, a first electrode, a second electrode, a first transition structure, and a second transition structure, wherein the optical waveguide is disposed on the substrate, the first electrode and the second electrode are located on both sides of the optical waveguide in a direction perpendicular to an extension direction of the optical waveguide, the first transition structure is located between the optical waveguide and the first electrode, and the second transition structure is located between the optical waveguide and the second electrode, a refractive index of an end of the substrate closer to the optical waveguide is lower than a refractive index of the optical waveguide, and a dielectric constant of the first transition structure and the second transition structure is higher than a dielectric constant of the optical waveguide.

2. 2. The phase shifter of claim 1, wherein the optical waveguide has an interconnected body structure and a ridge structure, the ridge structure protruding from the body structure toward a side away from the substrate, and the first transition structure and the second transition structure being spaced apart from the ridge structure.

3. 3. The phase shifter of claim 2, wherein in a direction perpendicular to the extension direction of the optical waveguide, the first electrode and the second electrode are located on either side of the ridge structure and arranged separately on the body structure, the first transition structure and the second transition structure are arranged separately on the body structure, the first transition structure is located between the ridge structure and the first electrode, and the second transition structure is located between the ridge structure and the second electrode.

4. 3. The phase shifter of claim 2, wherein the first electrode is disposed on the first transition structure, the second electrode is disposed on the second transition structure, the first transition structure and the second transition structure are separately disposed on the body structure, and the first electrode and the second electrode are located on either side of the ridge structure, respectively.

5. 3. The phase shifter of claim 1, wherein the first electrode and the second electrode are separately disposed on the substrate, and the first transition structure and the second transition structure are separately disposed on the substrate.

6. 3. The phase shifter of claim 1, wherein a first electrode is disposed on a first transition structure, a second electrode is disposed on a second transition structure, and the first transition structure and the second transition structure are separately disposed on the substrate.

7. 3. The phase shifter of claim 2, further comprising an insulating layer disposed between the first electrode and the body structure and between the second electrode and the body structure.

8. 8. The phase shifter of claim 7, wherein the insulating layer is further disposed between the first transition structure and the body structure and between the second transition structure and the body structure.

9. 9. The phase shifter of claim 1, wherein the substrate has a substrate layer and a first clad layer, the first clad layer being disposed on the substrate layer, the optical waveguide being disposed on a side of the first clad layer away from the substrate layer, and the refractive index of the first clad layer being lower than the refractive index of the optical waveguide.

10. 10. A phase shifter as claimed in any one of claims 3 to 9, further comprising a second cladding layer covering a surface of the optical waveguide away from the substrate, the second cladding layer having a refractive index lower than the refractive index of the optical waveguide.

11. 11. The phase shifter of claim 10, wherein the second cladding layer is filled between the first transition structure and the ridge structure and between the second transition structure and the ridge structure.

12. 12. A phase shifter according to any one of claims 1 to 11, wherein the material of the optical waveguide is lithium niobate, electro-optic polymer, tantalum niobate, barium titanate or lead zirconate titanate.

13. The first transition structure material and / or the second transition structure material may be barium titanate, titanium dioxide, aluminum oxide, magnesium oxide, LaF ３ , LaYO ３ , or LaAlO ３ 13. A phase shifter according to claim 1, wherein:

14. 14. A phase shifter according to any one of the preceding claims, wherein the refractive index of the first transition structure and / or the refractive index of the second transition structure is lower than the refractive index of the optical waveguide.

15. 15. An electro-optical device comprising a phase shifter according to any one of the preceding claims.

16. 16. The electro-optical device of claim 15, wherein the electro-optical device is an electro-optical modulator, an electro-optical switch, or an electric field sensor.

17. 17. An optical communication system comprising a phase shifter according to any one of claims 1 to 14 or an electro-optical device according to claim 15 or 16.

18. Prepare the substrate, forming an optical waveguide on a surface of the substrate, the refractive index of an end of the substrate closer to the optical waveguide being lower than the refractive index of the optical waveguide; a first electrode and a second electrode are formed on both sides of the optical waveguide in a direction perpendicular to an extension direction of the optical waveguide, and a first transition structure and a second transition structure are formed on both sides of the optical waveguide, the first transition structure is located between the optical waveguide and the first electrode, the second transition structure is located between the optical waveguide and the second electrode, and the dielectric constants of the first transition structure and the second transition structure are higher than the dielectric constant of the optical waveguide; A method for manufacturing a phase shifter comprising:

19. 20. The method of claim 18, wherein the optical waveguide has an interconnected body structure and a ridge structure, the ridge structure protruding from the body structure toward a side away from the substrate, and the first transition structure and the second transition structure being spaced apart from the ridge structure.

20. 20. The method of claim 19, further comprising forming an insulating layer between the first electrode and the body structure and between the second electrode and the body structure.

21. 21. The method of claim 19 or 20, further comprising forming the insulating layer between the first transition structure and the body structure and between the second transition structure and the body structure.

22. Providing a substrate includes: forming a first clad layer on a substrate layer to obtain the substrate, the refractive index of the first clad layer being lower than the refractive index of the optical waveguide, and an electro-optic crystal film layer being formed on a surface of the first clad layer away from the substrate layer; 20. The method of claim 18, further comprising:

23. 20. The phase shifter manufacturing method of claim 18, further comprising forming a second cladding layer on a surface of the optical waveguide remote from the substrate, the second cladding layer having a refractive index lower than the refractive index of the optical waveguide.

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