Electro-optic modulator and optical module

Abstract

An electro-optic modulator (22) and an optical module (m1). The electro-optic modulator (22) comprises a waveguide, electrodes and anisotropic structures (1), wherein the anisotropic structures (1) are arranged between the electrodes and the waveguide; and in a direction perpendicular to a connection interface between the waveguide and each anisotropic structure (1), each anisotropic structure (1) has a first refractive index, and the waveguide has a second refractive index, the first refractive index being less than the second refractive index. In general, the waveguide is made of an isotropic material, so the connection interface between the waveguide and each anisotropic structure (1) is a connection interface between an isotropic structure and said anisotropic structure (1). Since the first refractive index is less than the second refractive index, a carrier optical signal in the waveguide undergoes total reflection when being incident onto the connection interface, thereby improving the lateral diffusion of an optical field in the waveguide, preventing the carrier optical signal from being incident onto the surface of the electrode, which would cause the loss of the carrier optical signal, improving the transmission power and transmission quality of the carrier optical signal in the waveguide, and improving the effect of data transmission.

Description

Electro-optical modulator and optical module

[0001] Cross-reference to related applications

[0002] The present application claims priority to the Chinese patent application No. 202410813263.8, filed on June 21, 2024, entitled “Electro-optical modulator and optical module”, the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the field of optical communication technology, in particular to an electro-optical modulator and an optical module. BACKGROUND

[0004] In an electro-optical modulator, generally includes: a substrate, and a waveguide, a signal electrode and a ground electrode respectively arranged on the substrate, the waveguide is arranged between the signal electrode and the ground electrode, the carrier optical signal propagates in the waveguide, and the electrical signal can be applied to the carrier optical signal through the signal electrode and the ground electrode, so as to obtain the modulated optical signal. Although the waveguide can be made of total reflection material, so that the carrier optical signal propagates in the waveguide and is totally reflected, but inevitably, a part of the carrier optical signal will be emitted from the waveguide and incident to the surface of the signal electrode and / or the ground electrode. When the signal electrode and the ground electrode are made of metal, the metal will absorb the light incident to its surface, causing the part of the carrier optical signal incident to the surface of the metal to be absorbed and lost, so that the power of the carrier optical signal propagating in the waveguide is reduced, causing the quality of the carrier optical signal transmitted in the waveguide to be reduced, resulting in the deviation of the obtained modulated optical signal, and finally causing the abnormality of data transmission. SUMMARY

[0005] The present application provides an electro-optical modulator and an optical module, which can reduce the loss of the carrier optical signal, improve the transmission power and quality of the carrier optical signal in the waveguide, and improve the effect of data transmission.

[0006] In a first aspect, an electro-optical modulator is provided, comprising a waveguide, an electrode, and an anisotropic structure disposed between the electrode and the waveguide; the waveguide and the anisotropic structure form a connection interface, the anisotropic structure has a first refractive index in a direction perpendicular to the connection interface, and the waveguide has a second refractive index; the first refractive index is less than the second refractive index. Generally, the waveguide is made of an isotropic material, and the connection interface between the waveguide and the anisotropic structure is the connection interface between the isotropic structure and the anisotropic structure. Because the first refractive index is less than the second refractive index, when a carrier optical signal in the waveguide is incident on the connection interface, total reflection can occur, which can improve the lateral diffusion of the optical field in the waveguide, avoid the carrier optical signal from being incident on the surface of the electrode, and thus avoid the loss of the carrier optical signal, improve the transmission power and transmission quality of the carrier optical signal in the waveguide, and improve the effect of data transmission.

[0007] In addition, because the refractive indices of the anisotropic structure in different directions are different, when the anisotropic structure has a first refractive index in a direction perpendicular to the connection interface, the anisotropic structure also has a third refractive index in a direction parallel to the connection interface and parallel to the extension direction of the waveguide. By adjusting the third refractive index, the distance of the evanescent wave in the anisotropic structure can be reduced, and thus the distance between the electrode and the waveguide can be reduced. For example, the distance between the waveguide and the electrode can be set to 250 nm to 1500 nm, thereby reducing the size of the electro-optical modulator. For example, taking two electrodes as an example, when the anisotropic structure is not disposed between the waveguide and the electrode and the isotropic medium material is filled between the waveguide and the electrode, the distance between the two electrodes is generally set to at least 4 μm; when the anisotropic structure is disposed between the waveguide and the electrode, the distance between the two electrodes can be set to 500 nm to 3000 nm, i.e., the distance between the two electrodes is at most 3 μm, and the distance between the two electrodes is reduced by at least 25%, thereby effectively reducing the size of the electro-optical modulator and widening the application field of the electro-optical modulator. In addition, when the distance between the electrode and the waveguide is reduced, the size of the electrical signal applied by the electrode can also be reduced, i.e., the modulation voltage is reduced, thereby improving the performance of the electro-optical modulator. The specific value of the third refractive index can be set according to the distance requirement between the electrode and the waveguide and other factors, which is not limited herein.

[0008] Exemplarily, the anisotropic structure comprises: at least two first dielectric structures and at least one second dielectric structure arranged along a first direction, the first dielectric structures and the second dielectric structures are alternately arranged; the first direction is the arrangement direction of the anisotropic structure and the waveguide; the refractive index of the first dielectric structure is less than the refractive index of the second dielectric structure. Wherein, the number of the first dielectric structures is one more than the number of the second dielectric structures, and the number of the first dielectric structures and the second dielectric structures is not limited to odd or even, and can be set according to actual needs, which is not limited herein. For example, the more the number of the second dielectric structures, the better the effect of reducing the evanescent wave depth, but the more difficult the production, so the number of the second dielectric structures is set in a suitable range, which can effectively reduce the evanescent wave depth and reduce the production difficulty and cost. Wherein, the refractive index of the first dielectric structure is less than the refractive index of the second dielectric structure, so that the whole formed by the arrangement of the first dielectric structures and the second dielectric structures has anisotropic performance, thereby forming an anisotropic structure.

[0009] Optionally, the electrode and the second dielectric structure can not be in direct contact, and the first dielectric structure can be arranged between the electrode and the second dielectric structure to have a gap between the electrode and the second dielectric structure, which can effectively avoid the overflow of the carrier optical signal from the second dielectric structure closest to the electrode from being incident on the surface of the electrode, thereby avoiding the absorption of the carrier optical signal by the electrode and causing the loss of the carrier optical signal.

[0010] Exemplarily, the second dielectric structure and the waveguide can be made of the same material, but not limited to the same material, and the second dielectric structure can also be made of a different material from the waveguide, for example, the second dielectric structure and the waveguide can each independently be made of silicon, lithium niobate or other materials. In this way, when the second dielectric structure and the waveguide are made of the same material, the second dielectric structure and the waveguide can be formed in the same manufacturing process, which simplifies the manufacturing process of the electro-optical modulator and reduces the manufacturing cost of the electro-optical modulator. When the second dielectric structure and the waveguide are made of different materials, the design flexibility can be increased to meet the application requirements of different scenes. The first dielectric structure is made of organic electro-optical material, which is an organic material with electro-optical effect, such as but not limited to: polyphenylene vinylene, polyacetylene, poly-p-phenylene, polythiophene, polythiophene derivatives or polyalkylfluorene, etc., which can be selected according to actual needs, and is not limited herein. Based on this, the first dielectric structure and the second dielectric structure can be made of materials with electro-optical effect, and the refractive index of the materials with electro-optical effect will change under the action of the electric field, so that the two dielectric structures arranged and combined can form an anisotropic structure, thereby realizing the function of the anisotropic structure.

[0011] Exemplarily, the first medium structure has a first length along the first direction, and the second medium structure has a second length along the first direction, and the first length is less than the second length. If the length of the structure along the first direction is defined as a width, then the width of the first medium structure is less than the width of the second medium structure, so that the first refractive index of the anisotropic structure is adjusted to be less than the second refractive index of the waveguide, thereby avoiding overflow of the carrier optical signal from the waveguide and avoiding loss of the carrier optical signal. The first length and the second length can be set according to the wavelength of the carrier optical signal to be modulated, the height of the waveguide, and process conditions, and the like, and are not limited herein.

[0012] Further, when the first length is less than the second length, the ratio of the first length to the second length is less than 1, and the ratio of the first length to the second length can be set to 1 / 9 to 1 / 2, such as but not limited to 1 / 9, 1 / 8, 1 / 7, 1 / 6, 1 / 5, 1 / 4, 1 / 3, 1 / 2, and other values, as long as the first length is less than the second length. The ratio of the first length to the second length can be set according to actual needs, and is not specifically limited herein.

[0013] Further, the sum of the first length and the second length can be set to 40 nm-80 nm, and further, the sum of the first length and the second length can be set to 50 nm-70 nm, such as but not limited to 50 nm, 55 nm, 60 nm, 63 nm, 65 nm, 70 nm, and other numerical values. The sum of the first length and the second length can be set according to actual needs, and is not specifically limited herein. By adjusting the sum of the first length and the second length, the first refractive index of the anisotropic structure can be adjusted to be less than the second refractive index of the waveguide, thereby avoiding overflow of the carrier optical signal from the waveguide and avoiding loss of the carrier optical signal.

[0014] Exemplarily, the height of the anisotropic structure can be equal to the height of the waveguide, so that the carrier optical signal incident to the side surface of the waveguide can be effectively adjusted, and effective restriction of the lateral optical field in the waveguide is achieved, thereby avoiding loss of the carrier optical signal. It should be understood that the side surface of the waveguide refers to the side surface of the waveguide facing the anisotropic structure. Of course, the height of the anisotropic structure can also be greater than the height of the waveguide, thereby further improving the restriction of the lateral optical field in the waveguide. However, the specific value of the height of the anisotropic structure can be set according to actual needs, and is not limited herein. In summary, the height of the waveguide can be set to be not greater than the height of the anisotropic structure.

[0015] Exemplarily, the electro-optical modulator can further include an organic electro-optical medium layer, and the electro-optical coefficient of the organic electro-optical material can be, but is not limited to, greater than 40 pm / V, and the organic electro-optical medium layer covers at least the waveguide and the anisotropic structure. In this way, the electro-optical interaction can occur at the interface between the waveguide and the organic electro-optical medium layer, so that the modulation of the carrier optical signal can be realized when the carrier optical signal is incident to the interface, thereby improving the modulation efficiency. The anisotropic structure includes at least two first medium structures and at least one second medium structure arranged along a first direction, and the first medium structures and the second medium structures are alternately arranged; the first direction is the arrangement direction of the anisotropic structure and the waveguide; and the first medium structure is made of the same material as the organic electro-optical medium layer. At this time, when the electro-optical modulator is manufactured, the second medium structure, the waveguide and the electrode can be formed on the substrate first, and then the organic electro-optical material is filled in the gaps between the second medium structure, the waveguide and the electrode, and covers at least the waveguide and the second medium structure. In this way, the organic electro-optical material filled between the second medium structures, between the second medium structure and the waveguide, and between the second medium structure and the electrode forms the first medium structure, thereby forming the anisotropic structure and the organic electro-optical medium layer.

[0016] In a second aspect, the embodiments of the present application further provide an optical module, which can include: an optical source, and an electro-optical modulator as described in the first aspect and any one of the embodiments of the first aspect; the optical source is configured to generate a carrier optical signal and transmit the carrier optical signal to the electro-optical modulator; and the electro-optical modulator is configured to modulate the carrier optical signal according to an electrical signal to generate a modulated optical signal. In this way, the loss of the carrier optical signal can be avoided, and the transmission power and the transmission quality of the carrier optical signal in the waveguide can be improved, thereby improving the effect of data transmission.

[0017] It should be understood that, since the principle of solving the problem of the optical module is similar to that of the electro-optical modulator, the implementation and technical effects of the optical module can be referred to the implementation and technical effects of the electro-optical modulator, and the repeated parts will not be described herein. BRIEF DESCRIPTION OF DRAWINGS

[0018] FIG. 1 is a structural schematic diagram of an optical communication system provided by the embodiments of the present application;

[0019] FIG. 2 is a structural schematic diagram of an optical signal sending device provided by the embodiments of the present application;

[0020] FIG. 3 is a structural schematic diagram of an electro-optical modulator provided by the embodiments of the present application;

[0021] FIG. 4 is a sectional view along the direction of x1-x2 in FIG. 3;

[0022] FIG. 5 is a comparison diagram of the electric field diffusion provided by the embodiments of the present application;

[0023] FIG. 6 is a simulation result diagram of the light field diffused to both sides in the waveguide according to an embodiment of the present application;

[0024] FIG. 7 is a curve of the variation of the electro-optic coefficient and the half-wave voltage according to an embodiment of the present application;

[0025] FIG. 8 is a structural diagram of another electro-optic modulator according to an embodiment of the present application. DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the technical solutions provided by the embodiments of the present application, the application scenarios thereof will be first described below.

[0027] The electro-optic modulator provided by the embodiments of the present application can be widely applied in the field of optical communication. Referring to FIG. 1, a structural diagram of an optical communication system 100 is shown. The optical communication system 100 can include a signal processor 10, an optical signal sending device 20, an optical fiber 30, and an optical signal receiving device 40. The signal processor 10 can process voice, image, and other data information, generate an electrical signal, and transmit the electrical signal to the optical signal sending device 20. The optical signal sending device 20 is configured to generate an optical signal suitable for transmission in the optical fiber 30 according to the electrical signal. The optical fiber 30 transmits the optical signal generated by the optical signal sending device 20 to the optical signal receiving device 40. The optical signal receiving device 40 receives the optical signal and extracts information therefrom, and finally obtains voice, image, and other data information corresponding to the electrical signal generated by the signal processor 10, so as to realize the transmission of data through the optical fiber. The optical module m1 includes the optical signal sending device 20 and the optical signal receiving device 40, and the conversion between the electrical signal and the optical signal can be realized through the optical module m1. It should be understood that the optical communication system 100 shown in FIG. 1 can include more or fewer devices, and each device in the optical communication system 100 can also include more or fewer functional devices, which can be set according to actual conditions and are not limited herein.

[0028] Referring to FIG. 2, a structural diagram of the optical signal sending device 20 is shown. The optical signal sending device 20 includes a light source 21 and an electro-optic modulator 22. The light source 21 is configured to generate a carrier optical signal s1 and transmit the carrier optical signal s1 to the electro-optic modulator 22. The electrical signal s0 generated by the signal processor 10 is transmitted to the electro-optic modulator 22 in the optical signal sending device 20. The electro-optic modulator 22 modulates the carrier optical signal s1 according to the electrical signal s0, generates a modulated optical signal s2, and transmits the modulated optical signal s2 to the optical signal receiving device through the optical fiber.

[0029] In an electro-optical modulator, generally comprising: a substrate, and a waveguide, a signal electrode and a ground electrode arranged on the substrate respectively, the waveguide is arranged between the signal electrode and the ground electrode, a carrier optical signal propagates in the waveguide, and an electrical signal can be applied to the carrier optical signal through the signal electrode and the ground electrode to obtain a modulated optical signal. Although the waveguide can be made of a material with isotropy and total reflectivity, so that the carrier optical signal propagates in the waveguide and is totally reflected, but inevitably, part of the carrier optical signal will be emitted from the waveguide and incident on the surface of the signal electrode and / or the ground electrode. When the signal electrode and the ground electrode are made of metal, the metal will absorb the light incident on its surface, causing the part of the carrier optical signal incident on the surface of the metal to be absorbed and lost, reducing the power of the carrier optical signal propagating in the waveguide, causing the quality of the carrier optical signal transmitted in the waveguide to be reduced, resulting in deviation of the obtained modulated optical signal, and ultimately causing abnormal data transmission.

[0030] Based on this, the embodiment of the present application provides an electro-optical modulator, which can reduce the loss of the carrier optical signal, improve the transmission power and quality of the carrier optical signal in the waveguide, and improve the effect of data transmission.

[0031] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application will be further described in detail below with reference to the drawings. It should be noted that the same reference signs in the drawings of the present application represent the same or similar structures, so repeated description thereof will be omitted. The expressions of position and direction described in the present application are described with reference to the drawings, but changes can also be made as needed, and the changes made are all included in the protection scope of the present application. The drawings of the present application are only used to show the relative position relationship and do not represent the true proportion.

[0032] The electro-optical modulator provided by the present application can comprise: a waveguide, an electrode and an anisotropic structure, the electrode, the anisotropic structure and the waveguide are arranged along a first direction, the waveguide, the electrode and the anisotropic structure all extend along a second direction, the first direction intersects the second direction; the anisotropic structure is arranged between the electrode and the waveguide; the waveguide and the anisotropic structure form a connecting interface, the anisotropic structure has a first refractive index in a direction perpendicular to the connecting interface, the waveguide has a second refractive index, and the first refractive index is less than the second refractive index. Generally, the waveguide is made of an isotropic material, and the connecting interface of the waveguide and the anisotropic structure is the connecting interface of the isotropic structure and the anisotropic structure. Since the first refractive index is less than the second refractive index, the carrier optical signal in the waveguide can be totally reflected when it is incident on the connecting interface. This can improve the lateral diffusion of the optical field in the waveguide, avoid the carrier optical signal from being incident on the surface of the electrode, thereby avoiding the loss of the carrier optical signal, improving the transmission power and quality of the carrier optical signal in the waveguide, and improving the effect of data transmission.

[0033] The structure of the electro-optical modulator will be described below in combination with specific embodiments.

[0034] FIG. 3 schematically shows a structure of an electro-optical modulator provided by the present application. As shown in FIG. 3, the electro-optical modulator can include a substrate, a waveguide, an electrode and an anisotropic structure 1 arranged on the substrate in sequence. The electrode, the anisotropic structure 1 and the waveguide are arranged along a first direction, and the waveguide, the electrode and the anisotropic structure 1 extend along a second direction. The first direction intersects the second direction. That is, the first direction can be perpendicular to the second direction or not, as long as the first direction intersects the second direction. For example, but not limited to, the structure shown in FIG. 3, the first direction is x direction, and the second direction is y direction. The x direction is perpendicular to the y direction. In the following content, the first direction is x direction and the second direction is y direction as an example. It should be understood that FIG. 3 shows a top view of the electro-optical modulator. The substrate is not shown due to the viewing angle.

[0035] The structures in the electro-optical modulator will be introduced below respectively.

[0036] I. Substrate

[0037] The material of the substrate can include an insulating material or a semiconductor material, which can be set according to actual needs, as long as the substrate can provide certain support for the waveguide, the electrode and the anisotropic structure 1. The material of the substrate is not limited herein.

[0038] II. Electrode

[0039] The electrode can be provided with a plurality of electrodes, one of which is a signal electrode, and the other is a ground electrode. The signal electrode and the ground electrode are arranged on opposite sides of the waveguide along the first direction. The signal electrode and the ground electrode can be used to apply an electrical signal to modulate the carrier optical signal in the waveguide. The number of the signal electrode and the ground electrode can be set according to the function of the electro-optical modulator. For example, when the electro-optical modulator is a phase electro-optical modulator, the signal electrode and the ground electrode are each provided with one. Or, when the electro-optical modulator is an intensity electro-optical modulator, the signal electrode can be provided with two, and the ground electrode is provided with one. The ground electrode is arranged between the two signal electrodes, and two waveguides are provided. One of the waveguides is arranged between one of the signal electrodes and the ground electrode, and the other waveguide is arranged between the other signal electrode and the ground electrode.

[0040] Exemplarily, the anisotropic structure 1 can be arranged between the signal electrode and the waveguide, while no anisotropic structure 1 is arranged between the ground electrode and the waveguide, which is not shown; or, no anisotropic structure 1 is arranged between the signal electrode and the waveguide, while the anisotropic structure 1 is arranged between the ground electrode and the waveguide, which is not shown; or, the anisotropic structure 1 is arranged between the signal electrode and the waveguide, and the anisotropic structure 1 is also arranged between the ground electrode and the waveguide, as shown in FIG. 3, where the leftmost electrode can be regarded as the signal electrode, and the rightmost electrode can be regarded as the ground electrode; and the arrangement can be made according to actual needs, which is not limited herein.

[0041] The material of the electrode can include, but is not limited to, a conductive metal and other materials having a conductive property, where the conductive metal can include, but is not limited to, gold, copper, aluminum and other conductive metals, which can be arranged according to actual needs, which is not limited herein. When a voltage is applied through the electrode, an electric field perpendicular to the transmission direction of the carrier optical signal can be provided, for changing the refractive index of the waveguide, so as to adjust the phase, intensity and other characteristics of the carrier optical signal in the waveguide, and to realize the modulation of the carrier optical signal.

[0042] III. Waveguide.

[0043] In order to distinguish the first length d1 and the second length d2 mentioned later, the length of the waveguide along the first direction can be referred to as a third length d3, which can also be regarded as the width of the waveguide. The width of the waveguide can be set to 500 nm to 2000 nm, such as, but not limited to, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1500 nm, 2000 nm and other values, which can be arranged according to actual needs, which is not limited herein. In addition, the cross-sectional shape of the waveguide can be rectangular (as shown in FIG. 4) or trapezoidal (not shown) and other shapes. The height d5 of the waveguide can be set to 30 nm to 220 nm, such as, but not limited to, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm and other values, which can be arranged according to actual needs, which is not limited herein. In this way, the width and height of the waveguide are set in the above range, which can realize the effective transmission of the carrier optical signal by the waveguide, and facilitate the modulation of the carrier optical signal.

[0044] The waveguide can be generally made of a material with anisotropy and electro-optic effect, such as but not limited to silicon, lithium niobate and other materials. The refractive index of the material can change under the action of an electric field to produce an electro-optic effect, so that the phase, intensity and other characteristics of the carrier optical signal in the waveguide can be adjusted to modulate the carrier optical signal. The working mode of the waveguide can include TE mode and TM mode. The TE mode means that all electric field components are perpendicular to the transmission direction of the carrier optical signal. The TM mode means that all magnetic field components are perpendicular to the transmission direction of the carrier optical signal. The technical solutions provided by the embodiments of the present application are applicable to both TE mode and TM mode.

[0045] IV. Anisotropic structure

[0046] The anisotropic structure 1 can include: at least two first dielectric structures 1a and at least one second dielectric structure 1b arranged along a first direction, the first dielectric structures 1a and the second dielectric structures 1b are arranged alternately, so that any second dielectric structure 1b is arranged between two adjacent first dielectric structures 1a. In FIG. 3, four first dielectric structures 1a and three second dielectric structures 1b are taken as an example for illustration, but this does not mean that the first dielectric structures 1a are only provided with four, and the second dielectric structures 1b are only provided with three. The number of first dielectric structures 1a can also be 2, 3, 5 or other numbers, and the number of second dielectric structures 1b can also be 1, 2, 3 or other numbers. The number of first dielectric structures 1a is one more than the number of second dielectric structures 1b, and the number of first dielectric structures 1a and the number of second dielectric structures 1b are not limited to odd or even, and can be set according to actual needs, which is not limited herein. For example, the more the number of second dielectric structures 1b, the better the effect of reducing the penetration depth of evanescent waves (which will be described later), but the more difficult it is to manufacture. Therefore, by setting the number of second dielectric structures 1b in an appropriate range, the penetration depth of evanescent waves can be effectively reduced, and the manufacturing difficulty and cost can be reduced. The refractive index of the first dielectric structure 1a is less than the refractive index of the second dielectric structure 1b, so that the whole formed by the arrangement of each first dielectric structure 1a and each second dielectric structure 1b has anisotropic performance, thereby forming an anisotropic structure 1.

[0047] It is worth noting that the electrode and the second dielectric structure 1b can not be in direct contact, and the first dielectric structure 1a can be arranged between the electrode and the second dielectric structure 1b. In this way, a gap can be formed between the electrode and the second dielectric structure 1b, which can effectively prevent the carrier optical signal overflowing from the second dielectric structure 1b closest to the electrode from being incident on the surface of the electrode, thereby avoiding the absorption of the carrier optical signal by the electrode and causing the loss of the carrier optical signal.

[0048] Exemplarily, the material for manufacturing the first dielectric structure 1a can include an organic electro-optic material, which is an organic material having an electro-optic effect, such as but not limited to polyphenylene vinylene, polyacetylene, poly-p-phenylene, polythiophene, polythiophene derivatives, or polyalkylfluorene, etc., which can be selected according to actual needs, and is not specifically limited here. The second dielectric structure 1b can be manufactured using the material for manufacturing the waveguide, where the material for manufacturing the second dielectric structure 1b is the same as the material for manufacturing the waveguide, of course, the material for manufacturing the second dielectric structure 1b can also be different from the material for manufacturing the waveguide, for example, the second dielectric structure 1b and the waveguide can each be independently manufactured using silicon, lithium niobate, or other materials. In this way, when the second dielectric structure 1b and the waveguide are manufactured using the same material, the second dielectric structure 1b and the waveguide can be formed in the same manufacturing process, simplifying the manufacturing process of the electro-optic modulator and reducing the manufacturing cost of the electro-optic modulator. When the second dielectric structure 1b and the waveguide are manufactured using different materials, the design flexibility can be increased to meet the application requirements of different scenarios. Based on this, by setting the materials of the first dielectric structure 1a and the second dielectric structure 1b, the first dielectric structure 1a and the second dielectric structure 1b can each be manufactured using a material having an electro-optic effect. Since the material having an electro-optic effect will change in refractive index under the action of an electric field, the two dielectric structures arranged and combined can form an anisotropic structure 1, thereby realizing the function of the anisotropic structure 1.

[0049] Suppose the length of the first dielectric structure 1a along the first direction is a first length d1, and the length of the second dielectric structure 1b along the first direction is a second length d2. The first length d1 can be less than the second length d2. If the length of the structure along the first direction is defined as the width, then the width of the first dielectric structure 1a is less than the width of the second dielectric structure 1b, which can adjust the first refractive index of the anisotropic structure 1, so that the first refractive index is less than the second refractive index of the waveguide, thereby avoiding the overflow of the carrier optical signal from the waveguide and avoiding the loss of the carrier optical signal. The first length d1 and the second length d2 can be set according to the wavelength of the carrier optical signal to be modulated, the height of the waveguide, and process conditions, etc., which are not limited here. It should be understood that the relative positions between the structures are shown in FIG. 3, but the actual size of each structure is not represented.

[0050] Further, when the first length d1 is less than the second length d2, the ratio of the first length d1 to the second length d2 is less than 1, and the ratio of the first length d1 to the second length d2 can be set to 1 / 9 to 1 / 2, such as but not limited to: 1 / 9, 1 / 8, 1 / 7, 1 / 6, 1 / 5, 1 / 4, 1 / 3, 1 / 2, and other values, as long as the first length d1 is less than the second length d2. For a specific ratio of the first length d1 to the second length d2, it can be set according to actual needs, which is not specifically limited here.

[0051] Further, the sum of the first length d1 and the second length d2 can be set to 40nm-80nm, and further, the sum of the first length d1 and the second length d2 can be set to 50nm-70nm, such as but not limited to: 50nm, 55nm, 60nm, 63nm, 65nm, 70nm, and other numerical values. The sum of the first length d1 and the second length d2 can be set according to actual needs, which is not specifically limited here. By adjusting the sum of the first length d1 and the second length d2, the first refractive index of the anisotropic structure 1 can be adjusted so that the first refractive index is less than the second refractive index of the waveguide, thereby avoiding the overflow of the carrier optical signal from the waveguide and avoiding the loss of the carrier optical signal.

[0052] Based on this, by scanning and simulating the electric field along the x direction in the electro-optical modulator shown in FIG. 3, it can be found that when the sum of the first length d1 and the second length d2 (i.e. d1+d2) is 63nm and the proportion of d1 in d1+d2 is 0.8, the electric field along the x direction is the smallest, so that the anisotropic structure 1 has the strongest limiting effect on the lateral optical field inside the waveguide, thereby effectively avoiding the loss of the carrier optical signal.

[0053] For example, as shown in FIG. 4, which is a cross-sectional view along the x1-x2 direction shown in FIG. 3, the height of the anisotropic structure 1 is d4, and the height of the waveguide is d5. The height d4 of the anisotropic structure 1 can be equal to the height d5 of the waveguide, which can effectively adjust the carrier optical signal incident to the side surface of the waveguide, and effectively limit the lateral optical field inside the waveguide, thereby avoiding the loss of the carrier optical signal. It should be understood that the side surface of the waveguide refers to the side surface of the waveguide facing the anisotropic structure 1. Of course, the height d4 of the anisotropic structure 1 can also be greater than the height d5 of the waveguide, thereby further improving the limiting effect on the lateral optical field inside the waveguide. However, the specific value of the height d4 of the anisotropic structure 1 can be set according to actual needs, which is not limited here.

[0054] Five, other structures.

[0055] Continuing to refer to FIG. 4, the electro-optical modulator can further include a cover layer covering at least the waveguide and the anisotropic structure 1, such as the cover layer covering the waveguide and the anisotropic structure 1, or the cover layer covering the waveguide, the anisotropic structure 1 and the electrode. The cover layer can be made of an organic electro-optical material, and the electro-optical coefficient of the organic electro-optical material can be, but is not limited to, greater than 40 pm / V, so that the cover layer can also be referred to as an organic electro-optical medium layer 2, so that the electro-optical interaction occurs at the interface between the waveguide and the organic electro-optical medium layer 2, so that when the carrier optical signal is incident at the interface, the modulation of the carrier optical signal can be achieved, thereby improving the modulation efficiency.

[0056] For example, the first medium structure 1a can be made of the same material as the organic electro-optical medium layer 2, so that when the electro-optical modulator is manufactured, the second medium structure 1b, the waveguide and the electrode can be formed on the substrate first, and then the organic electro-optical material is filled in the gap between the second medium structure 1b, the waveguide and the electrode, and at least covers the waveguide and the second medium structure 1b. In this way, the organic electro-optical material filled between the second medium structures 1b, between the second medium structure 1b and the waveguide, and between the second medium structure 1b and the electrode forms the first medium structure 1a, thereby forming the anisotropic structure 1 and the organic electro-optical medium layer 2.

[0057] Alternatively, the first medium structure 1a can be made of a material different from the material of the organic electro-optical medium layer 2, so that when the electro-optical modulator is manufactured, the second medium structure 1b, the waveguide and the electrode can be formed on the substrate first, and then the organic electro-optical material is filled in the gap between the second medium structure 1b, the waveguide and the electrode to form the first medium structure 1a, thereby forming the anisotropic structure 1; and then the organic electro-optical medium layer 2 covering at least the anisotropic structure 1 and the waveguide is formed.

[0058] The thickness d6 of the organic electro-optical medium layer 2 can be set to 500 nm to 3 μm, such as, but not limited to, 500 nm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm and other values, which can be set according to actual needs, and is not limited herein. The refractive index of the organic electro-optical medium layer 2 can be in the range of 1.5 to 2.2, so that when the carrier optical signal is incident at the interface between the organic electro-optical medium layer 2 and the waveguide, total reflection can be formed, so that the carrier optical signal can effectively propagate in the waveguide.

[0059] Continuing to refer to FIG. 4, when the cover layer covers the electrode, the electro-optical modulator can further include a lead electrode 3 connected to the electrode through a through hole in the cover layer, so as to transmit signals to the electrode and achieve modulation of the carrier optical signal.

[0060] In summary, by setting various structures, the anisotropic structure 1 can improve the lateral diffusion of the optical field in the waveguide, avoid the carrier optical signal from being incident to the electrode surface, thereby avoiding the loss of the carrier optical signal, improving the transmission power and transmission quality of the carrier optical signal in the waveguide, and improving the data transmission effect.

[0061] For example, referring to FIG. 5, the curve s1 represents the test curve corresponding to the structure shown in FIG. 3, and the curve s2 represents the test curve corresponding to the structure without the anisotropic structure 1, where the width of the waveguide is 600 nm. From the results shown in the figure, it can be found that in the curve s2, the electric field component in the x direction gradually increases as the distance from the waveguide in the x direction gradually increases, indicating that the optical field in the waveguide diffuses to both sides along the x direction, and the diffused optical field is absorbed by the electrode when reaching the electrode, causing the loss of the carrier optical signal in the waveguide. In the curve s1, the anisotropic structure 1 is arranged between the waveguide and the electrode, so that the electric field component in the x direction is effectively reduced under the action of the anisotropic structure 1, indicating that the diffusion of the optical field in the waveguide to both sides is effectively limited, thereby achieving lateral limitation of the optical field in the waveguide, avoiding the loss of the carrier optical signal, improving the transmission power and transmission quality of the carrier optical signal in the waveguide, and improving the data transmission effect.

[0062] Referring to FIG. 6, the simulation results of the diffusion of the optical field in the waveguide to both sides are shown, where the closer the color is to black, the stronger the optical field is, and the closer the color is to white, the weaker the optical field is. From the results shown in the figure, it can be found that the optical field is effectively limited in the anisotropic structure 1 and the waveguide, making it difficult for the optical field to diffuse to the electrode, thereby avoiding the absorption of the carrier optical signal by the electrode.

[0063] In the simulation, the following formula 1 can be used, but any implementation process known to those skilled in the art can be used, and will not be described in detail here:

[0064] where Г represents the field interaction factor, c represents the speed of light in vacuum, ε0represents the vacuum permittivity, n EO represents the refractive index of the organic electro-optic medium layer 2, e z represents the unit vector in the z direction, ε0(x,y) represents the electric field vector, ε 0,x (x,y) represents the x component of the electric field vector, represents the magnetic field vector.

[0065] Since the anisotropic structure 1 has different refractive indexes in different directions, when the anisotropic structure 1 has a first refractive index perpendicular to the connecting interface, the anisotropic structure 1 also has a third refractive index in a direction parallel to the connecting interface and parallel to the extension direction of the waveguide. By adjusting the third refractive index, the distance of the evanescent wave in the anisotropic structure 1 can be reduced, and the distance between the electrode and the waveguide can be reduced. For example, the distance between the waveguide and the electrode can be set to 250 nm to 1500 nm, so as to reduce the size of the electro-optical modulator. For example, taking two electrodes as an example, when the anisotropic structure 1 is not arranged between the waveguide and the electrode, and the isotropic medium material is filled between the waveguide and the electrode, the distance between the two electrodes is generally set to at least 4 μm; when the anisotropic structure 1 is arranged between the waveguide and the electrode, the distance between the two electrodes can be set to 500 nm to 3000 nm, that is, the distance between the two electrodes is at most 3 μm. It can be seen that the distance between the two electrodes is reduced by at least 25%, so as to effectively reduce the size of the electro-optical modulator and widen the application field of the electro-optical modulator. It should be understood that the distance between the waveguide and the electrode can be understood as the distance between the center point of the waveguide and the center point of the electrode. The evanescent wave refers to that when the carrier optical signal is totally internally reflected in the waveguide, the carrier optical signal is not absolutely reflected on the connecting interface and returned to the waveguide, but is projected into the anisotropic structure 1 by a depth of about one wavelength. Therefore, by reducing the projection depth of the evanescent wave in the anisotropic structure 1, the distance between the electrode and the waveguide can be reduced.

[0066] In addition, when the distance between the electrode and the waveguide is reduced, the size of the electrical signal applied by the electrode can also be reduced, that is, the modulation voltage is reduced, so as to improve the performance of the electro-optical modulator. The specific value of the third refractive index can be set according to the distance requirement between the electrode and the waveguide and other factors, which is not limited herein.

[0067] Referring to FIG. 7, which shows the variation of electro-optic coefficient and half-wave voltage, curve s3 represents the corresponding curve when no anisotropic structure 1 is provided, curve s4 represents the corresponding curve of the structure shown in FIG. 3, the ordinate represents the product of half-wave voltage and modulation region length, the width of the waveguide is 600 nm, the height of the waveguide and the anisotropic structure 1 is 70 nm, the ratio of the first length to the second length is 1 / 4, and the sum of the first length and the second length is 63 nm. It can be found from the results shown in the figure that when the electro-optic coefficient is 100 pm / V, the product of half-wave voltage and modulation region length of the electro-optic modulator without the anisotropic structure 1 (referred to as the prior device) is 1.73, and the product of half-wave voltage and modulation region length of the electro-optic modulator with the anisotropic structure 1 (referred to as the device of the present application) is 1.23. When the modulation region length is the same, the half-wave voltage of the device of the present application is significantly lower than that of the prior device, which shows that the presence of the anisotropic structure 1 can effectively reduce the half-wave voltage of the electro-optic modulator, thereby improving the performance of the electro-optic modulator. It should be understood that the modulation region length can be understood as the length of the region in which the carrier optical signal interacts with the electric field in the electro-optic modulator. The half-wave voltage refers to the voltage required for the phase of the carrier optical signal to change by π radians when passing through the electro-optic modulator. The modulation voltage refers to the actual voltage applied to the electro-optic modulator, so when the half-wave voltage is equal to the modulation voltage, the phase of the carrier optical signal will change by 180°.

[0068] For example, when calculating the product of half-wave voltage and modulation region length, the following formula 2 can be used for calculation:

[0069] wherein V π represents the half-wave voltage, L represents the modulation region length, λ represents the wavelength of the carrier optical signal transmitted in the waveguide, W gap represents the distance between the two electrodes, n EO represents the refractive index of the organic electro-optic medium layer 2, r33-in device represents the electro-optic coefficient in the device, and Г represents the field interaction factor.

[0070] Fig. 8 shows a structural schematic diagram of another electro-optical modulator provided by the present application. As shown in Fig. 8, the electro-optical modulator in this embodiment has a structure similar to that of the electro-optical modulators shown in Figs. 3 and 5 of the foregoing embodiments, with the difference being that the electrode is provided with one. Specifically, as shown in Fig. 8, the electrode can be provided with one, so that the waveguide can be used not only for transmitting the carrier optical signal, but also as another electrode, and an electrical signal is applied through the waveguide and the electrode, so as to modulate the carrier optical signal. Here, the electrode can be a signal electrode, and correspondingly the waveguide can be a ground electrode; or the electrode can be a ground electrode, and correspondingly the waveguide can be a signal electrode; the specific arrangement can be made according to actual needs, which is not limited herein. In this way, the structure of the electro-optical modulator can be simplified, the size of the electro-optical modulator can be reduced, and the manufacturing cost of the electro-optical modulator can be lowered.

[0071] It should be understood that the structure of the electro-optical modulator in this embodiment is similar to that of the electro-optical modulators shown in Figs. 3 and 5 of the foregoing embodiments, and the relevant description can be referred to in the foregoing embodiments, and the repeated description is omitted herein.

[0072] In another electro-optical modulator provided by the present application, the structure of the electro-optical modulator in this embodiment is similar to that of the electro-optical modulators shown in Figs. 3 and 5 of the foregoing embodiments, with the difference being that the first dielectric structure 1a is made of a non-organic electro-optical material. Specifically, the first dielectric structure 1a is made of an inorganic electro-optical material, such as but not limited to silicon, lithium niobate, or other materials, and the first dielectric structure 1a and the second dielectric structure 1b are made of different materials, while satisfying that the refractive index of the first dielectric structure 1a is smaller than that of the second dielectric structure 1b. Since the refractive indexes of the first dielectric structure 1a and the second dielectric structure 1b can be changed under the action of an electric field, the combination of the two can form an anisotropic structure 1.

[0073] Alternatively, the first dielectric structure 1a is made of a non-electro-optical material, such as photoresist or gel, or other materials. Since the first dielectric structure 1a is made of a non-electro-optical material, the refractive index of the first dielectric structure 1a will not change under the action of an electric field, but the refractive index of the second dielectric structure 1b will change under the action of an electric field. At this time, through the arrangement and combination of the first dielectric structure 1a and the second dielectric structure 1b, an anisotropic structure 1 can also be formed, and since the non-electro-optical material has a lower cost, it is also beneficial to reduce the manufacturing cost of the electro-optical modulator. Therefore, the selection of the material for making the first dielectric structure 1a can be made according to actual needs, which is not limited herein.

[0074] It should be understood that the structure of the electro-optical modulator in this embodiment is similar to the structure of the electro-optical modulator shown in FIG. 3 and FIG. 5 of the foregoing embodiments, and the similarities can be referred to the relevant descriptions in the foregoing embodiments, and the repeated parts will not be described herein.

[0075] In another electro-optical modulator provided by the present application, the structure of the electro-optical modulator in this embodiment is basically similar to the structure of the electro-optical modulator shown in FIG. 3 and FIG. 5 of the foregoing embodiments, and the difference includes that the cover layer can be made of non-organic electro-optical material. Illustratively, the cover layer is made of inorganic material or organic material without electro-optical effect, such as silicon oxide and silicon nitride, and the refractive index of the cover layer is less than the refractive index of the waveguide, so that the light field can be limited in the waveguide by the principle of total internal reflection.

[0076] It should be understood that the structure of the electro-optical modulator in this embodiment is similar to the structure of the electro-optical modulator shown in FIG. 3 and FIG. 5 of the foregoing embodiments, and the similarities can be referred to the relevant descriptions in the foregoing embodiments, and the repeated parts will not be described herein.

[0077] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present application without departing from the spirit and scope of the embodiments of the present application. Thus, if these modifications and variations of the embodiments of the present application belong to the scope of the claims of the present application and the equivalent technologies thereof, the present application also intends to include these modifications and variations.

Claims

1. An electro-optic modulator, characterized in that, include: A waveguide, an electrode, and an anisotropic structure, wherein the anisotropic structure is disposed between the electrode and the waveguide; The waveguide is connected to the anisotropic structure to form a connection interface. The anisotropic structure has a first refractive index in a direction perpendicular to the connection interface, and the waveguide has a second refractive index. The first refractive index is less than the second refractive index.

2. The electro-optic modulator as described in claim 1, characterized in that, The anisotropic structure includes: at least two first dielectric structures and at least one second dielectric structure arranged along a first direction, wherein the first dielectric structures and the second dielectric structures are arranged alternately; the first direction is the arrangement direction of the anisotropic structure and the waveguide; The refractive index of the first dielectric structure is less than that of the second dielectric structure.

3. The electro-optic modulator as described in claim 2, characterized in that, The second dielectric structure is made of the same material as the waveguide.

4. The electro-optic modulator as described in claim 2 or 3, characterized in that, The materials used to fabricate the first dielectric structure include organic electro-optical materials.

5. The electro-optic modulator as described in any one of claims 2-4, characterized in that, The length of the first dielectric structure along the first direction is a first length, and the length of the second dielectric structure along the first direction is a second length, wherein the first length is less than the second length.

6. The electro-optic modulator as described in claim 5, characterized in that, The ratio of the first length to the second length is 1 / 9 to 1 / 2.

7. The electro-optic modulator as described in claim 5 or 6, characterized in that, The sum of the first length and the second length is 40nm-80nm.

8. The electro-optic modulator according to any one of claims 1-7, characterized in that, The height of the waveguide is not greater than the height of the anisotropic structure.

9. The electro-optic modulator according to any one of claims 1-8, characterized in that, The distance between the waveguide and the electrode is 250 nm to 1500 nm.

10. The electro-optic modulator according to any one of claims 1-9, characterized in that, The electro-optic modulator further includes: an organic electro-optic dielectric layer, wherein the organic electro-optic dielectric layer at least covers the waveguide and the anisotropic structure; The anisotropic structure includes: at least two first dielectric structures and at least one second dielectric structure arranged along a first direction, wherein the first dielectric structures and the second dielectric structures are arranged alternately; the first direction is the arrangement direction of the anisotropic structure and the waveguide; The first dielectric structure is made of the same material as the organic electro-optic dielectric layer.

11. An optical module, characterized in that, include: The light source, and the electro-optic modulator as described in any one of claims 1-10; The light source is used to: generate a carrier optical signal and transmit the carrier optical signal to the electro-optic modulator; The electro-optic modulator is used to modulate the carrier optical signal according to the electrical signal to generate a modulated optical signal.

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