Folded electro-optic modulator

Abstract

A folded electro-optic modulator is provided, comprising a first main electrode, a first waveguide arm, a second main electrode, a second waveguide arm, and a third main electrode arranged in sequence, and the following structure provided in any even-order radio frequency modulation region of the folded electro-optic modulator: a plurality of first sub-electrodes, each of which is insulated from the first waveguide arm and connected to a side of the first main electrode closer to the second main electrode by a first connecting arm intersecting the first waveguide arm; and a plurality of second sub-electrodes, each of which is insulated from the first waveguide arm and connected to a side of the first main electrode closer to the second main electrode by a first connecting arm intersecting the first waveguide arm. The optical waveguide includes a plurality of second sub-electrodes connected to a side of the second main electrode closer to the first main electrode by a second connection arm that intersects with the first waveguide arm, a plurality of third sub-electrodes, each of which is insulated from the second waveguide arm and connected to a side of the second main electrode closer to the third main electrode by a third connection arm that intersects with the second waveguide arm, and a plurality of fourth sub-electrodes, each of which is connected to a side of the third main electrode closer to the second main electrode by a fourth connection arm that is insulated from the second waveguide arm and intersects with the second waveguide arm.

Description

[Technical Field]

[0001] Book The disclosure relates to the field of optical communications, and more particularly to folded electro-optic modulators. [Background technology]

[0002] In recent years, with the rapid development of emerging network application services such as the Internet of Things, autonomous driving, telemedicine, and distance learning, the requirements for high-speed, high-capacity communication technologies are increasing. Optical communication has achieved rapid development in the direction of high-speed, high-capacity communication due to its characteristics such as large bandwidth, high reliability, low cost, and strong anti-interference capability. The method of loading high-speed electrical signals onto optical carriers is a core research topic.

[0003] An electro-optic modulator is a modulator based on the electro-optic effect of electro-optic materials. The electro-optic effect means that when a voltage is applied to an electro-optic material, such as lithium niobate, gallium arsenide, or lithium tantalate crystal, the refractive index of the electro-optic material fluctuates, resulting in a change in the properties of the light wave passing through the electro-optic material. The use of the electro-optic effect allows for modulation of parameters such as the phase, amplitude, intensity, and polarization state of an optical signal. Summary of the Invention [Problem to be solved by the invention]

[0004] As the requirements for high-speed and large-capacity communication technology become more and more urgent, the requirements for the device performance and device size of electro-optical modulators also become more and more. [Means for solving the problem]

[0005] An embodiment of the present disclosure provides a folded electro-optic modulator, which includes: a first waveguide arm and a second waveguide arm that are folded as a whole and do not intersect with each other; a first main electrode, a second main electrode, and a third main electrode that are folded as a whole and do not intersect with each other, wherein the first waveguide arm is located between the first main electrode and the second main electrode, the second waveguide arm is located between the second main electrode and the third main electrode, the first main electrode and the third main electrode are ground electrodes for radio frequency signals, and the second main electrode is a signal electrode for radio frequency signals; and the following structure provided in any even-order radio frequency modulation region of the folded electro-optic modulator in the transmission direction of the first waveguide arm and the second waveguide arm: a plurality of first sub-electrodes, each of which is connected to a side of the first main electrode closer to the second main electrode by a first connecting arm insulated from the first waveguide arm and intersecting the first waveguide arm; a plurality of second sub-electrodes, each of which is connected to a side of the second main electrode closer to the first main electrode by a second connecting arm insulated from the first waveguide arm and intersecting the first waveguide arm; and a plurality of a plurality of third sub-electrodes, each of which is connected to a side of the second main electrode closer to the third main electrode by a third connecting arm insulated from the second waveguide arm and intersecting the second waveguide arm; and a plurality of fourth sub-electrodes, each of which is connected to a side of the third main electrode closer to the second main electrode by a fourth connecting arm insulated from the second waveguide arm and intersecting the second waveguide arm.

[0006] In some embodiments, each of the first sub-electrodes and the corresponding first connecting arm form a first T-shaped structure, each of the second sub-electrodes and the corresponding second connecting arm form a second T-shaped structure, the first T-shaped structures and the second T-shaped structures are alternately arranged in the extension direction of the radio frequency modulation area, the gap between adjacent first sub-electrodes is smaller than the length of the second sub-electrode and the gap between adjacent second sub-electrodes is smaller than the length of the first sub-electrode, each of the third sub-electrodes and the corresponding third connecting arm form a third T-shaped structure, each of the fourth sub-electrodes and the corresponding fourth connecting arm form a fourth T-shaped structure, the third T-shaped structures and the fourth T-shaped structures are alternately arranged in the extension direction of the radio frequency modulation area, the gap between adjacent third sub-electrodes is smaller than the length of the fourth sub-electrode and the gap between adjacent fourth sub-electrodes is smaller than the length of the third sub-electrode.

[0007] In some embodiments, each first sub-electrode and its corresponding first connecting arm form a first L-shaped structure, each second sub-electrode and its corresponding second connecting arm form a second L-shaped structure, the first L-shaped structures and the second L-shaped structures are alternately arranged in the extension direction of the radio frequency modulation region, and an orthogonal projection of each first sub-electrode overlaps with an orthogonal projection of one second sub-electrode in the extension direction of the radio frequency modulation region, each third sub-electrode and its corresponding third connecting arm form a third L-shaped structure, and each fourth sub-electrode and its corresponding fourth connecting arm form a fourth L-shaped structure, the third L-shaped structures and the fourth L-shaped structures are alternately arranged in the extension direction of the radio frequency modulation region, and an orthogonal projection of each third sub-electrode overlaps with an orthogonal projection of one fourth sub-electrode in the extension direction of the radio frequency modulation region.

[0008] In some embodiments, a folded electro-optic modulator comprises a substrate, an isolation layer, a waveguide layer, an insulating layer, and an electrode layer arranged in sequence, wherein the first waveguide arm and the second waveguide arm are located in the waveguide layer, the first main electrode, the second main electrode, the third main electrode, the first sub-electrode, the first connecting arm, the second sub-electrode, the second connecting arm, the third sub-electrode, the third connecting arm, the fourth sub-electrode, and the fourth connecting arm are located in the electrode layer, and the first connecting arm and the second connecting arm are insulated from the first waveguide arm by the insulating layer, and the third connecting arm and the fourth connecting arm are insulated from the second waveguide arm by the insulating layer.

[0009] In some embodiments, the waveguide layer is a ridged ridge pattern layer, or the waveguide layer is a ridged ridge pattern layer comprising a flat plate layer and a ridged ridge pattern layer located on a side of the flat plate layer away from the substrate, and the first waveguide arm and the second waveguide arm are located in the ridged ridge pattern layer.

[0010] In some embodiments, the waveguide layer is a ridge waveguide layer including a flat layer and a ridge-shaped pattern layer located on a side of the flat layer away from the substrate, the first waveguide arm and the second waveguide arm are located in the ridge-shaped pattern layer, the insulating layer covers the ridge-shaped pattern layer and exposes at least a portion of the area of ​​the flat layer, and the first main electrode, the second main electrode, and the third main electrode are formed on the surface of the flat layer exposed from the insulating layer, or the insulating layer covers the ridge-shaped pattern layer and covers at least a portion of the area of ​​the flat layer, and the first main electrode, the second main electrode, and the third main electrode are formed on the surface of the portion of the insulating layer covering the flat layer.

[0011] In some embodiments, the protruding structures formed by the portions of the insulating layer covering the first waveguide arm are located between the first sub-electrode and the first main electrode and between the second sub-electrode and the second main electrode, and the protruding structures formed by the portions of the insulating layer covering the second waveguide arm are located between the third sub-electrode and the second main electrode and between the fourth sub-electrode and the third main electrode.

[0012] In some embodiments, the first sub-electrode and the second sub-electrode are formed on a surface of a protruding structure formed by a portion of the insulating layer covering the first waveguide arm, and the third sub-electrode and the fourth sub-electrode are formed on a surface of a protruding structure formed by a portion of the insulating layer covering the second waveguide arm.

[0013] In some embodiments, the folded electro-optic modulator comprises the following structures provided in at least one odd-order radio frequency modulation region of the folded electro-optic modulator: a plurality of fifth sub-electrodes, each of which is located between the first main electrode and the first waveguide arm and connected to one of the first main electrodes closer to the first waveguide arm by a fifth connecting arm; and a plurality of sixth sub-electrodes, each of which is located between the second main electrode and the first waveguide arm and connected to one of the second main electrodes closer to the first waveguide arm by a sixth connecting arm. The optical waveguide further includes at least one of a plurality of sixth sub-electrodes connected to a side closer to the first waveguide arm, a plurality of seventh sub-electrodes, each of which is located between the second main electrode and the second waveguide arm and connected to a side of the second main electrode closer to the second waveguide arm by a seventh connecting arm, and a plurality of eighth sub-electrodes, each of which is located between the third main electrode and the second waveguide arm and connected to a side of the third main electrode closer to the second waveguide arm by an eighth connecting arm.

[0014] In some embodiments, the substrate is provided with a recessed structure.

[0015] It should be understood that the contents described in this section are not intended to identify key or important features of the embodiments of the present disclosure, nor should they be used to limit the scope of the present disclosure. Other features of the present disclosure will be readily apparent from the following description.

[0016] Further details, features and advantages of the present disclosure are disclosed in the following description of exemplary embodiments with reference to the accompanying drawings. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a top view of a simplified structure of a conventional electro-optic modulator. [Figure 2] 1A-1C are top views of simplified structures of folded electro-optic modulators according to some exemplary embodiments of the present disclosure. [Figure 3] 1A-1C are top views of simplified structures of folded electro-optic modulators according to some exemplary embodiments of the present disclosure. [Figure 4] 1A-1C are perspective views of a partial structure of a folded electro-optic modulator according to some exemplary embodiments of the present disclosure. [Figure 5] 1A-1C are perspective views of a partial structure of a folded electro-optic modulator according to some exemplary embodiments of the present disclosure. [Figure 6] 1A-1C are perspective views of a partial structure of a folded electro-optic modulator according to some exemplary embodiments of the present disclosure. [Figure 7] 1A-1C are perspective views of a partial structure of a folded electro-optic modulator according to some exemplary embodiments of the present disclosure. [Figure 8] 1A-1C are perspective views of a partial structure of a folded electro-optic modulator according to some exemplary embodiments of the present disclosure. [Figure 9] 1A-1C are perspective views of a partial structure of a folded electro-optic modulator according to some exemplary embodiments of the present disclosure. [Figure 10] 1A-1C are perspective views of a partial structure of a folded electro-optic modulator according to some exemplary embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0018] Only a few exemplary embodiments are briefly described below. As will be understood by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present disclosure. Accordingly, the accompanying drawings and descriptions are to be regarded as illustrative in nature and not as restrictive.

[0019] A Mach-Zehnder modulator is a type of electro-optic modulator in which an input optical signal is split into two branch optical signals, which then enter two waveguide arms. Each of the two waveguide arms is made of electro-optic material and has a refractive index that changes with the applied modulation voltage. The change in the refractive index of the waveguide arms can cause a change in the phase of the branch optical signals. Therefore, the output from the convergence of the two branch optical signals is an interference signal whose intensity changes with the modulation voltage. In short, a Mach-Zehnder modulator can implement modulation of different sidebands by controlling the modulation voltage applied to the two waveguide arms. As a device for converting electrical signals to optical signals, a Mach-Zehnder modulator is one of the common core devices in optical interconnection, optical computing, and optical communication systems.

[0020] Figure 1 shows a schematic diagram of a conventional Mach-Zehnder modulator. Theoretically, the Mach-Zehnder modulator 001 has two identical waveguide arms 02. When the Mach-Zehnder modulator 001 is not functioning, neither of the two waveguide arms 02 is subject to the electro-optic effect. The input light passes through the optical splitting element 01 and is then equally split into two branch optical signals. After passing through the respective waveguide arms 02, the two branch optical signals are still in phase, and the coherently reinforced signals for the two branch optical signals are then output from the optical combining element 05. When the Mach-Zehnder modulator 001 is functioning, the modulation electrodes 04 (e.g., including a signal electrode 040, a first ground electrode 041, and a second ground electrode 042) apply modulation voltages to the two waveguide arms 02. After each of the two branch optical signals passes through one waveguide arm 02, the phases of the two branch optical signals can differ by an odd multiple of π or by an even multiple of π. When the phases of the two branch optical signals differ by an even multiple of π, the optical combining element 05 outputs coherently enhanced signals for the two branch optical signals. When the phases of the two branch optical signals differ by an odd multiple of π, the optical combining element 05 outputs coherently suppressed signals for the two branch optical signals.

[0021] As can be seen from this figure, such conventional Mach-Zehnder modulators have elongated structural features, with lengths typically on the order of a few millimeters or centimeters and widths typically on the order of a few hundred micrometers. In addition, increasing the lengths of the two waveguide arms is also considered to minimize the driving voltage. Although Mach-Zehnder modulators have a small width dimension, their overall size is still primarily determined by their length dimension. Therefore, how to achieve a miniaturized device design without affecting device performance is a technical challenge that must be urgently addressed by those skilled in the art.

[0022] Embodiments of the present disclosure provide a folded electro-optic modulator that can achieve a miniaturized device design while meeting device performance requirements.

[0023] 2 , some embodiments of the present disclosure provide a folded electro-optic modulator 100 including N radio frequency modulation regions 10 and N−1 turning regions 20, where N≧2. The folded electro-optic modulator 100 includes a first waveguide arm 30 and a second waveguide arm 40 that are generally folded and do not intersect with each other, and a first main electrode 111, a second main electrode 112, and a third main electrode 113 that are generally folded and do not intersect with each other, where the first waveguide arm 30 is located between the first main electrode 111 and the second main electrode 112, the second waveguide arm 40 is located between the second main electrode 112 and the third main electrode 113, and the first main electrode 111 and the third main electrode 113 are generally folded and do not intersect with each other. The first main electrode 113 is a ground electrode for the radio frequency signal, and the second main electrode 112 is a signal electrode for the radio frequency signal. In addition, the folded electro-optic modulator 100 further includes, within any even-order radio frequency modulation region 10, a plurality of first sub-electrodes 1a, a plurality of second sub-electrodes 1b, a plurality of third sub-electrodes 1c, and a plurality of fourth sub-electrodes 1d, arranged in the transmission direction (indicated by the arrow with dotted lines in this figure) of the first waveguide arm 30 and the second waveguide arm 40. The radio frequency modulation regions 10 are sequentially arranged in the transmission direction of the first waveguide arm 30 and the second waveguide arm 40.

[0024] As shown in FIG. 2, each of the first sub-electrodes 1 a is connected to the side of the first main electrode 111 that is closer to the second main electrode 112 by a first connecting arm 2 a that is insulated from and crosses the first waveguide arm 30, and each of the second sub-electrodes 1 b is connected to the side of the second main electrode 112 that is closer to the first main electrode 111 by a second connecting arm 2 b that is insulated from and crosses the first waveguide arm 30. , each of the third sub-electrodes 1c is connected to the side of the second main electrode 112 closer to the third main electrode 113 by a third connecting arm 2c that is insulated from and crosses the second waveguide arm 40, and each of the fourth sub-electrodes 1d is connected to the side of the third main electrode 113 closer to the second main electrode 112 by a fourth connecting arm 2d that is insulated from and crosses the second waveguide arm 40.

[0025] In one embodiment of the present disclosure, the folded electro-optic modulator 100 further includes an input element (e.g., optical splitting element 50) and an output element (e.g., optical combining element 60) to realize the input and output of optical signals. In this embodiment, the optical splitting element 50 serves as the input element of the folded electro-optic modulator 100 and includes one input end and two output ends; the optical combining element 60 serves as the output element of the folded electro-optic modulator 100 and includes two input ends and one output end; the first waveguide arm 30 is connected to one of the output ends of the optical splitting element 50 and one of the input ends of the optical combining element 60; and the second waveguide arm 40 is connected to the other output end of the optical splitting element 50 and the other input end of the optical combining element 60. The structures of the input and output elements are not limited to the elements including three ports shown in this figure, and the designs may be selected according to the actual needs of the folded electro-optic modulator 100.

[0026] In one embodiment of the present disclosure, N is a natural number, and N≧2. It should be understood that when there is an even number of radio frequency modulation regions 10 (e.g., when N=2 as shown in FIG. 2 ), the optical splitting element 50 and the optical combining element 60 are located on the same side of the folded electro-optic modulator, and when there is an odd number of radio frequency modulation regions, the optical splitting element and the optical combining element are located on opposite sides of the folded electro-optic modulator.

[0027] The first waveguide arm 30 and the second waveguide arm 40 are made of an electro-optic material such as lithium niobate, lithium tantalate, or potassium titanyl phosphate. When a radio frequency signal is input to the first main electrode 111, the second main electrode 112, and the third main electrode 113 in each radio frequency modulation region 10, the first waveguide arm 30 is in an electric field formed by the plurality of first sub-electrodes 1a and the plurality of second sub-electrodes 1b, and the second waveguide arm 40 is in an electric field formed by the plurality of third sub-electrodes 1c and the plurality of fourth sub-electrodes 1d. The directions of the electric fields are respectively indicated by the dotted arrows shown in this figure.

[0028] Because the refractive index change of electro-optical materials is related to the direction of the electric field, the electric field direction in the even-order radio frequency modulation region is exactly opposite to that in the odd-order radio frequency modulation region unless the electric field direction in the even-order radio frequency modulation region is reversed. In this way, the phase difference generated by the two waveguide arms in the odd-order radio frequency modulation region is canceled out in the next even-order radio frequency modulation region, making it impossible to achieve optical modulation function.

[0029] In response to the above problem, the embodiment of the present disclosure designs the above-described sub-electrode and connecting arm structures. As shown in FIG. 2, the electric fields formed by the plurality of first sub-electrodes 1a and the plurality of second sub-electrodes 1b, and the electric fields formed by the plurality of third sub-electrodes 1c and the plurality of fourth sub-electrodes 1d are respectively indicated by dotted arrows in the figure. It can be seen that the electric fields when the first waveguide arm 30 is located in the first radio frequency modulation region (i.e., the upper radio frequency modulation region 10 in the figure) and the second radio frequency modulation region (i.e., the lower radio frequency modulation region 10 in the figure) have the same direction, and the electric fields when the second waveguide arm 40 is located in the first radio frequency modulation region and the second radio frequency modulation region have the same direction.

[0030] The folded electro-optic modulator 100 provided in the embodiment of the present disclosure is a folded design, and therefore has a significantly reduced dimension in the length direction compared to conventional electro-optic modulators. To obtain better performance of the device, the length of the waveguide arm can be designed to be increased as needed, and the overall length of the device will not be significantly affected.

[0031] In addition, compared with some designs in the art that use insulation and crossover to realize bridging through vias, the first waveguide arm 30, the second waveguide arm 40, the first main electrode 111, the second main electrode 112, and the third main electrode 113 all have a crossover-free design, realizing a simpler structure design and relatively lower requirements on manufacturing precision control, which is conducive to improving production efficiency and production yield and reducing production costs.

[0032] 2 , in some embodiments of the present disclosure, each of the first sub-electrodes 1 a and the corresponding first connecting arm 2 a forms a first T-shaped structure, each of the second sub-electrodes 1 b and the corresponding second connecting arm 2 b forms a second T-shaped structure, the multiple first T-shaped structures and the multiple second T-shaped structures are alternately arranged in the extension direction of the radio frequency modulation region 10 (i.e., the extension direction of the two waveguide arms in the radio frequency modulation region 10), the gap between adjacent first sub-electrodes 1 a is smaller than the length of the second sub-electrode 1 b, and the gap between adjacent second sub-electrodes 1 b is smaller than the length of the first sub-electrode 1 a. Some portions of the multiple first sub-electrodes 1 a and multiple second sub-electrodes 1 b located opposite each other can form an electric field, and thus phase modulation for light transmitted in the first waveguide arm 30 may be performed.

[0033] Similarly, each third sub-electrode 1c and the corresponding third connecting arm 2c form a third T-shaped structure, and each fourth sub-electrode 1d and the corresponding fourth connecting arm 2d form a fourth T-shaped structure, the third T-shaped structures and the fourth T-shaped structures being alternately arranged in the extension direction of the radio frequency modulation region 10, the gap between adjacent third sub-electrodes 1c being smaller than the length of the fourth sub-electrode 1d, and the gap between adjacent fourth sub-electrodes 1d being smaller than the length of the third sub-electrode 1c. Some portions of the plurality of third sub-electrodes 1c and the plurality of fourth sub-electrodes 1d located opposite each other can form an electric field, and thus phase modulation for light transmitted in the second waveguide arm 40 may be performed.

[0034] 3 , in some other embodiments of the present disclosure, each of the first sub-electrodes 1 a and the corresponding first connecting arm 2 a forms a first L-shaped structure, each of the second sub-electrodes 1 b and the corresponding second connecting arm 2 b forms a second L-shaped structure, the first L-shaped structures and the second L-shaped structures are alternately arranged in the extension direction of the radio frequency modulation region 10, and the orthogonal projection of each of the first sub-electrodes 1 a overlaps the orthogonal projection of one second sub-electrode 1 b in the extension direction of the radio frequency modulation region 10. Some portions of the multiple first sub-electrodes 1 a and multiple second sub-electrodes 1 b located opposite each other can form an electric field, and thus phase modulation for light transmitted in the first waveguide arm 30 may be performed.

[0035] Similarly, each third sub-electrode 1c and the corresponding third connecting arm 2c form a third L-shaped structure, and each fourth sub-electrode 1d and the corresponding fourth connecting arm 2d form a fourth L-shaped structure, the third L-shaped structures and the fourth L-shaped structures being alternately arranged in the extension direction of the radio frequency modulation region 10, and the orthogonal projection of each third sub-electrode 1c overlaps the orthogonal projection of one fourth sub-electrode 1d in the extension direction of the radio frequency modulation region 10. Some portions of the plurality of third sub-electrodes 1c and the plurality of fourth sub-electrodes 1d located opposite each other can form an electric field, and thus phase modulation for light transmitted in the second waveguide arm 40 may be performed.

[0036] The overall structure of the sub-electrodes and connecting arms described above may have a symmetrical or asymmetrical shape, and the specific shapes of the sub-electrodes and connecting arms are not defined in this disclosure and are not limited to the above embodiments.

[0037] In one embodiment of the present disclosure, as shown in FIG. 4 , the layer structure of the folded electro-optic modulator includes a substrate 151, an isolation layer 152, a waveguide layer 153, an insulating layer 154, and an electrode layer 155 arranged in order, wherein the first waveguide arm 30 and the second waveguide arm 40 are located in the waveguide layer 153, and the first main electrode 111, the second main electrode 112, the third main electrode 113, the first sub-electrode 1a, the first connecting arm 2a, the second sub-electrode 114, the third sub-electrode 115, the first sub-electrode 116, the second sub-electrode 117, the third sub-electrode 118, the first sub-electrode 119, the second sub-electrode 220, the third sub-electrode 221, the third sub-electrode 222, the fourth sub-electrode 223, the fourth sub-electrode 224, the fourth sub-electrode 225, the fourth sub-electrode 226, the fourth sub-electrode 227, the fifth sub-electrode 228, the fifth sub-electrode 229, the fifth sub-electrode 229, the fifth sub-electrode 229, the fifth sub-electrode 229, the fifth sub-electrode 229, the fifth sub-electrode 226, the fifth sub-electrode 227, the fifth sub-electrode 228, the fifth sub-electrode 229 ... sixth sub-electrode 229, the sixth sub-electrode 229, the sixth sub-electrode 229, the sixth sub- The first sub-electrode 1b, the second connecting arm 2b, the third sub-electrode 1c, the third connecting arm 2c, the fourth sub-electrode 1d, and the fourth connecting arm 2d are located in the electrode layer 155, and the first connecting arm 2a and the second connecting arm 2b are insulated from the first waveguide arm 30 by the insulating layer 154, and the third connecting arm 2c and the fourth connecting arm 2d are insulated from the second waveguide arm 40 by the insulating layer 154. Some layer structures of the folded electro-optic modulator may be fabricated by a mask patterning process, and the specific materials for making these layers are not limited and may be selected according to actual needs.

[0038] 4 , in some embodiments of the present disclosure, the waveguide layer 153 is a ridge waveguide layer including a flat plate layer 1531 and a ridge-shaped pattern layer 1532 located on a side of the flat plate layer 1531 away from the substrate 151, and the first waveguide arm 30 and the second waveguide arm 40 are located within the ridge-shaped pattern layer 1532. In some other embodiments of the present disclosure, the waveguide layer 153 may not include the flat plate layer 1531 and may include only the ridge-shaped pattern layer 1532, and the first waveguide arm 30 and the second waveguide arm 40 are at least part of the ridge-shaped pattern layer 1532.

[0039] As shown in Figures 4, 5, 6, and 7, in this embodiment, the insulating layer 154 covers the ridge pattern layer 1532 and exposes at least a portion of the area of ​​the flat layer 1531, and the first main electrode 111, the second main electrode 112, and the third main electrode 113 are formed on the surface of the flat layer 1531 exposed from the insulating layer 154.

[0040] 8 and 9 , in some other embodiments of the present disclosure, the insulating layer 154 covers the ridge-shaped ridge pattern layer 1532 and at least a portion of the area of ​​the flat layer 1531, and the first main electrode 111, the second main electrode 112, and the third main electrode 113 are formed on the surface of the portion of the insulating layer 154 that covers the flat layer 1531. In this embodiment, the insulating layer 154 covers the entire flat layer 1531, i.e., the insulating layer 154 covers the entire waveguiding layer 153.

[0041] 4 and 5 , in some embodiments of the present disclosure, the protruding structure 3a formed by the portion of the insulating layer 154 covering the first waveguide arm 30 is located between the first sub-electrode 1a and the first main electrode 111 and between the second sub-electrode 1b and the second main electrode 112, and the protruding structure 3b formed by the portion of the insulating layer 154 covering the second waveguide arm 40 is located between the third sub-electrode 1c and the second main electrode 112 and between the fourth sub-electrode 1d and the third main electrode. That is, the connecting arms span the protruding structures of the insulating layer 154.

[0042] 6, 7, 8, and 9, in some other embodiments of the present disclosure, the first sub-electrode 1a and the second sub-electrode 1b are formed on the surface of a protruding structure 3c formed on the portion of the insulating layer 154 that covers the first waveguide arm 30, and the third sub-electrode 1c and the fourth sub-electrode 1d are formed on the surface of a protruding structure 3d formed on the portion of the insulating layer 154 that covers the second waveguide arm 40. That is, the connecting arms do not completely span the protruding structure of the insulating layer 154.

[0043] Whether the connecting arm completely spans the protruding structure of the insulating layer 154 or not, the connecting arm intersects with the waveguide arm while being insulated from the waveguide arm, and thus the sub-electrode and the corresponding main electrode are located on both sides of the waveguide arm, respectively, thereby ensuring the consistency of the direction of the electric field applied to the waveguide arm.

[0044] As shown in FIG. 3, in some embodiments of the present disclosure, the folded electro-optic modulator 100 includes at least one odd-order radio frequency modulation region 10: a plurality of fifth sub-electrodes 1e, each of which is located between the first main electrode 111 and the first waveguide arm 30 and connected to a side of the first main electrode 111 that is closer to the first waveguide arm 30 by a fifth connecting arm 2e; a plurality of sixth sub-electrodes 1f, each of which is located between the second main electrode 112 and the first waveguide arm 30 and connected to a side of the second main electrode 112 closer to the first waveguide arm 30 by a sixth connecting arm 2f; a plurality of seventh sub-electrodes 1g, each of which is located between the second main electrode 112 and the second waveguide arm 40 and connected to a side of the second main electrode 112 closer to the second waveguide arm 40 by a seventh connecting arm 2g; The optical fiber further includes at least one of the structures including a plurality of eighth sub-electrodes 1h, each of which is located between the third main electrode 113 and the second waveguide arm 40 and connected to the side of the third main electrode 113 closer to the second waveguide arm 40 by an eighth connecting arm 2h.

[0045] The fifth sub-electrode 1e, the sixth sub-electrode 1f, the seventh sub-electrode 1g, and the eighth sub-electrode 1h may be selected and arranged as desired, and their number and shape may also be selected and designed as desired. The selection and arrangement of these sub-electrodes can reduce impedance mismatches that may exist in different regions of the folded electro-optic modulator 100 and reduce microwave reflection of the electrical signal, which contributes to further improving device performance. In addition, because the speed of optical transmission is generally greater than the speed of electrical transmission, the design of these sub-electrodes can compensate to a certain extent for the difference in transmission speed between the optical signal and the electrical signal, so as to match the transmission of the optical field with the transmission of the electric field as closely as possible, thereby further improving the device performance of the folded electro-optic modulator.

[0046] 10, the fifth and sixth sub-electrodes 1e and 1f may be disposed on the surface of the protruding structure 3e shown in this figure, and the seventh and eighth sub-electrodes 1g and 1h may be disposed on the surface of the protruding structure 3f shown in this figure. In some other embodiments, the fifth and sixth sub-electrodes may also be disposed on opposite sides of the protruding structure, with the fifth and sixth connecting arms not spanning the protruding structure, and the seventh and eighth sub-electrodes may also be disposed on opposite sides of the protruding structure, with the seventh and eighth connecting arms not spanning the protruding structure.

[0047] As shown in FIGS. 5, 7, and 8, in some embodiments of the present disclosure, the substrate 151 is provided with a recessed structure 1510 facing towards the separation layer 152.

[0048] Since the speed of optical transmission is generally greater than that of electrical transmission, in this embodiment, the concave structure 1510 on the substrate 151 can reduce the propagation constant of the electrical signal to a certain degree, so as to match the transmission of the optical field with the transmission of the electric field in the radio frequency modulation region, and thus increase the transmission speed of the electrical signal to compensate for the difference in the transmission speeds mentioned above, thereby further improving the performance of the folded electro-optic modulator device. In other embodiments of the present disclosure, the concave structure may also be designed to have other orientations according to actual needs, and such orientations are not specifically defined in the present disclosure.

[0049] In some embodiments of the present disclosure, as shown in FIG. 3 , the folded electro-optic modulator 100 further includes a phase compensation modulation module 70 disposed between the electrode structure and the optical coupling element 60. If desired, the phase compensation modulation module 70 can modulate the first waveguide arm 30 and the second waveguide arm 40 to compensate for the inherent phase difference between the two waveguide arms, thereby further improving the accuracy of the modulation output of the electro-optic modulator. The phase compensation modulation module 70 is not limited to being disposed in the above-described position and may be disposed, for example, between the optical splitting element 50 and the electrode structure.

[0050] The phase compensation modulation module 70 is not limited to a specific type, and may be, for example, an electro-optic phase compensation modulation module based on the electro-optic effect, or a thermo-optic phase compensation modulation module based on the thermo-optic effect. When the phase compensation modulation module 70 is an electro-optic phase compensation modulation module based on the electro-optic effect, some layer structures may be fabricated in the same layers as some layer structures of the above-described folded electro-optic modulator, in order to simplify the process and reduce the fabrication cost.

[0051] In some embodiments, the phase compensation modulation module 70 may not be provided if desired.

[0052] In summary, the folded electro-optic modulator 100 provided by the embodiments of the present disclosure can achieve a miniaturized device design while meeting the requirements of device performance, and thus is more easily integrated into a hardware system.

[0053] In this description, the orientations, positional relationships, or dimensions indicated by terms such as "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" are orientations, positional relationships, or dimensions shown based on the accompanying drawings, and it should be understood that these terms are used for ease of description only and do not indicate or suggest that the referenced devices or elements must have a particular orientation or be constructed and operated in a particular orientation, and therefore should not be construed to limit the scope of protection of the present disclosure.

[0054] Additionally, terms such as "first," "second," and "third" are for descriptive purposes only and should not be construed as indicating or suggesting relative importance or implicitly indicating the number of technical features being shown. Thus, features defined by "first," "second," and "third" can explicitly or implicitly include one or more features. In describing this disclosure, the term "plurality" means two or more, unless explicitly and specifically defined otherwise.

[0055] In this disclosure, unless expressly stated or defined otherwise, terms such as "attach," "connect," "connected," and "fix" should be interpreted broadly, for example, these terms may refer to a fixed connection, a detachable connection, or an integral connection, a mechanical connection, or an electrical connection or communication, a direct connection or an indirect connection through an intermediate medium, or an internal communication between two elements or an interaction between two elements. Those skilled in the art will understand the specific meanings of the above terms in this disclosure according to the specific circumstances.

[0056] In this disclosure, unless expressly stated or defined otherwise, a first feature being "above" or "below" a second feature can include cases where the first feature directly contacts the second feature, or cases where the first and second features are not directly in contact but are contacted via another feature between them. Furthermore, a first feature being "over," "above," or "on" a second feature can include cases where the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher level than the second feature. A first feature being "below," "under," or "beneath" a second feature can include cases where the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower level than the second feature.

[0057] This description provides many different implementations or examples that can be used to implement the present disclosure. It should be understood that these different implementations or examples are purely illustrative and are not intended to limit the scope of protection of the present disclosure in any way. Based on the disclosure of the description of the present disclosure, those skilled in the art will be able to think of various modifications or replacements. All these modifications or replacements shall fall within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure shall be governed by the scope of protection of the claims.

Claims

1. 1. A folded electro-optic modulator, comprising: a first waveguide arm and a second waveguide arm that are generally folded and do not intersect with each other; a first main electrode, a second main electrode, and a third main electrode that are generally folded and do not intersect with one another, wherein the first waveguide arm is located between the first main electrode and the second main electrode, the second waveguide arm is located between the second main electrode and the third main electrode, the first main electrode and the third main electrode being ground electrodes for a radio frequency signal, and the second main electrode being a signal electrode for the radio frequency signal; The following structure is provided in any even-order radio frequency modulation region of the folded electro-optic modulator in the transmission direction of the first waveguide arm and the second waveguide arm: a plurality of first sub-electrodes, each of which is connected to a side of the first main electrode closer to the second main electrode by a first connecting arm insulated from the first waveguide arm and crossing the first waveguide arm; a plurality of second sub-electrodes, each of which is connected to a second main electrode closer to the first main electrode by a second connecting arm insulated from the first waveguide arm and crossing the first waveguide arm; a plurality of third sub-electrodes, each of which is connected to a side of the second main electrode closer to the third main electrode by a third connecting arm insulated from the second waveguide arm and crossing the second waveguide arm; a plurality of fourth sub-electrodes, each of which is connected to a side of the third main electrode closer to the second main electrode by a fourth connecting arm insulated from the second waveguide arm and crossing the second waveguide arm; Equipped with the electric fields in which the first waveguide arm is located within any even-order radio frequency modulation region and any odd-order radio frequency modulation region have the same direction; 10. A folded electro-optic modulator, wherein the electric fields in which the second waveguide arm is located within any even order radio frequency modulation region and any odd order radio frequency modulation region have the same direction.

2. each of the first sub-electrodes and a corresponding first connecting arm forms a first T-shaped structure, each of the second sub-electrodes and a corresponding second connecting arm forms a second T-shaped structure, a plurality of first T-shaped structures and a plurality of second T-shaped structures are alternately arranged in an extension direction of the arbitrary even-order radio frequency modulation region, a gap between adjacent first sub-electrodes is smaller than a length of the second sub-electrode, and a gap between adjacent second sub-electrodes is smaller than a length of the first sub-electrode; each of the third sub-electrodes and the corresponding third connecting arm forms a third T-shaped structure, each of the fourth sub-electrodes and the corresponding fourth connecting arm forms a fourth T-shaped structure, a plurality of third T-shaped structures and a plurality of fourth T-shaped structures are alternately arranged in the extension direction of the arbitrary even-order radio frequency modulation region, a gap between adjacent third sub-electrodes is smaller than a length of the fourth sub-electrode, and a gap between adjacent fourth sub-electrodes is smaller than a length of the third sub-electrode; 10. The folded electro-optic modulator of claim 1.

3. each of the first sub-electrodes and a corresponding first connecting arm forms a first L-shaped structure, each of the second sub-electrodes and a corresponding second connecting arm forms a second L-shaped structure, a plurality of first L-shaped structures and a plurality of second L-shaped structures are alternately arranged in an extension direction of the arbitrary even-order radio frequency modulation area, and an orthogonal projection of each of the first sub-electrodes overlaps an orthogonal projection of one second sub-electrode in the extension direction of the arbitrary even-order radio frequency modulation area; each of the third sub-electrodes and the corresponding third connecting arm forms a third L-shaped structure, each of the fourth sub-electrodes and the corresponding fourth connecting arm forms a fourth L-shaped structure, a plurality of third L-shaped structures and a plurality of fourth L-shaped structures are alternately arranged in the extension direction of the arbitrary even-order radio frequency modulation region, and an orthogonal projection of each of the third sub-electrodes overlaps with an orthogonal projection of one fourth sub-electrode in the extension direction of the arbitrary even-order radio frequency modulation region; 10. The folded electro-optic modulator of claim 1.

4. the folded electro-optic modulator comprises a substrate, an isolation layer, a waveguiding layer, an insulating layer, and an electrode layer, arranged in sequence; the first waveguide arm and the second waveguide arm are located within the waveguide layer; the first main electrode, the second main electrode, the third main electrode, the first sub-electrode, the first connecting arm, the second sub-electrode, the second connecting arm, the third sub-electrode, the third connecting arm, the fourth sub-electrode, and the fourth connecting arm are located in the electrode layer; the first connection arm and the second connection arm are insulated from the first waveguide arm by the insulating layer, and the third connection arm and the fourth connection arm are insulated from the second waveguide arm by the insulating layer.

10. The folded electro-optic modulator of claim 1.

5. the waveguide layer is a ridged ridge pattern layer, or the waveguide layer is a ridge waveguide layer including a flat layer and a ridge-like pattern layer located on a side of the flat layer away from the substrate, and the first waveguide arm and the second waveguide arm are located in the ridge-like pattern layer; 5. The folded electro-optic modulator of claim 4.

6. the waveguide layer is a ridge waveguide layer including a flat plate layer and a ridge-like pattern layer located on a side of the flat plate layer away from the substrate, the first waveguide arm and the second waveguide arm being located in the ridge-like pattern layer; the insulating layer covers the ridge-like protrusion pattern layer and exposes at least a part of the area of ​​the flat plate layer, and the first main electrode, the second main electrode, and the third main electrode are formed on the surface of the flat plate layer that is exposed from the insulating layer, or the insulating layer covers the ridge-like protrusion pattern layer and covers at least a part of the area of ​​the flat plate layer, and the first main electrode, the second main electrode, and the third main electrode are formed on the surface of the part of the insulating layer that covers the flat plate layer.

5. The folded electro-optic modulator of claim 4.

7. a protruding structure formed by a portion of the insulating layer covering the first waveguide arm is located between the first sub-electrode and the first main electrode and between the second sub-electrode and the second main electrode; a protruding structure formed by a portion of the insulating layer covering the second waveguide arm is located between the third sub-electrode and the second main electrode and between the fourth sub-electrode and the third main electrode; 5. The folded electro-optic modulator of claim 4.

8. the first sub-electrode and the second sub-electrode are formed on a surface of a protruding structure formed by a portion of the insulating layer covering the first waveguide arm, the third sub-electrode and the fourth sub-electrode are formed on a surface of a protruding structure formed by a portion of the insulating layer covering the second waveguide arm.

5. The folded electro-optic modulator of claim 4.

9. The following structure provided in at least one odd-order radio frequency modulation region of said folded electro-optic modulator: a plurality of fifth sub-electrodes, each of which is located between the first main electrode and the first waveguide arm and connected to a side of the first main electrode closer to the first waveguide arm by a fifth connecting arm; a plurality of sixth sub-electrodes, each of which is located between the second main electrode and the first waveguide arm and connected to a side of the second main electrode closer to the first waveguide arm by a sixth connecting arm; a plurality of seventh sub-electrodes, each of which is located between the second main electrode and the second waveguide arm and connected to a side of the second main electrode closer to the second waveguide arm by a seventh connecting arm; a plurality of eighth sub-electrodes, each of which is located between the third main electrode and the second waveguide arm and connected to a side of the third main electrode that is closer to the second waveguide arm by an eighth connecting arm; 9. The folded electro-optic modulator of claim 1, further comprising at least one of:

10. 9. A folded electro-optic modulator according to any one of claims 4 to 8, wherein the substrate is provided with a recessed structure.

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