Folding phase modulation module and electro-optical modulator

Abstract

Provided in the present disclosure are a folding phase modulation module and an electro-optical modulator. The folding phase modulation module in the present disclosure comprises a traveling wave electrode and a folding waveguide, wherein the traveling wave electrode comprises a first ground electrode, a first signal electrode, a second ground electrode, a second signal electrode and a third ground electrode, which are arranged spaced apart from one another; the traveling wave electrode comprises first linear extension portions, second linear extension portions and curved connection portions, the first linear extension portions and the second linear extension portions extending in a first direction and being alternately arranged in a second direction, and two ends of each curved connection portion being respectively connected to the first linear extension portion and the second linear extension portion which are adjacent to the curved connection portion; and the folding direction of the folding waveguide is the same as the folding direction of the traveling wave electrode, and the folding waveguide comprises a first waveguide and a second waveguide, the first waveguide and the second waveguide being configured such that same are applied with opposite electric fields by the first signal electrode at the first linear extension portions and are applied with opposite electric fields by the second signal electrode at the second linear extension portions.

Description

Folded phase modulation module and electro-optical modulator

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese invention patent application No. 202311388591.X, filed on October 24, 2023, entitled “Folded Phase Modulation Module and Electro-Optical Modulator”, and the disclosure of the priority claimed in this application is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates to the field of optical waveguide technology, and in particular to a folded phase modulation module and an electro-optical modulator. Background Art

[0004] In recent years, the rapid development of emerging network applications such as the Internet of Things, autonomous driving, telemedicine, and distance education has placed higher demands on high-speed, high-capacity communication technologies. Optical communications, due to their high bandwidth, high reliability, low cost, and strong anti-interference capabilities, have achieved rapid development in this field. Loading high-speed electrical signals onto optical carriers is a core research topic. Electro-optical modulators, devices that convert electrical signals into optical signals, are core components in optical interconnect, optical computing, and optical communication systems. Modulator performance plays a crucial role in the transmission distance and speed of optical signals. With the increasingly urgent demand for high-speed, high-capacity communication technologies, higher requirements are being placed on the modulation rate of electro-optical modulators.

[0005] Electro-optic modulators utilize the electro-optic effect of certain electro-optic crystals, such as lithium niobate (LiNbO3), gallium arsenide (GaAs), and lithium tantalate (LiTaO3). The electro-optic effect refers to the change in the refractive index of an electro-optic crystal when a voltage is applied. This changes the properties of the light wave passing through the crystal, modulating the phase, amplitude, intensity, and polarization of the optical signal.

[0006] However, with the increasingly urgent demand for high-speed, large-capacity, integrated communication technology, people hope to minimize the size of integrated devices while ensuring the modulation effect of electro-optical modulators, which places high demands on electrode design.

[0007] Summary of the Invention

[0008] The embodiments of the present disclosure provide a folded phase modulation module and an electro-optical modulator to reduce the size of the phase modulation module and improve device performance.

[0009] According to one aspect of the present disclosure, a folded phase modulation module is provided, comprising a traveling wave electrode and a folded waveguide, the traveling wave electrode comprising a first ground electrode, a first signal electrode, a second ground electrode, a second signal electrode and a third ground electrode arranged at intervals from each other, the traveling wave electrode comprising at least one first straight extension portion, at least one second straight extension portion and at least one curved connection portion, the first straight extension portion and the second straight extension portion extending in a first direction and alternately arranged in a second direction different from the first direction, and the two ends of any curved connection portion are respectively connected to adjacent first direct extension portions and second straight extension portions; the folding direction of the folded waveguide is the same as the folding direction of the traveling wave electrode, the folded waveguide comprising a first waveguide and a second waveguide, the first waveguide and the second waveguide being constructed so that opposite electric fields are applied by the first signal electrode in the first straight extension portion, and opposite electric fields are applied by the second signal electrode in the second straight extension portion.

[0010] In some embodiments, the first waveguide includes a plurality of first straight waveguide portions spaced apart from each other along the second direction, and a first curved waveguide portion connecting two adjacent first straight waveguide portions; the second waveguide includes a plurality of second straight waveguide portions spaced apart from each other along the second direction, and a second curved waveguide portion connecting two adjacent second straight waveguide portions; in the first straight extension portion, the first straight waveguide portion and the second straight waveguide portion are respectively located on both sides of the first signal electrode; and in the second straight extension portion, the first straight waveguide portion and the second straight waveguide portion are respectively located on both sides of the second signal electrode.

[0011] In some embodiments, in the first straight extension portion, the first straight waveguide portion is located between the first signal electrode and the first ground electrode, and the second straight waveguide portion is located between the first signal electrode and the second ground electrode. In the second straight extension portion, the first straight waveguide portion is located between the second signal electrode and the third ground electrode, and the second straight waveguide portion is located between the second signal electrode and the second ground electrode.

[0012] In some embodiments, the first linear waveguide portion and the second linear waveguide portion both extend along the first direction, and a length of the first linear waveguide portion is different from a length of the first signal electrode in the first linear extension portion.

[0013] In some embodiments, the length of the first linear waveguide portion is different from the length of the second signal electrode in the second linear extension portion.

[0014] In some embodiments, the length of the second linear waveguide portion is different from the length of the first signal electrode in the first linear extension portion.

[0015] In some embodiments, the length of the second linear waveguide portion is different from the length of the second signal electrode in the second linear extension portion.

[0016] In some embodiments, the transmission speed of the optical signal in the waveguide is greater than the transmission speed of the radio frequency signal in the traveling wave electrode, and the length of the first straight waveguide portion and the length of the second straight waveguide portion are both greater than the length of the first signal electrode in the first straight extension portion and the length of the second signal electrode in the second straight extension portion.

[0017] In some embodiments, the transmission speed of the optical signal in the waveguide is lower than the transmission speed of the radio frequency signal in the traveling wave electrode, and the length of the first straight waveguide portion and the length of the second straight waveguide portion are both greater than the length of the first signal electrode in the first straight extension portion and the length of the second signal electrode in the second straight extension portion.

[0018] In some embodiments, the product of the length of the first curved waveguide portion and the effective refractive index of the first waveguide is Q1, the product of the length of the second curved waveguide portion and the effective refractive index of the second waveguide is Q2, and 0≤|Q1-Q2| / min{Q1, Q2}≤0.5 is satisfied.

[0019] In some embodiments, the length of the first curved waveguide section is the same as the length of the second curved waveguide section.

[0020] In some embodiments, the length of the first curved waveguide portion is greater than the length of the second curved waveguide portion, and the cross-sectional area of ​​the first curved waveguide portion is smaller than the cross-sectional area of ​​the second curved waveguide portion.

[0021] In some embodiments, the first signal electrode and the second signal electrode are configured to receive a differential signal.

[0022] In some embodiments, the electrode structure of the first signal electrode in the first linear extension portion is different from the electrode structure of the first signal electrode in the second linear extension portion.

[0023] In some embodiments, the electrode structure of the second signal electrode in the first linear extension portion is different from the electrode structure of the second signal electrode in the second linear extension portion.

[0024] In some embodiments, the first ground electrode, the second ground electrode, and the third ground electrode are connected to each other at a bent connection portion.

[0025] According to another aspect of the present disclosure, an electro-optic modulator is provided, comprising the above-mentioned folded phase modulation module.

[0026] According to one or more embodiments of the present disclosure, the phases of the first waveguide and the second waveguide in the folded phase modulation module are changed by different signal electrodes in the traveling wave electrode before and after turning, respectively. This can simplify the speed matching between the waveguide and the signal electrode, thereby reducing the size of the phase modulation module and reducing transmission loss.

[0027] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present disclosure, nor are they intended to limit the scope of the present disclosure. Other features of the present disclosure will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Further details, features and advantages of the present disclosure are disclosed in the following description of exemplary embodiments in conjunction with the accompanying drawings, in which:

[0029] FIG1 is a schematic structural diagram of a folded phase modulation module according to some exemplary embodiments of the present disclosure;

[0030] FIG2 is a schematic structural diagram of a folded phase modulation module according to some other exemplary embodiments of the present disclosure;

[0031] FIG3 is a schematic structural diagram of a folded phase modulation module according to some further exemplary embodiments of the present disclosure;

[0032] FIG4 is a schematic structural diagram of a folded phase modulation module according to some exemplary embodiments of the present disclosure;

[0033] FIG5 is a schematic structural diagram of an electro-optic modulator according to some exemplary embodiments of the present disclosure.

[0034] Explanation of the accompanying drawings: Folded phase modulation module 100, electro-optical modulator 200; traveling wave electrode 110, first ground electrode 111, first signal electrode 112, second ground electrode 113, second signal electrode 114, third ground electrode 115; first straight extension portion 110A, curved connection portion 110B, second straight extension portion 110C; folded waveguide 120, first waveguide 121, first straight waveguide portion 121A, first curved waveguide portion 121B, second waveguide 122, second straight waveguide portion 122A, second curved waveguide portion 122B; splitting unit 210, combining unit 220; first direction X, second direction Y. DETAILED DESCRIPTION

[0035] The following description of exemplary embodiments of the present disclosure is made in conjunction with the accompanying drawings, including various details of the embodiments of the present disclosure to facilitate understanding, which should be considered as merely exemplary. Therefore, it should be appreciated by those skilled in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope of the present disclosure. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0036] In this disclosure, unless otherwise specified, the use of terms such as "first" and "second" to describe various elements is not intended to limit the positional relationship, temporal relationship, or importance relationship of these elements. Such terms are only used to distinguish one element from another. In some examples, the first element and the second element may refer to the same instance of the element, while in some cases, based on the context of the description, they may also refer to different instances.

[0037] The terms used in the descriptions of the various examples described in this disclosure are for the purpose of describing specific examples only and are not intended to be limiting. Unless the context clearly indicates otherwise, if the number of elements is not specifically limited, the element may be one or more. In addition, the term "and / or" used in this disclosure encompasses any one and all possible combinations of the listed items.

[0038] Electro-optical modulators often employ Mach-Zehnder optical waveguides. These consist of an input waveguide for introducing light from the outside, a branching section for splitting the light introduced by the input waveguide into two propagation paths, two parallel waveguides that propagate the branched light beams after the branching section, and an output waveguide for combining the light beams propagating through the two parallel waveguides and outputting them externally. Mach-Zehnder optical modulators include control electrodes that control the phase of the light waves propagating through the parallel waveguides by applying a voltage and utilizing the electro-optic effect. These control electrodes typically consist of an RF (high-frequency) signal electrode (hereinafter referred to as the "signal electrode") formed above or near the parallel waveguides and a ground electrode disposed separately from the signal electrode.

[0039] The embodiments of the present disclosure provide a folded phase modulation module and an electro-optical modulator to simplify the velocity matching between the waveguide and the signal electrode, thereby reducing the size of the phase modulation module and lowering the transmission loss, thereby improving the performance of the device.

[0040] As shown in FIG1 , according to one aspect of the present disclosure, a folded phase modulation module 100 is provided. The folded phase modulation module 100 includes a traveling wave electrode 110 and a folded waveguide 120. The traveling wave electrode 110 includes a first ground electrode 111, a first signal electrode 112, a second ground electrode 113, a second signal electrode 114, and a third ground electrode 115 that are spaced apart from each other. The traveling wave electrode 110 includes at least one first straight extension portion 110A, at least one second straight extension portion 110C, and at least one curved connection portion 110B. The first straight extension portion 110A and the second straight extension portion 110C are arranged along a first straight extension portion 110A. The folded waveguide 120 extends in the direction X and is alternately arranged along the second direction Y, and the two ends of any curved connection portion 110B are respectively connected to the adjacent first direct extension portion 110A and the second straight extension portion 110C; the first direction X intersects with the second direction Y; the folding direction of the folded waveguide 120 is the same as the folding direction of the traveling wave electrode 110, and the folded waveguide 120 includes a first waveguide 121 and a second waveguide 122. The first waveguide 121 and the second waveguide 122 are configured so that opposite electric fields are applied to the first straight extension portion 110A by the first signal electrode 112, and opposite electric fields are applied to the second straight extension portion 110C by the second signal electrode 114.

[0041] The folded phase modulation module 100 exhibits a curved or continuously curved structure with alternating straight and curved segments in the plane of the first direction X and the second direction Y. The first straight extension portion 110A and the second straight extension portion 110C of the traveling wave electrode 110 extend along the first direction X and are alternately arranged along the second direction Y. In some embodiments, the length of the first straight extension portion 110A along the first direction X can be the same as or different from the length of the second straight extension portion 110C along the first direction X. The curved connection portion 110B can be an arc, such as a semicircular arc. The curved connection portion 110B may or may not include a straight segment. In some embodiments, the first direction X and the second direction Y are both parallel to the plane of the substrate of the folded phase modulation module 100, and the first direction X is perpendicular to the second direction Y.

[0042] The potentials at the first ground electrode 111, the second ground electrode 113, and the third ground electrode 115 are ground potential G, which can be achieved, for example, by connecting to a ground line. The first signal electrode 112 and the second signal electrode 114 are used to receive corresponding drive signals, thereby forming an electric field with a certain potential difference between the signal electrode and the ground electrode, which can modulate the phase of the light waves in the waveguide within the electric field. The provision of the second ground electrode 113 between the first signal electrode 112 and the second signal electrode 114 allows them to form an electric field for phase modulation with the two signal electrodes, respectively, and also reduces crosstalk between adjacent signal electrodes, thereby improving the modulation effect.

[0043] The first ground electrode 111, the first signal electrode 112, the second ground electrode 113, the second signal electrode 114, and the third ground electrode 115 are folded as a whole and do not intersect with each other. The shape of the folded waveguide 120 can be adapted to the shape of the traveling wave electrode 110, and the folding direction of the folded waveguide 120 is the same as the folding direction of the traveling wave electrode 110. For example, the folded waveguide 120 may include a straight segment corresponding to the straight extension of the traveling wave electrode 110 and a curved connecting segment corresponding to the curved connecting portion of the traveling wave electrode 110. The folded phase modulation module 100 has an overall S-shaped bend, which can reduce the size of the device in the length direction (first direction X), facilitating device miniaturization and integration.

[0044] Since the first signal electrode 112 and the second signal electrode 114 have different bending lengths in the curved connection portion 110B, the delay of the electrical signal before and after the turn will also be different, which will bring greater difficulties to the speed matching between the waveguide and the signal electrode. In this embodiment, in the first straight extension portion 110A before the turn, the first waveguide 121 and the second waveguide 122 are both provided with a modulated electric field by the first signal electrode 112, and in the second straight extension portion 110C after the turn, the first waveguide 121 and the second waveguide 122 are both provided with a modulated electric field by the second signal electrode 114. In this way, it is only necessary to match the speed of the waveguide and the second signal electrode. Compared with the first waveguide 12 The first signal electrode 112 provides an electric field for phase modulation, and the second waveguide 122 provides an electric field for phase modulation by the second signal electrode 114. After turning, due to the difference in delay between the first signal electrode 112 and the second signal electrode 114, it is necessary to re-match the speeds of the optical signal in the first waveguide 121 and the electrical signal in the first signal electrode 112, as well as the speeds of the optical signal in the second waveguide 122 and the electrical signal in the second signal electrode 124. In this embodiment, it is only necessary to match the speed of light in the waveguide with the speed of the electrical signal in the signal electrode applying the electric field, thereby reducing transmission loss and improving electro-optical modulation efficiency.

[0045] In some embodiments, the first waveguide 121 includes a plurality of first straight waveguide portions 121A spaced apart from each other along the second direction Y, and a first curved waveguide portion 121B connecting two adjacent first straight waveguide portions 121A; the second waveguide 122 includes a plurality of second straight waveguide portions 122A spaced apart from each other along the second direction Y, and a second curved waveguide portion 122B connecting two adjacent second straight waveguide portions 122A; in the first straight extension portion 110A, the first straight waveguide portion 121A and the second straight waveguide portion 122A are respectively located on both sides of the first signal electrode 112, and in the second straight extension portion 110C, the first straight waveguide portion 121A and the second straight waveguide portion 122A are respectively located on both sides of the second signal electrode 114.

[0046] Ground electrodes are located on either side of the first signal electrode 112. When a voltage is applied to the first signal electrode 112, electric fields in opposite directions are formed on both sides of the first signal electrode 112. Similarly, when a voltage is applied to the second signal electrode 114, electric fields in opposite directions are also formed on both sides. Therefore, placing the first waveguide 121 and the second waveguide 122 on either side of a single signal electrode can achieve phase modulation within the first waveguide 121 and the second waveguide 122.

[0047] In some embodiments, the first linear waveguide portion 121A and the second linear waveguide portion 122A may be located on both sides of the second signal electrode 114 in the first linear extension portion 110A, and on both sides of the first signal electrode 112 in the second linear extension portion 110C.

[0048] The first signal electrode 112 and the second signal electrode 114 can input different radio frequency voltages according to modulation requirements, thereby improving modulation efficiency.

[0049] In some embodiments, in the first linear extension portion 110A, the first linear waveguide portion 121A is located between the first signal electrode 112 and the first ground electrode 111, and the second linear waveguide portion 122A is located between the first signal electrode 112 and the second ground electrode 113. In the second linear extension portion 110C, the first linear waveguide portion 121A is located between the second signal electrode 114 and the third ground electrode 115, and the second linear waveguide portion 122A is located between the second signal electrode 114 and the second ground electrode 113.

[0050] In some embodiments, as shown in FIG2 , which is a schematic structural diagram of a folded phase modulation module according to other exemplary embodiments of the present disclosure, in the folded phase modulation module 100, the first linear waveguide portion 121A and the second linear waveguide portion 122A both extend along the first direction X. The length of the first linear waveguide portion 121A is different from the length of the first signal electrode 112 in the first linear extension portion 110A and / or the length of the second signal electrode 114 in the second linear extension portion 110C; and the length of the second linear waveguide portion 122A is different from the length of the first signal electrode 112 in the first linear extension portion 110A and / or the length of the second signal electrode 114 in the second linear extension portion 110C.

[0051] The length of the first signal electrode 112 in the first linear extension portion 110A refers to the length of the portion of the first signal electrode 112 that linearly extends along the first direction X in the first linear extension portion 110A. Similarly, the length of the second signal electrode 114 in the second linear extension portion 110C refers to the length of the portion of the second signal electrode 114 that linearly extends along the first direction X in the second linear extension portion 110C.

[0052] Since it is difficult to keep the optical signal transmission speed of the waveguide consistent with the transmission speed of the radio frequency signal in the signal electrode, when designing the structure of the folded phase modulation module, the length of each straight extension part can be adjusted according to the specific structural form and transmission speed of the two. This can better achieve the matching and synchronization of the transmission speed of the optical signal in the waveguide and the transmission speed of the radio frequency signal in the signal electrode, thereby helping to improve the reliability of signal modulation.

[0053] In some embodiments, as shown in FIG2 , the transmission speed of the optical signal in the folded waveguide 120 is lower than the transmission speed of the radio frequency signal in the traveling wave electrode 110 , and the length of the first straight waveguide portion 121A and the length of the second straight waveguide portion 122A are both greater than the length of the first signal electrode 112 in the first straight extension portion 110A and the length of the second signal electrode 114 in the second straight extension portion 110C.

[0054] As shown in Figure 2, in the second linear extension portion 110C, along the first direction X, the length of the first linear waveguide portion 121A and the second linear waveguide portion 122A are both L1, and the length of the first signal electrode 112 and the second signal electrode 114 are both L2, where L1 is less than L2. This means that within the folded phase modulation module, the folded waveguide 120 begins to bend earlier, while the traveling wave electrode bends later. Generally speaking, the length of the curved portion of the component that bends first is shorter than that of the component that bends later. As a result, the time required for the folded waveguide 120 that bends earlier to pass through the curved waveguide portion and reach the second linear extension portion 110C is less than the time it takes for the RF signal in the traveling wave electrode 110 to reach the second linear extension portion 110C. This allows the optical signal and the RF signal to be synchronized at the starting positions of the second linear extension portion 110C, thereby improving modulation efficiency.

[0055] In some embodiments, as shown in FIG3 , which is a schematic structural diagram of a folded phase modulation module according to further exemplary embodiments of the present disclosure, in the folded phase modulation module 100, the optical signal transmission speed in the folded waveguide 120 is greater than the RF signal transmission speed in the traveling wave electrode 110, and the length of the first linear waveguide portion 121A and the length of the second linear waveguide portion 122A are both greater than the length of the first signal electrode 112 in the first linear extension portion 110A and the length of the second signal electrode 114 in the second linear extension portion 110C.

[0056] As shown in Figure 3, in the second linear extension portion 110C, along the first direction X, the lengths of the first linear waveguide portion 121A and the second linear waveguide portion 122A are both L1, and the lengths of the first signal electrode 112 and the second signal electrode 114 are both L2, where L1 is greater than L2. This means that within the folded phase modulation module 100, the traveling wave electrode 110 begins to bend first, followed by the folded waveguide 120. This allows the optical signal, which transmits at a faster speed, to travel a relatively longer path, allowing it to synchronize with the RF signal at its starting position in the second linear extension portion 110C. It is understood that the lengths of the first linear waveguide portion 121A and the second linear waveguide portion 122A can be the same or different. The lengths of the first signal electrode 112 and the second signal electrode 114 in the first linear extension portion 110A can be the same or different. The lengths of the first signal electrode 112 and the second signal electrode 114 in the second linear extension portion 110C can be the same or different.

[0057] In some embodiments, the product of the length of the first curved waveguide portion 121B and the effective refractive index of the first waveguide 121 is Q1, the product of the length of the second curved waveguide portion and the effective refractive index of the second waveguide is Q2, and 0≤|Q1-Q2| / min{Q1, Q2}≤0.5 is satisfied.

[0058] The length of a curved waveguide section refers to the cumulative length of the waveguide along its extension between the two straight waveguide sections. The effective refractive index, on the other hand, refers to the ratio of the propagation constant in the waveguide to the vacuum wave number. In waveguide structural design, it is desirable to synchronize the transmission of optical signals within the first and second waveguides as much as possible. This means that the transmission time of the optical signal within the first and second waveguides must be the same. The transmission time is the ratio of the transmission length to the transmission speed, and the transmission speed is the speed of light divided by the effective refractive index of the waveguide. Since the speed of light is a constant, to keep the transmission times of the first and second waveguides as close as possible, the product of the waveguide length and the effective refractive index must not differ too much. Since it is difficult to maintain the same length of a curved waveguide section, it is possible to achieve synchronized transmission of the optical signals between the two waveguides by limiting the size of the product of the curved waveguide length and the effective refractive index. Theoretically, a smaller value of |Q1-Q2| / min{Q1, Q2} means more synchronized signal transmission between the two. However, this also requires higher precision in waveguide fabrication, significantly increasing costs. Therefore, limiting this value to within 0.5 can balance the waveguide's transmission requirements and manufacturing costs, improving the device's overall performance.

[0059] In some examples, Q1 of the first curved waveguide portion 121B and Q2 of the second curved waveguide portion 122B may further satisfy: 0≤|Q1-Q2| / min{Q1, Q2}≤0.3. In some examples, Q1 and Q2 may further satisfy: 0≤|Q1-Q2| / min{Q1, Q2}≤0.1.

[0060] In some embodiments, the length of the first curved waveguide portion 121B is the same as the length of the second curved waveguide portion 122B.

[0061] To simplify the structure and facilitate manufacturing, the difference in effective refractive index between the first waveguide 121 and the second waveguide 122 is minimal, and the length difference between the straight waveguide portions is also typically minimal. By adjusting the lengths of the first curved waveguide portion 121B and the second curved waveguide portion 122B, the optical signal can be transmitted as synchronously as possible between the first waveguide 121 and the second waveguide 122. As shown in Figures 2 and 3, in the region of the curved connection portion 110B, the first waveguide 121 is located outside the second waveguide 122, and the overall bending radius of the first curved waveguide portion 121B is greater than that of the second curved waveguide portion 122B. This length difference can cause a delay in the transmission of the optical signal within the first waveguide 121 and the second waveguide 122. By adjusting the lengths of the two waveguides to be the same, the optical signal can be transmitted along the same path in the region of the curved connection portion 110B, thereby maintaining optical signal synchronization.

[0062] In some examples, the second curved waveguide portion 122B may include a continuous curved curve, such as an S-shaped wavy line, so that although the overall bending radius of the second curved waveguide portion 122B is smaller than that of the first curved waveguide portion 121B, the cumulative length is equal to that of the first curved waveguide portion 121B. It is understood that the extension of the second curved waveguide portion 122B can also be any other form, as long as the cumulative length is the same as that of the first curved extension portion 121B.

[0063] In some embodiments, as shown in FIG4 , which is a schematic structural diagram of a folded phase modulation module according to some other exemplary embodiments of the present disclosure, in the folded phase modulation module 100 , the length of the first curved waveguide portion 121B is greater than the length of the second curved waveguide portion 122B, and the cross-sectional area of ​​the first curved waveguide portion 121B is smaller than the cross-sectional area of ​​the second curved waveguide portion 122B.

[0064] The cross-sectional areas of the first curved waveguide portion 121B and the second curved waveguide portion 122B refer to the cross-sectional areas perpendicular to the extension direction of the corresponding curved waveguide. In some embodiments, the folded waveguide 120 adopts a ridge waveguide design and also includes a slab waveguide. The first waveguide 121 and the second waveguide 122 are located on a side of the slab waveguide away from the substrate and are integrally connected to the slab waveguide. In this case, the cross-sectional areas of the first curved waveguide portion 121B and the second waveguide portion 122 refer to the cross-sectional areas of the corresponding ridge waveguides.

[0065] In some embodiments, the first curved waveguide portion 121B and the second curved waveguide portion 122B have the same height, and the first curved waveguide portion 121B has a smaller width than the second curved waveguide portion 122B. The height here refers to the dimension perpendicular to the plane of the first direction X and the second direction Y.

[0066] Since the optical signal is continuously transmitted forward through reflection in the waveguide, by increasing the width of the curved waveguide portion, the propagation length of the optical signal can be increased, thereby adjusting the transmission time of the optical signal in the curved waveguide portion, so that the curved waveguide portions of the two waveguides are kept as synchronized as possible, thereby improving the modulation performance of the device.

[0067] In some embodiments, the first signal electrode 112 and the second signal electrode 114 are configured to receive differential signals.

[0068] The RF voltage signals received by the first signal electrode 112 and the second signal electrode 114 are differential signals (ie, S+ and S-) with the same amplitude and opposite phases. The differential signal can provide a larger modulation voltage, thereby improving the modulation efficiency.

[0069] In some embodiments, the electrode structure of the first signal electrode 112 in the first linear extension portion 110A is different from that in the second linear extension portion 110C.

[0070] In some embodiments, the electrode structure of the second signal electrode 114 in the first linear extension portion 110A is different from that in the second linear extension portion 110C.

[0071] The electrode structure of the signal electrode has a direct impact on the modulation effect and RF transmission loss. Therefore, the electrode structure can be adjusted according to the performance requirements of the signal electrodes in different locations. In some embodiments, in the first linear extension 110A, the first signal electrode 112 applies opposite electric fields to the first waveguide 121 and the second waveguide 122 for modulation. Sub-electrodes can be provided on the surface of the first signal electrode 112 facing the first waveguide 121 and / or the second waveguide 122. This is more conducive to adjusting the transmission speed of the waveguide and the transmission speed of the electrode to meet the speed matching requirements between the two. However, this will increase the RF transmission loss to a certain extent. For example, a plurality of spaced "T"-shaped sub-electrodes can be provided on the surface of the first signal electrode 112. In the second linear extension 110C, since the first signal electrode 112 does not require modulation in this portion and does not need to meet the transmission speed matching requirements, a modulation structure with lower RF transmission loss can be selected, which can further improve the modulation efficiency. Similarly, the second signal electrode 114 may also use a modulation structure with lower RF transmission loss in the first linear extension portion 110A, and a modulation structure that is conducive to matching the transmission speed in the second linear extension portion 110C, thereby improving the overall performance of the device.

[0072] In some embodiments, the first ground electrode 101 , the second ground electrode 103 , and the third ground electrode 105 are connected to each other at the bent connection portion 110B.

[0073] The first ground electrode 101, the second ground electrode 103 and the third ground electrode 105 are all ground electrodes, and their corresponding potential is ground potential. In some embodiments, the first ground electrode 101, the second ground electrode 103 and the third ground electrode 105 can be connected by a bridge.

[0074] Considering the long length of the ground electrodes in the folded phase modulation module 100, connecting the first ground electrode 101, the second ground electrode 103, and the third ground electrode 105 to each other at the bent connection portion 110B can ensure that the potentials of the three ground electrodes remain stable and consistent, thereby improving the stability of the potential difference between the signal electrode and the ground electrode along the extension direction of the folded phase modulation module, thereby suppressing the degradation of the modulation effect caused by fluctuations in the potential difference at different positions.

[0075] Embodiments of the second aspect of the present disclosure provide an electro-optic modulator, as shown in FIG5 , which is a schematic structural diagram of an electro-optic modulator according to some exemplary embodiments of the present disclosure. The electro-optic modulator 200 includes a light splitting unit 210, a light combining unit 220, and the folded phase modulation module 100 described in the above embodiments. The light splitting unit 210 is connected to the input end of the folded waveguide 120, and the light combining unit 220 is connected to the output end of the folded waveguide 120.

[0076] The optical splitting unit 210 may employ a Y-branch splitting optical waveguide, and the optical combining element 220 may employ a Y-branch combining optical waveguide. In one example, the optical splitting unit 210 is specifically a 1 / 2 optical splitter, configured to split the optical signal into two branch optical signals at a 1:1 splitting ratio and output them to the input end of the first waveguide 121 and the input end of the second waveguide 122, respectively. The optical combining unit 220 is specifically a 2-in-1 optical combiner, configured to combine the two modulated branch optical signals received from the output end of the first waveguide 121 and the output end of the second waveguide 122 into one modulated optical signal and output it.

[0077] It should be understood that in this specification, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships or dimensions based on the orientations or positional relationships or dimensions shown in the accompanying drawings, and these terms are used only for the convenience of description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present disclosure.

[0078] Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first," "second," or "third" may explicitly or implicitly include one or more of the features. Throughout the present disclosure, "plurality" means two or more, unless otherwise specifically defined.

[0079] In this disclosure, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections, electrical connections, or communication; direct connections or indirect connections through an intermediate medium; and internal connections between two components or interactions between two components. Those skilled in the art will understand the specific meanings of these terms in this disclosure based on specific circumstances.

[0080] In the present disclosure, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature includes the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0081] This specification provides many different embodiments or examples that can be used to implement the present disclosure. It should be understood that these different embodiments or examples are purely exemplary and are not intended to limit the scope of protection of the present disclosure in any way. Those skilled in the art can conceive of various changes or replacements based on the disclosure of the specification of the present disclosure, all of which should be included within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection defined by the appended claims.

Claims

1. A folded phase modulation module, comprising: A traveling wave electrode, comprising a first grounding electrode, a first signal electrode, a second grounding electrode, a second signal electrode and a third grounding electrode arranged at intervals from each other, the traveling wave electrode comprising at least one first straight extension portion, at least one second straight extension portion and at least one curved connection portion, the first straight extension portion and the second straight extension portion extending along a first direction and alternately arranged along a second direction intersecting the first direction, and two ends of any of the curved connection portions respectively connecting adjacent first straight extension portions and second straight extension portions; and A folded waveguide, wherein the folding direction of the folded waveguide is the same as the folding direction of the traveling wave electrode, the folded waveguide comprises a first waveguide and a second waveguide, wherein the first waveguide and the second waveguide are configured such that opposite electric fields are applied to the first straight extension portion by the first signal electrode, and opposite electric fields are applied to the second straight extension portion by the second signal electrode.

2. The folded phase modulation module according to claim 1, wherein: The first waveguide includes a plurality of first straight waveguide portions spaced apart from each other along the second direction, and a first curved waveguide portion connecting two adjacent first straight waveguide portions. The second waveguide includes a plurality of second straight waveguide portions spaced apart from each other along the second direction, and a second curved waveguide portion connecting two adjacent second straight waveguide portions. In the first linear extension portion, the first linear waveguide portion and the second linear waveguide portion are respectively located on both sides of the first signal electrode. In the second linear extension portion, the first linear waveguide portion and the second linear waveguide portion are respectively located on both sides of the second signal electrode.

3. The folded phase modulation module according to claim 2, wherein: In the first linear extension portion, the first linear waveguide portion is located between the first signal electrode and the first ground electrode, and the second linear waveguide portion is located between the first signal electrode and the second ground electrode. In the second linear extension portion, the first linear waveguide portion is located between the second signal electrode and the third ground electrode, and the second linear waveguide portion is located between the second signal electrode and the second ground electrode.

4. The folded phase modulation module according to claim 2 or 3, wherein: The first linear waveguide portion and the second linear waveguide portion both extend along the first direction, The length of the first linear waveguide portion is different from the length of the first signal electrode in the first linear extension portion and / or the length of the second signal electrode in the second linear extension portion. The length of the second linear waveguide portion is different from the length of the first signal electrode in the first linear extension portion and / or the length of the second signal electrode in the second linear extension portion.

5. The folded phase modulation module according to claim 4, wherein: The transmission speed of the optical signal in the waveguide is greater than the transmission speed of the radio frequency signal in the traveling wave electrode, and the length of the first linear waveguide portion and the length of the second linear waveguide portion are both greater than the length of the first signal electrode in the first linear extension portion and the length of the second signal electrode in the second linear extension portion; or The transmission speed of the optical signal in the waveguide is lower than the transmission speed of the radio frequency signal in the traveling wave electrode, and the length of the first linear waveguide portion and the length of the second linear waveguide portion are both greater than the length of the first signal electrode in the first linear extension portion and the length of the second signal electrode in the second linear extension portion.

6. The folded phase modulation module according to any one of claims 2 to 5, wherein: The product of the length of the first curved waveguide portion and the effective refractive index of the first waveguide is Q1, the product of the length of the second curved waveguide portion and the effective refractive index of the second waveguide is Q2, and 0≤|Q1-Q2| / min{Q1, Q2}≤0.5 is satisfied.

7. The folded phase modulation module according to any one of claims 2 to 6, wherein: The length of the first curved waveguide portion is the same as the length of the second curved waveguide portion.

8. The folded phase modulation module according to any one of claims 2 to 6, wherein: The length of the first curved waveguide portion is greater than the length of the second curved waveguide portion, and the cross-sectional area of ​​the first curved waveguide portion is smaller than the cross-sectional area of ​​the second curved waveguide portion.

9. The folded phase modulation module according to any one of claims 1 to 8, wherein: The first signal electrode and the second signal electrode are configured to receive a differential signal.

10. The folded phase modulation module according to any one of claims 1 to 9, wherein: The electrode structure of the first signal electrode in the first linear extension portion is different from the electrode structure of the first signal electrode in the second linear extension portion, and / or The electrode structure of the second signal electrode in the first linear extension portion is different from the electrode structure of the second signal electrode in the second linear extension portion.

11. The folded phase modulation module according to any one of claims 1 to 10, wherein: The first ground electrode, the second ground electrode, and the third ground electrode are connected to each other at the bent connection portion.

12. An electro-optic modulator comprising the folded phase modulation module according to any one of claims 1 to 11.

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