Folding phase modulation module and electro-optical modulator

Abstract

The invention provides a folded phase modulation module and an electro-optical modulator, the folded phase modulation module comprises a traveling wave electrode and a folded waveguide, and the traveling wave electrode comprises a first grounding electrode, a first signal electrode, a second grounding electrode, a second signal electrode and a third grounding electrode which are arranged at intervals. The traveling wave electrode comprises a first linear extension part, a second linear extension part and a bent connecting part, the first linear extension part and the second linear extension part extend in the first direction and are alternately arranged in the second direction, and the two ends of the bent connecting part are connected with the adjacent first linear extension part and second linear extension part respectively; 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, and the first waveguide and the second waveguide are configured to apply opposite electric fields by the first signal electrode at the first linear extension part and apply opposite electric fields by the second signal electrode at the second linear extension part.

Description

Technical Field

[0001] The present disclosure relates to the field of optical waveguide technology, and in particular to a folded phase modulation module and an electro-optic modulator. Background Art

[0002] In recent years, the rapid development of emerging network application services such as the Internet of Things, unmanned driving, telemedicine, and distance education has put forward higher requirements for high-speed and large-capacity communication technology. Optical communication has achieved rapid development in the direction of high-speed and large-capacity communication due to its large bandwidth, high reliability, low cost, and strong anti-interference ability. How to load high-speed electrical signals onto optical carriers is a core research content. As a device that converts electrical signals into optical signals, the electro-optic modulator is one of the core components in optical interconnection, optical computing, and optical communication systems. The performance of the modulator plays an important role in the transmission distance and transmission speed of optical signals. With the increasingly urgent demand for high-speed and large-capacity communication technology, higher requirements are also placed on the modulation rate of electro-optic modulators.

[0003] Electro-optic modulators are modulators made using the electro-optic effect of certain electro-optic crystals, such as lithium niobate crystals (LiNbO3), gallium arsenide crystals (GaAs) and lithium tantalate crystals (LiTaO3). The electro-optic effect means that when voltage is applied to an electro-optic crystal, the refractive index of the electro-optic crystal will change, resulting in changes in the characteristics of the light wave passing through the crystal, thereby modulating the phase, amplitude, intensity and polarization state of the optical signal.

[0004] However, with the increasingly urgent demand for high-speed, large-capacity, integrated communication technology, people hope to reduce the size of integrated devices as much as possible while ensuring the modulation effect of electro-optical modulators, which puts high demands on electrode design. Summary of the invention

[0005] The embodiments of the present disclosure provide a folded phase modulation module and an electro-optic modulator to reduce the size of the phase modulation module and improve device performance.

[0006] 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 grounding electrode, a first signal electrode, a second grounding electrode, a second signal electrode and a third grounding electrode which are spaced apart 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 different from the first direction, and the two ends of any curved connection portion respectively connecting 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.

[0007] 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.

[0008] 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, the second straight waveguide portion is located between the first signal electrode and the second ground electrode, and 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.

[0009] In some embodiments, the first linear waveguide portion and the second linear waveguide portion both extend along the first direction, and the length of the first linear waveguide portion is different from the length of the first signal electrode in the first linear extension portion.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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 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;

[0014] 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.

[0015] 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.

[0016] In some embodiments, the length of the first curved waveguide portion is the same as the length of the second curved waveguide portion.

[0017] 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.

[0018] In some embodiments, the first signal electrode and the second signal electrode are configured to receive a differential signal.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] According to another aspect of the present disclosure, an electro-optic modulator is provided, comprising the above-mentioned folded phase modulation module.

[0023] 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 losses.

[0024] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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:

[0026] Figure 1 is a schematic structural diagram of a folded phase modulation module of some exemplary embodiments of the present disclosure;

[0027] Figure 2 is a schematic structural diagram of a folded phase modulation module according to some other exemplary embodiments of the present disclosure;

[0028] Figure 3 is a schematic structural diagram of a folded phase modulation module according to some further exemplary embodiments of the present disclosure;

[0029] Figure 4 is a structural schematic diagram of a folded phase modulation module according to some exemplary embodiments of the present disclosure;

[0030] Figure 5 is a schematic structural diagram of an electro-optic modulator according to some exemplary embodiments of the present disclosure.

[0031] Reference numerals:

[0032] Folded phase modulation module 100, electro-optic modulator 200;

[0033] 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;

[0034] 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;

[0035] Light splitting unit 210, light combining unit 220;

[0036] The first direction is X, and the second direction is Y. DETAILED DESCRIPTION

[0037] The following is a description of exemplary embodiments of the present disclosure 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 recognized by those of ordinary skill 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, the description of well-known functions and structures is omitted in the following description.

[0038] In the present disclosure, unless otherwise specified, the use of the terms "first", "second", etc. to describe various elements is not intended to limit the positional relationship, temporal relationship, or importance relationship of these elements, and such terms are only used to distinguish one element from another element. In some examples, the first element and the second element may refer to the same instance of the element, and in some cases, based on the description of the context, they may also refer to different instances.

[0039] The terms used in the description of various examples in this disclosure are only for the purpose of describing specific examples and are not intended to be limiting. Unless the context clearly indicates otherwise, if the number of elements is not specifically limited, the element can be one or more. In addition, the term "and / or" used in this disclosure covers any one of the listed items and all possible combinations.

[0040] Electro-optical modulators often use Mach-Zehnder optical waveguides, which are composed of an input waveguide for introducing light from the outside, a branching portion for dividing the light introduced by the input waveguide into two paths for propagation, two parallel waveguides for propagating the branched lights at the rear of the branching portion, and an output waveguide for combining the lights propagating in the two parallel waveguides and outputting them to the outside. Mach-Zehnder optical modulators have a control electrode for controlling the phase change of the light wave propagating in the parallel waveguides by applying a voltage and utilizing the electro-optical effect. The control electrode is usually composed of an RF (high frequency) signal electrode (hereinafter referred to as a "signal electrode") formed on the upper part of the parallel waveguide or in the vicinity thereof and a ground electrode arranged separately from the signal electrode.

[0041] The embodiments of the present disclosure provide a folded phase modulation module and an electro-optic modulator to simplify the velocity matching between the waveguide and the signal electrode, thereby reducing the size of the phase modulation module and reducing the transmission loss, thereby improving the performance of the device.

[0042] like Figure 1As shown, 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 grounding electrode 111, a first signal electrode 112, a second grounding electrode 113, a second signal electrode 114 and a third grounding electrode 115 which are arranged at intervals 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 direction 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 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, and the first waveguide 121 and the second waveguide 122 are configured such that opposite electric fields are applied by the first signal electrode 112 in the first straight extension portion 110A, and opposite electric fields are applied by the second signal electrode 114 in the second straight extension portion 110C.

[0043] The folded phase modulation module 100 has a bending or continuous multi-channel bending structure in which straight segments and bending segments are alternately arranged in the plane where the first direction X and the second direction Y are located. Among them, 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 and the length of the second straight extension portion 110C along the first direction X can be the same or different, and the curved connection portion 110B can be an arc, such as a semicircular arc. The curved connection portion 110B may include or not include a straight segment. In some embodiments, the first direction X and the second direction Y are parallel to the plane where the substrate of the folded phase modulation module 100 is located, and the first direction X is perpendicular to the second direction Y.

[0044] The potential on the first ground electrode 111, the second ground electrode 113, and the third ground electrode 115 is the ground potential G, for example, grounding can be achieved 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 wave in the waveguide within the electric field. The first signal electrode 112 and the second signal electrode 114 are provided with a second ground electrode 113, on the one hand, they can form an electric field for phase modulation with the two signal electrodes respectively, and on the other hand, they can reduce the crosstalk between two adjacent signal electrodes, which is conducive to improving the modulation effect.

[0045] 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 cross 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 line segment corresponding to the straight extension portion of the traveling wave electrode 110 and a curved connection segment corresponding to the curved connection portion of the traveling wave electrode 110. The folded phase modulation module 100 is in an S-shaped bending shape as a whole, which can reduce the size of the device in the length direction (first direction X), which is conducive to the miniaturization and integration of the device.

[0046] Since the bending lengths of the first signal electrode 112 and the second signal electrode 114 in the curved connection portion 110B are different, 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 different delays of 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 electric signal in the first signal electrode 112, as well as the speeds of the optical signal in the second waveguide 122 and the electric signal in the second signal electrode 124. In this embodiment, it is only necessary to match the light speed in the waveguide with the transmission speed of the electric signal in the signal electrode applying the electric field, which is more conducive to reducing transmission loss and improving electro-optical modulation efficiency.

[0047] 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.

[0048] Ground electrodes are provided on both sides 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, electric fields in opposite directions are formed on both sides of the second signal electrode 114 after a voltage is applied. Therefore, the first waveguide 121 and the second waveguide 122 are arranged on both sides of a single signal electrode, respectively, so that phase modulation can be achieved in the first waveguide 121 and the second waveguide 122.

[0049] In some embodiments, the first linear waveguide portion 121A and the second linear waveguide portion 122A may also 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.

[0050] 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.

[0051] In some embodiments, in the first straight extension portion 110A, the first straight waveguide portion 121A is located between the first signal electrode 112 and the first ground electrode 111, and the second straight waveguide portion 122A is located between the first signal electrode 112 and the second ground electrode 113; in the second straight extension portion 110C, the first straight waveguide portion 121A is located between the second signal electrode 114 and the third ground electrode 115, and the second straight waveguide portion 122A is located between the second signal electrode 114 and the second ground electrode 113.

[0052] In some embodiments, Figure 2 As shown, Figure 2 Schematic diagram of the structure of the folded phase modulation module of some 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, and 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; 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.

[0053] 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.

[0054] Since it is difficult to keep the optical signal transmission speed of the waveguide consistent with the transmission speed of the RF signal in the signal electrode, when designing the structure of the folded phase modulation module, the lengths of their respective straight extension parts can be adjusted according to their specific structural forms and transmission speeds. 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 RF signal in the signal electrode, thereby helping to improve the reliability of signal modulation.

[0055] In some embodiments, Figure 2 As shown, 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.

[0056] like Figure 2 As shown, in the second straight extension portion 110C, along the first direction X, the lengths of the first straight waveguide portion 121A and the second straight waveguide portion 122A are both L1, and the lengths of the first signal electrode 112 and the second signal electrode 114 are both L2, wherein L1 is less than L2. This means that in the folded phase modulation module, the folded waveguide 120 will begin to bend in advance, while the traveling wave electrode will bend later. Generally speaking, the length of the bent portion of the component that bends first will be shorter than that of the component that bends later, so that the time required for the folded waveguide 120 that bends in advance to reach the second straight extension portion 110C through the bent waveguide portion is less than the time for the radio frequency signal in the traveling wave electrode 110 to reach the second straight extension portion 110C, so that the optical signal and the radio frequency signal can be synchronized at the starting position of the second straight extension portion 110C, thereby improving the modulation efficiency.

[0057] In some embodiments, Figure 3 As shown, Figure 3 Schematic diagram of the structure of the folded phase modulation module of some exemplary embodiments of the present disclosure. In the folded phase modulation module 100, the transmission speed of the optical signal in the folded waveguide 120 is greater 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.

[0058] like Figure 3As shown, in the second straight extension portion 110C, along the first direction X, the lengths of the first straight waveguide portion 121A and the second straight 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 in the folded phase modulation module 100, the traveling wave electrode 110 will begin to bend first, and the folded waveguide 120 will bend later. In this way, the optical signal with a faster transmission speed will transmit a relatively longer path so that the starting position of the second straight extension portion 110C is synchronized with the radio frequency signal. It can be understood that the length of the first straight waveguide portion 121A and the length of the second straight 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 straight 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 straight extension portion 110C can be the same or different.

[0059] 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.

[0060] The length of the curved waveguide portion refers to the cumulative length of the waveguide along its extension direction between the two straight waveguide portions. The effective refractive index refers to the ratio of the propagation constant in the waveguide to the vacuum wave number. In the structural design of the waveguide, it is hoped that the transmission of the optical signal in the first waveguide and the second waveguide is as synchronized as possible, that is, the transmission time of the optical signal in the first waveguide and the second waveguide is required to be the same, and 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, in order to make the transmission time of the first waveguide and the second waveguide as close as possible, the product of the length of the waveguide and the effective refractive index should not differ too much. Since the length of the curved waveguide part is difficult to keep consistent, the synchronous transmission of the optical signals of the two can be achieved as much as possible by limiting the size relationship between the length of the curved waveguide and the product of the effective refractive index. Theoretically, the smaller the value of |Q1-Q2| / min{Q1, Q2} is, the more synchronized the signal transmission between the two is. However, this also places higher demands on the accuracy of waveguide preparation, which greatly increases the cost. Therefore, limiting the value to within 0.5 can take into account both the transmission requirements and manufacturing costs of the waveguide and improve the overall performance of the device.

[0061] In some examples, Q1 of the first curved waveguide portion 121B and Q2 of the second curved waveguide portion 122B may also satisfy: 0≤|Q1-Q2| / min{Q1, Q2}≤0.3. In some examples, Q1 and Q2 may also satisfy: 0≤|Q1-Q2| / min{Q1, Q2}≤0.1.

[0062] 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.

[0063] In order to simplify the structure and facilitate manufacturing, the effective refractive index difference between the first waveguide 121 and the second waveguide 122 is small, and the length of the straight waveguide portion is usually small. The length of the first curved waveguide portion 121B and the length of the second curved waveguide portion 122B can be adjusted to make the optical signal between the first waveguide 121 and the second waveguide 122 transmitted synchronously as much as possible. Figure 2 and Figure 3 As shown, in the area 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. Such a length difference will cause a delay in the transmission of the optical signal in the first waveguide 121 and the second waveguide 122. The lengths of the two can be adjusted to be the same, so that the transmission paths of the optical signals in the area of ​​the curved connection portion 110B are the same, thereby maintaining the synchronization of the optical signals.

[0064] In some examples, the second curved waveguide portion 122B may include a continuous curved curve, such as an S-shaped wave 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 understandable that the extension form 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.

[0065] In some embodiments, Figure 4 As shown, Figure 4 1 is a schematic diagram of a folded phase modulation module according to some 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.

[0066] The cross-sectional area of ​​the first curved waveguide portion 121B and the second curved waveguide portion 122B refers to the cross-sectional area along the extension direction perpendicular to the corresponding curved waveguide. In some embodiments, the folded waveguide 120 adopts a ridge waveguide design, which also includes a slab waveguide, and 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 area of ​​the first curved waveguide portion 121B and refers to the cross-sectional area of ​​the corresponding ridge waveguide.

[0067] 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 where the first direction X and the second direction Y are located.

[0068] Since the optical signal is continuously transmitted forward through reflection in the waveguide, the propagation length of the optical signal can be increased by increasing the width of the curved waveguide portion, thereby adjusting the transmission time of the optical signal in the curved waveguide portion, so that the curved waveguide portions of the two waveguides can be kept as synchronized as possible, thereby improving the modulation performance of the device.

[0069] In some embodiments, the first signal electrode 112 and the second signal electrode 114 are configured to receive a differential signal.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] The electrode structure of the signal electrode has a direct impact on the modulation effect and the RF transmission loss, so the electrode structure can be adjusted according to the performance requirements of the signal electrodes in different parts. In some embodiments, in the first straight extension section 110A, the first signal electrode 112 applies opposite electric fields to the first waveguide 121 and the second waveguide 122 for modulation. Some sub-electrodes can be set on the surface of the first signal electrode 112 facing the first waveguide 121 and / or the second waveguide 122, which is more conducive to adjusting the transmission speed of the waveguide and the transmission speed of the electrode to meet the speed matching requirements of the two, but this will increase the RF transmission loss to a certain extent. For example, a plurality of "T"-shaped sub-electrodes arranged at intervals can be set on the surface of the first signal electrode 112. In the second straight extension section 110C, since the first signal electrode 112 has no modulation requirements in this part and does not need to meet the transmission speed matching requirements, a modulation structure with smaller 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 use 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.

[0074] 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.

[0075] The first ground electrode 101, the second ground electrode 103 and the third ground electrode 105 are all ground electrodes, and their corresponding potentials are ground potentials. 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.

[0076] Considering that the length of the grounding electrode in the folded phase modulation module 100 is relatively long, connecting the first grounding electrode 101, the second grounding electrode 103 and the third grounding electrode 105 to each other at the bent connection portion 110B can make the potentials of the three grounding 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 the fluctuation of the potential difference at different positions.

[0077] The second aspect of the present disclosure provides an electro-optic modulator, such as Figure 5 As shown, Figure 5 Schematic diagram of the structure of the electro-optic modulator of 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.

[0078] The light splitting unit 210 may adopt a Y-branch beam splitting optical waveguide, and the light combining element 220 may adopt a Y-branch beam combining optical waveguide. In one example, the light splitting unit 210 is specifically a half-splitter, which is used to split the optical signal into two branch optical signals at a splitting ratio of 1:1 and output them to the input end of the first waveguide 121 and the input end of the second waveguide 122 respectively, and the light combining unit 220 is specifically a two-in-one light combiner, which is used 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.

[0079] 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 that are 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 referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present disclosure.

[0080] In addition, the terms "first", "second", "third", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", "third" may explicitly or implicitly include one or more of the feature. In the description of the present disclosure, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0081] In the present disclosure, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0082] In the present disclosure, unless otherwise expressly specified and limited, a first feature being “above” or “below” a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being “above”, “above”, and “above” a second feature includes that the first feature is 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 that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0083] 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 present specification, which should all be included in 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 attached 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, 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 5, 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 5, 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 5, 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 5, 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 5, 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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