Electro-optical modulator and electro-optical device

Abstract

An electro-optical modulator and an electro-optical device are provided. The electro-optical modulator includes a first optical waveguide, a second optical waveguide, and a traveling-wave electrode, the traveling-wave electrode includes a first ground electrode, a first signal electrode, a second signal electrode, and a second ground electrode that are spaced apart from each other, and the first optical waveguide and the second optical waveguide are both disposed between the first signal electrode and the second signal electrode. The electro-optical modulator has a plurality of extensions along its extension direction. The plurality of extensions includes a plurality of straight portions and at least one curved portion. Each curved portion is disposed between two adjacent straight portions. According to one or more embodiments of the present disclosure, since the electro-optical modulator uses a curved and folded design and the plurality of straight portions can be stacked together, the size in the length direction is greatly reduced when compared with a conventional electro-optical modulator, and the manufacturing cost of the electro-optical modulator can be reduced.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates to electro-optic modulation techniques, and in particular to electro-optic modulators and electro-optic devices. [Background technology]

[0002] An electro-optic modulator is a modulator that uses the electro-optic effect of some electro-optic crystals, such as lithium niobate (LiNbO3), gallium arsenide (GaAs), or lithium tantalate (LiTaO3). When a voltage is applied to the electro-optic crystal, the refractive index of the electro-optic crystal changes, resulting in modulation of the phase, amplitude, intensity, polarization state, and other properties of the optical signal. A common modulator among electro-optic modulators is the Mach-Zehnder modulator. This interferometric modulator mainly uses the phase difference between two arms in the modulator to achieve signal modulation of coherent enhancement and coherent cancellation.

[0003] However, with the rapidly growing demand for high-speed, high-capacity, integrated communication technology, it is desirable to minimize the size of the integrated device while ensuring the modulation effect of the electro-optic modulator, which places high demands on the electrode design. Summary of the Invention [Problem to be solved by the invention]

[0004] It would be advantageous to provide a mechanism for mitigating, alleviating or eliminating one or more of the aforementioned problems. [Means for solving the problem]

[0005] According to one aspect of the present disclosure, there is provided an electro-optical modulator comprising a first optical waveguide, a second optical waveguide, and a traveling-wave electrode, each of which is arranged to extend along an extension direction of the electro-optical modulator, the traveling-wave electrode comprising a first ground electrode, a first signal electrode, a second signal electrode, and a second ground electrode, each of which extends along the extension direction of the electro-optical modulator and is spaced apart from one another, the first optical waveguide and the second optical waveguide are both arranged between the first signal electrode and the second signal electrode, and an optical signal transmitted in the first optical waveguide and the second optical waveguide is subjected to voltage modulation between the first signal electrode and the second signal electrode, the electro-optical modulator has a plurality of extension portions along its extension direction, the plurality of extension portions comprising a plurality of straight portions and at least one curved portion each provided between two adjacent straight portions.

[0006] According to another aspect of the present disclosure, there is provided an electro-optic device comprising the electro-optic modulator described above.

[0007] According to one or more embodiments of the present disclosure, the electro-optic modulator uses a curved and folded design, and multiple straight sections can be stacked together, so that the lengthwise size is significantly reduced when compared with conventional electro-optic modulators, and the manufacturing cost of the electro-optic modulator can be reduced.

[0008] These and other aspects of the present disclosure will be apparent from and elucidated with reference to the embodiments described hereinafter.

[0009] Further details, features and advantages of the present disclosure are disclosed in the following description of exemplary embodiments with reference to the accompanying drawings. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a schematic top view of an electro-optic modulator according to an exemplary embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic top view of an electro-optic modulator according to another exemplary embodiment of the present disclosure. [Diagram 3] 2 is a schematic top view of a first type of straight section of an electro-optic modulator according to an exemplary embodiment of the present disclosure. FIG. [Figure 4] FIG. 2 is a schematic top view of a second type of straight section of an electro-optic modulator according to an exemplary embodiment of the present disclosure. [Diagram 5] FIG. 13 is a schematic top view of an electro-optic modulator according to yet another exemplary embodiment of the present disclosure. [Figure 6] FIG. 13 is a schematic top view of an electro-optic modulator according to yet another exemplary embodiment of the present disclosure. [Figure 7] FIG. 2 is a schematic perspective view of a straight section of an electro-optic modulator according to an exemplary embodiment of the present disclosure. [Figure 8] 1 is a schematic block diagram of an electro-optical device according to an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] In this disclosure, unless otherwise stated, the terms "first," "second," and the like, used to describe various elements are intended only to distinguish one element from another, not to limit the location, time, or importance relationship of those elements. In some instances, a first element and a second element may represent the same instance of an element, and in some cases, based on contextual descriptions, a first element and a second element may represent different instances.

[0012] In this disclosure, the terms used in the description of various examples are merely intended to describe specific examples and are not intended to be limiting in any way. Where the number of elements is not specifically specified, one or more elements may be present unless otherwise indicated by the context. Furthermore, the term "and / or" used in this disclosure includes any and all possible combinations of the described items.

[0013] Electro-optic modulation related technologies have been widely developed and applied in the fields of optical communication, microwave photonics, laser beam deflection, wavefront modulation, etc. In the prior art Mach-Zehnder modulator, the use of one signal electrode and two ground electrodes generates two electric fields in opposite directions by inputting signals in the form of 0 (ground signal), 1 (modulation voltage signal), and 0 (ground signal). That is, the "GSG" type electro-optic modulator described later. The use of opposite electric field directions performs reverse modulation of the two optical path signals placed in the two electric fields, thereby generating a phase difference to achieve coherent enhancement or coherent cancellation.

[0014] However, to achieve a sufficient phase difference, a relatively large modulation voltage and a relatively long transmission distance are required. Existing electro-optic modulators have the disadvantages of large size or low modulation efficiency, which makes it difficult to meet the integration and high efficiency requirements of the current market.

[0015] SUMMARY OF THE DISCLOSURE Embodiments of the present disclosure provide an improved electro-optic modulator that may mitigate, alleviate or eliminate the aforementioned disadvantages.

[0016] 1 is a schematic top view of an electro-optic modulator 1 according to an exemplary embodiment. Referring to FIG. 1, the electro-optic modulator 1 may include an optical splitter 110, an optical coupler 150, a first optical waveguide 120a, a second optical waveguide 120b, and a traveling wave electrode 130.

[0017] The traveling wave electrode 130 extends along the overall extension direction of the electro-optical modulator 1, and in one example may include a first ground electrode 131, a first signal electrode 132, a second signal electrode 133, and a second ground electrode 134, each extending along the extension direction of the electro-optical modulator 1 and spaced apart from each other. The first optical waveguide 120a and the second optical waveguide 120b are both disposed between the first signal electrode 132 and the second signal electrode 133, and configured such that the optical signals transmitted in the first optical waveguide 120a and the second optical waveguide 120b are subjected to voltage modulation between the first signal electrode 132 and the second signal electrode 133. In one example, the optical signals transmitted in the first optical waveguide 120a and the second optical waveguide 120b are modulated by two voltages of equal magnitude but opposite direction, respectively, to generate a phase difference between the two optical signals.

[0018] In this embodiment, since both the first optical waveguide 120a and the second optical waveguide 120b are disposed between the first signal electrode 132 and the second signal electrode 133, the differential voltage of the two signal electrodes is applied to the optical signal transmitted in the first optical waveguide 120a and the second optical waveguide 120b, thereby improving efficiency. In one example, the signals input to the first signal electrode 132 and the second signal electrode 133 are opposite (one is 1 and the other is -1). Compared with a conventional GSG electro-optic modulator (i.e., only one signal electrode is disposed between two ground electrodes, and the signal at the ground electrode is zero), in the electro-optic modulator of this embodiment, the magnitude of the differential signal between the first signal electrode 132 and the second signal electrode 133 is substantially twice that of the signal between the ground electrode and the signal electrode in the conventional GSG electro-optic modulator, so that the phase difference generated by the two optical waveguides between the two signal electrodes can be approximately doubled. Therefore, the differential electro-optic modulator of this embodiment has a higher modulation efficiency than the conventional GSG electro-optic modulator.

[0019] Furthermore, the electro-optical modulator 1 has a plurality of extension portions along its extension direction, and the plurality of extension portions includes a plurality of straight portions and at least one curved portion provided between each two adjacent straight portions. As an example, the electro-optical modulator 1 shown in FIG. 1 includes a first straight portion 11, a second straight portion 12, and a first curved portion 21 disposed between the first straight portion 11 and the second straight portion 12.

[0020] It is understood that in other embodiments of the present disclosure, the above-mentioned multiple extensions may include three or more straight portions. FIG. 2 is a schematic top view of an electro-optical modulator 1 according to another exemplary embodiment. As shown in FIG. 2, the electro-optical modulator 1 includes three straight portions 10 and two curved portions 20 so as to be substantially curved and folded into an "S" shape. In the above-mentioned embodiment, the curved portions 20 are designed as 180° arcs so that the multiple straight portions 10 are parallel to each other, but in other embodiments, the curved portions 20 may be designed as arcs of other angles, such as 90°, 60°, or 45°, i.e., the multiple straight portions 10 may not be parallel to each other. In some embodiments, the curved portions 20 may be curved in a non-arc shape. For example, they may be bent at a right angle.

[0021] According to one or more embodiments of the present disclosure, the electro-optical modulator 1 employs a curved and folded design, and multiple straight sections can be stacked together, so that the lengthwise size is significantly reduced compared to conventional electro-optical modulators, and the manufacturing cost of the electro-optical modulator can be reduced.

[0022] 1, the electro-optic modulator 1 further comprises a plurality of first electrode extensions 141 connected to and spaced apart from the first signal electrode 132, and a plurality of second electrode extensions 142 connected to and spaced apart from the second signal electrode 133. The plurality of first electrode extensions 141 are all arranged to extend toward the second signal electrode 133, and each includes a first sub-electrode 141a and a second sub-electrode 141b. The plurality of second electrode extensions 142 are all arranged to extend toward the first signal electrode 132, and each includes a third sub-electrode 142a and a fourth sub-electrode 142b.

[0023] The plurality of first electrode extensions 141 and the plurality of second electrode extensions 142 may all be arranged along the optical transmission path. In one example, the number of the first electrode extensions 141 is equal to the number of the second electrode extensions 142, and each of the first electrode extensions 141 and the corresponding second electrode extensions 142 form a group. Then, the first sub-electrode 141a of the first electrode extension 141 is arranged opposite to the third sub-electrode 142a of the second electrode extension 142, and the first optical waveguide 120a is between the first sub-electrode 141a and the third sub-electrode 142a. Also, the second sub-electrode 141b of the first electrode extension 141 is disposed opposite the fourth sub-electrode 142b of the second electrode extension 142, and the second optical waveguide 120b is between the second sub-electrode 141b and the fourth sub-electrode 142b. In one example, the above-mentioned first sub-electrode 141a, second sub-electrode 141b, third sub-electrode 142a, and fourth sub-electrode 142b are all disposed to extend along the same extension direction as the first optical waveguide 120a and the second optical waveguide 120b.

[0024] In some embodiments, as shown in Fig. 1, after passing through the optical splitter 110, the optical input signal is split into a first optical signal and a second optical signal, which are transmitted along the optical transmission paths provided by the first optical waveguide 120a and the second optical waveguide 120b, respectively. A voltage is applied to the first signal electrode 132 and the second signal electrode 133, and the first ground electrode 131 and the second ground electrode 134 are grounded. Since the first signal electrode 132 is electrically connected to the first sub-electrode 141a and the second sub-electrode 141b, and the second signal electrode 133 is electrically connected to the third sub-electrode 142a and the fourth sub-electrode 142b, each of the sub-electrodes has the same potential as the traveling-wave electrode to which it is electrically connected. When the first optical signal and the second optical signal pass through the gap of the traveling-wave electrode 130, the first sub-electrode 141a and the third sub-electrode 142a can modulate the first optical signal, and the second sub-electrode 141b and the fourth sub-electrode 142b can modulate the second optical signal.

[0025] In the embodiment of the present disclosure, the sub-electrodes are disposed on the two sides of each optical waveguide, and the electrical connection structure of the sub-electrodes is configured so that the sub-electrodes on the two sides of each optical waveguide have opposite potentials. For example, the first sub-electrode 141a and the third sub-electrode 142a have potentials of U and -U, respectively. In this case, the potential difference between the sub-electrodes on the two sides of each optical waveguide is 2U or -2U. The larger the potential difference, the larger the change in the refractive index of the electro-optic crystal, and therefore the larger the change in the light wave characteristics of the electro-optic crystal, and the faster the ideal phase difference can be achieved. To achieve the same phase difference as the prior art (e.g., the GSG-type electro-optic modulator), the optical signal propagation distance required under the same conditions is shorter in the embodiment of the present disclosure, so that the space can be significantly saved by significantly reducing the size of the equipment.

[0026] As described above, the electro-optical modulator 1 includes a plurality of straight portions, which are divided into two types including a first type of straight portion and a second type of straight portion. FIG. 3 is a schematic diagram of a first type of straight portion 10a according to an embodiment of the present disclosure, and FIG. 4 is a schematic diagram of a second type of straight portion 10b according to an embodiment of the present disclosure. For convenience of explanation, the first optical waveguide 120a is defined as having a first side facing the second optical waveguide 120b and a second side away from the second optical waveguide 120b, and the second optical waveguide 120b is defined as having a third side facing the first optical waveguide 120a and a fourth side away from the first optical waveguide 120a. As shown in FIG. 3, the first type of straight portion 10a is configured such that the first sub-electrode 141a and the second sub-electrode 141b are arranged on the first side of the first optical waveguide 120a and the third side of the second optical waveguide 120b, respectively, and the third sub-electrode 142a and the fourth sub-electrode 142b are arranged on the second side of the first optical waveguide 120a and the fourth side of the second optical waveguide 120b, respectively. As shown in Fig. 4, the second type straight section 10b is configured such that the first sub-electrode 141a and the second sub-electrode 141b are arranged on the second side of the first optical waveguide 120a and the fourth side of the second optical waveguide 120b, respectively, and the third sub-electrode 142a and the fourth sub-electrode 142b are arranged on the first side of the first optical waveguide 120a and the third side of the second optical waveguide 120b. As can be seen in Fig. 3 and Fig. 4, the first type straight section 10a differs from the second type straight section 10b in that the positions of the first sub-electrode 141a and the second sub-electrode 141b are exchanged with the positions of the third sub-electrode 142a and the fourth sub-electrode 142b with respect to the first optical waveguide 120a and the second optical waveguide 120b.

[0027] It will be appreciated that both the first type of straight section 10a and the second type of straight section 10b allow the sub-electrodes on the two sides of each optical waveguide to have opposite potentials.

[0028] 1 and 2, it should be noted that the plurality of first electrode extensions 141 and the plurality of second electrode extensions 142 are provided only in the straight portion 10, and no electrode extensions are provided in the curved portion 20. In other words, the optical signals in the first optical waveguide 120a and the second optical waveguide 120b are modulated only in the straight portion 10.

[0029] In some embodiments, as shown in FIG. 1, the multiple extensions of the electro-optic modulator 1 include a first straight portion 11, a second straight portion 12, and a first curved portion 21 provided between the first straight portion 11 and the second straight portion 12. The first optical waveguide 120a and the second optical waveguide 120b are arranged to extend apart at the first curved portion 21. That is, the first optical waveguide 120a and the second optical waveguide 120b are in their respective extension paths without intersecting each other. In this case, the first straight portion 11 and the second straight portion 12 are the same type of straight portion. As shown in FIG. 1, both the first straight portion 11 and the second straight portion 12 are the first type of straight portion 10a as described above.

[0030] In the electro-optical modulator 1 shown in FIG. 1, the first optical waveguide 120a and the second optical waveguide 120b do not exchange positions with each other at the curved portion, in other words, the positions of the first optical waveguide 120a and the second optical waveguide 120b relative to the first signal electrode 132 and the second signal electrode 133 do not change. Therefore, the first straight portion 11 and the second straight portion 12 need to be the same type of straight portion so that the direction of the voltage signal applied to the first optical waveguide 120a and the second optical waveguide 120b, respectively, does not change. In the embodiment shown in FIG. 1, both the first straight portion 11 and the second straight portion 12 are the first type of straight portion 10a, but it is understood that in other embodiments, both the first straight portion 11 and the second straight portion 12 may be the second type of straight portion 10b.

[0031] 5 is a schematic top view of an electro-optical modulator 1 according to another exemplary embodiment of the present disclosure. As shown in FIG. 5, the multiple extensions of the electro-optical modulator 1 include a third straight portion 13, a fourth straight portion 14, and a second curved portion 22 provided between the third straight portion 13 and the fourth straight portion 14. As shown in FIG. 5, the first optical waveguide 120a and the second optical waveguide 120b are arranged to intersect at the second curved portion 22. In this case, the third straight portion 13 and the fourth straight portion 14 are different types of straight portions. As shown in FIG. 5, the third straight portion 13 is a first type of straight portion 10a, and the fourth straight portion 14 is a second type of straight portion 10b.

[0032] 5, the first optical waveguide 120a and the second optical waveguide 120b exchange positions with each other at the curved portion, in other words, the positions of the first optical waveguide 120a and the second optical waveguide 120b relative to the first signal electrode 132 and the second signal electrode 133 change. In one example, the first optical waveguide 120a, which is initially close to the first signal electrode 132, becomes closer to the second signal electrode 133, and the second optical waveguide 120b, which is initially close to the second signal electrode 133, becomes closer to the first signal electrode 132. Therefore, the third straight portion 13 and the fourth straight portion 14 need to be different types of straight portions so that the directions of the voltage signals applied to the first optical waveguide 120a and the second optical waveguide 120b, respectively, do not change. In the embodiment shown in FIG. 5, the third straight portion 13 and the fourth straight portion 14 are the first and second types of straight portions 10a, 10b, respectively, but it will be understood that in other embodiments, the third straight portion 13 and the fourth straight portion 14 may be the second and first types of straight portions 10b, 10a, respectively.

[0033] In the embodiment shown in FIG. 1 and FIG. 5 above, only the electro-optic modulator 1 including three extensions is shown, but it is understood that in other embodiments, the electro-optic modulator 1 may include four or more extensions (e.g., five, seven, or nine extensions). All of the multiple extensions of the electro-optic modulator 1 may be arranged as in the example shown in FIG. 1, i.e., all adjacent straight sections are the same type of straight section, and the first optical waveguide 120a and the second optical waveguide 120b are arranged to extend apart at a curved section. Alternatively, all of the multiple extensions may be arranged as in the example shown in FIG. 5, i.e., all adjacent straight sections are different types of straight sections, and the first optical waveguide 120a and the second optical waveguide 120b are arranged to intersect at a curved section. As a further alternative, the multiple extensions may be a combination of the examples shown in FIG. 1 and FIG. 5, i.e., some adjacent straight sections are the same type of straight section, and some are different types of straight sections. In short, embodiments of the present disclosure are not limited by the number, type, and distribution of extensions.

[0034] 1, the first electrode extension 141 further includes a first extension arm 141c, and the second electrode extension 142 further includes a second extension arm 142c, and in one example, the first extension arm 141c and the second extension arm 142c are both disposed perpendicular to the traveling wave electrode 130. The first extension arm 141c is configured to electrically connect the first signal electrode 132 to the first sub-electrode 141a and the second sub-electrode 141b. The second extension arm 142c is configured to electrically connect the second signal electrode 133 to the third sub-electrode 142a and the fourth sub-electrode 142b. In some embodiments, the first extension arm 141c may be integrally formed with the first signal electrode 132, the first sub-electrode 141a, and the second sub-electrode 141b, and the second extension arm 142c may be integrally formed with the second signal electrode 133, the third sub-electrode 142a, and the fourth sub-electrode 142b.

[0035] The above configuration can stabilize the electrical connection between each signal electrode and its sub-electrodes, and facilitate device patterning and packaging integration.

[0036] For convenience of explanation, the following is exemplified as an electrical connection method between the traveling-wave electrode 130 and each sub-electrode using the extension arm. Of course, the electrical connection method between the traveling-wave electrode 130 and each sub-electrode is not limited thereto, and other methods may be used as long as an electrical signal can be transmitted from the traveling-wave electrode 130 to the corresponding sub-electrode.

[0037] In the above embodiment, the connection of the extension arm and the secondary electrode is L-shaped, i.e., the secondary electrode extends from only one side of the corresponding extension arm, but it is understood that the connection of the extension arm and the secondary electrode can be T-shaped, i.e., the secondary electrode extends from two sides of the corresponding extension arm, or other feasible shapes can be used. Of course, the shapes shown in the embodiments of the present disclosure are not limiting, and other shapes can be used based on the actual needs to achieve suitable velocity matching.

[0038] 6 is a schematic top view of an electro-optical modulator 1 according to yet another embodiment of the present disclosure. As shown in FIG. 6, the multiple extensions of the electro-optical modulator 1 include a fifth straight section 15, a first transition section 31, a third curved section 23, a second transition section 32, and a sixth straight section 16, which are connected in sequence. Unlike the electro-optical modulator 1 shown in FIG. 1, an additional transition section is provided between directly adjacent straight and curved sections, and the transition section is configured such that the shape of each straight section gradually changes to the shape of the curved section.

[0039] In some embodiments, the width of at least one of the first signal electrode 132, the second signal electrode 133, the first ground electrode 131, and the second ground electrode 134 in the straight portion is different from the width of the corresponding electrode in the curved portion. As shown in Fig. 6, the width of the first ground electrode 131, the first signal electrode 132, the second signal electrode 133, and the second ground electrode 134 in the third curved portion 23 is smaller than the width of the first ground electrode 131, the first signal electrode 132, the second signal electrode 133, and the second ground electrode 134 in the fifth straight portion 15, respectively.

[0040] Since the total extension of the inner electrodes (e.g., the second ground electrode 134 and the second signal electrode 133) is different from the total extension of the outer electrodes (e.g., the first ground electrode 131 and the first signal electrode 132), it may be necessary to design each of the electrodes (e.g., set the electrode width of each electrode) so that the transmission times of the electrical signals on the inner and outer electrodes are as similar as possible. Therefore, the width of each electrode in the straight and curved portions may be set to different specific values ​​so that the transmission times of the electrical signals on the inner and outer electrodes are as similar as possible.

[0041] As mentioned above, the width of each electrode in the straight section is different from the width of the corresponding electrode in the curved section. Therefore, in the embodiment shown in Fig. 6, a transition section is additionally provided between the straight section and the curved section, where the width of each electrode in the straight section gradually changes to the width of the corresponding electrode in the curved section, thereby avoiding abrupt changes in the electrode width and making the transmission of electrical signals unstable.

[0042] Continuing to refer to FIG. 1, in some embodiments, the electro-optical modulator 1 may further include an optical splitter 110 and an optical combiner 150. The optical splitter 110 is configured to split the optical input signal into optical signals transmitted in the first optical waveguide 120a and the second optical waveguide 120b. The modulated first optical signal and the second optical signal are combined into an optical combined signal after passing through the optical combiner 150. The optical combined signal may be directly output as an optical output signal or may be split into two or more optical output signals before being output.

[0043] In some embodiments, the electro-optic modulator 1 further comprises a protective layer configured to cover at least one component, for example, the traveling wave electrode 130, the first electrode extension 141, and the second electrode extension 142, which can retard natural oxidation or accidental surface damage of the electrodes and increase the service life of the elements.

[0044] In some embodiments, the first optical waveguide 120a and the second optical waveguide 120b are lithium niobate optical waveguides. Lithium niobate crystal is an optical material with a smooth surface and excellent electro-optic and acousto-optic effects. High-quality optical waveguides made using lithium niobate crystal can support ultra-low transmission loss and have many excellent properties, such as mature technology, low cost, and mass production.

[0045] 7 is a schematic perspective view of a straight portion of an electro-optic modulator 1 according to an example embodiment. As shown in FIG 7, the electro-optic modulator 1 may include a first optical waveguide 120a, a second optical waveguide 120b, a traveling-wave electrode 130, a first electrode extension 141, and a second electrode extension 142.

[0046] 7, the electro-optic modulator 1 may further include a substrate 210, an insulating layer 220 disposed on the substrate, a thin film layer 230 configured to form the first optical waveguide 120a and the second optical waveguide 120b, and a cladding layer 240 disposed on the first optical waveguide 120a and the second optical waveguide 120b. The cladding layer 240 includes a first cladding layer 241 disposed on the first optical waveguide 120a and a second cladding layer 242 disposed on the second optical waveguide 120b.

[0047] 7, in some embodiments, traveling-wave electrode 130 may be disposed on thin film layer 230, and first electrode extension 141 and second electrode extension 142 may be disposed on cover layer 240. As a result of this structural arrangement, the distance between sub-electrodes on two sides of the same optical waveguide is reduced, resulting in higher electric field strength under the same conditions, and improving the electro-optical conversion efficiency.

[0048] In some embodiments, the first electrode extension 141 and the second electrode extension 142 both extend to the upper surfaces of the first covering layer 241 and the second covering layer 242. The first sub-electrode 141a and the third sub-electrode 142a are disposed on the upper surface of the first covering layer 241, and the second sub-electrode 141b and the fourth sub-electrode 142b are disposed on the upper surface of the second covering layer 242. In one example, in this embodiment, the first covering layer 241 and the second covering layer 242 may be two structures that extend along the direction of the optical waveguide and protrude upward (i.e., protrude in the D3 direction shown in FIG. 7). In one example, the cross section of these protrusions is trapezoidal. With respect to the first covering layer 241, for example, the first optical waveguide 120a is centrally disposed under the first covering layer 241, and the first sub-electrode 141a and the third sub-electrode 142a are disposed on the upper surface of the trapezoidal body of the first covering layer 241 and aligned with each other. It will thus be understood that the first electrode extension 141 passes over the first optical waveguide 120a via the first covering layer 241, thereby preventing the first extension arm 141c of the first electrode extension 141 from interfering with the first optical waveguide 120a.

[0049] In the embodiment shown in FIG. 7, traveling wave electrode 130 , first electrode extension 141 and second electrode extension 142 may be disposed on thin film layer 230 .

[0050] In some embodiments, at least a portion of traveling-wave electrode 130 and at least a portion of first electrode extension 141 and second electrode extension 142 may be disposed in thin-film layer 230. In the embodiment shown in FIG. 7, traveling-wave electrode 130, first electrode extension 141, and second electrode extension 142 are disposed on thin-film layer 230, although in other embodiments, these elements may be disposed in thin-film layer 230.

[0051] In addition, in some embodiments, the traveling wave electrode 130, the first electrode extension 141, and the second electrode extension 142 may be disposed on the insulating layer 220 or in the insulating layer 220.

[0052] 8 is a simplified block diagram of an electro-optical device 800 according to an exemplary embodiment of the present disclosure. In one example, the electro-optical device 800 may include an electro-optical modulator 810, an electrical interface 811 coupled to the electro-optical modulator 810, and an optical interface 812 coupled to the electro-optical modulator 810. The electro-optical modulator 810 may be configured according to any one of the embodiments described above.

[0053] Although the embodiments and examples of the present disclosure have been described above with reference to the drawings, it is to be understood that the above-mentioned methods, systems, and devices are merely exemplary embodiments or examples, and the scope of the present disclosure is not limited to these embodiments or examples, but is defined only by the patented claims and their equivalents. Various elements in these embodiments or examples may be omitted or replaced by their equivalent elements. Furthermore, these steps may be performed in a different order than the order described in this disclosure. Furthermore, various elements in these embodiments or examples may be combined in various ways. It is important to note that as technology evolves, many elements described herein may be replaced by equivalent elements that appear later in this disclosure.

Claims

1. 1. An electro-optic modulator comprising: a first optical waveguide, a second optical waveguide, and a traveling wave electrode, each of which is arranged to extend along an extension direction of the electro-optic modulator; the traveling wave electrode comprises a first ground electrode, a first signal electrode, a second signal electrode, and a second ground electrode spaced apart from one another, and a differential voltage between the first signal electrode and the second signal electrode is applied to an optical signal transmitted in the first optical waveguide and the second optical waveguide; the first optical waveguide and the second optical waveguide are both disposed between the first signal electrode and the second signal electrode, and an optical signal transmitted in the first optical waveguide and the second optical waveguide is configured to be subjected to voltage modulation between the first signal electrode and the second signal electrode; the electro-optic modulator has a plurality of extension portions along the extension direction; The plurality of extension portions include a plurality of straight portions and at least one curved portion provided between two adjacent straight portions; a plurality of first electrode extensions connected to and spaced apart from the first signal electrode and all arranged to extend toward the second signal electrode, each of the first electrode extensions comprising a first sub-electrode and a second sub-electrode; a plurality of second electrode extensions connected to and spaced apart from the second signal electrode and all arranged to extend toward the first signal electrode, each of the second electrode extensions comprising a third sub-electrode and a fourth sub-electrode; the first sub-electrode and the third sub-electrode are respectively disposed on two side surfaces of the first optical waveguide; An electro-optic modulator, wherein the second sub-electrode and the fourth sub-electrode are respectively disposed on two sides of the second optical waveguide.

2. the first optical waveguide has a first side facing the second optical waveguide and a second side away from the second optical waveguide, the second optical waveguide has a third side facing the first optical waveguide and a fourth side away from the first optical waveguide, the plurality of straight portions comprises a first type of straight portion and / or a second type of straight portion; the first type of straight portion is configured such that the first sub-electrode and the second sub-electrode are disposed on the first side surface of the first optical waveguide and the third side surface of the second optical waveguide, respectively, and the third sub-electrode and the fourth sub-electrode are disposed on the second side surface of the first optical waveguide and the fourth side surface of the second optical waveguide; 2. The electro-optical modulator of claim 1, wherein the second type of straight portion is configured such that the first sub-electrode and the second sub-electrode are disposed on the second side of the first optical waveguide and the fourth side of the second optical waveguide, respectively, and the third sub-electrode and the fourth sub-electrode are disposed on the first side of the first optical waveguide and the third side of the second optical waveguide.

3. each of the first electrode extensions further comprising a first extension arm configured to connect the first sub-electrode and the second sub-electrode to the first signal electrode; 2. The electro-optic modulator of claim 1, wherein the second electrode extension further comprises a second extension arm configured to connect the third sub-electrode and the fourth sub-electrode to the second signal electrode, respectively.

4. the number of the first electrode extensions is equal to the number of the second electrode extensions; the first sub-electrode of each of the first electrode extensions is disposed opposite the third sub-electrode of the corresponding second electrode extension; 2. The electro-optic modulator of claim 1, wherein the second sub-electrode of each of the first electrode extensions is disposed opposite the fourth sub-electrode of the corresponding second electrode extension.

5. the plurality of extension portions include a first straight portion, a second straight portion, and a first curved portion provided between the first straight portion and the second straight portion; the first optical waveguide and the second optical waveguide are arranged to extend apart at the first curved portion; The electro-optic modulator of claim 2 , wherein the first linear portion and the second linear portion are the same type of linear portion.

6. the plurality of extension portions include a third straight portion, a fourth straight portion, and a second curved portion provided between the third straight portion and the fourth straight portion; the first optical waveguide and the second optical waveguide are arranged to intersect at the second curved portion; The electro-optic modulator of claim 2 , wherein the third linear portion and the fourth linear portion are different types of linear portions.

7. 2. The electro-optic modulator of claim 1, wherein a width at the straight portion of at least one of the first signal electrode, the second signal electrode, the first ground electrode, and the second ground electrode is different from a width at the curved portion of the corresponding electrode.

8. the plurality of extensions further comprising a plurality of transition sections each configured to connect the straight portion to a curved portion directly adjacent the straight portion; 8. The electro-optical modulator of claim 7, wherein in each of the transition sections, the width of each of the first signal electrode, the second signal electrode, the first ground electrode, and the second ground electrode gradually changes from the width of the corresponding electrode at the straight portion to the width of the corresponding electrode at the curved portion along a direction from the straight portion to the curved portion.

9. A substrate; an insulating layer disposed on the substrate; a thin film layer configured to form the first optical waveguide and the second optical waveguide; a first coating layer disposed on the first optical waveguide; a second coating layer disposed on the second optical waveguide; The electro-optic modulator of claim 1 further comprising:

10. The electro-optic modulator of claim 9 , wherein the first electrode extension and the second electrode extension both extend to a top surface of the first cover layer and the second cover layer.

11. the first sub-electrode and the third sub-electrode are disposed on an upper surface of the first covering layer; 11. The electro-optic modulator of claim 10, wherein the second sub-electrode and the fourth sub-electrode are disposed on an upper surface of the second cover layer.

12. an optical splitter configured to split an optical input signal into optical signals transmitted in the first optical waveguide and the second optical waveguide; an optical coupler configured to recombine the optical signals transmitted in the first optical waveguide and the second optical waveguide into an optical output signal; The electro-optic modulator of claim 1 further comprising:

13. An electro-optical device comprising an electro-optical modulator according to any one of claims 1 to 12.

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