Electro-optic modulators and electro-optic devices

Abstract

The electro-optical modulator includes an optical splitter (110), a first optical waveguide (120a) and a second optical waveguide (120b), a traveling wave electrode (130) including a first ground electrode (131), a first signal electrode (132), a second signal electrode (133) and a second ground electrode (134), and an extended electrode (140) including at least one first signal partial electrode (142a, 142b) and two second signal partial electrodes (143a, 143b), the two second signal partial electrodes (143a, 143b) being disposed on both sides of the at least one first signal partial electrode (142a, 142b), and the first optical waveguide (120a) includes two second signal partial electrodes (143a, 143b). The second signal partial electrode (143a or 143b) of the two second signal partial electrodes is disposed between the first signal partial electrode (142a or 142b) adjacent to the one second signal partial electrode, the second optical waveguide (120b) is disposed between the other second signal partial electrode (143a or 143b) of the two second signal partial electrodes and the first signal partial electrode (142a or 142b) adjacent to the other second signal partial electrode, the first signal electrode (132) is electrically connected to the first signal partial electrode (142a, 142b), and the second signal electrode (133) is electrically connected to the second signal partial electrode (143a, 143b). Further, an electro-optical device including an electro-optical modulator is provided.

Description

[Technical Field]

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

[0002] Electro-optic modulators are modulators made by using the electro-optic effect of several 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, thereby modulating the phase, amplitude, intensity, polarization state, and other properties of the optical signal. A common electro-optic modulator is the Mach-Zehnder modulator. This interferometer-type modulator primarily uses the phase difference between two arms within the modulator to achieve signal modulation for coherence enhancement and coherence cancellation.

[0003] However, the demand for higher speed, larger capacity, and more integrated communication technology is rapidly increasing, and it is desirable to minimize the size of integrated devices while maintaining the modulation effect of electro-optic modulators, which places high demands on electrode design. Summary of the Invention [Problem to be solved by the invention]

[0004] It would be advantageous to provide a mechanism that reduces, mitigates, or even eliminates one or more of the above-mentioned problems. [Means for solving the problem]

[0005] According to one aspect of the present disclosure, there is provided an electro-optic modulator including: an optical splitter configured to split an optical input signal into a first optical signal and a second optical signal; a first optical waveguide and a second optical waveguide configured to provide optical transmission paths for the first optical signal and the second optical signal, respectively; a traveling wave electrode extending along a first direction and configured to transmit a radio frequency signal, the traveling wave electrode including a first ground electrode, a first signal electrode, a second signal electrode, and a second ground electrode arranged in sequence along a second direction, the second direction intersecting the first direction; and an extension electrode disposed along the optical transmission path in a gap between the first signal electrode and the second signal electrode, the extension electrode configured to modulate the first optical signal and the second optical signal based on the radio frequency signal. The extended electrodes include at least one first signal partial electrode and two second signal partial electrodes arranged side by side in the second direction and each having a length direction parallel to the first direction, the two second signal partial electrodes being arranged on both sides of the at least one first signal partial electrode, the first optical waveguide being arranged between one second signal partial electrode of the two second signal partial electrodes and a first signal partial electrode adjacent to the one second signal partial electrode, and the second optical waveguide being arranged between the other second signal partial electrode of the two second signal partial electrodes and the other second signal partial electrode portion The electrode is disposed between the first signal portion electrode and the adjacent first signal portion electrode.

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

[0007] These and other aspects of the present disclosure will be apparent from and elucidated with reference to the embodiments described hereinafter.

[0008] Further details, features and advantages of the present disclosure are disclosed in the following description of exemplary embodiments with reference to the accompanying drawings. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic top view of an electro-optic modulator according to an exemplary embodiment. [Figure 2] 1 is a schematic top view of an electro-optic modulator according to an exemplary embodiment. [Figure 3] 1 is a schematic perspective view of an electro-optic modulator according to an exemplary embodiment; [Figure 4] 1 is a schematic perspective view of an electro-optic modulator according to an exemplary embodiment; [Figure 5] 1 is a schematic perspective view of an electro-optic modulator according to an exemplary embodiment; [Figure 6] 1 is a schematic perspective view of an electro-optic modulator according to an exemplary embodiment; [Figure 7] 1 is a schematic perspective view of an electro-optic modulator according to an exemplary embodiment; [Figure 8] 1 is a schematic perspective view of an electro-optic modulator according to an exemplary embodiment; [Figure 9] 1 is a schematic block diagram of an electro-optical device in accordance with an illustrative embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] In this disclosure, terms such as "first," "second," and the like used to describe various elements are not intended to limit the positional, temporal, or importance relationships of these elements, but are intended only to distinguish one element from another, unless otherwise specified. In some examples, a first element and a second element may refer to the same instance of an element, and in some cases, a first element and a second element may refer to different instances based on contextual descriptions.

[0011] The terms used in the description of various embodiments in this disclosure are merely for the purpose of describing particular embodiments and are not intended to be limiting. Where the number of elements is not specifically defined, one or more elements may be present unless otherwise clearly indicated by the context. Furthermore, the term "and / or" as used in this disclosure encompasses any and all possible combinations of the listed items.

[0012] Electro-optic modulation-related technologies have been widely developed and applied in optical communications, microwave photonics, laser beam deflection, wavefront modulation, and more. In a related technology, the Mach-Zehnder modulator, one signal electrode and two ground electrodes are used to input a signal in the form of 0 (ground signal), 1 (modulation voltage signal), 0 (ground signal), thereby generating two electric fields with opposite directions. The opposite electric field directions are used to realize opposite modulation of the two optical path signals located in the two electric fields, thereby generating a phase difference and achieving coherence enhancement or coherence cancellation.

[0013] However, achieving a sufficient phase difference requires a relatively large modulation voltage and a relatively long transmission distance. Existing electro-optic modulators have the disadvantages of being large in size or having low modulation efficiency, making it difficult to meet the current market demands for integration and high efficiency.

[0014] SUMMARY OF THE INVENTION Embodiments of the present disclosure provide an improved electro-optic modulator that may reduce, mitigate, or even eliminate the above-mentioned drawbacks.

[0015] 1 is a schematic top view of an electro-optic modulator 100 according to an exemplary embodiment. Referring to FIG. 1, the electro-optic modulator 100 may include an optical splitter 110, a first optical waveguide 120a, a second optical waveguide 120b, a traveling-wave electrode 130, and an extension electrode 140.

[0016] The traveling-wave electrode 130 may extend along a first direction D1 and include a first ground electrode 131, a first signal electrode 132, a second signal electrode 133, and a second ground electrode 134 arranged in sequence along a second direction D2. The traveling-wave electrode 130 extending along the first direction D1 refers to the length of the traveling-wave electrode 130 extending along the first direction D1. The extension electrode 140 may be arranged along the optical transmission path and include at least one first signal partial electrode (two first signal partial electrodes 142a and 142b in the embodiment shown in FIG. 1 ) of the first signal electrode 132 and two second signal partial electrodes 143a and 143b of the second signal electrode 133 arranged side by side in the second direction D2, each partial electrode having a length direction parallel to the first direction D1. Two second signal partial electrodes 143a and 143b are arranged on either side of at least one first signal partial electrode. As shown in FIG. 1, two first signal partial electrodes 142a and 142b are provided, and each of the two first signal partial electrodes 142a and 142b is located between the two second signal partial electrodes 143a and 143b. The first optical waveguide 120a is arranged between one second signal partial electrode 143a and the first signal partial electrode 142a adjacent to the second signal partial electrode 143a, and the second optical waveguide 120b is arranged between the other second signal partial electrode 143b and the first signal partial electrode 142b adjacent to the second signal partial electrode 143b. The second direction D2 intersects with the first direction D1. In the embodiment shown in FIG. 1, the second direction D2 is substantially perpendicular to the first direction D1.

[0017] In other embodiments, only one first signal partial electrode may be provided (not shown), and two second signal partial electrodes 143 a and 143 b are arranged on either side of the only one first signal partial electrode. The first optical waveguide 120 a is arranged between the only one first signal partial electrode and one second signal partial electrode 143 a of the second signal electrodes 133, and the second optical waveguide 120 b is arranged between the only one first signal partial electrode 142 b and the other second signal partial electrode 143 b of the second signal electrodes 133.

[0018] In some embodiments, as shown in FIG. 1 , an optical input signal passes through an optical splitter 110 and is split into a first optical signal and a second optical signal. The first optical signal and the second optical signal are transmitted along optical transmission paths provided by a first optical waveguide 120a and a second optical waveguide 120b, respectively. A voltage is applied to the first signal electrode 132 and the second signal electrode 133, respectively, and the first ground electrode 131 and the second ground electrode 134 are grounded. The first signal electrode 132 is electrically connected to first signal partial electrodes 142a and 142b, and the second signal electrode 133 is electrically connected to second signal partial electrodes 143a and 143b, such that each partial electrode has a potential equal to the potential of the traveling-wave electrode electrically connected to the partial electrode. When the first optical signal and the second optical signal pass through the gap between the extension electrodes 140, the potential difference between the partial electrodes may be used to modulate the optical signal.

[0019] In electro-optic modulators in the related art, electrodes on both sides of an optical waveguide are typically arranged so that one electrode is grounded and has a potential of 0, while the other electrode is applied with a voltage U. In this case, the potential difference between the two electrodes is U or -U, and this potential difference can be used to modulate two optical signals using potential differences of opposite polarity. However, in this embodiment of the present disclosure, partial electrodes are arranged on both sides of each optical waveguide, and the electrical connection structure of the partial electrodes is adjusted so that the partial electrodes on both sides of each optical waveguide have opposite potentials, such as -U and U. In this case, the potential difference between the partial electrodes on both sides of each optical waveguide is 2U or -2U. As the potential difference increases, the refractive index of the electro-optic crystal changes more rapidly, and the optical wave characteristics of the electro-optic crystal also change more rapidly, thereby enabling the ideal phase difference, such as π, to be reached more quickly. To achieve the same phase difference as the potential difference in the prior art, this embodiment of the present disclosure requires a shorter optical signal propagation distance under the same conditions, thereby significantly reducing the device size and saving space.

[0020] Continuing to refer to FIG. 1, the locations of the electrical connections cause each of the first signal partial electrodes 142a and 142b and the second signal partial electrodes 143a and 143b to be divided into one or more sections in the first direction D1.

[0021] Appropriately shortening the length of the corresponding partial electrode or dividing the corresponding partial electrode into multiple sections as required can minimize the transmission loss of the electrical signal, while minimizing the impact on the transmission speed of the electrical signal, and ensure that the transmission speed of the electrical signal is the same as or close to the transmission group velocity of the optical signal in the waveguide.

[0022] 1 , in some embodiments, the electro-optic modulator 100 may further include an optical combiner 150. After passing through the optical combiner 150, the modulated first and second optical signals are combined into an optically combined signal. The optically combined signal may be output as an optical output signal directly, or may be split into two or more optical output signals and output.

[0023] In some embodiments, the electro-optic modulator 100 further includes a protective layer configured to cover at least one component, for example, the traveling wave electrode 130 or the extended electrode 140, which may retard natural oxidation or accidental surface damage of the electrode and increase the useful life of the element.

[0024] In some embodiments, the first optical waveguide 120a and the second optical waveguide 120b are lithium niobate optical waveguides. Lithium niobate crystals are optical materials with smooth surfaces and excellent electro-optic and acousto-optic effects. High-quality optical waveguides prepared using lithium niobate crystals support ultra-low transmission loss and have many excellent properties, including mature technology, low cost, and mass production.

[0025] 2 is a schematic top view of an electro-optic modulator 200 according to an exemplary embodiment. Referring to FIG. 2, the electro-optic modulator 200 may include an optical splitter 210, a first optical waveguide 220a, a second optical waveguide 220b, a traveling-wave electrode 230, an extension electrode 240, and an optical coupler 250.

[0026] The traveling-wave electrode 230 may include a first ground electrode 231, a first signal electrode 232, a second signal electrode 233, and a second ground electrode 234 arranged in order along the second direction D2. The extended electrode 240 is arranged along the optical transmission path and includes at least one first signal partial electrode 242a and 242b and two second signal partial electrodes 243a and 243b arranged side by side in the second direction D2. The two second signal partial electrodes 243a and 243b are arranged on either side of the at least one first signal partial electrode 242a and 242b. The first optical waveguide 220a and the second optical waveguide 220b are each arranged to extend into the gap between one first signal partial electrode and the second signal partial electrode adjacent to the first signal partial electrode. Reference numerals similar to those in FIG. 1 indicate similar elements, and therefore detailed descriptions thereof have been omitted for the sake of brevity.

[0027] 2 differs from the electro-optic modulator 100 shown in FIG. 1 in that a first extension arm and a second extension arm 241 are provided between the traveling-wave electrode 230 and the extension electrode 240. The first extension arm is configured to electrically connect the first signal electrode 232 to the first signal sub-electrodes 242a and 242b. The second extension arm is configured to electrically connect the second signal electrode 233 to the second signal sub-electrodes 243a and 243b. In some embodiments, the first extension arm may be integrally formed with the first signal electrode 232 and the first signal sub-electrodes 242a and 242b, and the second extension arm may be integrally formed with the second signal electrode 233 and the second signal sub-electrodes 243a and 243b.

[0028] The above-described arrangement may stabilize the electrical connection between each signal electrode and its sub-electrodes, and facilitate device patterning and packaging integration.

[0029] 2 , the extension arm 241 divides each of the first signal partial electrodes 242 a and 242 b and the second signal partial electrodes 243 a and 243 b into one or more sections in the first direction D1. The length of the partial electrodes can be appropriately shortened or divided into multiple sections as required, which can minimize the transmission loss of the electrical signal while minimizing the impact on the transmission speed of the electrical signal and ensure that the transmission speed of the electrical signal is the same as or close to the transmission group velocity of the optical signal in the waveguide.

[0030] For convenience of explanation, the following description will be given using an example in which an extension arm is used as an electrical connection method between the traveling-wave electrode and the extension electrode. Of course, the electrical connection method between the traveling-wave electrode and the extension electrode is not limited thereto, and other methods may be used instead as long as an electrical signal can be transmitted from the traveling-wave electrode to the extension electrode.

[0031] The connecting shape between the extension arm and the partial electrode may be T-shaped or L-shaped. Of course, the connecting shape is not limited to the shape shown in this embodiment of the present disclosure. Other shapes may be adopted instead according to actual requirements to meet the appropriate speed.

[0032] 3 is a schematic perspective view of an electro-optic modulator 300 according to an example embodiment. The electro-optic modulator 300 may include a first optical waveguide 320a, a second optical waveguide 320b, a traveling-wave electrode 330, an extension electrode 340, and an extension arm 341.

[0033] 3, the traveling-wave electrode 330 may include a first ground electrode 331, a first signal electrode 332, a second signal electrode 333, and a second ground electrode 334 arranged in order along the second direction D2. The extended electrode 340 is arranged along the optical transmission path and includes two first signal partial electrodes 342a and 342b and two second signal partial electrodes 343a and 343b arranged side by side in the second direction D2. The two second signal partial electrodes 343a and 343b are arranged on both sides of every first signal partial electrode 342a and 342b. The first optical waveguide 320a is arranged to extend into the gap between one first signal partial electrode 342a and the adjacent second signal partial electrode 343a, and the second optical waveguide 320b is arranged to extend into the gap between the other first signal partial electrode 342b and the adjacent second signal partial electrode 343a. Like reference numerals to those in Figure 2 indicate like elements, and therefore detailed descriptions thereof have been omitted for the sake of brevity.

[0034] The electro-optic modulator 300 may further include a substrate 360, an insulating layer 370 on the substrate 360, a thin film layer 320 configured to form a first optical waveguide 320a and a second optical waveguide 320b, and a cover layer 380 on the first optical waveguide 320a and the second optical waveguide 320b.

[0035] 3, in some embodiments, traveling-wave electrode 330 may be located on thin-film layer 320, and extended electrode 340 may be located on cover layer 380. In this structure, the distance between partial electrodes on either side of the same optical waveguide is smaller, and the resulting electric field strength under the same conditions is larger, which may improve the electro-optical conversion efficiency.

[0036] In some embodiments, the traveling wave electrode 330 and the extended electrode 340 may be located within an insulating layer 370 .

[0037] In some embodiments, the traveling wave electrode 330 and the extended electrode 340 may be located on an insulating layer 370 .

[0038] In some embodiments, at least a portion of the traveling wave electrode 330 and at least a portion of the extended electrode 340 may be located within the thin film layer 320 .

[0039] In some embodiments, traveling wave electrodes 330 and extended electrodes 340 may be located on thin film layer 320, as shown in FIG.

[0040] 5 is a schematic perspective view of an electro-optic modulator 500 according to an example embodiment. The electro-optic modulator 500 may include a first optical waveguide 520a, a second optical waveguide 520b, a traveling-wave electrode 530, an extension electrode 540, an extension arm 541, a substrate 560, an insulating layer 570, a thin film layer 520, and a cover layer 580.

[0041] 5, the traveling-wave electrode 530 may include a first ground electrode 531, a first signal electrode 532, a second signal electrode 533, and a second ground electrode 534 arranged in order along the second direction D2. The extended electrode 540 is arranged along the optical transmission path and includes two first signal partial electrodes 542a and 542b and two second signal partial electrodes 543a and 543b arranged side by side in the second direction D2. The two second signal partial electrodes 543a and 543b are arranged on both sides of every first signal partial electrode 542a and 542b. The first optical waveguide 520a is arranged to extend into the gap between one first signal partial electrode 542a and the adjacent second signal partial electrode 543a, and the second optical waveguide 520b is arranged to extend into the gap between the other first signal partial electrode 542b and the adjacent second signal partial electrode 543b. Reference numerals similar to those in Figure 3 indicate similar elements, and therefore detailed descriptions thereof have been omitted for the sake of brevity.

[0042] The difference between the electro-optical modulator 500 shown in FIG. 5 and the electro-optical modulator 300 shown in FIG. 3 is that the covering layer extends to areas on the thin film layer 520 other than the first optical waveguide 520a and the second optical waveguide 520b, forming a covering layer 581 on the other areas.

[0043] 5 , in some embodiments, the traveling-wave electrode 530 may be located on a covering layer 581 covering other regions, and the extended electrode 540 may be located on the covering layer 580. In this structure, the thickness of the covering layer 580 and the covering layer 581 covering other regions may be adjusted according to actual requirements, thereby adjusting the transmission speed of the electrical signal and better achieving a match between the transmission speed of light and the transmission speed of electricity.

[0044] In some embodiments, as shown in FIG. 6, the traveling wave electrode 530 and the extended electrode 540 may be located on a cover layer 581 that covers other areas.

[0045] Of course, the positions of the traveling wave electrode 530 and the extension electrode 540 are not limited to the above example, and the positions of both may be flexibly adjusted to achieve a structure that is most conducive to device assembly and integration.

[0046] 7 is a schematic perspective view of an electro-optic modulator 700 according to an exemplary embodiment. Like reference numerals to those in FIG. 3 indicate like elements, and therefore detailed descriptions thereof have been omitted for the sake of brevity.

[0047] The difference between the electro-optic modulator 700 shown in FIG. 7 and the electro-optic modulator 300 shown in FIG. 3 is that a substrate 760 may be provided with a groove 761 .

[0048] The number of grooves is not limited to 1. Figure 8 is a schematic perspective view of an electro-optic modulator 800 according to an exemplary embodiment. Reference numerals similar to those in Figure 3 indicate similar elements, and therefore detailed descriptions thereof have been omitted for the sake of brevity.

[0049] The difference between the electro-optic modulator 800 shown in FIG. 8 and the electro-optic modulator 300 shown in FIG. 3 is that the substrate 860 may be provided with two grooves 861a and 861b.

[0050] In some embodiments, the insulating layer may also be grooved.

[0051] According to actual requirements, one or more grooves may be provided in the substrate or insulating layer, and parameters such as the shape, depth, and position of the grooves may be adjusted to adjust the transmission speed of the electrical signal and better achieve matching between the transmission speed of light and the transmission speed of electricity.

[0052] 9 is a simplified block diagram of an electro-optical device 900 according to an exemplary embodiment of the present disclosure. In one example, the electro-optical device 900 may include an electro-optical modulator 910, an electrical interface 911 coupled to the electro-optical modulator 910, and an optical interface 912 coupled to the electro-optical modulator 910. The electro-optical modulator 910 may be constructed according to any one of the embodiments described above.

[0053] Although embodiments or examples of the present invention have been described with reference to the drawings, it should be understood that the methods, systems, and devices described above are merely exemplary embodiments or examples, and that the scope of the present disclosure is not limited by the embodiments or examples, but is defined only by the appended claims and their equivalents. Various elements in the embodiments or examples may be omitted or replaced by equivalent elements. Furthermore, steps may be performed in an order different from that described in this disclosure. Furthermore, various elements in the 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 after this disclosure.

Claims

1. an optical splitter configured to split an optical input signal into a first optical signal and a second optical signal; a first optical waveguide and a second optical waveguide configured to provide optical transmission paths for the first optical signal and the second optical signal, respectively; a traveling wave electrode extending along a first direction and configured to transmit a radio frequency signal, a traveling wave electrode, the traveling wave electrode including a first ground electrode, a first signal electrode, a second signal electrode, and a second ground electrode arranged in that order along a second direction, the second direction intersecting the first direction; an extension electrode disposed along the optical transmission path in the gap between the first signal electrode and the second signal electrode, the extension electrode configured to modulate the first optical signal and the second optical signal based on the radio frequency signal; An electro-optic modulator comprising: the extension electrode includes at least one first signal partial electrode and two second signal partial electrodes arranged side by side in the second direction and each having a length direction parallel to the first direction; the two second signal partial electrodes are arranged on both sides of the at least one first signal partial electrode; the first optical waveguide is disposed between one second signal partial electrode of the two second signal partial electrodes and a first signal partial electrode adjacent to the one second signal partial electrode, and the second optical waveguide is disposed between the other second signal partial electrode of the two second signal partial electrodes and a first signal partial electrode adjacent to the other second signal partial electrode; the first signal electrode is electrically connected to the first signal partial electrode, the second signal electrode is electrically connected to the second signal partial electrode, and each partial electrode has a potential equal to the potential of the traveling wave electrode electrically connected thereto; a position of an electrical connection between the first signal electrode and the first signal partial electrode divides each of the first signal partial electrodes into two or more sections in the first direction, and a position of an electrical connection between the second signal electrode and the second signal partial electrode divides each of the second signal partial electrodes into two or more sections in the first direction; Electro-optic modulator.

2. 2. The electro-optic modulator of claim 1, further comprising a first extension arm and a second extension arm configured to electrically connect the first signal electrode to the first signal partial electrode and the second signal electrode to the second signal partial electrode, respectively.

3. 3. The electro-optic modulator of claim 2, wherein the first extension arm and the second extension arm divide the first signal partial electrode and the second signal partial electrode into one or more sections in the first direction by the first extension arm and the second extension arm, respectively.

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

5. 5. The electro-optic modulator according to claim 4, wherein the covering layer extends to an area on the thin film layer other than the first optical waveguide and the second optical waveguide.

6. 6. The electro-optic modulator of claim 4, wherein at least a portion of the traveling wave electrode and at least a portion of the extended electrode are located within the insulating layer.

7. 6. The electro-optic modulator of claim 4, wherein the traveling wave electrode and the extended electrode are located on the insulating layer.

8. 6. The electro-optic modulator of claim 4, wherein at least a portion of the traveling wave electrode and at least a portion of the extended electrode are located within the thin film layer.

9. 6. The electro-optic modulator of claim 4, wherein the traveling wave electrode and the extended electrode are located on the thin film layer.

10. the traveling wave electrode is located on the thin film layer; 5. The electro-optic modulator of claim 4, wherein the extended electrodes are located on the cover layer.

11. the traveling wave electrode is located on the covering layer that covers an area on the thin film layer other than the first optical waveguide and the second optical waveguide; 6. The electro-optic modulator of claim 5, wherein the extended electrodes are located on the cladding layer that covers the first optical waveguide and the second optical waveguide.

12. 6. The electro-optic modulator of claim 5, wherein the traveling wave electrode and the extended electrode are located on the cover layer that covers an area on the thin film layer other than the first optical waveguide and the second optical waveguide.

13. 5. The electro-optic modulator of claim 4, wherein the substrate is provided with grooves.

14. 5. The electro-optic modulator of claim 4, wherein the insulating layer is grooved.

15. 13. The electro-optic modulator of claim 1, further comprising an optical combiner configured to combine the first optical signal and the second optical signal into an optical output signal.

16. 13. The electro-optic modulator of any one of claims 1 to 5 and claims 10 to 12, wherein the first optical waveguide and the second optical waveguide are lithium niobate optical waveguides.

17. 13. The electro-optic modulator of any one of claims 1 to 5 and claims 10 to 12, further comprising a protective layer configured to cover at least one element.

18. An electro-optical device comprising the electro-optical modulator of claim 1.

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