Antenna electrode electro-optic modulator

Abstract

To provide an antenna electrode electrooptic modulator capable of performing electro-optical conversion with higher conversion efficiency than the conventional art.SOLUTION: An antenna electrode electrooptic modulator 10 comprises: a base substrate 12; patch antennas 20 to 23 arranged in a y-axis direction on an upper surface of the base substrate 12; and an electro-optical crystal substrate 14 composed of dielectric materials, arranged over the patch antennas 20 to 23. Each of the patch antennas 20 to 23 includes a first antenna element 20a, a first line 20b, a resonant electrode 20c, a second line 20d, and a second antenna element 20e all of which are arranged along an x-axis direction. An optical waveguide 30 extending in the y-axis direction is formed on a surface of the electro-optical crystal substrate 14 facing the patch antennas 20 to 23. The electro-optical crystal substrate 14 is only arranged above the resonant electrode 20c from among above the patch antennas 20 to 23.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present disclosure relates to an antenna electrode electro-optic modulator that modulates an optical signal with a wireless signal and outputs the modulated signal. [Background technology]

[0002] Mobile wireless communication systems are entering the fifth generation (5G). The features of the 5G system are high-speed data transfer, low latency, and simultaneous connection of multiple terminals. Furthermore, research and development of the next generation of 5G (Beyond 5G / 6G) has also begun.

[0003] Under these circumstances, millimeter waves are expected to be the mainstay of next-generation and next-next-generation mobile communications and high-resolution radar systems. However, millimeter waves have a problem of large propagation loss, which is a significant constraint in terms of signal transmission and signal processing. For this reason, RoF (Radio-over-Fiber) technology, which converts millimeter waves into optical signals and transmits them using low-loss quartz optical fibers, is useful. In the future, it is expected that various devices, systems, and applications using millimeter waves will be created, so devices that convert millimeter-wave wireless signals to optical signals are expected to become even more important.

[0004] Therefore, an antenna electrode electro-optic modulator has been proposed as a RoF-based wireless communication technology for next-generation (Beyond 5G) wireless communication (see, for example, Patent Document 1). Patent Document 1 discloses an antenna electrode electro-optic modulator that combines a planar antenna and an electro-optic modulator. This antenna electrode electro-optic modulator has a configuration in which antenna electrodes are arranged in an array along a single-mode optical waveguide. The antenna electrode is configured by coupling a pair of microstrip patch antennas to a standing wave resonant electrode. This converts a millimeter wave wireless signal into an optical signal without requiring a power source. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6739808 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the antenna electrode electro-optical modulator of Patent Document 1 uses plate-shaped LiNbO3, and as the frequency increases, resonance occurs throughout the entire plate-shaped LiNbO3 layer, resulting in a problem of a decrease in the conversion efficiency in electro-optical conversion.

[0007] Therefore, the present disclosure has been made in consideration of the above problems, and has an object to provide an antenna electrode electro-optical modulator that can perform electro-optical conversion with higher conversion efficiency than conventional ones. [Means for solving the problem]

[0008] In order to achieve the above object, an antenna electrode electro-optical modulator according to one embodiment of the present disclosure is an antenna electrode electro-optical modulator that modulates an optical signal with a radio signal and outputs the modulated optical signal, comprising: a base substrate; a plurality of patch antennas arranged in a first direction on an upper surface of the base substrate and receiving the radio signal; and an electro-optical crystal substrate made of a dielectric material arranged above the plurality of patch antennas, each of the plurality of patch antennas having a first antenna element, a first line connected to the first antenna element, a resonant electrode connected to the first line, a second line connected to the resonant electrode, and a second antenna element connected to the second line, arranged along a second direction perpendicular to the first direction on the upper surface of the base substrate, and an optical waveguide for transmitting the optical signal is formed on a surface of the electro-optical crystal substrate facing the plurality of patch antennas, the optical waveguide extending in the first direction at a position corresponding to above the resonant electrode, and the electro-optical crystal substrate is arranged in a first direction above the plurality of patch antennas, A portion of the first line; The resonance electrode and a part of the second line It is placed only above. Effect of the Invention

[0009] The present disclosure provides an antenna electrode electro-optical modulator that can perform electro-optical conversion with higher conversion efficiency than conventional techniques. [Brief description of the drawings]

[0010] [Figure 1A] FIG. 1A is an external view showing the configuration of an antenna electrode electro-optic modulator according to an embodiment. [Figure 1B] FIG. 1B is a cross-sectional view of the antenna electrode electro-optic modulator shown in FIG. 1A taken along a plane including line 1B-1B. [Figure 1C] FIG. 1C is a plan view of one patch antenna included in the antenna electrode electro-optic modulator shown in FIG. 1A. [Diagram 2] FIG. 2 is a diagram showing the analysis results of the patch antenna portion of the antenna electrode electro-optic modulator shown in FIG. 1A. [Diagram 3] FIG. 3 is a diagram showing the analysis results of the resonant electrode portion of the antenna electrode electro-optic modulator shown in FIG. 1A. [Figure 4] FIG. 4 is a diagram showing the analysis results of the entire patch antenna in which the patch antenna portion and the resonant electrode portion are coupled together. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. Each of the embodiments described below shows a specific example of the present disclosure. The numerical values, shapes, materials, components, the arrangement and connection of the components, steps, and the order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure. In addition, each figure is not necessarily a strict illustration. In each figure, the same reference numerals are used for substantially the same configurations, and duplicated explanations are omitted or simplified.

[0012] FIG. 1A is an external view showing a configuration of an antenna electrode electro-optical modulator 10 according to an embodiment. Here, a see-through external view of the antenna electrode electro-optical modulator 10 is shown, as seen obliquely from above. FIG. 1B is a cross-sectional view obtained by cutting the antenna electrode electro-optical modulator 10 shown in FIG. 1A along a plane including line 1B-1B. FIG. 1C is a plan view of one patch antenna 20 included in the antenna electrode electro-optical modulator 10 shown in FIG. 1A. Although one patch antenna 20 is shown in FIG. 1C, the other patch antennas 21 to 23 have the same structure as the patch antenna 20. Also, FIGS. 1A to 1C show an x-axis, a y-axis, and a z-axis that are orthogonal to each other.

[0013] The antenna electrode electro-optical modulator 10 is an electro-optical modulator that can perform electro-optical conversion with higher conversion efficiency than conventional ones without requiring a power source, and as shown in FIG. 1A, its main components include a base substrate 12, a plurality of patch antennas 20-23 arranged in a line in a first direction (y-axis direction) on the upper surface of the base substrate 12 and receiving a wireless signal 40, and an electro-optical crystal substrate 14 made of a dielectric material arranged above the plurality of patch antennas 20-23.

[0014] As shown in FIG. 1B, a buffer layer 16, which is an insulating layer that covers the lower surface of the electro-optic crystal substrate 14, the upper surface of the base substrate 12, and the patch antennas 20-23, is provided between the electro-optic crystal substrate 14 and the base substrate 12.

[0015] As shown in FIG. 1C, each of the multiple patch antennas 20 to 23 has a first antenna element 20a arranged along a second direction (x-axis direction) perpendicular to a first direction (y-axis direction) on the upper surface of the base substrate 12, a first line 20b connected to the first antenna element 20a, a resonant electrode 20c connected to the first line 20b, a second line 20d connected to the resonant electrode 20c, and a second antenna element 20e connected to the second line 20d.

[0016] As shown in Figures 1A and 1B, an optical waveguide 30 for transmitting an optical signal (i.e., light) 35 is formed on the surface of the electro-optic crystal substrate 14 facing the multiple patch antennas 20-23, extending in a first direction (y-axis direction) at a position corresponding to above the resonant electrode 20c.

[0017] A characteristic feature here is that, in the cross section shown in FIG. 1B, the electro-optic crystal substrate 14 is disposed only above the resonant electrode 20c among the plurality of patch antennas 20 to 23.

[0018] Each of the components constituting the antenna electrode electro-optic modulator 10 will now be described in detail.

[0019] The base substrate 12 is a reinforcing substrate for reducing the effective dielectric constant of the antenna electrode electro-optical modulator 10 to improve the performance of the patch antennas 20-23 (particularly, the resonant electrode 20c) and for preventing the electro-optical crystal substrate 14 from cracking when subjected to external forces from the patch antennas 20-23, and is, for example, a substrate made of SiO2 with a thickness of approximately 57 μm and a ground pattern 12a applied to its bottom surface.

[0020] The buffer layer 16 is, for example, a thin film made of SiO2 and has a thickness of 0.2 μm. Patch antennas 20-23 are formed on the lower surface of the buffer layer 16. The buffer layer 16 on which the patch antennas 20-23 are formed and the base substrate 12 are bonded with an adhesive made of an ultraviolet curing resin or the like.

[0021] The electro-optic crystal substrate 14 is a flat substrate made of a ferroelectric material (e.g., z-cut LiNbO3 or z-cut LiTaO3) and has a thickness of about 25 μm. An optical waveguide 30 having a groove structure (e.g., a width of about 4 μm and a depth of about 1.5 μm) is formed on the lower surface of the electro-optic crystal substrate 14. One end of the optical waveguide 30 is an input port 31 to which an optical signal 35 is input, and the other end is an output port 32 from which the modulated optical signal 35 is output. In FIG. 1A, an example spectrum of the input optical signal 35 is drawn near the input port 31, and an example spectrum of the output optical signal 35 (optical signal 35 modulated by a radio signal 40 with a frequency fm) is drawn near the output port 32.

[0022] As described above, the electro-optic crystal substrate 14 is disposed only above the resonant electrode 20c among the multiple patch antennas 20 to 23 in the cross section shown in Fig. 1B. More specifically, the electro-optic crystal substrate 14 may be of any size as long as it is large enough to cover (disposed above) the entire resonant electrode 20c and not cover (disposed above) any part of the first antenna element 20a and the second antenna element 20e in the cross section shown in Fig. 1B.

[0023] Each of the patch antennas 20 to 23 is an aluminum square microstrip patch antenna designed to resonate with a 78 GHz radio signal 40, and is composed of a first antenna element 20a, a first line 20b, a resonant electrode 20c, a second line 20d, and a second antenna element 20e as shown in Fig. 1C. The patch antennas 20 to 23 are arranged at intervals of, for example, 3.50 mm.

[0024] The first antenna element 20a and the second antenna element 20e have a square shape with one side measuring 1236 μm (i.e., the electrical length is a half wavelength). This size is due to the fact that the electro-optic crystal substrate 14 is not disposed above the first antenna element 20a and the second antenna element 20e. If the electro-optic crystal substrate 14 were disposed above the first antenna element 20a and the second antenna element 20e as in the conventional technology, the antenna elements would need to be square with one side measuring 536 μm in order to resonate with the 78 GHz wireless signal 40.

[0025] The first line 20b includes (1) a first partial line 20b1 having a first width (here, 170 μm), which is formed at a position above which the electro-optic crystal substrate 14 is not positioned, and one end of which is connected to the first antenna element 20a, and (2) a second partial line 20b2 having a second width (here, 40 μm) smaller than the first width, which is formed at a position above which the electro-optic crystal substrate 14 is positioned, one end of which is connected to the other end of the first partial line 20b1 and the other end of which is connected to the resonant electrode 20c. Similarly, the second line 20d includes (1) a third partial line 20d1 having a first width (here, 170 μm) formed at a position above which the electro-optic crystal substrate 14 is not disposed, one end of which is connected to the second antenna element 20e, and (2) a fourth partial line 20d2 having a second width (here, 40 μm) formed at a position above which the electro-optic crystal substrate 14 is disposed, one end of which is connected to the other end of the third partial line 20d1, and the other end of which is connected to the resonant electrode 20c. This ensures impedance matching between the first partial line 20b1 and the second partial line 20b2, and impedance matching between the third partial line 20d1 and the fourth partial line 20d2, and the power received by the first antenna element 20a and the second antenna element 20e is efficiently supplied to the resonant electrode 20c.

[0026] The other end of the first line portion 20b1 has a tapered portion (tapered portion 20b3) whose width gradually narrows toward the second line portion 20b2. The tapered portion 20b3 is a region where the width of the first line portion 20b changes from a first width (170 μm here) to a second width (40 μm here), and has a length of, for example, 180 μm. Similarly, the other end of the third line portion 20d1 has a tapered portion (tapered portion 20d3) whose width gradually narrows toward the fourth line portion 20d2. The tapered portion 20d3 is a region where the width of the second line portion 20d changes from a first width (170 μm here) to a second width (40 μm here), and has a length of, for example, 180 μm. This suppresses unnecessary electromagnetic wave radiation at the connection points between the first partial line 20b1 and the second partial line 20b2 and the connection points between the third partial line 20d1 and the fourth partial line 20d2, and the power received by the first antenna element 20a and the second antenna element 20e is supplied to the resonant electrode 20c with suppressed propagation loss.

[0027] As shown in FIG. 1C, the resonant electrode 20c has a track-shaped loop shape including two sides extending in a first direction (y-axis direction), one side constituting the loop shape is connected perpendicularly to the first line 20b, and the other side constituting the loop shape is connected perpendicularly to the second line 20d.

[0028] The antenna electrode electro-optic modulator 10 of the present embodiment configured as above is manufactured in the following steps. That is, in a state in which the cross-sectional view shown in FIG. 1B is turned upside down, the manufacturing process is carried out from the lower layer (i.e., the electro-optic crystal substrate) to the upper layer.

[0029] Specifically, first, an electro-optic crystal substrate having a planar size approximately equal to that of the base substrate 12 is prepared, and a groove-structured optical waveguide 30 is formed on the surface of the electro-optic crystal substrate by a benzoic acid proton exchange method. Next, a buffer layer 16 made of SiO2 is formed on the entire surface of the electro-optic crystal substrate 14, and aluminum patch antennas 20-23 are formed on the upper surface of the buffer layer 16 by photolithography. Then, an adhesive is applied to the lower surface of the buffer layer 16 on which the patch antennas 20-23 are formed, and the base substrate 12 having the ground pattern 12a on its bottom surface is bonded thereto so that the surface on which the ground pattern 12a is not applied is bonded. Finally, an electro-optic crystal substrate 14 arranged only above the resonance electrode 20c is formed by removing a region wider than the upper portion of the resonance electrode 20c in the cross section shown in FIG. 1B from the electro-optic crystal substrate on which the buffer layer 16 is formed.

[0030] Next, the operation of the antenna electrode electro-optic modulator 10 according to this embodiment manufactured as described above will be described.

[0031] When a radio signal 40 is irradiated to the antenna electrode electro-optic modulator 10, the radio signal 40 is received by the first antenna element 20a and the second antenna element 20e in the patch antennas 20-23, and power is supplied to the resonant electrode 20c, generating a standing wave in the resonant electrode 20c. This generates an electric field around the resonant electrode 20c, and the refractive index of the electro-optic crystal substrate 14 changes due to the Pockels effect. As a result, the optical signal 35 input from the input port 31 of the optical waveguide 30 is modulated in each of the resonant electrodes 20c of the four patch antennas 20-23, and the modulated optical signal 35 is output from the output port 32 of the optical waveguide 30.

[0032] Next, the characteristics of the antenna electrode electro-optic modulator 10 according to this embodiment were analyzed, and the results will be described.

[0033] In order to perform the analysis efficiently, first, the patch antenna part (part including the first antenna element 20a and the first partial line 20b1, or part including the second antenna element 20e and the third partial line 20d1) and the resonant electrode part (part including the second partial line 20b2, the resonant electrode 20c, and the fourth partial line 20d2) were separated and analyzed, and then the two parts were combined and analyzed. For each analysis, the three-dimensional electromagnetic field simulator HFSS was used.

[0034] Figure 2 is a diagram showing the analysis results of the patch antenna portion of the antenna electrode electro-optic modulator 10 shown in Figure 1A. This shows the frequency (GHz) dependence of the reflection coefficient (dB) of the patch antenna portion. It can be seen that the patch antenna portion has a structure that resonates at 78GHz.

[0035] Fig. 3 is a diagram showing the analysis results of the resonant electrode portion of the antenna electrode electro-optic modulator 10 shown in Fig. 1A. This shows the frequency (GHz) dependence of the reflection coefficient (dB) of the resonant electrode portion. It can be seen that the resonant electrode portion has a structure that resonates at 78GHz.

[0036] FIG. 4 is a diagram showing the analysis results of the entire patch antenna 20 (or 21 to 23) in which the patch antenna portion and the resonant electrode portion are coupled. Here, the electric field distribution on the surface of the resonant electrode 20c of the patch antenna 20 in which the patch antenna portion and the resonant electrode portion are coupled is shown. Here, the horizontal axis indicates the position in the y-axis direction on the resonant electrode 20c (horizontal axis: Distance (mm)), and the vertical axis indicates the electric field E in the z-axis direction due to a standing wave generated on the resonant electrode 20c relative to the incident electric field E0 in the x-axis direction induced in the patch antenna 20. z The ratio (E z / E0).

[0037] As can be seen from Fig. 4, in the antenna electrode electro-optic modulator 10 according to this embodiment, a signal enhancement of about 3000 times the input signal can be confirmed on the surface of the resonant electrode 20c. This is because, in the antenna electrode electro-optic modulator 10 according to this embodiment, the electro-optic crystal substrate 14 is disposed only above the resonant electrode 20c among above the patch antennas 20-23 in the cross section shown in Fig. 1B.

[0038] That is, in the case of a conventional antenna electrode electro-optic modulator having a structure in which an electro-optic crystal substrate is arranged so as to cover the entire patch antenna, as described above, the antenna element of the patch antenna had to be a square shape with one side measuring 536 μm, and therefore the signal was amplified by about 200 times at most. In contrast, in the antenna electrode electro-optic modulator 10 according to the present embodiment, the electro-optic crystal substrate 14 is arranged only above the resonant electrode 20c among the areas above the patch antennas 20-23, so that the antenna elements of the patch antennas 20-23 can be made large, with one side measuring 1236 μm in a square shape (more than four times the area ratio), and it is considered that an extremely large signal amplified by about 3000 times has become possible.

[0039] As described above, the antenna electrode electro-optic modulator 10 according to the present embodiment is an electro-optic modulator that modulates an optical signal 35 with a radio signal 40 and outputs the modulated optical signal 35, and includes a base substrate 12, a plurality of patch antennas 20 to 23 arranged in a first direction on the upper surface of the base substrate 12 and receiving the radio signal 40, and an electro-optic crystal substrate 14 made of a dielectric material arranged above the plurality of patch antennas 20 to 23. Each of the plurality of patch antennas 20 to 23 includes a first antenna element 20a arranged along a second direction perpendicular to the first direction on the upper surface of the base substrate 12. The electro-optic crystal substrate 14 has a first line 20b connected to the first antenna element 20a, a resonant electrode 20c connected to the first line 20b, a second line 20d connected to the resonant electrode 20c, and a second antenna element 20e connected to the second line 20d. An optical waveguide 30 for transmitting an optical signal 35 is formed on the surface of the electro-optic crystal substrate 14 facing the multiple patch antennas 20-23, extending in the first direction at a position corresponding to above the resonant electrode 20c, and the electro-optic crystal substrate 14 is disposed only above the resonant electrode 20c among the multiple patch antennas 20-23.

[0040] As a result, since the electro-optic crystal substrate 14 is disposed only above the resonant electrode 20c above the patch antennas 20-23, the antenna elements of the patch antennas 20-23 can be made larger in size and a greater signal amplification can be achieved compared to a conventional antenna electrode electro-optic modulator having a structure in which an electro-optic crystal substrate is disposed so as to cover the entire patch antenna. Thus, an antenna electrode electro-optic modulator capable of performing electro-optic conversion with higher conversion efficiency than the conventional one is realized.

[0041] In each of the patch antennas 20 to 23, the first line 20b is made up of: (1) a first partial line 20b1 having a first width, which is formed in a position above which the electro-optic crystal substrate 14 is not disposed, and one end of which is connected to the first antenna element 20a; and (2) a second partial line 20b1 having a second width smaller than the first width, which is formed in a position above which the electro-optic crystal substrate 14 is disposed, and one end of which is connected to the other end of the first partial line 20b1 and the other end of which is connected to the resonant electrode 20c. The second line 20d includes (1) a third partial line 20d1 having a first width, which is formed at a position above which the electro-optic crystal substrate 14 is not arranged and has one end connected to the second antenna element 20e, and (2) a fourth partial line 20d2 having a second width, which is formed at a position above which the electro-optic crystal substrate 14 is arranged, has one end connected to the other end of the third partial line 20d1 and the other end connected to the resonant electrode 20c.

[0042] This ensures impedance matching between the first partial line 20b1 and the second partial line 20b2, and impedance matching between the third partial line 20d1 and the fourth partial line 20d2, and the power received by the first antenna element 20a and the second antenna element 20e is efficiently supplied to the resonant electrode 20c.

[0043] In each of the multiple patch antennas 20 to 23, the other end of the first partial line 20b1 has a tapered portion (tapered portion 20b3) whose width gradually narrows as it approaches the second partial line 20b2, and the other end of the third partial line 20d1 has a tapered portion (tapered portion 20d3) whose width gradually narrows as it approaches the fourth partial line 20d2.

[0044] This suppresses unnecessary electromagnetic wave radiation at the connection points between the first partial line 20b1 and the second partial line 20b2 and the connection points between the third partial line 20d1 and the fourth partial line 20d2, and the power received by the first antenna element 20a and the second antenna element 20e is supplied to the resonant electrode 20c with suppressed propagation loss.

[0045] The antenna electrode electro-optic modulator 10 according to the present disclosure has been described above based on the embodiment, but the present disclosure is not limited to this embodiment. As long as it does not deviate from the gist of the present embodiment, various modifications conceivable by a person skilled in the art to the present embodiment and other forms constructed by combining some of the components in the embodiment are also included within the scope of the present disclosure.

[0046] For example, in the above embodiment, four patch antennas 20-23 are provided in the antenna electrode electro-optic modulator 10, but only one patch antenna may be provided. The number of patch antennas (the number of modulator stages) provided in the antenna electrode electro-optic modulator 10 may be appropriately determined according to the required modulation depth.

[0047] In addition, in the above embodiment, the patch antennas 20-23 of the antenna electrode electro-optical modulator 10 are square patch antennas with an electrical length of half the wavelength, but this is not limited to this and may be rectangular patch antennas with an electrical length of a quarter wavelength or the like.

[0048] In addition, in the above embodiment, the antenna electrode electro-optical modulator 10 has been described as a modulator receiving a 78 GHz radio signal 40, but this frequency is not limited and the modulator can be widely applied to millimeter wave (30 GHz band to 300 GHz band) radio signals.

[0049] In addition, in the above embodiment, one optical waveguide 30 is formed in the antenna electrode electro-optical modulator 10, but the number of optical waveguides is not limited to this, and two or more optical waveguides, for example, two optical waveguides extending in parallel, or four optical waveguides may be formed. [Industrial Applicability]

[0050] The present disclosure can be used as an antenna electrode electro-optical modulator that modulates an optical signal with a wireless signal and outputs the modulated signal, for example, as a modulator in an RoF transmission system that converts millimeter-wave wireless signals into optical signals for transmission. [Explanation of symbols]

[0051] 10 Antenna electrode electro-optic modulator 12 Base board 12a Ground Pattern 14 Electro-optic crystal substrate 16 Buffer Layer 20~23 Patch antenna 20a First antenna element 20b 1st track 20b1 1st section track 20b2 2nd section track 20b3 Tapered section 20c resonant electrode 20d 2nd track 20d1 3rd section track 20d2 4th section track 20d3 Tapered section 20e second antenna element 30 Optical waveguide 31 Input Ports 32 output ports 35 Optical Signal 40 Radio Signal

Claims

1. An antenna electrode electro-optic modulator that modulates an optical signal with a wireless signal and outputs the modulated signal, A base substrate; a plurality of patch antennas arranged in a first direction on an upper surface of the base substrate and receiving the wireless signal; an electro-optic crystal substrate made of a dielectric material disposed above the plurality of patch antennas; Each of the plurality of patch antennas includes a first antenna element, a first line connected to the first antenna element, a resonant electrode connected to the first line, a second line connected to the resonant electrode, and a second antenna element connected to the second line, the first antenna element and the first line being arranged along a second direction perpendicular to the first direction on the upper surface of the base substrate; an optical waveguide for transmitting the optical signal is formed on a surface of the electro-optic crystal substrate facing the plurality of patch antennas at a position corresponding to an upper portion of the resonant electrode and extending in a first direction; the electro-optic crystal substrate is disposed only above a portion of the first line, the resonant electrode, and a portion of the second line above the plurality of patch antennas; Antenna electrode electro-optic modulator.

2. In each of the plurality of patch antennas, the first line includes: (1) a first partial line having a first width, formed at a position above which the electro-optic crystal substrate is not disposed, one end of which is connected to the first antenna element; and (2) a second partial line having a second width smaller than the first width, formed at a position above which the electro-optic crystal substrate is disposed, one end of which is connected to the other end of the first partial line and the other end of which is connected to the resonant electrode; The second line includes: (1) a third partial line having the first width, which is formed at a position above which the electro-optic crystal substrate is not disposed, and one end of which is connected to the second antenna element; and (2) a fourth partial line having the second width, which is formed at a position above which the electro-optic crystal substrate is disposed, and one end of which is connected to the other end of the third partial line and the other end of which is connected to the resonant electrode.

2. The antenna electrode electro-optic modulator of claim 1.

3. In each of the plurality of patch antennas, the other end of the first partial line has a tapered shape whose width gradually narrows toward the second partial line, the other end of the third line portion has a tapered shape whose width gradually narrows toward the fourth line portion; 3. The antenna electrode electro-optic modulator of claim 2.

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