Optical modulation device, optical observation device, and light irradiation device

Abstract

An optical modulation device (21) comprises: an electro-optical crystal (22); a transparent electrode (23) that is provided on the input surface (22a) side of the electro-optical crystal (22) and that transmits input light (Lp); a gap buffer layer (24) that is provided between the transparent electrode (23) and the electro-optical crystal (22); and a reflection part (25) that has a plurality of pixel electrodes (30) arranged on the back surface (22b) side of the electro-optical crystal (22) and reflects the input light (Lp) toward the transparent electrode (23), the relative permittivity of the gap buffer layer (24) being a value between the relative permittivity of the transparent electrode (23) and the relative permittivity of the electro-optical crystal (22), and the transparent electrode (23) having a gap (G) that divides the transparent electrode (23) into a plurality of electrode regions (R) facing at least one of the plurality of pixel electrodes (30).

Description

Light modulation device, light observation device, and light irradiation device

[0001] The present disclosure relates to a light modulation device, a light observation device, and a light irradiation device.

[0002] One example of technology related to light modulation devices is a reflective spatial light modulator described in Patent Document 1. This reflective spatial light modulator includes an electro-optic crystal, a light input / output unit having a first electrode disposed on one side of the electro-optic crystal and transmitting input light, a plurality of second electrodes disposed on the other side of the electro-optic crystal, a reflector that reflects the input light toward the light input / output unit, a plurality of pixel electrodes corresponding to the plurality of second electrodes, and a drive circuit that inputs an electric signal to each of the plurality of pixel electrodes and applies an electric field between the first electrode and the second electrode.

[0003] International Publication No. 2017 / 213098

[0004] In the optical modulation device described above, since the dielectric constant of the electro-optic crystal is relatively high, it is important to efficiently apply an electric field in the thickness direction of the electro-optic crystal. If the electric field in the horizontal direction that intersects the thickness direction (hereinafter referred to as the "transverse electric field") spreads and the value of the transverse electric field becomes large, it is thought that it becomes difficult to obtain stable optical modulation.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a light modulation device, a light observation device, and a light irradiation device that can achieve stable light modulation.

[0006] An optical modulation device according to one aspect of the present disclosure is an optical modulation device that modulates input light and outputs it as modulated light, and includes an electro-optic crystal having an input surface to which the input light is input and a back surface opposite the input surface, a transparent electrode provided on the input surface side of the electro-optic crystal and transmitting the input light, a gap buffer layer provided between the transparent electrode and the electro-optic crystal, and a reflective section having a plurality of pixel electrodes arranged on the back surface side of the electro-optic crystal and reflecting the input light that has reached the back surface toward the transparent electrode, wherein the relative dielectric constant of the gap buffer layer is a value between the relative dielectric constant of the transparent electrode and the relative dielectric constant of the electro-optic crystal, and the transparent electrode has a gap that divides the transparent electrode into a plurality of electrode regions facing at least one of the plurality of pixel electrodes.

[0007] In this light modulation device, the transparent electrode is divided by gaps into multiple electrode regions facing at least one of the multiple pixel electrodes. This allows the horizontal electric field generated at the edges of the pixel electrodes to be diffused in the horizontal direction (the direction in which the pixel electrodes are arranged) when an electric field is applied between the transparent electrode and the pixel electrode. Furthermore, in this light modulation device, the relative permittivity of the gap buffer layer is between the relative permittivity of the transparent electrode and the relative permittivity of the electro-optic crystal. The placement of this gap buffer layer not only reduces the loss of the electric field between the transparent electrode and the electro-optic crystal, but also smooths the horizontal electric field diffused by the formation of the gap, thereby smoothing the disturbance in the phase modulation pattern caused by the diffusion of the horizontal electric field. Therefore, this light modulation device achieves stable light modulation.

[0008] The plurality of electrode regions may be rectangular, and the gaps may be provided to correspond to the sides of the plurality of electrode regions. With this configuration, the transverse electric field is further smoothed in the direction connecting the sides of the plurality of electrode regions.

[0009] The plurality of electrode regions may be rectangular, and the gaps may be provided to correspond to corners of the plurality of electrode regions. With this configuration, the transverse electric field is further smoothed in a direction connecting the corners of the plurality of electrode regions.

[0010] The plurality of electrode regions may be rectangular, and the gaps may be provided to correspond to both the sides and the corners of the plurality of electrode regions. With this configuration, the transverse electric field is further smoothed in both the direction connecting the sides of the plurality of electrode regions and the direction connecting the corners.

[0011] The plurality of electrode regions may be connected to one another except for the gaps. By connecting the plurality of electrode regions to one another, it is possible to apply a voltage uniformly between the plurality of pixel electrodes.

[0012] The relative permittivity of the electro-optic crystal is ε ｒｃ and the relative dielectric constant of the gap buffer layer is ε ｒｆ In this case, ε ｒｃ / 100<ε ｒｆ <ε ｒｃ / 5. By satisfying such a relationship of relative dielectric constants, loss of the electric field between the transparent electrode and the electro-optic crystal can be more effectively suppressed.

[0013] The gap may be an air gap, which allows the horizontal electric field generated at the edge of the pixel electrode to be diffused in the horizontal direction more reliably.

[0014] The gap may be made of an insulator. By making the gap an insulator, the horizontal electric field generated at the edge of the pixel electrode can be more reliably diffused in the horizontal direction. Furthermore, by surrounding multiple electrode regions with an insulator, a voltage can be applied uniformly between multiple pixel electrodes.

[0015] The light modulation device may include a drive substrate having a plurality of drive electrodes electrically connected to the plurality of pixel electrodes, a first power supply electrically connected to the transparent electrodes, and a second power supply electrically connected to the drive substrate. By using two power supplies, one on the transparent electrode side and the other on the drive substrate side, it is possible to apply a voltage to the transparent electrodes that is independent of the withstand voltage and control method of the drive substrate. This improves the degree of freedom in the modulation pattern for input light.

[0016] An optical observation device according to one aspect of the present disclosure includes a light source that outputs input light, the optical modulation device, an optical system that guides the modulated light output from the optical modulation device to a sample, and a detector that detects light from the sample. Also, an optical irradiation device according to one aspect of the present disclosure includes a light source that outputs input light, the optical modulation device, and an optical system that guides the modulated light output from the optical modulation device to a sample.

[0017] In this light observation device and light irradiation device, the transparent electrode in the light modulation device is divided by gaps into multiple electrode regions facing at least one of the multiple pixel electrodes. This allows the horizontal electric field generated at the edge of the pixel electrode to be diffused in the horizontal direction (the direction of the pixel electrodes) when an electric field is applied between the transparent electrode and the pixel electrode. Furthermore, in the light modulation device, the relative permittivity of the gap buffer layer is a value between the relative permittivity of the transparent electrode and the relative permittivity of the electro-optic crystal. The placement of this gap buffer layer not only suppresses electric field loss between the transparent electrode and the electro-optic crystal, but also smooths the horizontal electric field diffused by the formation of the gap, thereby smoothing the disturbance in the phase modulation pattern caused by the diffusion of the horizontal electric field. Therefore, this light observation device and light irradiation device can achieve stable light modulation.

[0018] According to the present disclosure, stable optical modulation can be achieved.

[0019] 1 is a schematic diagram showing a configuration of a light observation device according to an embodiment of the present disclosure; FIG. 2 is a schematic diagram showing a configuration of a light irradiation device according to an embodiment of the present disclosure; FIG. 3 is a schematic cross-sectional view showing a configuration of a light modulation device according to an embodiment of the present disclosure; FIG. 4(a) is a diagram showing the relationship between a crystal axis, a light propagation direction, and an electric field in retardation modulation, and FIG. 4(b) is a diagram showing each axis in a plane; FIG. 4(a) is a plan view showing a pixel electrode, and FIG. 4(b) is a plan view showing a drive electrode; FIG. 5 is a schematic plan view showing an example of patterning of a transparent electrode; FIG. 6 is a schematic plan view showing an example of patterning of a transparent electrode; FIG. 7 is a schematic plan view showing an example of patterning of a transparent electrode; FIG. 8 is a schematic plan view showing an example of patterning of a transparent electrode; FIG. 9 is a schematic plan view showing an example of patterning of a transparent electrode; FIG. 10 is a schematic plan view showing an example of patterning of a transparent electrode; FIG. 11 is a schematic plan view showing an example of patterning of a transparent electrode; 1 is a schematic cross-sectional view showing the configuration of an optical modulation device according to a modified example; FIG. 2 is a schematic plan view showing an example of gap patterning; FIG. 3 is a schematic plan view showing an example of gap patterning; FIG. 4 is a schematic plan view showing an example of gap patterning; FIG. 5 is a diagram showing a calculation model for a phase modulation simulation, and FIG. 6 is a diagram showing each parameter used in the phase modulation simulation; FIG. 7 is a diagram showing simulation results of the total number versus position in the in-plane direction, where (a) shows the results of Comparative Example 1, (b) shows the results of Comparative Example 2, and (c) shows the results of an Example; FIG. 8 is a diagram showing the first-order dispersion of the total number in the range 60≦X<100, where (a) shows the results of Comparative Example 1, (b) shows the results of Comparative Example 2, and (c) shows the results of an Example; FIG. 9 is a diagram showing the first-order dispersion of the total number in the range 100≦X≦150, where (a) shows the results of Comparative Example 1, (b) shows the results of Comparative Example 2, and (c) shows the results of an Example; and FIG. 10 is a diagram showing the average value of the total number in the range 60≦X<100, where (a) shows the results of Comparative Example 1, (b) shows the results of Comparative Example 2, and (c) shows the results of an Example. 10A shows the average value of the total number in the range of 100≦X≦150, where (a) shows the results of Comparative Example 1, (b) shows the results of Comparative Example 2, and (c) shows the results of the Example. 10B shows the results of the simulation of the amount of phase modulation, where (a) shows the results of Comparative Example 1, (b) shows the results of Comparative Example 2, and (c) shows the results of the Example.10 is a graph showing the calculation results of the modulation performance index in Comparative Examples 1 and 2 and the example; 11 is a graph showing the reduction results of power consumption in the example;

[0020] Hereinafter, preferred embodiments of a light modulation device, a light observation device, and a light irradiation device according to one aspect of the present disclosure will be described in detail with reference to the drawings.

[0021] Fig. 1 is a schematic diagram showing the configuration of an optical observation device according to an embodiment of the present disclosure. The optical observation device 1 shown in Fig. 1 is configured as, for example, a fluorescence microscope that captures a fluorescent image of a sample S. The optical observation device 1 acquires an image of the sample S by irradiating the surface of the sample S with inspection light Ld and capturing light (such as fluorescence or reflected light) from the sample S in response to the irradiation of the inspection light Ld as observation light Lf.

[0022] Examples of the sample S include cells containing fluorescent substances such as fluorescent dyes and fluorescent proteins, and biological samples. The sample S may also be a semiconductor device or a film. When irradiated with light in a predetermined wavelength range (excitation light or illumination light), the sample S emits observation light Lf such as fluorescence. The sample S may be housed in a holder that is transparent to the inspection light Ld and the observation light Lf. In this case, the holder may be held on a movable stage.

[0023] As shown in Figure 1, the optical observation device 1 is composed of a light source 2, a collimator lens 3, a polarizing element 4, a polarizing beam splitter 5, an optical modulation device 21, a first optical system 6, a beam splitter 7, an objective lens 8, a second optical system 9, a detector 10, and a control unit C.

[0024] The light source 2 outputs light including a wavelength that excites the sample S as the inspection light Ld. The inspection light Ld may be either coherent light or incoherent light. Examples of light sources that output coherent light include laser diodes (LDs). Examples of light sources that output incoherent light include light-emitting diodes (LEDs), superluminescent diodes (SLDs), and lamp light sources.

[0025] The collimator lens 3 collimates the inspection light Ld output from the light source 2. The polarizing element 4 selectively transmits the inspection light Ld depending on its polarization component. The polarizing element 4 is, for example, a polarizing filter. In this example, the polarizing element 4 transmits the S-wave component of the inspection light Ld. The polarizing beam splitter 5 reflects the inspection light Ld that has transmitted through the polarizing element 4 toward the optical modulator 21.

[0026] The light modulation device 21 is a spatial light modulator that modulates the phase or phase difference (retardation) of the inspection light Ld. In this embodiment, the light modulation device 21 is configured as a reflective spatial light modulator. The light modulation device 21 modulates the inspection light Ld and outputs modulated light Lm. The modulated light Lm output from the light modulation device 21 passes through the polarizing beam splitter 5 and is guided to the first optical system 6.

[0027] The light modulation device 21 is electrically connected to the control unit C, and constitutes a spatial light modulation unit. The operation of the light modulation device 21 is controlled by the control unit C. The light modulation device 21 performs functions such as limiting the position of the irradiation spot of the inspection light Ld (modulated light Lm) irradiated onto the sample S in the light observation device 1, moving the position, simultaneously forming multiple irradiation spots, and controlling the phase.

[0028] The first optical system 6 optically couples the light modulation device 21 and the objective lens 8. The first optical system 6 includes, for example, a condenser lens. The first optical system 6 condenses the modulated light Lm output from the light modulation device 21 at the pupil position of the objective lens 8.

[0029] The beam splitter 7 is an optical element that separates the modulated light Lm from the observation light Lf. The beam splitter 7 may be a polarizing beam splitter or a dichroic mirror. The beam splitter 7 is configured to transmit, for example, the modulated light Lm, which has an excitation wavelength, and reflect the observation light Lf, which has a fluorescence wavelength. Depending on the configuration of the optical systems before and after the beam splitter 7 (e.g., the first optical system 6 and the second optical system 9), or the type of microscope to which the optical observation device 1 is applied, the beam splitter 7 may be configured to reflect the modulated light Lm and transmit the observation light Lf.

[0030] The objective lens 8 focuses the modulated light Lm and irradiates it onto the sample S, and also guides the observation light Lf from the sample S in response to the irradiation of the modulated light Lm to the detector 10 in cooperation with the beam splitter 7. The objective lens 8 may be configured to be movable along the optical axes of the modulated light Lm and the observation light Lf by a driving element such as a piezoelectric actuator or a stepping motor. In this case, it becomes possible to arbitrarily adjust the focusing position of the modulated light Lm and the focal position of the observation light Lf.

[0031] The second optical system 9 optically couples the objective lens 8 and the detector 10. The second optical system 9 includes, for example, an imaging lens. The second optical system 9 forms an image of the observation light Lf from the objective lens 8 on the light-receiving surface of the detector 10.

[0032] The detector 10 is a device that detects the observation light Lf. The detector 10 is configured with an image sensor such as a CCD image sensor or a CMOS image sensor. The detector 10 captures an image of the observation light Lf that is formed on the light receiving surface by the second optical system 9.

[0033] The control unit C is physically a computer system equipped with storage devices such as RAM and ROM, a processor (arithmetic circuit) such as a CPU, a communication interface, etc. The computer can be, for example, a personal computer, a cloud server, or a smart device (smartphone, tablet terminal, etc.). The control unit C causes the computer to execute a program for controlling the operation of the light source 2, objective lens 8, detector 10, etc. in the optical observation device 1, or a program for controlling the phase modulation amount or phase difference (retardation) modulation amount in the light modulation device 21, thereby performing the desired control.

[0034] 2 is a schematic diagram showing the configuration of a light irradiation device according to an embodiment of the present disclosure. The light irradiation device 11 is the same as the configuration of the light observation device 1 shown in FIG. 1 except for the beam splitter 7, the objective lens 8, the second optical system 9, and the detector 10. That is, the light irradiation device 11 is composed of a light source 2, a collimator lens 3, a polarizing element 4, a polarizing beam splitter 5, a light modulation device 21, a first optical system 6, and a controller C.

[0035] In the light irradiation device 11, the modulated light Lm output from the light modulation device 21 passes through the polarizing beam splitter 5 and the first optical system 6 and is then irradiated onto the sample S. The light modulation device 21 performs the following operations in the light irradiation device 11: limiting the position of the irradiation spot of the inspection light Ld (modulated light Lm) irradiated onto the sample S, moving the position, simultaneously forming multiple irradiation spots, and controlling the phase.

[0036] Next, the above-mentioned optical modulation device 21 will be described in more detail.

[0037] FIG. 3 is a schematic cross-sectional view showing the configuration of an optical modulation device according to an embodiment of the present disclosure. The optical modulation device 21 shown in FIG. 3 is a device that modulates input light Lp and outputs modulated light Lm, and a reflective spatial light modulator is shown here as an example. The input light Lp is the inspection light Ld in the optical observation device 1 and the light irradiation device 11 described above. As shown in FIG. 3, the optical modulation device 21 includes an electro-optic crystal 22, a transparent electrode 23, a gap buffer layer 24, a reflector 25, a drive substrate 26, a first power supply 27, and a second power supply 28.

[0038] The electro-optic crystal 22 has an input surface 22a onto which the input light Lp is input, and a back surface 22b opposite the input surface 22a. The electro-optic crystal 22 has, for example, a perovskite crystal structure, and changes the refractive index of the electro-optic crystal 22 based on an electro-optic effect such as the Pockels effect or the Kerr effect. The electro-optic crystal 22, which has a perovskite crystal structure, is an isotropic crystal belonging to the cubic point group m3m, and has a relative dielectric constant of 1000 or greater. The relative dielectric constant of the electro-optic crystal 22 can be, for example, a value of approximately 1000 to 20000.

[0039] Such an electro-optic crystal 22 is, for example, KTa. １-ｘ Nb ｘ O ３ (0≦x≦1) crystal (KTN crystal), K １-ｙ Li ｙ Ta １-ｘ Nb ｘ O ３ (0≦x≦1, 0<y<1) crystal, PLZT crystal, etc., specifically BaTiO ３ , or K３ Pb ３ (Zn ２ Nb ７ ) O ２７ , K(Ta ０．６５ Nb ０．３５ ) P ３ , Pb ３ MgNb ２ O ９ , Pb ３ NiNb ２ O ９ Examples include:

[0040] In this embodiment, a KTN crystal is used as the electro-optic crystal 22. Because KTN crystals are cubic m3m point groups, they do not exhibit the Pockels effect, but instead perform phase modulation based on the Kerr effect. Phase modulation can be achieved by inputting light parallel or perpendicular to the crystal axis of the electro-optic crystal 22 and applying an electric field in the same direction. Retardation modulation can be achieved by rotating the other two axes around any crystal axis at any angle other than 0° and 90°.

[0041] FIG. 4(a) shows the relationship between the crystal axes, the light propagation direction, and the electric field in retardation modulation. FIG. 4(b) shows each axis in a planar view. Here, we illustrate the case where the crystal is rotated by an angle of 45°. When axes X2 and X3 are rotated 45° around axis X1 to define new axes X1, X2', and X3', retardation modulation can be achieved by inputting light into the electro-optic crystal 22 parallel or perpendicular to these axes X1, X2', and X3'. In the examples of FIGS. 4(a) and 4(b), the electric field application direction 1102 is set parallel to the propagation direction 1101 of the input light in the crystal 1104. In this case, the Kerr coefficients used to modulate the input light Lp are g11, g12, and g44.

[0042] The dielectric constant of KTN crystal is easily affected by temperature. For example, at around -5°C, the dielectric constant is highest at about 20,000, and at room temperature, around 20°C, the dielectric constant decreases to about 5,000. In this embodiment, as shown in FIG. 3, the optical modulator 21 has a temperature control element 29. The temperature control element 29 is configured, for example, by a Peltier element. The temperature control element 29 maintains the temperature of the electro-optic crystal 22 at about -5°C during operation.

[0043] The transparent electrode 23 is provided on the input surface 22a side of the electro-optic crystal 22. The transparent electrode 23 is made of, for example, ITO (indium tin oxide) and is transparent to the input light Lp and the modulated light Lm. The input light Lp passes through the transparent electrode 23 and is input to the electro-optic crystal 22, and the modulated light Lm modulated by the electro-optic crystal 22 is output to the outside of the light modulation device 21 via the transparent electrode 23.

[0044] The gap buffer layer 24 is a layer that suppresses the spread of the transverse electric field generated by the gap G. The gap buffer layer 24 is provided between the transparent electrode 23 and the electro-optic crystal 22. The gap buffer layer 24 is transparent to the input light Lp and the modulated light Lm. The gap buffer layer 24 may be made of, for example, KTN or KTaO. ３ , KNbO ３ The polycrystalline or amorphous gap buffer layer 24 can be formed by various film formation techniques, such as vacuum deposition, sputtering, pulsed laser deposition, atomic layer deposition, and spin coating. The gap buffer layer 24 may also be formed by material modification using ion implantation or plasma. In this case, examples of ion species used for the gap buffer layer 24 include B, N, C, F, Al, P, Li, Na, K, and Mg.

[0045] The relative dielectric constant of the gap buffer layer 24 is a value between the relative dielectric constant of the transparent electrode 23 and the relative dielectric constant of the electro-optic crystal 22. That is, when the relative dielectric constant of the transparent electrode 23 is ε ｒｔｃо and the relative dielectric constant of the electro-optic crystal 22 is ε ｒｃ and the relative dielectric constant of the gap buffer layer 24 is εｒｆ , the relative dielectric constant ε of the gap buffer layer 24 ｒｆ is ε ｒｔｃо <ε ｒｆ <ε ｒｃ Meet the following.

[0046] In this embodiment, the relative dielectric constant of the electro-optic crystal 22 is set to ε ｒｃ and the relative dielectric constant of the gap buffer layer 24 is ε ｒｆ , the relative dielectric constant ε of the gap buffer layer 24 ｒｆ is ε ｒｃ / 100<ε ｒｆ <ε ｒｃ / 5 is satisfied. As an example, KTN crystal has a relative dielectric constant of several tens of thousands in the state of single crystal bulk, but in the state of a thin film, the relative dielectric constant is reduced by approximately 1 / 10 to 1 / 100 compared to the state of single crystal bulk. Therefore, for example, by constructing the electro-optic crystal 22 from a single crystal bulk of KTN crystal and constructing the gap buffer layer 24 from a thin film of KTN crystal, it is possible to easily satisfy the above-mentioned relationship of relative dielectric constants.

[0047] The reflector 25 reflects the input light Lp that reaches the rear surface 22b of the electro-optic crystal 22 toward the transparent electrode 23. The reflector 25 has a plurality of pixel electrodes 30 arranged on the rear surface 22b side of the electro-optic crystal 22. The pixel electrodes 30 are metal electrodes made of, for example, aluminum. The pixel electrodes 30 can be formed, for example, by metal vapor deposition using a mask pattern. In the reflector 25, as shown in FIG. 5( a), for example, the pixel electrodes 30, which are rectangular (square) in plan view, are arranged in a matrix. In the example of FIG. 5( a), for convenience of explanation, the pixel electrodes 30 are arranged in a 4×4 pattern, but the number of pixel electrodes 30 arranged can be arbitrary.

[0048] The width dimension (here, the length of one side) of the pixel electrode 30 is, for example, approximately the same as the thickness of the electro-optic crystal 22. If the width dimension of the pixel electrode 30 is excessive relative to the thickness of the electro-optic crystal 22, it is thought that crosstalk of electrical signals between adjacent pixel electrodes 30, 30 will increase. Therefore, by making the width dimension of the pixel electrode 30 approximately the same as the thickness of the electro-optic crystal 22, crosstalk of electrical signals between adjacent pixel electrodes 30, 30 can be suppressed.

[0049] The drive substrate 26 applies an electric field between the transparent electrode 23 and the pixel electrodes 30. The drive substrate 26 is a so-called CMOS substrate. The drive substrate 26 may be fixed to an organic substrate such as a glass epoxy substrate (an epoxy resin with a glass fiber sheet as a core material), or a ceramic substrate. The drive substrate 26 has a plurality of drive electrodes 31 electrically connected to the plurality of pixel electrodes 30, respectively.

[0050] On the drive substrate 26, as shown in Fig. 5(b), for example, drive electrodes 31, which are rectangular (square) in plan view, are arranged in a matrix at the same arrangement pitch as the pixel electrodes 30. In the example of Fig. 5(b), for convenience of explanation, the drive electrodes 31 are arranged in a 4x4 pattern, but the number of arranged drive electrodes 31 is set according to the number of arranged pixel electrodes 30. Each drive electrode 31 is provided with a drive switch 32. The application of voltage to each pixel electrode 30 is controlled by the operation of the switch 32.

[0051] 3, the drive electrodes 31 and the pixel electrodes 30 are arranged opposite each other in the thickness direction of the electro-optic crystal 22 and are individually electrically connected by bumps 33. The bumps 33 are made of, for example, gold or solder. In the region between the electro-optic crystal 22 and the drive substrate 26, there may be gaps between adjacent pixel electrodes 30, 30 and between adjacent bumps 33, 33, or an insulator may be disposed therebetween.

[0052] The first power supply 27 and the second power supply 28 are power supplies for applying an electric field between the transparent electrode 23 and the pixel electrode 30. The first power supply 27 is electrically connected to the transparent electrode 23 and applies a voltage to the transparent electrode 23. The second power supply 28 is electrically connected to the drive substrate 26 and applies a voltage to the pixel electrode 30 via the drive electrode 31. The voltage of the transparent electrode 23 is V ｃｏｍ and the voltage of the pixel electrode 30 is V ｐｘ When modulating, for example, V ｃｏｍ ≧2×V ｐｘ A voltage is applied to the transparent electrode 23 and the pixel electrode 30 so as to satisfy the following.

[0053] In this embodiment, as described above, the plurality of drive electrodes 31 and the plurality of pixel electrodes 30 are individually electrically connected by the bumps 33. Therefore, an electric field can be applied individually to each of the plurality of pixel electrodes 30 between the transparent electrode 23 and the pixel electrode 30. This suppresses crosstalk of electrical signals between the pixel electrodes and contributes to improving modulation accuracy.

[0054] In the light modulation device 21 described above, voltages are applied to the transparent electrode 23 and the pixel electrodes 30 by the first power supply 27 and the second power supply 28, respectively, and the refractive index of the electro-optic crystal 22 changes in response to the electric field generated by the applied voltage. By presenting a desired modulation pattern to the multiple pixel electrodes 30, the input light Lp passing through the electro-optic crystal 22 is phase-modulated in response to the change in refractive index. The input light Lp is reflected by the pixel electrodes 30, passes through the electro-optic crystal 22, and is again phase-modulated, and is output to the outside as modulated light Lm.

[0055] Next, the configuration of the transparent electrode 23 will be described in more detail.

[0056] In the light modulation device 21, the transparent electrode 23 has gaps G that divide the transparent electrode 23 into a plurality of electrode regions R that face at least one of the plurality of pixel electrodes 30. In this embodiment, the gaps G are formed by voids 34, and the gap buffer layer 24 is exposed from the transparent electrode 23 at the positions of the gaps G.

[0057] In plan view, the gaps G are formed at positions between the pixel electrodes 30 arranged in a matrix and at positions that are the outer edges of the areas where the pixel electrodes 30 are arranged. Part of the gaps G may overlap the edges of the pixel electrodes 30 in plan view. The multiple electrode regions R are rectangular. The multiple electrode regions R are separated from each other at the gaps G and connected to each other in areas other than the gaps G.

[0058] The transparent electrode 23 including the gap G can be patterned by, for example, etching, lift-off, mask deposition, etc. Etching can be dry etching such as plasma etching or reactive ion etching, or wet etching such as dip etching or spin etching. Lift-off can be performed by a peeling liquid immersion method or laser lift-off. Mask deposition can be performed by a method using a metal mask.

[0059] 6 to 13 are schematic plan views showing examples of patterning of the transparent electrode. In the examples of FIGS. 6 and 7, the multiple electrode regions R are divided into rectangular (square) sections in one-to-one correspondence with the pixel electrodes 30 arranged in a matrix. In the example of FIG. 6, gaps G are provided to correspond to the respective sides of the multiple electrode regions R. In adjacent electrode regions R, R, the sides are separated by the gaps G, and the corners are connected to each other. Gaps G are also provided in the portion corresponding to the outer edge of the transparent electrode 23 so as to correspond to the respective sides of the multiple electrode regions R. In the portion corresponding to the outer edge of the transparent electrode 23, the gaps G corresponding to the sides may extend to the corners, and the gaps G, G of adjacent electrode regions R, R may be connected to each other.

[0060] 7, gaps G are provided so as to correspond to the corners of each of the plurality of electrode regions R. In adjacent electrode regions R, R, the corners are separated by gaps G, and the sides are connected to each other. Gaps G are also provided in the portion corresponding to the outer edge of the transparent electrode 23 so as to correspond to the corners of each of the plurality of electrode regions R. In the portion corresponding to the outer edge of the transparent electrode 23, the gaps G corresponding to the corners may extend to the sides, and the gaps G, G of adjacent electrode regions R, R may be connected to each other.

[0061] In the examples of FIGS. 8 to 13 , the multiple electrode regions R are divided into rectangular shapes (square or rectangular) to correspond to the multiple pixel electrodes 30. In the example of FIG. 8 , the multiple electrode regions R are divided into rectangular shapes to correspond to 1×2 pixel electrodes 30. In adjacent electrode regions R, R, the sides are separated by gaps G, and the corners are connected to each other. In the center of the long sides of the electrode regions R, the gaps G are separated in the extension direction of the sides. Gaps G are also provided in the portion corresponding to the outer edge of the transparent electrode 23 so as to correspond to each side of the multiple electrode regions R. In the portion corresponding to the outer edge of the transparent electrode 23, the gaps G corresponding to the sides may extend to the corners, and the gaps G, G of adjacent electrode regions R, R may be connected to each other.

[0062] In the example of Fig. 9, the multiple electrode regions R are divided into squares corresponding to the 2 x 2 pixel electrodes 30. In adjacent electrode regions R, R, the sides are separated by gaps G, and the corners are connected to each other. In the center of the sides, gaps G are separated in the direction in which the sides extend. Gaps G are also provided in the parts corresponding to the outer edges of the transparent electrode 23 so as to correspond to each side of the multiple electrode regions R. In the parts corresponding to the outer edges of the transparent electrode 23, the gaps G corresponding to the sides may extend to the corners, and the gaps G, G of adjacent electrode regions R, R may be connected to each other.

[0063] 10 , the multiple electrode regions R are divided into rectangular shapes corresponding to 1×2 pixel electrodes 30. In adjacent electrode regions R, R, the corners are separated by gaps G, and the sides are connected to each other. Gaps G are also provided in the portions corresponding to the outer edges of the transparent electrode 23 so as to correspond to the corners of each of the multiple electrode regions R. In the portions corresponding to the outer edges of the transparent electrode 23, the gaps G corresponding to the corners may extend to the sides, and the gaps G, G of adjacent electrode regions R, R may be connected to each other.

[0064] 11 , the plurality of electrode regions R are divided into squares corresponding to the 2×2 pixel electrodes 30. In adjacent electrode regions R, R, the corners are separated by gaps G, and the sides are connected to each other. Gaps G are also provided in the portions corresponding to the outer edges of the transparent electrode 23 so as to correspond to the corners of each of the plurality of electrode regions R. In the portions corresponding to the outer edges of the transparent electrode 23, the gaps G corresponding to the corners may extend to the sides, and the gaps G, G of adjacent electrode regions R, R may be connected to each other.

[0065] 12 and 13, gaps G are provided so as to correspond to both the sides and corners of the plurality of electrode regions R. In the example of FIG. 12, the plurality of electrode regions R are divided into rectangular shapes so as to correspond to 1×2 pixel electrodes 30. In adjacent electrode regions R, R, the corners and sides are separated by gaps G. Between the gaps G at the corners and the gaps G at the sides, the gaps G are spaced apart, and the adjacent electrode regions R, R are connected at the spaced apart portions. In the portion corresponding to the outer edge of the transparent electrode 23, the gaps G corresponding to the corners and the gaps G corresponding to the sides may be connected.

[0066] 13, the plurality of electrode regions R are divided into squares corresponding to the 2×2 pixel electrodes 30. In adjacent electrode regions R, R, the corners and sides are separated by gaps G. Between the gaps G at the corners and the gaps G at the sides, the gaps G are spaced apart, and adjacent electrode regions R, R are connected at the spaced apart portions. In the portion corresponding to the outer edge of the transparent electrode 23, the gaps G corresponding to the corners and the gaps G corresponding to the sides may be connected.

[0067] 14 is a schematic diagram illustrating the effects of the gap buffer layer and the gap. In the optical modulation device described above, since the relative dielectric constant of the electro-optic crystal is relatively high (in this embodiment, it is approximately 1,000 to 20,000), it is important to efficiently apply an electric field in the thickness direction of the electro-optic crystal. If the electric field in the horizontal direction that intersects the thickness direction (hereinafter referred to as the "transverse electric field") spreads and the value of the transverse electric field becomes large, it is thought that it becomes difficult to obtain stable optical modulation.

[0068] As shown in FIG. 14, in the comparative example without the gap buffer layer and the gap, the voltage V ｐｘ When a potential difference occurs between adjacent pixel electrodes, a disturbance in the phase modulation amount may occur in a region R1 corresponding to the edge of the pixel electrode. ｐｘ However, it is difficult to actually control the voltage applied to the electro-optic crystal, making it difficult to obtain stable optical modulation.

[0069] In the comparative example, even in region R2 corresponding to the center of the pixel electrode, the phase modulation amount is not flat, and a curvature may occur. Also, in region R3, which is outside the edge of the pixel electrode, the value of the lateral electric field becomes relatively high, which may reduce the contrast between the phase modulation amount in region R2 and the phase modulation amount in region R3.

[0070] In contrast, in the light modulation device 21, the transparent electrode 23 is divided by gaps G into multiple electrode regions R facing at least one of the multiple pixel electrodes 30. In this case, when a voltage is applied between the transparent electrode 23 and the pixel electrode 30, a lateral electric field smaller than that generated in the pixel electrode 30 is generated between the transparent electrode 23 and gap G. This makes it possible to enhance the electric field in regions R1 corresponding to the edges of the pixel electrode 30, and to diffuse the lateral electric field generated at the edges of the pixel electrode 30 in the lateral direction (the arrangement direction of the pixel electrodes 30). Therefore, as shown in FIG. 14 , it is possible to eliminate the disturbance in the amount of phase modulation in regions R1 corresponding to the edges of the pixel electrode, and the amount of phase modulation is also flat in region R2 corresponding to the center of the pixel electrode 30.

[0071] Furthermore, in the optical modulation device 21, the dielectric constant of the gap buffer layer 24 is a value between the dielectric constants of the transparent electrode 23 and the electro-optic crystal 22. The placement of the gap buffer layer 24 in this manner suppresses electric field loss between the transparent electrode 23 and the electro-optic crystal 22, and also smooths the lateral electric field diffused by the formation of the gap G. This also contributes to eliminating the disturbance in the amount of phase modulation in the region R1 corresponding to the edge of the pixel electrode, and by reducing the value of the lateral electric field in the region R3 outside the edge of the pixel electrode, the contrast between the amount of phase modulation in the region R2 and the amount of phase modulation in the region R3 is improved. Therefore, the optical modulation device 21 can achieve stable optical modulation.

[0072] Furthermore, by disposing the gap buffer layer 24 between the transparent electrode 23 and the electro-optic crystal 22, charges from the transparent electrode 23 are trapped in the gap buffer layer 24, which also has the effect of suppressing unexpected charge movement. This makes it possible to achieve more stable light modulation and is also expected to have the effect of suppressing charge injection.

[0073] This embodiment includes an aspect in which the plurality of electrode regions R are rectangular, and the gaps G are provided so as to correspond to the sides of the plurality of electrode regions R. With this configuration, the transverse electric field is further smoothed in the direction connecting the sides of the plurality of electrode regions R.

[0074] This embodiment includes an aspect in which the plurality of electrode regions R are rectangular, and the gaps G are provided so as to correspond to the corners of the plurality of electrode regions R. With this configuration, the transverse electric field is further smoothed in the direction connecting the corners of the plurality of electrode regions R.

[0075] This embodiment includes an aspect in which the plurality of electrode regions R are rectangular, and the gaps G are provided so as to correspond to both the sides and corners of the plurality of electrode regions R. With this configuration, the transverse electric field is further smoothed in both the direction connecting the sides of the plurality of electrode regions R and the direction connecting the corners.

[0076] In this embodiment, the plurality of electrode regions R are connected to one another except for the gaps G. By connecting the plurality of electrode regions R to one another, a voltage can be applied uniformly between the plurality of pixel electrodes 30.

[0077] In this embodiment, the relative dielectric constant of the electro-optic crystal 22 is set to ε ｒｃ and the relative dielectric constant of the gap buffer layer 24 is ε ｒｆ In this case, ε ｒｃ / 100<ε ｒｆ <ε ｒｃ By satisfying such a relationship of relative dielectric constants, the loss of the electric field between the transparent electrode 23 and the electro-optic crystal 22 can be more effectively suppressed.

[0078] In this embodiment, the gap G is formed by the air gap 34. By forming the gap G as an air gap, the horizontal electric field generated at the edge of the pixel electrode 30 can be more reliably diffused in the horizontal direction.

[0079] In this embodiment, the light modulation device 21 includes a drive substrate 26 having a plurality of drive electrodes 31 electrically connected to each of a plurality of pixel electrodes 30, a first power supply 27 electrically connected to the transparent electrode 23, and a second power supply 28 electrically connected to the drive substrate 26. By using two power supplies, one on the transparent electrode 23 side and the other on the drive substrate 26 side, it becomes possible to apply a voltage to the transparent electrode 23 that is independent of the withstand voltage and control method of the drive substrate 26. This improves the degree of freedom in the modulation pattern for the input light Lp.

[0080] 15 is a schematic cross-sectional view showing the configuration of an optical modulation device according to a modified example. As shown in FIG. 15, an optical modulation device 41 according to the modified example differs from the optical modulation device 21 described above in that the gap G is formed of an insulator 44.

[0081] The insulator 44 is preferably transparent to the input light Lp and the modulated light Lm. The insulator 44 may be made of, for example, SiO. ２, SiN, or hydrogen silsesquioxane (HSQ). By using the insulator 44 for the gap G, the horizontal electric field generated at the edge of the pixel electrode 30 can be more reliably diffused in the horizontal direction. Furthermore, by surrounding the multiple electrode regions R with the insulator 44, a voltage can be applied uniformly between the multiple pixel electrodes 30.

[0082] In this embodiment, an insulator 44 is patterned on the gap buffer layer 24, and the transparent electrode 23 is provided on the entire surface of the gap buffer layer 24 so as to cover the insulator 44. That is, in this embodiment, the transparent electrode 23 is divided into a plurality of electrode regions R by gaps G, which are the insulator 44, and the plurality of electrode regions R are connected to each other by the electrode portions of the transparent electrode 23 provided so as to cover the gaps G.

[0083] 16 to 18 are schematic plan views showing an example of gap patterning. For ease of explanation, the electrode portions of the transparent electrode 23 that are provided to cover the gaps G are omitted from the illustrations in FIGS. 16 to 18. In the example of FIG. 16, the plurality of electrode regions R are divided into rectangular (square) sections in one-to-one correspondence with the pixel electrodes 30 arranged in a matrix. Gaps G, which are insulators 44, are provided in a grid pattern between the plurality of electrode regions R and in portions corresponding to the outer edges of the transparent electrode 23.

[0084] In the example of Fig. 17, the plurality of electrode regions R are divided into rectangular sections corresponding to 1 x 2 pixel electrodes 30. Gaps G, which are insulators 44, are provided in a lattice pattern between the plurality of electrode regions R and in the portions corresponding to the outer edges of the transparent electrodes 23. In the example of Fig. 18, the plurality of electrode regions R are divided into square sections corresponding to 2 x 2 pixel electrodes 30. Gaps G, which are insulators 44, are provided in a lattice pattern between the plurality of electrode regions R and in the portions corresponding to the outer edges of the transparent electrodes 23.

[0085] When the gap G is formed by the insulator 44, it is not necessary to connect the plurality of electrode regions R with the electrode portion of the transparent electrode 23 provided so as to cover the gap G, as in the above-described optical modulation device 41. For example, in the patterning of the transparent electrode 23 shown in FIGS. 6 to 13 , the gap G formed by the void 34 may be replaced with the gap G formed by the insulator 44.

[0086] Next, a test for confirming the effects of the present disclosure will be described.

[0087] This test assumes a calculation model 101 shown in FIG. 19(a), and calculates the voltage V ｐｘ In the calculation model 101 of the embodiment, the electro-optic crystal 122 is a KTN crystal, a gap buffer layer 124 and a transparent electrode 123 are set on the input surface of the electro-optic crystal 122, and a plurality of pixel electrodes 130 are set on the back surface of the electro-optic crystal. ｐｘ A gap G is set in the transparent electrode 123 corresponding to the position of the boundary with the pixel electrode 130 .

[0088] The parameters used in the phase modulation simulation are summarized in Fig. 19(b). Here, the wavelength of the input light was 632.8 nm, the thickness of the electro-optic crystal was 50 µm, the relative dielectric constant of the electro-optic crystal was 20,000, the refractive index of the electro-optic crystal was 2.318, the Kerr coefficient g12 was -0.038, the thickness of the gap buffer layer was 0.5 µm, and the relative dielectric constant of the gap buffer layer was 2,000.

[0089] A calculation model 101 in which the gap buffer layer 124 and the gap G in the transparent electrode 123 were omitted was used as a calculation model of Comparative Example 1. A calculation model 101 in which the gap G was set in the transparent electrode 123 and the gap buffer layer 124 was omitted was used as a calculation model of Comparative Example 2.

[0090] 20(a) is a diagram showing the simulation results of Comparative Example 1, and FIG. 20(b) is a diagram showing the simulation results of Comparative Example 2. FIG. 20(c) is a diagram showing the simulation results of the Example. In these diagrams, the horizontal axis represents the in-plane position X, and the vertical axis represents the total number. The total number is the total number of amplitudes of the electric field components of input light input at the in-plane position X. As shown in FIGS. 20(a) and 20(b), in Comparative Examples 1 and 2, the total number is not flat in the region corresponding to the center of the pixel electrode, and there is also variation in the total number in the region corresponding to the edge of the pixel electrode.

[0091] 20(c), in the example, the total number in the region corresponding to the center of the pixel electrode is flat, and the fluctuation in the total number in the region corresponding to the edge of the pixel electrode is also suppressed. It can also be seen that the contrast between the total number in the pixel electrode region and the total number in the region outside the edge of the pixel electrode is improved compared to Comparative Examples 1 and 2.

[0092] 21 to 25 are based on the results of FIG. 20 and are in the range of 60≦X<100 (when the applied voltage is V ｐｘ 21(a) to 21(c) are diagrams showing the results of quantitative evaluations divided into the range of 60≦X<100 (range in which X<100 is applied) and the range of 100≦X≦150 (range in which the applied voltage is 0 V). FIGS. 21(a) to 21(c) are diagrams showing the primary dispersion of the total number in the range of 60≦X<100, where (a) shows the results of Comparative Example 1, (b) shows the results of Comparative Example 2, and (c) shows the results of the Example. As shown in FIGS. 21(a) to 21(c), it was confirmed that in the range of 60≦X<100, the primary dispersion of the total number in the Example was smaller than in Comparative Examples 1 and 2. In Comparative Examples 1 and 2, the applied voltage V ｐｘ As the applied voltage V ｐｘ Even when the applied voltage V ｐｘ The difference is also kept to less than 0.002.

[0093] 22(a) to 22(c) are diagrams showing the primary dispersion of the total number in the range of 100≦X≦150, where (a) shows the results of Comparative Example 1, (b) shows the results of Comparative Example 2, and (c) shows the results of the Example. As shown in FIGS. 22(a) to 22(c), it was confirmed that the primary dispersion of the total number in the Example was smaller than that in Comparative Examples 1 and 2, even in the range of 100≦X≦150. In Comparative Examples 1 and 2, the applied voltage V ｐｘ As the applied voltage V ｐｘ Even when the applied voltage V ｐｘ is also kept to almost zero.

[0094] 23(a) to 23(c) are diagrams showing the average value of the total number in the range of 60≦X<100, where (a) shows the results of Comparative Example 1, (b) shows the results of Comparative Example 2, and (c) shows the results of the Example. As shown in FIGS. 23(a) to 23(c), in the range of 60≦X<100, in all of Comparative Examples 1 and 2 and the Example, the applied voltage V ｐｘ As the applied voltage V increases, the average value of the total number tends to decrease. ｐｘ It can be seen that the average value of the total number is smaller in the example than in the comparative examples 1 and 2.

[0095] 24(a) to 24(c) are diagrams showing the average value of the total number in the range of 100≦X≦150, where (a) shows the results of Comparative Example 1, (b) shows the results of Comparative Example 2, and (c) shows the results of the Example. As shown in FIGS. 24(a) and 24(b), in Comparative Examples 1 and 2, even though the applied voltage was 0 V, V ｐｘ 24(c), the average value of the total number shows a tendency similar to that in the range of 60≦X<100, due to the influence of the part where the applied voltage V ｐｘ Therefore, it was confirmed that the influence of the horizontal electric field of the adjacent pixels was reduced in the example.

[0096] 25(a) to 25(c) are diagrams showing the results of a simulation of the amount of phase modulation, with (a) showing the results of Comparative Example 1, (b) showing the results of Comparative Example 2, and (c) showing the results of the Example. Here, the amount of phase modulation θ was determined as the difference between the average value of the total number in the range of 100≦X≦150 and the average value of the total number in the range of 60≦X<100. As shown in FIGS. 25(a) to 25(c), in all of Comparative Examples 1 and 2 and the Example, the applied voltage V ｐｘ As the applied voltage V increases, the phase modulation amount θ tends to increase. ｐｘ It can be seen that the phase modulation amount θ is larger in the example than in the first and second comparative examples.

[0097] From the above results, it was confirmed that the configuration disclosed herein, in which gaps are provided in the transparent electrode to divide it into multiple electrode regions, and further, a gap buffer layer is provided whose relative dielectric constant is between that of the transparent electrode and the electro-optic crystal, contributes to realizing stable optical modulation in an optical modulation device.

[0098] 26 is a graph showing the calculation results of the modulation performance index in Comparative Examples 1 and 2 and the Example. This graph shows the modulation performance index calculated based on the voltage V ｃｏｍ When fixed at 30V, the bias ratio V ｂｒ The phase modulation amount is a value calculated as the difference between the average value of the total number of positions X in the in-plane direction in the range of 100<X<150 and the average value of the total number of positions X in the in-plane direction in the range of 60≦X<100. ｂｒ is ΔV ｐｘ / V ｃｏｍ The modulation performance index α is a parameter calculated by the following equation: Ｂｒ This parameter is calculated by the following equation, which quantifies the efficiency of the phase modulation amount relative to the applied voltage. ｐｘ is set to 0V, and in other ranges, V ｂｒ V so that is 0.5 or less ｐｒ The phase modulation amount is set as V ｐｘ The difference was calculated based on the difference between the average values ​​in the range where the voltage was 0 V and the other ranges.

[0099] 26 , the modulation figure of merit α was 0.733 in Comparative Example 1, and 0.681 in Comparative Example 2. In contrast, the modulation figure of merit α was 1.255 in the example, and it was confirmed that the configuration of the present disclosure improved the modulation figure of merit α and improved the efficiency of the phase modulation amount.

[0100] 27 is a graph showing the reduction in power consumption in the example. This graph shows the reduction in power consumption in the example when the voltage V ｃｏｍ When the voltage of the transparent electrode is set to 30V, ｃｏｍ When the applied voltage V is set to 60V, ｐｘ 27 shows the relationship between the phase modulation amount θ and V ｃｏｍ Compared to when V is set to 60V, ｃｏｍ When the voltage is set to 30V, the same V ｐｘ The amount of phase modulation is large when the voltage is applied.

[0101] This result shows that the voltage V ｃｏｍ It is presumed that this is because, when the voltage V of the transparent electrode becomes high, the disturbance of the phase modulation becomes large and the amount of phase modulation is dispersed in the horizontal direction. ｃｏｍ It was suggested that lowering the value reduces the disturbance of the phase modulation and suppresses the lateral dispersion of the phase modulation amount, thereby making it possible to more effectively secure the phase modulation amount.

[0102] 1...light observation device, 2...light source, 6...first optical system (optical system), 10...detector, 11...light irradiation device, 21, 41...light modulation device, 22...electro-optic crystal, 22a...input surface, 22b...rear surface, 23...transparent electrode, 24...gap buffer layer, 25...reflector, 26...drive substrate, 27...first power supply, 28...second power supply, 30...pixel electrode, 31...drive electrode, 34...gap, 44...insulator, Lp...input light, Lm...modulated light, G...gap, R...electrode region, S...sample.

Claims

1. An optical modulation device that modulates input light and outputs it as modulated light, comprising: an electro-optic crystal having an input surface to which the input light is input and a back surface opposite the input surface; a transparent electrode provided on the input surface side of the electro-optic crystal and transmitting the input light; a gap buffer layer provided between the transparent electrode and the electro-optic crystal; and a reflective section having a plurality of pixel electrodes arranged on the back surface side of the electro-optic crystal and reflecting the input light that reaches the back surface toward the transparent electrode, wherein the relative dielectric constant of the gap buffer layer is a value between the relative dielectric constant of the transparent electrode and the relative dielectric constant of the electro-optic crystal, and the transparent electrode has a gap that divides the transparent electrode into a plurality of electrode regions facing at least one of the plurality of pixel electrodes.

2. The optical modulation device according to claim 1, wherein the plurality of electrode regions are rectangular, and the gaps are provided so as to correspond to the sides of the plurality of electrode regions.

3. The optical modulation device according to claim 1, wherein said plurality of electrode regions are rectangular, and said gaps are provided so as to correspond to corners of said plurality of electrode regions.

4. An optical modulation device according to claim 1, wherein said plurality of electrode regions are rectangular, and said gaps are provided so as to correspond to both sides and corners of said plurality of electrode regions.

5. An optical modulation device according to any one of claims 1 to 4, wherein the plurality of electrode regions are connected to each other except for the gap.

6. The relative dielectric constant of the electro-optic crystal is ε ｒｃ and the relative dielectric constant of the gap buffer layer is ε ｒｆ In this case, ε ｒｃ / 100<ε ｒｆ <ε ｒｃ 6. The optical modulation device according to claim 1, wherein the optical modulation device satisfies .gamma.

7. The optical modulation device according to any one of claims 1 to 6, wherein the gap is constituted by an air gap.

8. The optical modulation device according to any one of claims 1 to 6, wherein the gap is made of an insulator.

9. An optical modulation device according to any one of claims 1 to 8, comprising: a drive substrate having a plurality of drive electrodes electrically connected to each of the plurality of pixel electrodes; a first power supply electrically connected to the transparent electrode; and a second power supply electrically connected to the drive substrate.

10. An optical observation device comprising: a light source that outputs the input light; an optical modulation device according to any one of claims 1 to 9; an optical system that guides the modulated light output from the optical modulation device to a sample; and a detector that detects light from the sample.

11. A light irradiation device comprising: a light source that outputs the input light; an optical modulation device according to any one of claims 1 to 9; and an optical system that guides the modulated light output from the optical modulation device to a sample.

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