JPS63220219A - Electrooptic element and its production - Google Patents

Abstract

PURPOSE:To enable the practical application of an optical element having good characteristics by using a thin film crystal of SPCD composed of an org. material for the electrooptic element, thereby obtaining the large electrooptical effect of the titled device. CONSTITUTION:The titled device is constituted of the thin film crystal M of SPCD (Styrylpyridinium Cyanine Dye) composed of the org. material. At the method for producing the titled element, at first SPCD is dissolved in solvent to form a solution, and disposing at least two sheets of substrate plates (2a, 2b) overlapping with each other in said solution (N). The solution (N) infiltrates between the substrate plates, and then said solvent is evaporated, thereby forming the thin film crystal of SPCD between the substrates 2a, 2b. Thus, the titled element having the good electrooptical effect is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [1] Summary of the Invention The present invention provides an electro-optical element and a method for manufacturing the same, using 3P CD (Styrylpyrid), which is an organic material.
IniumCyaninc Dye) has a very high SHG (second harmonic generation) efficiency, and this SPCD's a! grow film crystals,
By configuring the electro-optical element in this way, it has become possible to realize an electro-optical element with a very good electro-optic effect.

[Industrial application field]

The present invention relates to an electro-optical element used in, for example, an optical modulator or an optical switch, and a method for manufacturing the same.

[Traditional techniques]

Conventionally, 1tNb, an inorganic material, has been used as an electro-optic material.
Qi and the like are known, and optical switches and optical modulators that utilize the electro-optic effect of these materials have also been proposed.

[Problem that the invention seeks to solve]

However, since a sufficient electro-optic effect cannot be achieved with the above-mentioned inorganic materials, for example, even if a total reflection type optical switch is manufactured, the optical path change angle is only about 1°, which makes it difficult to create a matrix, concentrator, or product ratio. was a gift. In addition, when manufacturing not only the above-mentioned optical switch but also various other optical devices, the small electro-optic effect is a drawback.
This hindered its practical application.

SUMMARY OF THE INVENTION An object of the present invention is to overcome the above-mentioned problems and provide an electro-optical element and a method for manufacturing the same that can obtain good electro-optic effects.

[Means for solving problems]

The electro-optical element of the present invention is characterized in that it is composed of a 5pCD thin film crystal which is an organic material.

In addition, the method for manufacturing an electro-optical element of the present invention first includes a 5PC
Dissolve D in a solvent. Then, at least two substrates are placed one on top of the other in the solution, and the solution is allowed to penetrate between the substrates. Thereafter, the solvent is evaporated to form a thin film crystal of SPCD between the substrates. This method is characterized by having the above steps.

[For production]

The inventor of the present invention has developed SHG of SPCD which is an organic material.
We focused on the fact that the efficiency is significantly higher than that of conventional inorganic materials. Since the above S 1Ka efficiency belongs to the second-order nonlinear optical effect like the electro-optic effect, it is expected that if the S HG efficiency is large, the electro-optic effect is also large.

Therefore, the inventor thought that by newly using a SPCD thin film crystal having such characteristics as an electro-optical element, a very good electro-optic effect can be obtained. However, in reality, the electro-optic effect of SPCD has not been observed until now. This results in the formation of small crystals (
This was due to the lack of evaluation methods. The inventor solved the above two points, discovered for the first time that the electro-optic effect of SPCD is much larger than that of LiNbO3, and developed this into a device.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 (11) to (P) show 5 according to an embodiment of the present invention.
FIG. 3 is a manufacturing process diagram showing a method for manufacturing a pCD thin film crystal.

First, 5PCD (the molecular formula is shown in Fig. 2) and methyl alcohol solution (N) are placed in a petri dish 1 as shown in Fig. 1 (al). Or two substrates 2 made of quartz etc.
Place a and 2b on top of each other and leave them as they are. Then, the methyl alcohol solution N of SPCD penetrates between the groups Fi2a and 2b by capillary action (at the same time, only the methyl alcohol in the methyl alcohol solution N of SPCD gradually evaporates as shown in tc+ in the same figure. I'm doing it (.

With the evaporation of this methyl alcohol, when the concentration of SPCD in the methyl alcohol solution N of SPCD reaches a saturated state, as shown in (dl and (p, l) in the same figure, a 5PCD thin film is formed between groups 1 and 2a and 2b. A crystal (single crystal) M grows.According to this embodiment, for example, the area is 21×101−
A 5pcD thin film concretion M having a thickness of about 1 to 10 μm can be obtained.

Note that although two substrates 2a and 2b were used here, three
It is also possible to align more than one substrate. Also,
The solvent for melting 5PCD may also be other than methyl alcohol.

Next, the 5PCD thin film crystal M
We will discuss the optical properties of

First, 5PCD thin film concretion M was observed using a polarizing microscope. Schematically, as shown in FIG. 3(a), a polarizer (Po
The linearly polarized light obtained through the polarizer 11 is incident on the 5PCD thin film crystal M, and the transmitted light is passed through an analyzer (Analyzer) arranged at right angles to the direction of the polarizer 11.
) observed through 12. Then, as shown in FIG. 3(b), the polarization direction of the polarizer 11 for the 5PCD thin film condensate M is dl, dz+da.

When changing to d4, it is darkest in the direction of d, , da,
d2. The brightest light was observed in the da direction.

From this it can be seen that dl and da are the optical axes of the crystal.

Further, the crystal has dichroism and exhibits strong light absorption for polarized light in the d1 direction. Here, ST'CD thin membrane conjunctiva M
For °ζ, the optical axis direction (d+ direction) with large light absorption is Z
The optical axis direction (d3 direction) with low light absorption is defined as the y-axis.

When measuring the light absorption spectrum of the 5PCD thin film compact M, as shown in Fig. 4, the light absorption coefficient α for polarized light in the Z-axis direction is the light absorption coefficient α, and the (dashed line) is the light absorption coefficient α- for light polarized in the y-axis direction. It is significantly larger than (dotted chain line). That is, it was found that 5PCD thin film conjunctiva M exhibited very strong dichroism. In FIG. 4, for reference, the light absorption coefficient α0 for unpolarized light is shown by a solid line.

In addition, the 5PCD thin film condensate M has a refractive index n of 1.55 for polarized light in the Z-axis direction for light with a wavelength of 6328 people.
, the refractive index n# for polarized light in the Y-axis direction was 1.31. Furthermore, the 5PCD thin film condensate M had photoluminescence and exhibited a peak at about 2e■ with excitation light: 3,250 people.

The optical properties of the 5PCD thin film crystal M measured as described above are summarized in Table 1 below.

5 Optical Properties of PCD Thin Film Crystal Table 1 In addition to having the above-mentioned properties, the 5PCDi film crystal M has SHG that succumbs to the second-order nonlinear optical effect as described above.
The efficiency is very high, and even compared to MNΔ (methyl nitro aniline), for which the electro-optic effect of 3(5) has been found, for example, it is about one order of magnitude higher.In this way, the 5IIG efficiency is It is expected that a large electro-optic effect will be obtained if the A reflective optical switch can be constructed.

FIG. 5 shows an optical modulator constructed using 5PCD thin film condensate M. In the same figure, first, a transparent substrate (such as a quartz substrate) 22a on which a slit-type electrode 213.21b with a gap of 5 μm and a width of 100 μm is formed is attached to a 5PCD thin film crystal formed in the center of another substrate 22b. M
is pressing against. and the above groups 1 & 22a,
In this configuration, a polarizer 23 and an analyzer 24 are arranged at opposing positions with the polarizer 22b in between. The light modulation is performed by the function generator 25, for example, ΔC of 8K11z.
This is done by applying a voltage between the electrodes 21;], 21b. Note that the configurations of the electrodes 21a and 21b and the configuration of the 5PCD thin film crystal M are not limited to the configurations described above.

FIG. 6 shows an example of light modulation by the above optical modulator.

This measurement can be performed using, for example, helium-neon (lle-Nc).
L□-The light (6328 people) with a polarizer (1'olariz
cr) 5PCD of linearly polarized light polarized in the direction of 23
The θ component of the transmitted light is detected by an analyzer (
The sample was taken out with a photodetector (eg, solar cell, photodiode, etc.) 26, and observed with an oscilloscope 27. At this time, θ=Z=45°, and the applied voltage V [
=he sin (2πνt), v=8 K11z)
The case where the amplitude is set to 10 (V) is shown in Figure 6 (, 11), and the case where the amplitude is set to 50 (V) is shown in the same figure (b). From the figure, it can be seen that as the amplitude of the applied voltage , it can be seen that the amount of transmitted light is modulated well.

The optical modulator shown in FIG. 5 also functions as a phase modulator by setting the polarization direction of the light incident on the 5PCD thin film crystal M in the Z-axis direction.

Therefore, using the configuration shown in FIG. 5, the phase delay (1' hase
When the relationship between (Retardation) Δδ and the applied voltage was measured, it was as shown in FIG. 7 (black circles).

It can be seen that this is significantly larger than Δδ (white circle in FIG. 7) when an electric field is applied in the Z-axis direction of the LiNbO3 single crystal.

Furthermore, based on the results shown in Fig. 7, the figure of merit of the phase delay due to the electro-optic effect is
F was determined and the results are shown in FIG. This value of F serves as a measure of the magnitude of the electro-optic effect, and the larger F is, the greater the electro-optic effect is. From the same figure, 5pCD is LiN
It can be seen that the value is more than 5 times larger than bO3.

Furthermore, 5PCD crystals are known to be orthorhombic. In this case, the electro-optic coefficient matrix becomes. Among these, when the electro-optic coefficient ri3 in the Z-axis direction is calculated based on the value of F above, r 33 = 3.3 X 10
m/V. This value is r 33 of LiNbO3
= 0.32X IQ m/One order of magnitude larger than V,
It is also five times larger than MNA's r + + =0.67X 10 m/V.

Next, FIG. 9 shows a total reflection type optical switch constructed using 5PCD thin film condensate M. In the figure, a 5PCD thin film crystal M is formed only at a portion of the optical waveguide 31 that will become the switch section 32, and slit-shaped electrodes 33a and 33b are provided on both sides of the crystal. Note that the entire optical waveguide 31 is 5PCDV4.
It is also possible to fabricate the V-membrane conjunctive material M and form stud electrodes 33a and 33b only at the portions that will become the switch portion 32. In the figure, when an ACC voltage is applied between the electrodes 33a and 33b, the refractive index of the 5PCD thin film crystal M between them becomes smaller than when no voltage is applied. Therefore, when no voltage is applied, the light that passes through the switch section 32 as it is (dashed line)
is totally reflected due to the change in refractive index caused by voltage application (
solid line). In this case, the optical path change angle θ is approximately 5° (however, the angle is exaggerated in FIG. 9). This value is much larger than that obtained with conventional LiNb03 etc., which is only about 1°. Therefore, matrix formation and integration of optical switches becomes very easy.

As described above, the optical modulator, phase shifter S, and total internal reflection type optical switch constructed using 5PCD thin film crystal M can obtain very good characteristics due to the unprecedented large electro-optic effect. Understood.

In addition to the above-mentioned optical elements, the 5PCD thin film condensate M can be applied to various optical elements that utilize electro-optic effects. Further, the method for producing a thin film crystal of SPCD is not limited to the method shown in FIG. 1.

〔Effect of the invention〕

According to the present invention, by newly using a thin film crystal of SPCD, which is an organic material, as an electro-optical element, it has become possible to obtain a very large electro-optic effect that has never been seen before. Moreover, this has made it possible to put into practical use various optical devices with very good characteristics.

[Brief explanation of the drawing]

FIG. 1(a) to (ei are sr' according to an embodiment of the present invention)
These are manufacturing process diagrams showing the method for producing cD thin film crystals, in which figure (0) is a plan view of figure fd), figure 2 is a figure showing the molecular formula of SPCD, and figure 3 (al and (bl are polarizing microscope images). Figure 4 is a diagram showing the optical absorption spectrum (relationship between optical absorption coefficient α and photon energy (eV)) of 5PCD thin film crystal M, and Figure 5 is a diagram showing the observation method of 5PCD thin film crystal M. A configuration diagram of an optical modulator using thin film condensate M, Fig. 6 (a) and [b> are waveform diagrams showing an example of optical modulation of the optical modulator shown in Fig. 5, Fig. 7 is a 5PCD thin film Figure 8 shows the relationship between the phase delay Δδ due to the electro-optic effect and the applied voltage in single crystal M and LiNbO3 single crystal products. A diagram showing the characteristic number F, Figure 9 is 5PC
It is a block diagram of the total internal reflection type optical switch using D thin film condensation material M. 2 a, 2 b ・ ・ ・ Group 1 anti 21a, 21b
...Electrical device, 23...Polarizer, 24...Analyzer, 25...Function generator, 31...Optical waveguide, 32...Switch 7 section, 33a, 33b... Electric harvest, M...5PCD thin film crystal, N...5PCD methyl alcohol solution.

Claims (1)

[Claims] 1) An electro-optical element constructed from a thin film crystal (M) of SPCD. 2) The electro-optical device according to claim 1, wherein an optical modulator is constructed using the thin film crystal (M) of the SPCD. 3) The optical modulator is provided with a pair of electrodes (21a, 21b) for applying voltage to the thin film crystal (M) of the SPCD, and at opposing positions sandwiching the thin film crystal (M), respectively. The electro-optical element according to claim 2, characterized in that the electro-optical element has a configuration in which a detector (23) and an analyzer (24) are arranged. 4) The electro-optical device according to claim 1, wherein a phase modulator is constructed using the thin film crystal (M) of the SPCD. 5) The phase modulator is a thin film crystal (M) of the SPCD.
A pair of electrodes (21a, 21b) for applying a voltage is provided to the electrode, and a polarizer (23) and an analyzer (24) are respectively arranged at opposite positions sandwiching the thin film crystal (M),
5. The electro-optical device according to claim 4, wherein the polarization direction of light incident on the thin film crystal (M) is aligned with an optical axis direction having a large light absorption coefficient. 6) The electro-optical device according to claim 1, wherein a total reflection type optical switch is constructed using the thin film crystal (M) of the SPCD. 7) The total internal reflection type optical switch includes at least a region of the optical waveguide (31) that will become the switch section (32) at the SP.
The present invention is characterized in that it is formed of a thin film crystal (M) of CD and has a configuration in which a pair of electrodes (33a, 33b) for voltage application is provided to the region that becomes the switch section (32). The electro-optical element according to range 6. 8) Dissolve SPCD in a solvent, place at least two substrates (2a, 2b) on top of each other in the solution (N), allow the solution (N) to enter between the substrates, and then remove the solvent. A method for manufacturing an electro-optical element, comprising the step of forming the SPCD (7) thin film crystal (M) between the substrates by evaporation. 9) The method for manufacturing an electro-optical element according to claim 8, wherein the solvent is methyl alcohol.