JPH0493822A - Nonlinear optical material and nonlinear optical element - Google Patents

Abstract

PURPOSE:To easily obtain the nonlinear optical material of a low loss and high efficiency by using a high polymer or a specific low-molcular material having high solubility in org. solvents. CONSTITUTION:This material contains the org. material having the structure expressed by formula I. In the formula I, pi electron conjugation rings may be the structures equal to each other or different from each other; X1 to Xn-1 and Y1 to Yn-1 are respectively either N or CH which may be equal to or different from each other; R and R' denote a substituent and at least either thereof exhibits the group expressed by formula II or III; n denotes 3 to 8 integer. In the formulas II, III, Z and Z' denote H or -OCOpH2p+1(p>=) and at least either thereof denotes a group exclusive of H; k>1, m>1, x and y>=3. The optical material of the low loss and high efficiency is obtd. in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a nonlinear optical material, and the material has optical functions that apply nonlinear optical effects such as optical force-shutter, optical bistability, and optical switching. It can be used as a material for nonlinear optical elements that make up devices.

[Conventional technology]

Conventionally, crystalline polymers such as polydiacetylene and polyacetylene have been representative materials of this kind, and their nonlinear optical constants have been measured [Reference (1):
C,5auteret et al., Physical Review Letters (Phys, Rev,
Letter, ) Volume 36, pp. 956-959 (19
76):], it is necessary to produce single crystals or single crystal thin films for device applications, and it is often very difficult to produce high-quality crystals, and there is a high optical loss for use in optical devices, making it impractical. It is unsuitable for fabricating large-scale devices.

On the other hand, in order to solve the above-mentioned problems, there are examples in which a low molecule with a high nonlinear susceptibility is dispersed in a polymer, or a material dissolved in a solution is used as a material for a nonlinear device. This type of material is advantageous in that it has low optical quality loss and is easy to fabricate waveguides.

[Problem to be solved by the invention]

In general, for low-molecular materials with high nonlinear susceptibility, it is necessary to lengthen the π-conjugated chain, which is involved in nonlinearity, to a certain extent.

As a result, the molecule itself becomes rigid, and its solubility in organic solvents and polymeric materials becomes extremely low. For this reason, the nonlinear optical constants of nonlinear optical material systems dispersed in polymers or solvents are generally not very large at present, making it difficult to apply them to practical devices.

For example, many low-molecular materials that exhibit large nonlinear susceptibility have strong electron-donating groups, amino groups, etc. at the terminals of their π-conjugated chains. Specifically, 5BAC: Molecular structure: "1 DEANS: Molecular structure: None.

An object of the present invention is to provide a nonlinear optical material and a nonlinear optical element that solve the above problems.

[Means to solve the problem]

To summarize the present invention, the first invention of the present invention relates to a nonlinear optical material, which includes the following general formula I: etc., and the third-order nonlinear optical constant χ(3) value is 10
- Large values of approximately ``esu'' have been reported [Reference (2)
): Takashi Kurihara, Chemical Physics Letters (
Chem, Phys, Letter,) Volume 165,
171-174 (1990)).

In order to apply these materials to devices, it is advantageous to use them in the form of dispersion in polymeric materials in terms of loss, ease of processing, and stability, but since they can only be dissolved in amounts of a few wt% at most. , the χ(3) value of the dispersed material itself is 10−
It is an effective material because only a low χ(3) value of approximately ``esu'' can be obtained [■], and the structures may be the same or different. ~Y n -1 is either N or CH, and may be equal to or different from each other. Furthermore, R and R' represent substituents, and at least one of them is represented by the following general formula (■) or (■).
: (wherein Z and Z' are H or -〇(1:QCpH2, +
, (where p≧1), but at least one of H
Indicates a group other than k>, 1, m>1) (in the formula, X and y≧3).

Further, it is characterized by containing an organic material having a structure represented by the following formula: n is an integer of 3 to 8.

Further, a second invention of the present invention relates to a nonlinear optical element, and is a nonlinear optical element used in a nonlinear optical device composed of an optical medium having a nonlinear refractive index or a nonlinear absorption coefficient and other optical elements. In the first
The invention is characterized by using any of the materials described in the invention as an optical medium.

In order to improve the low nonlinearity that is a problem with conventional materials in which organic materials are dispersed, the present invention has developed a highly nonlinear It concerns both the material system that makes it possible to express this property and the material in which it is dispersed in polymers or solvents.

In the present invention, in order to prevent the reduction of optical nonlinearity due to the π-electron conjugated chain by adding a substituent with high solubility, only the amino skeleton constituting the electron donating group attached to the π-electron conjugated chain is dissolved. By chemically modifying the material with substituents that increase its properties, we have created materials with high solubility in solutions or polymers.

There are groups with large electron-withdrawing properties such as NO2.

The number of n in the compound represented by the general formula CI] of the present invention is 3
〜8 for materials with similar solubility and χ(3
) value was obtained. However, if n is 9, the solubility is 1%.
As a result, only a low χ(3) value of about 1×10 −”esu was obtained.

Furthermore, similar results were obtained when p in the general formula [■] was 1 to 4.

Furthermore, as an example of the nonlinear optical material of the present invention, there is one in which one or more of the organic materials described in the first invention is dispersed in a polymer or a solution.

In the examples of the present invention, only ethyl acetate and polymethyl methacrylate (PMMA) were described as the dispersion medium, but the same degree of nonlinearity can be obtained using other solvents or polymers.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The invention is not limited to these examples.

Example 1 0.2 mole of 4-(N-ethyl-N-hydroxyethyl)amino-aniline and 0.1 mole of 2,5-dichloroterephthalaldehyde are dissolved in tetrahydrofuran (THF) and benzenetoluenesulfonic acid was used as a catalyst to react.

After removing the solvent, obtain ○H-8BAC Molecular structure: 0.05 mol of ShiL and 0.1 mol of acetyl chloride in THF
A-3BAC, which is one of the materials of the present invention, had the following molecular structure.

This A c-3BAC was deposited on a glass substrate by vapor deposition.
．． 1 μm was deposited, and the χ(3) value of this material was determined from the intensity of the third harmonic. χ33 at the fundamental wave of 1.9 μm)
The value was on the order of 10-''esu.

Next, this material was dispersed in PMMA to obtain a polymer-dispersed material according to the present invention. 5BAC is 1w to PMMA
Whereas Ac-3BAC dissolves only up to t%, PM
It was possible to dissolve up to 20 wt% in MA.

Similar to the deposited film of Ac-3BAC, a thin film of this dispersed material was prepared by spin coating (thickness: 0.1 μm).
When the χ(3) value was calculated from the intensity of the third harmonic,
It was about 2 x 10-12 esu.

We also fabricated a polymer rod with a thickness of 5 mm using this material, and conducted experiments on a light-shutter element that utilizes the third-order nonlinear optical effect (the light-power effect in which the refractive index of the material changes). The optical system is shown in Figure 1. 1 is a signal light with a linearly polarized component (wavelength: 0.84 μm)
2 is a gate light (wavelength: 0.7 μm); 3 is a material sample of the present invention. 4 is a polarizer, 5 is a gate light removal filter, and 6 is a photodetector. If the gate light of 2 is not irradiated, 4 is arranged in crossed nicols, so
The signal light 7 cannot pass through the polarizer, and the light intensity detected by the photodetector 6 is O. However, when the gate light from No. 2 is irradiated onto the sample from No. 3, the refractive index of the material changes due to the third-order nonlinear optical effect, and the gate light, which was linearly polarized light, changes to elliptically polarized light when it passes through the sample No. 3. However, the signal light was able to pass through the polarizer No. 4, and the signal light could be observed with a photodetector, confirming the optical power-shutter operation.

The obtained χ[31 value was approximately 2.2 × 10-"esu, which was almost the same as the χ33) value obtained from the third harmonic) intensity. The switching speed confirmed high-speed response of less than ns order. T-ko.

Furthermore, the loss value of this material was less than 0.1 dB/cm.

Example 2 Ac2-3BAC: Molecular structure was obtained by the same reaction as in Example 1. The same vapor deposition method as in Example 1 (Ac2-3
When a vapor deposited film of BAC was prepared and the χ[31 value was calculated, it was found to be approximately 10-"esu. Furthermore, when the material was similarly dispersed in PMMA, Ac2-5BA
C could be dissolved up to 3Qwt%. When the intensity of the third harmonic of the sample was calculated, it was approximately 3 x 10-I2esu. When an optical power-shutter experiment was conducted in the same manner as in Example 1, the detection power of the signal light by the gate light was observed (observable), and the optical power-shutter operation was confirmed.

Example 3 HH-3BA shown below was produced by the same reaction as in Example 1.
C: The molecular structure was obtained. The χ131 value of the deposited film of this material is about 10 esu, and when it was dissolved in the organic solvent ethyl acetate, it was able to dissolve up to 40 wt%, and the intensity of the third harmonic of this liquid sample in the glass cell was determined. By the way, 4 x 10
It was about -12 esu.

When an optical power-shutter experiment was conducted in the same manner as in Example 1 above, detection of signal light by the gate light could be observed, and the optical power-shutter experiment was observed.
I checked the shutter operation.

Example 4 HH-8BAC in Example 3 and A in Example 2
When two types of c2-3BAC were simultaneously dispersed in PMMA, HH-3BAC10wt%, Ac2-3BAC
It can dissolve up to 30wt%, and the χ33) value is 4.
X 10-"esu was obtained. With HH-3BAC alone, P
Although it is only soluble up to 5 wt% in MMA, by mixing different types of molecules, it was possible to increase the solubility in PMMA. Kerr shutter operation was similarly confirmed for this material as well.

Table 1 shows the χ13) values determined from the intensity of the third harmonic of other main materials proposed by the present invention and their polymer-dispersed materials.

In the compounds of Table 1 above, the number of p in formula [11,1 is 4
We tried the same thing with low-molecular-weight materials that had been changed up to
3) There was no significant difference in the values.

Example 5 An optical fiber having the shape shown in FIG. 2 was produced by synthesizing the polymer-dispersed materials shown in Examples 1 and 2 in a glass capillary. The diameter of the core is 125 μm and the length of one fiber is 10 cm. With this fiber,
When experiments were conducted on the optical force-shutter element in the same manner as in Example 1, a signal light intensity approximately 10 times greater than that of the rod-shaped material shown in Examples 1 and 2 was obtained. In addition, in Figure 2,
7 is a glass capillary; 8 is a core made of the material of the present invention.

Example 6 A waveguide having the shape shown in FIG. 3 was obtained by spin-coding the polymer-dispersed materials shown in Examples 1 and 2 onto a glass substrate. The film thickness is 5 μm and the optical path length is 1 cm.

When a light power-shutter experiment was conducted and compared in the same manner as in Example 5, a signal light intensity of about 20 times that of the rod-shaped material was obtained. In addition, in FIG. 3, 9 is a thin film made of the material of the present invention, and 10 is a glass substrate.

〔Effect of the invention〕

As explained above, the material of the present invention has the advantage that it can be easily made into a low-loss and highly efficient nonlinear optical material because it uses a polymer or a low-molecular material with high solubility in organic solvents. are doing. Therefore, a practical nonlinear optical element that is low loss and effective can be easily realized.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing a measurement system for an optical force-shutter experiment using the material of the present invention, Fig. 2 is a diagram showing an example of the configuration of an optical fiber of the present invention, and Fig. 3 is a diagram showing the configuration of a waveguide of the present invention. It is a figure which shows an example. DESCRIPTION OF SYMBOLS 1... Signal light having a linearly polarized component, 2... Gate light, 3... Material sample of the present invention, 4... Polarizer, 5
...Gate light removal filter 6...Photodetector,
7... Glass capillary 8... Core made of the material of the present invention, 9... Thin film made of the material of the present invention, 10...
・Glass substrate

Claims (1)

[Claims] 1. The following general formula I: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ... [I] [In the formula, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ~ ▲ Numerical formulas,
There are chemical formulas, tables, etc. ▼ is a π-electron conjugated ring, and they may have the same structure or different structures. X_1~X_n_-_1 and Y_1~Y_n_-_
1 is either N or CH, and may be equal to or different from each other. In addition, R and R' represent substituents, and at least one of them is represented by the following general formula II or III: ▲There are mathematical formulas, chemical formulas, tables, etc.▼... [II] {In the formula, Z and Z' are H or -OCOC_pH_2_p
___+_1 (in the formula, p≧1), and at least one of them represents a group other than H. k>1, m>1}, ▲There are mathematical formulas, chemical formulas, tables, etc.▼...[II] Indicates a group represented by (in the formula, x and y≧3). and n represents an integer of 3 to 8] A nonlinear optical material characterized by containing an organic material having a structure represented by the following. 2. A nonlinear optical material comprising one or more of the organic materials according to claim 1 dispersed in a polymer or a solution. 3. A nonlinear optical element used in a nonlinear optical device composed of an optical medium having a nonlinear refractive index or nonlinear absorption coefficient and other optical elements, in which any one of the materials according to claim 1 is used as the optical medium. A nonlinear optical element characterized by: