JPH0670697B2 - Organic nonlinear optical material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a non-linear optical material used for a high frequency multiplier, an optical shutter, an EO converter, and the like, and more specifically, has a diyne group in the main chain. The present invention relates to an organic nonlinear optical material composed of a polymer.

(Prior Art) Conventionally, inorganic ferroelectric materials such as potassium dihydrogen phosphate (KDP) and lithium niobate (LiNbO ₃ ) have been put to practical use as optical frequency multipliers as nonlinear optical materials. On the other hand, organic non-linear optical materials have characteristics such as larger non-linear optical constants, faster non-linear optical response, and higher breakdown threshold, and are attracting attention as conventional basic materials in the field of optoelectronics. In addition, since organic materials also have the advantage that they can be made into various materials and can be modified with molecules, research on organic nonlinear optical materials is being actively conducted. A material exhibiting a third-order nonlinear optical effect can be applied to an element utilizing the change in the refractive index depending on the light intensity, and can be expected to be applied to an optical memory or an optical logic element.

(Problems to be Solved by the Invention) As an organic material exhibiting a large third-order nonlinear optical effect,
Polyacetylene, polydiacetylene, and metal phthalocyanine having a π-electron conjugated system are well known. However, since these materials do not melt and also do not dissolve in a general organic solvent, it is difficult to control the film thickness and it is difficult to obtain a thin film having excellent mechanical strength. Therefore, the reality is that there is a limit to the expansion to optical elements.

(Means for Solving Problems) As a result of intensive investigations by the present inventors in view of the above problems,
It was clarified that a polymer having a diyne group in the main chain shows a nonlinear optical effect and becomes soluble in an organic solvent by introducing an alkyl group or an alkylene group. Furthermore, they have found that the nonlinear optical effect of these polymers is improved by heat treatment, light irradiation, or radiation irradiation. That is, the general concept of the present invention is a polymer nonlinear optical material having a diyne group in the main chain and containing an alkyl group or an alkylene group, in other words, a general formula C≡C—R—C≡C _n [. In the formula, R is an alkylene group or a group containing an alkylene group or an alkyl group such as an alkylphenylene group or an alkoxyphenylene group] and relates to an organic nonlinear optical material comprising a polymer having a diyne group in the main chain. Furthermore, it relates to an organic nonlinear optical material obtained by subjecting these polymers to heat treatment, light irradiation or radiation irradiation.

In the definition of the above formula, an example of R is a hexylene group, p
A dibutoxyphenylene group.

Of these polymers, those in which R is an alkylene group are soluble in common organic solvents such as methylene chloride and tetrahydrofuran, and those in which p-dibutoxyphenylene group is 1,3-dimethylimidazolidinone. It was soluble. Polymer films were obtained from these polymer solutions by spin coating or casting.

The material represented by the above general formula is generally obtained by oxidative coupling polymerization of a monomer having two terminal acetylene groups with oxygen.

(Effects of the Invention) Conventionally known materials exhibiting a third-order nonlinear optical effect are inferior in workability and a thin film excellent in mechanical strength has not been obtained. The polymer of the present invention is excellent in mechanical strength and can realize a thin film exhibiting a third-order nonlinear optical effect. In addition, since a simple casting method or spin coating method can be used for forming a thin film, it is possible to easily control the film thickness, etc. Furthermore, since this polymer is a photoresist using a solid phase reaction of a diyne group, patterning is possible. By using this, an optical integrated circuit or the like can be realized.

(Example) Hereinafter, the present invention will be described more specifically by way of examples.

Example 1 100 mg of cuprous chloride, 1 ml of N, N, N ′, N′-tetramethylethylenediamine were mixed with pyridine (20 ml) and chlorobenzene (80 m
l) was dissolved in the mixed solvent and pre-oxidized by blowing oxygen for 15 minutes into the solution, and the monomer 1,9-decadiyne (5
g) was added and polymerization was carried out at 60 ° C. for 5 hours while blowing oxygen. The reaction solution was poured into 500 ml of methanol containing hydrochloric acid, and the deposited precipitate was filtered, washed with methanol, pure water and acetone, and dried under reduced pressure to obtain white poly (1,9-decadiyne) (4.2 g , Yield 84%).

This polymer (3 g) was dissolved in 1,2-dichloroethane (300 ml) and cast on quartz glass to obtain a polymer thin film.
Further, this thin film was heat-treated at 150 ° C. for 48 hours. FIG. 1 shows the UV-visible absorption spectra of this polymer thin film before and after heat treatment.

Third-order nonlinear optical effect, optical third-harmonic generation (THG)
According to the measurement. Basic wavelength of Nd: YAG laser (1064nm)
The THG maker fringe method was carried out using Raman shift light (1907 nm) obtained by passing the light in a high-pressure hydrogen cell.
The measurement was performed under reduced pressure to remove the influence of air.

The measurement results of the THG maker fringe of the quartz substrate and the heat-treated poly (1,9-decadiyne) / quartz substrate are shown in FIGS. 2 and 3. The incident light intensity was calculated from the fringe pattern of the quartz substrate, which is a reference sample, and the third-order nonlinear susceptibility (χ ⁽³⁾ ) was calculated from the intensity. As a result, a value of 1.2 × 10 ⁻¹² (esu) was obtained for poly (1,9-decadiyne).

Heat treated poly (1,9-decadiyne) produced on a quartz substrate
For the (thickness: 1.7 μm), light was guided using the device shown in FIG. This device measures the light totally reflected on the bottom surface of the prism by changing the incident angle.
A He-Ne laser (633 nm) was used as a light source. Light is incident on the prism (material: FD-11) by the coupling method.
The measurement was performed in the E mode, and the intensity of the light totally reflected by the bottom surface of the prism without being incident on the film was measured. FIG. 5 shows the relationship between the incident angle and the reflected light intensity. It was found that the reflected light intensity has a minimum value at three angles, a, b, and c in the figure, and is incident and guided in the polymer film at these incident angles.

Example 2 Cupric chloride (50 mg), N, N, N ', N'-tetramethylethylenediamine (0.5 ml) was added to pyridine (10 ml) and chlorobenzene (4 ml).
(0 ml) in a mixed solvent, and oxygen was blown therein for 15 minutes to preoxidize the solution, and the monomer 1,4-diethynyl-
2,5-Dibutoxybenzene (500 mg) was added and polymerization was carried out at 60 ° C. for 5 hours while blowing oxygen. The reaction solution was poured into 300 ml of methanol containing hydrochloric acid, and the deposited precipitate was filtered, washed with methanol, pure water and acetone, and dried under reduced pressure to give dark yellow poly (1,4-diethynyl-2,5-di- Butoxybenzene) PDEDBB was obtained (420 mg, yield 84%). 6A, 6B
The ¹³ C-NMR spectrum of this polymer (polymer in FIG. 6A and monomer in FIG. 6B) is shown in the figure.

This PDEDBB (100 mg) was added to 1,3-dimethylimidazolidinone (100 ml) and heated to 120 ° C to dissolve it. By casting this solution on a quartz substrate, the thickness is 1.5 μm.
A polymer film of FIG. 7 shows the UV-visible absorption spectrum of this film.

Third-order nonlinear optical effect is generated by optical third-order harmonic generation (THG)
According to the measurement. Basic wavelength of Nd: YAG laser (1064nm)
The THG maker fringe method was carried out using Raman shift light (1907 nm) obtained by passing the light in a high-pressure hydrogen cell.
The measurement was performed under reduced pressure to remove the influence of air.

Fig. 8 shows the measurement results of the THG maker fringe on the PDEDBB / quartz substrate. The incident light intensity was calculated from the fringe pattern of the quartz substrate, which is a reference sample, and the third-order nonlinear susceptibility (χ ⁽³⁾ ) was calculated from the intensity. As a result, a value of 9 × 10 _-11 (esu) was obtained for PDEDBB.

[Brief description of drawings]

FIG. 1 is a drawing showing an ultraviolet-visible absorption spectrum of a poly (1,9-decadiyne) film produced on a quartz substrate (A: before heat treatment, B: after heat treatment). FIG. 2 and FIG. 3 are drawings showing the measurement results of the THG maker fringe of a quartz substrate and a poly (1,9-decadiyne) / quartz substrate, respectively. FIGS. 4A and 4B are drawings of an apparatus used for measuring the waveguiding property of poly (1,9-decadiyne). FIG. 5 is a drawing showing the waveguiding characteristics of poly (1,9-decadiyne). 6A and 6B are drawings showing ¹³ C-NMR spectra of PDEDBB polymer (FIG. 6A) and monomer (FIG. 6B). FIG. 7 is a drawing showing an ultraviolet-visible absorption spectrum of PDEDBB. FIG. 8 is a drawing showing the measurement results of the THG maker fringe of PDEDBB / quartz substrate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Sparrow Part 2-1, Hirosawa, Wako-shi, Saitama RIKEN

Claims (2)

[Claims] 1. A polymer having a diyne group in the main chain represented by the general formula C≡C—R—C≡C _n [wherein R is an alkylene group, an alkylphenylene group, or an alkoxyphenylene group] Organic nonlinear optical material consisting of molecules. 2. An organic nonlinear optical material obtained by heat-treating, light-irradiating, or irradiating the polymer non-linear optical material according to claim 1.