JP2937280B2 - Third-order nonlinear optical material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a third-order nonlinear optical material useful in fields such as optoelectronics, optical information processing, and optical communication.

[0002]

2. Description of the Related Art A nonlinear optical material is a material that exhibits a second-order or higher nonlinear response under a strong electric field of laser light, and is an important material in optical signal processing such as frequency conversion, oscillation, and switching. is there. In particular, tertiary nonlinear optical materials are attracting attention as key materials in next-generation optical communication and information processing that fully exhibit the excellent characteristics of light, such as high speed and parallelism.

[0003] Among these nonlinear optical materials, organic nonlinear optical materials are particularly important because some of them have high-speed response and a large nonlinear optical constant as compared with conventional inorganic nonlinear optical materials.

At present, organic non-linear materials having a large tertiary effect include polydiacetylene [particularly, PTS: 2,4-hexadiyne-1,6-bis (p-toluenesulfonate)] and π-conjugated materials represented by polyacetylene. Molecular systems and aminonitrostilbenes (especially DEANS:
N, N-diethyl-4-amino-4'-nitrostilbene), which are classified into two types of low molecular weight systems in which donors and acceptors are asymmetrically substituted.

The non-linearity of the π-conjugated polymer system is based on the polarization of free electrons in the valence band. Therefore, the defect is very similar to that of an inorganic semiconductor, that is, the response speed decreases due to the resonance effect based on a narrow band gap. Can not escape. Further, the donor-acceptor asymmetrically substituted low-molecular-weight system exhibits the same drawbacks as an attempt to increase the effect beyond the current state (DEANS) by increasing the wavelength of the absorption band due to intramolecular charge transfer.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide an organic nonlinear optical material exhibiting a high-speed and high-response optical nonlinear response. The present invention relates to a third-order nonlinear optical material containing a compound represented by the following general formula [I].

[0007]

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The main features of the organic nonlinear optical material according to the present invention are that it has a longer third-order nonlinear optical effect than ever before, while suppressing a longer wavelength of absorption to prevent a decrease in response speed. . This has the disadvantage of increasing the wavelength of absorption due to an increase in π-conjugation and an increase in charge transfer when trying to increase the nonlinear optical effect. The disadvantage of the prior art is that the π-conjugated system has three aromatic rings (including imidazole rings). The problem was solved by the intramolecular charge transfer effect utilizing the electron donating property of the imidazole ring.

By using imidazole as a π-conjugated system, it was possible to limit the absorption to a short wavelength, and it was also confirmed that the third-order nonlinear optical effect was improved by introducing an electron accepting group into the 2-position phenyl group. Further, it is possible to shift the absorption by introducing an appropriate electron donating group into the phenyl group at the 4- or 5-position.

[0010]

Embodiments are described below. Synthesis Example 1 0.05 mol of benzyl, 0.05 mol of p-nitroaldehyde and 40 g of ammonium acetate were added to 100 ml of acetic acid and heated under reflux for 1 hour. Water was added to the solution after the reaction to precipitate crystals. Then, it was filtered, washed, dried and recrystallized from ethanol to obtain 2- (p-nitrophenyl) -4,5-diphenylimidazole.

Example 1 2- (p-nitrophenyl) -4, obtained in Synthesis Example 1,
Third-order nonlinear optical characteristics were measured using 5-diphenylimidazole by a polarization / nonlinear constant measuring apparatus shown in FIG. As a light source, a dye laser 2 produced by exciting a third harmonic (355 nm) of a Q-switched Nd: YAG laser 1 is used.
The light is divided into linearly polarized lights by the polarizers P1 and P2. After passing through the sample 3, the probe light 21 is quenched by the analyzer P3. Here, the sample 3 was irradiated with the polarization plane of the pump light 11 and the probe light 21 at an angle of 45 °. The light transmitted through the analyzer P3 was detected by the photomultiplier tube 5 through the spectroscope 4. As a result, C
A third-order nonlinear optical effect 160 times that of S ₂ was observed.

Example 2 Compounds having the substituents shown in Table 1 were synthesized in place of 2- (p-nitrophenyl) -4,5-diphenylimidazole, and third-order nonlinear optical characteristics were obtained in the same manner as in Example 1. Was measured. Table 1 shows the results.

[0013]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a polarization / nonlinear constant measuring apparatus.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-167531 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02F 1/35 504 CA (STN)

Claims (1)

(57) [Claims] 1. A third-order nonlinear optical material comprising a compound represented by the following general formula [I]. Embedded image