JPH0841323A - Composition for active optical waveguide, production of active optical waveguide therefrom and active optical wavegude - Google Patents

Abstract

PURPOSE:To obtain a composition for an active optical waveguide being applicable in a wide frequency region and improved in heat resistance and electrooptic effect by mixing a fluoropolyamic acid with a specified compound. CONSTITUTION:A diamine substituted with a fluoro(alkyl) group is reacted with a tetracarboxylic acid (derivative) in a polar organic solvent to obtain a fluoropolyamic acid which, when cyclized, can give a fluoropolyimide having a refractive index of 1.4-1.9 (at 589nm), a dielectric constant of 2.6-3.5 (at 1MHz) and a glass transition temperature of 300 deg.C or above. 100 pts.wt. this acid is mixed with 0.1-10 pts.wt. electrooptical material being a compound having a hetero ring represented by formula I (wherein X<1> and X<2> are each a chalcogen, NH or NR<2>; R<1> is H, 1-6 C alkyl or aryl; R is 1-6 C alkyl; and Ar is an electron- donating group of formula II or III] as an electron-donating group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for active optical waveguide, a method for producing an active optical waveguide using the same, and an active optical waveguide.

[0002]

2. Description of the Related Art Optoelectronic ICs (OEI)
The optical waveguide in C) is conventionally made of LiNbO ₃ , L
Inorganic materials such as iTaO ₃ , PLZT, Sr ₂ Nb ₂ O ₇ are used. However, these materials have a problem that the response speed is slow due to deliquescent property, low threshold value for destruction, and high dielectric constant, which limits the applicable frequency band. On the other hand, organic polymer materials are generally superior to inorganic materials in that they have no deliquescent property and have a high threshold value for destruction, but such polymer materials generally have no orientation, and as-is It cannot be used as a material for optical switches and modulators that utilize the optical effect. In general, a polymer material having no orientation is applied with a DC electric field while being heated to orient, that is, a method of expressing an electro-optical effect by a poling treatment is used. As a result, the orientation is lost and the electro-optic effect is lost, which is a serious problem. Conventionally, polymethylmethacrylate (PMMA), etc., has been vigorously studied as a polymer-based optical waveguide material, but the glass transition temperature (Tg) is as low as about 150 ° C, and poling is performed at a temperature of 200 ° C or higher required during OEIC manufacturing. However, there is a problem that the orientation generated by the above is completely lost.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the prior art as described above, and is excellent in heat resistance and electro-optical effect and for an active optical waveguide applicable to a wide frequency band. The present invention provides a composition, a method for producing an active optical waveguide using the composition, and an active optical waveguide.

[0004]

The present invention is a composition for an active optical waveguide containing a fluorinated polyamic acid and an electro-optic material, wherein the electro-optic material has a general formula (I) having a heterocycle as an electron-accepting group. )

[Chemical 7] (In the formula, X ¹ and X ² each independently represent a chalcogen atom, NH or NR ² , and R ¹ is a hydrogen atom or a carbon number of 1 to 1.
6 represents an alkyl group or an aryl group, and R ² has 1 carbon atom
Represents an alkyl group of 6 and Ar represents an electron donating group)
The present invention relates to a composition for active optical waveguide, which is a compound represented by

Further, according to the present invention, the method for producing an active optical waveguide is characterized in that the fluorinated polyamic acid in the composition for active optical waveguide is imide ring-closed to give a fluorinated polyimide, and the electro-optical material is oriented. Regarding

The present invention also relates to an active optical waveguide manufactured by the method for manufacturing an active optical waveguide described above.

The present invention will be described in detail below. The fluorinated polyamic acid used in the present invention is a polyamic acid having a fluoro group, a fluoroalkyl group, etc., and can be produced under the same conditions as in the production of ordinary polyamic acid, and generally N-methyl-2-pyrrolidone is used. , N, N-dimethylacetamide, N, N-dimethylformamide and the like, in a polar organic solvent, at least one of which is substituted with a fluoro group or a fluoroalkyl group, and a tetracarboxylic acid or a derivative thereof is reacted. be able to. Examples of the diamine substituted with a fluoro group, a fluoroalkyl group or the like include 3-fluoro-1,2-phenylenediamine, 4-fluoro-1,2-phenylenediamine,
3,4-difluoro-1,2-phenylenediamine, 3
-Fluoro-1,3-phenylenediamine, 4-fluoro-1,3-phenylenediamine, 3,4-difluoro-1,3-phenylenediamine, 3-fluoro-1,4
-Phenylenediamine, 4-fluoro-1,4-phenylenediamine, 3,4-difluoro-1,4-phenylenediamine, 3-trifluoromethyl-1,2-phenylenediamine, 4-trifluoromethyl-1,2 -Phenylenediamine, 3-trifluoromethyl-1,3-phenylenediamine, 4-trifluoromethyl-1,3-
Phenylenediamine, 3-trifluoromethyl-1,4
-Phenylenediamine, 4-trifluoromethyl-1,
4-Phenylenediamine, 2,2 '-(bistrifluoromethyl) -4,4'-diaminobiphenyl, 2,2'
-Difluoro-4,4'-diaminobiphenyl and the like.

The tetracarboxylic acid substituted with a fluoro group, a fluoroalkyl group or the like, or an acid anhydride, an acid chloride or an ester compound as a derivative thereof is, for example, 1-
Fluoropyromellitic acid, 1,4-difluoropyromellitic acid, 1-trifluoromethylpyromellitic acid, 2,
2-bis (2,3-dicarboxyphenyl) -hexafluoropropane, 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene,
2,2'-difluoro-3,3 ', 4,4'-biphenyltetracarboxylic acid, 2,2'-bis (trifluoromethyl) -3,3', 4,4'-biphenyltetracarboxylic acid and these Acid anhydrides, acid chlorides, ester compounds, and the like. It should be noted that diamines or tetracarboxylic acids and their derivatives which are not substituted with fluoro groups, fluoroalkyl groups and the like other than the above may be used within the range not impairing the object of the present invention.

The fluorinated polyamic acid in the present invention is
From the viewpoint of electro-optical effect, heat resistance, etc., when the imide ring-closes to give a fluorinated polyimide, the refractive index is 1.4 to 1.9.
(589 nm), a dielectric constant of 2.6 to 3.5 (1 MHz) and a glass transition temperature (Tg) of 300 ° C. or higher are preferable.

The fluorinated polyamic acid in the present invention is
From the viewpoint of electro-optical effect, heat resistance, etc., formula (IV-1)

Embedded image And a repeating unit represented by the formula (IV-2)

[Chemical 9] At least one of the repeating units represented by the formula (V-
1)

[Chemical 10] And a repeating unit represented by the formula (V-2)

[Chemical 11] A fluorinated polyamic acid having at least one repeating unit represented by

The above formula (IV-
To provide the repeating unit represented by 1) or the repeating unit represented by the above formula (IV-2), for example, 2,2 ′-(bistrifluoromethyl) -4,4 ′ as a diamine is provided.
-Diaminobiphenyl may be used, and pyromellitic acid anhydride may be used as the tetracarboxylic acid anhydride.

The above formula (V-
To provide the repeating unit represented by 1) or the repeating unit represented by the formula (V-2), for example, 2,2 ′-(bistrifluoromethyl) -4,4 ′ as a diamine
-Using diaminobiphenyl, as a tetracarboxylic acid anhydride, 2,2'-bis (trifluoromethyl) -3,
3 ', 4,4'-biphenyltetracarboxylic acid anhydride may be used.

The refractive index of the fluorinated polyimide obtained by subjecting the fluorinated polyamic acid in the present invention to imide ring closure can be easily adjusted by appropriately selecting the type and amount of the diamine or tetracarboxylic acid and its derivative to be used. can do. For example, when the content of the repeating unit represented by the formula (IV-1) or the repeating unit represented by the formula (IV-2) in the fluorinated polyamic acid is increased, the refractive index of the obtained fluorinated polyimide is increased. Can be increased. On the other hand, when the content of the repeating unit represented by the formula (V-1) or the repeating unit represented by the formula (V-2) in the fluorinated polyamic acid is increased, the refractive index of the obtained fluorinated polyimide is increased. Can be reduced.

In the present invention, the diamine, tetracarboxylic acid or its derivative is not only used alone but
A plurality of diamines, tetracarboxylic acids or their derivatives can be used in combination. In that case, it is preferable that the total number of moles of a plurality or single diamine and the total number of moles of a plurality or single tetracarboxylic acid or its derivative are equal or almost equal. In the solution of the fluorinated polyamic acid obtained by the reaction of the diamine and the tetracarboxylic acid or its derivative, the solid content concentration of the solution is preferably 5 to 40% by weight, particularly 10 to 25% by weight. Further, when the solid content concentration of the fluorinated polyamic acid is 15% by weight, the n-methyl-2-pyrrolidone solution has a rotational viscosity (20 ° C.) of 2000 to 800.
It is preferably 0 mPa · s, 4000 to 6000 mPa
-S is more preferable.

The fluorinated polyimide of the present invention has the following formula (IV) from the viewpoint of electro-optical effect, heat resistance and the like.

[Chemical 12] And the following formula (V)

[Chemical 13] A fluorinated polyimide having a repeating unit represented by

The electro-optical material in the present invention has the general formula (I) having a hetero ring as an electron-accepting group from the viewpoint of heat resistance and electro-optical effect.

Embedded image (In the formula, X ¹ and X ² are each independently a chalcogen atom,
NH or NR ² , R ¹ represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group, and R ² represents 1 to 6 carbon atoms.
Represents an alkyl group, and Ar represents an electron donating group). Examples of the chalcogen atom in the above general formula (I) include an oxygen atom, sulfur, selenium, tellurium and polonium, X ¹ is preferably NH or sulfur, and R ¹ is preferably a hydrogen atom. Examples of R ² include a methyl group, a phenyl group and a naphthyl group.

Further, from the viewpoint of the electro-optical effect, the electron donating group Ar of the compound represented by the general formula (I) is represented by the general formula (II) or the general formula (III).

[Chemical 15] (In the formula, n represents an integer of 1 to 4). Examples of the compound represented by the general formula (I) include the following compounds.

[0018]

Embedded image

[0019]

[Chemical 17]

The compound represented by the general formula (I) includes an aldehyde compound having an electron-donating group and a rhodaline (R ¹ represented by the following formula (VI) as represented by the following formula (VI). = H, X ¹ = X ² = S), hydantoin (R ¹ = H,
X ¹ = NH, X ² = O), creatinine (R ¹ = H, X ¹ =
It can be synthesized by a simple one-step reaction of reacting with a compound such as NCH ₃ , X ² = NH).

Embedded image The reaction conditions are not particularly limited, but these are substantially equimolar and in the presence of a solvent such as morpholine / glycerin or sodium acetate / acetic anhydride at 90 to 130 ° C.,
It is preferable to react for 1 to 6 hours.

The composition for active optical waveguide of the present invention is
For example, it can be easily produced by adding an electro-optical material to a polar organic solvent solution of fluorinated polyamic acid and mixing them by stirring or the like. At this time, the amount of the electro-optical material used is preferably in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the fluorinated polyamic acid, and is preferably 0.1.
The amount is more preferably 5 to 5 parts by weight, and particularly preferably 0.5 to 3 parts by weight. If the amount used is too small or too large, electro-optical properties, other optical properties, mechanical properties, stability, workability, etc. tend to be poor. The composition for active optical waveguide of the present invention includes a polymer other than fluorinated polyamic acid (for example, polyamic acid containing no fluorine atom, liquid crystalline polymer such as liquid crystal polyester), pinhole inhibitor, leveling agent, plasticizer. An additive such as an adhesion improver can be included.

The active optical waveguide of the present invention will be described. The active optical waveguide of the present invention is used, for example, in optical matrix switches, modulators, optical polarizers, optical isolators, and the like. The basic form of the optical matrix switch and modulator is shown in FIG. In forming the optical waveguide, a general film forming method, for example, a spin coating method, a dipping method, a doctor blade method, a wire bar method, a roller method, a spray method or the like can be used. The core material and the clad material of the optical waveguide may be selected so that the difference between the wavelength of light and the refractive index suitable for the intended use.

In the active optical waveguide of the present invention, the composition for active optical waveguide is spin-coated on, for example, a silicon substrate and heat-treated in a nitrogen atmosphere to subject the fluorinated polyamic acid in the composition for active optical waveguide to imide. It can be formed by ring closure to give a fluorinated polyimide and orienting the electro-optic material. For example, manufacturing of a directional coupler type optical switch, which is one mode of the active optical waveguide, will be described with reference to FIG. 1 is a substrate, 2 is a lower electrode, 3 is a lower clad layer, 4 is a core layer, 5 is an aluminum layer, 6 is a resist layer, 7 is an upper clad layer, 8
Means the upper electrode. A lower electrode 2 of aluminum or the like is formed on a substrate of silicon or the like by a vapor deposition method, a sputtering method, or the like, and then has a smaller refractive index than the core layer 4 made of the active optical waveguide composition of the present invention. A lower clad layer 3 composed of fluorinated polyimide, which is one of the two essential components in the composition for active optical waveguide, is formed. A core layer 4 is obtained by applying the active optical waveguide composition of the present invention (containing an electro-optical material and a fluorinated polyamic acid as essential constituents) to a predetermined thickness and heating and curing the composition. Next, after applying the aluminum layer 5 by a vapor deposition method or the like, resist coating, pre-baking, exposure, development and after-baking are performed to obtain a patterned resist layer 6. After aluminum which is not protected by the resist layer 6 is removed by wet etching, the polyimide layer of the core layer 4 which is not protected by the aluminum layer 5 is removed by dry etching. The remaining aluminum layer 6 is removed by wet etching, and an upper clad layer 7 is formed thereon by using the polyimide used for forming the lower clad layer 3. Finally, an upper electrode 8 is formed on a predetermined core layer 4 through a mask pattern by a vapor deposition method, a sputtering method, or the like to obtain a directional coupler type optical switch.

To orient the electro-optical material contained in the core layer in the active optical waveguide, poling treatment or the like may be performed. For example, it is possible to orient the electro-optical material at the same time while heating while applying an electric field to perform imidization by imide ring closure. Examples of the method of applying the electric field include a method of providing an electrode and a method of charging the surface by corona discharge. The strength of the electric field is 10 ⁵ V / cm
And more preferably 10 ⁶ V / cm or more. It is also possible to orient the electro-optical material by applying an electric field to this and heating it to a temperature of Tg or higher after imidizing by imide ring closure to give a final structure of fluorinated polyimide. Waveguide is usually 10 μm
The width is about 15 μm and the height is about 3 μm to 4 μm. The pattern interval is about 2 μm to 3 μm.

In the present invention, fluorinated polyimide having the highest heat resistance among plastics is used for either or both of the core layer and the clad layer of the optical waveguide.
Further, a compound represented by the general formula (I) having a heterocycle, which is an electro-optical material having excellent heat resistance, as an electron-accepting group is contained in the fluorinated polyimide.

[0026]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples.

Production Example 1 Synthesis of 5- (4'-dimethylaminocinnamylidene) -hydantoin (H-1) Hydantoin 2 g (20 mmol), 4-dimethylaminocinnamaldehyde 3.5 g (20 mmol), morpholine 1
ml was dissolved in 30 ml of glycerin and heated at 120 ° C. for 1 hour. The generated crystals were separated by filtration and washed with water and methanol in this order to obtain 2.1 g of red crystals (H-1) (yield 41%). The melting point of this product is 280 ° C (decomposition), and the UV-
Visible absorption spectrum (dimethyl sulfoxide (DMSO)
(Solvent) has an absorption maximum wavelength λ _max of 420 nm and a molar extinction coefficient ε at that wavelength of 4.2 × 10 ⁴ M ^-1 cm ^-1 ).
Met. In addition, ¹ H-NMR (HMDS / d ⁶ -DMS
The result of (O) is shown in Table 1, and the structural formula thereof is shown below.

[0028]

[Table 1]

[0029]

[Chemical 19]

Example 1 5 as an electro-optical material produced in the above Production Example 1
1 part by weight of-(4'-dimethylaminocinnamylidene) -hydantoin (H-1) and fluorinated polyamic acid OPI
−1005 (Hitachi Chemical Co., Ltd. product name) 15 parts by weight N
-Methylpyrrolidone (NMP) is dissolved in 200 parts by weight to obtain a 100 nm solution of the composition for active optical waveguide.
Number of rotations 2 on quartz glass with thick semi-transparent aluminum electrode
Spin coating was performed at 000 rpm to form a 2 μm film. NM
To remove the P solvent, soft baking was performed at 120 ° C. for 6 hours under vacuum, and then a 100 nm thick semitransparent aluminum electrode was formed on the film to prepare a sandwich type sample.
The sample was heated to 250 ° C. (poling temperature) at a temperature rising rate of 2 ° C./min while applying a voltage of 400 V between the electrodes, and further, at a temperature of 1 ° C. while applying a voltage of 400 V.
Hold for a period of time, and then cool to room temperature while applying a voltage of 400 V. Samples for active optical waveguide test (here, only the core portion corresponding to the portion of the core layer 4 in FIG. Not).

The thermal stability of the active optical waveguide test sample was examined using the measuring apparatus shown in FIG.
This device is an electro-optical constant measuring device, and the measuring method is CCTe.
ng and HTMan, Appl. Phys. Lett. 56 (18) 1734 (1990). The measuring device shown in FIG. 3 is configured as follows. The light from the He-Ne laser 9 is passed through the polarizer 10 to be linearly polarized light, and then the sample 11 tilted so that the angle formed by the normal axis of the sample 11 and the beam axis is θ is transmitted, and the Babinet is used. Detecting with a detector (photodiode) 14 through a Soleil compensator 12 and an analyzer 13. The detected light intensity is used as a voltage, and the DC voltmeter 16 and the lock-in amplifier 15 are used.
Is measured at. The angle of the transmission axis of the analyzer when measuring is
The analyzer is set to rotate so that the difference between the maximum value and the minimum value of the DC voltage measured by the DC voltmeter 16 is 1/2. When an oscillator 17 applies a frequency of 1 kHz and an AC voltage of 10 V to the sample 11, the output signal is also modulated at 1 kHz by the electro-optic effect. At this time, the AC component is measured by the lock-in amplifier 15 and the DC component is measured by the DC voltmeter 16. When the measured voltages at the lock-in amplifier 15 and the DC voltmeter 16 are defined as V _m and V, respectively, the electro-optical constant r
₃₃ is calculated from the following formula (1).

[Equation 1] The refractive index n was measured with an Abbe refractometer. Thermal stability is determined by electro-optic constant r ₃₃ (0) and temperature of 15 after poling.
The electro-optical constant r ₃₃ (T) of the sample after standing in a constant temperature bath of 0 ° C. for 250 hours was measured, and the retention was calculated from the above r ₃₃ (0) and r ₃₃ (T) by using the following formula (2). Evaluation was made from the rate d (T), and the results are shown in Table 2.

[Equation 2]

Example 2 Electro-optical material used in Example 1 5- (4'-dimethylaminocinnamylidene) -hydantoin (H-1)
Instead of (H-6), an active optical waveguide test sample was prepared in the same manner as in Example 1, and the retention rate d (T) of electro-optical characteristics was evaluated. The results are shown in Table 2. .

Comparative Example 1 In place of 5- (4'-dimethylaminocinnamylidene) -hydantoin (H-1) and fluorinated polyamic acid OPI-1005 used in Example 1, 4-shown in Table 2 was used.
[N-Ethyl-N- (2-hydroxyethyl)]-amino-4′-nitroazobenzene (Disperse Red 1) and polymethylmethacrylate (PMMA) solution (12 wt%) were used, except that the poling temperature was 150 ° C. A sample for active optical waveguide test was prepared in the same manner as in Example 1, the retention rate d (T) of electro-optical characteristics was evaluated, and the results are shown in Table 2. The electro-optical properties disappeared by 75% only by heating to 100 ° C.

[0034]

[Table 2]

[0035]

The composition for active optical waveguide of the present invention gives an optically excellent transparent film. The active optical waveguide produced by using the composition for active optical waveguide of the present invention is very stable thermally and is suitable for producing electro-optical elements such as optical switches and modulators. By using a fluorinated polyimide having excellent heat resistance and a compound represented by the general formula (I) having a heterocycle as an electron-accepting group, the thermal stability required when producing an optical waveguide is improved. Furthermore, the spin coating method has an advantage that a large-area optical waveguide can be easily manufactured, and the cost of the optical waveguide can be reduced.

[Brief description of drawings]

FIG. 1 is a basic form of an optical matrix switch and a modulator.

FIG. 2 is an explanatory diagram of an active optical waveguide manufacturing process.

FIG. 3 is an explanatory diagram of an electro-optical constant measuring device used in Examples and Comparative Examples.

[Explanation of symbols]

 1 Substrate 2 Lower Electrode 3 Lower Cladding Layer 4 Core Layer 5 Aluminum Layer 6 Resist Layer 7 Upper Cladding Layer 8 Upper Electrode 9 He-Ne Laser 10 Polarizer 11 Sample 12 Habine-Soleil Compensator 13 Analyzer 14 Detector 15 Lock-in Amplifier

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Claims (6)

[Claims] 1. A composition for an active optical waveguide containing a fluorinated polyamic acid and an electro-optical material, wherein the electro-optical material has a general formula (I) having a heterocycle as an electron-accepting group. (In the formula, X ¹ and X ² each independently represent a chalcogen atom, NH or NR ² , and R ¹ is a hydrogen atom or a carbon number of 1 to 1.
6 represents an alkyl group or an aryl group, and R ² has 1 carbon atom
Represents an alkyl group of 6 and Ar represents an electron donating group)
A composition for an active optical waveguide, which is a compound represented by: 2. The electron-donating group Ar of the compound having a heterocycle as an electron-accepting group in the above general formula (I),
General formula (II) or general formula (III) The composition for active optical waveguides according to claim 1, which is an electron-donating group represented by the formula (n represents an integer of 1 to 4). 3. A fluorinated polyamic acid having an imide ring closure to form a fluorinated polyimide having a refractive index of 1.4 to
1.9 (589 nm), dielectric constant 2.6-3.5 (1 MH
The composition for active optical waveguides according to claim 1 or 2, wherein z) and the glass transition temperature (Tg) are 300 ° C or higher. 4. The fluorinated polyamic acid has the formula (IV-1): A repeating unit represented by the formula and the formula (IV-2): At least one of the repeating units represented by the formula (V-
1) [Chemical 5] The repeating unit represented by the formula and formula (V-2): The composition for active optical waveguides according to claim 1, which is a fluorinated polyamic acid having at least one repeating unit represented by: 5. The fluorinated polyamic acid in the composition for active optical waveguide according to claim 1, 2, 3 or 4 is imide ring-closed to give a fluorinated polyimide to orient the electro-optical material. Manufacturing method of active optical waveguide. 6. An active optical waveguide manufactured by the method for manufacturing an active optical waveguide according to claim 5.