JP2008039909A - Nonlinear optical material and waveguide device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonlinear optical material with which high light transmittance and light stability are made compatible with each other, and a waveguide device which uses the material and which has high optical reliability. <P>SOLUTION: The nonlinear optical material contains a low molecular weight compound which exhibits nonlinear optical characteristics and which has 100-5,000 molecular weight, and a compound which is inactive against a photo-reaction in a state in which these compounds are mixed or chemically bonded to each other, and is characterized in that its transmission attenuation coefficient per 1 cm with respect to light of a specified wavelength in 0.6-1.8 μm wavelength range is 0.5 or less, and the waveguide device is fabricated by using the nonlinear optical material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a nonlinear optical material that can be applied to fields such as optical communication, optical wiring, optical information processing, sensors, and image processing, and a waveguide device obtained using the nonlinear optical material.

  The progress of the information society is remarkable, especially recently, large volumes of information such as videos are frequently exchanged not only between companies but also between individuals, and there is a need for higher-capacity high-speed communication means. ing. Therefore, the importance of optical communication capable of high-capacity high-speed information communication is increasing.

One of the technologies that support high-capacity high-speed communication is optical communication technology. There are various waveguide devices such as optical fibers, optical switch elements, optical modulators, and routers as devices used for optical communication. By combining these devices, optical circuits having various functions can be obtained. Produced. In particular, a non-linear optical material having an “electro-optic effect (EO effect)” in which a refractive index changes depending on an electric field is often used for an optical element such as an optical switch element or an optical modulator. In particular, organic EO materials are attracting attention because there is no speed mismatch between the microwave / millimeter wave region and the light wave region because the dielectric constant of the material is low, and the response speed may be greatly improved. Furthermore, the organic EO material is dispersed or bonded to a polymer material, so that a large-area thin film can be easily formed by a spin coating method or the like, and the workability is improved. Have. Specific examples of EO materials include those in which EO molecules are dispersed in a polymer material, those in which EO molecules are bound to a host polymer, and DAST (4-N, N-dimethylamino-4 ' -N-methyl-stilbazolium tosylate) can be cited as examples (see, for example, Patent Documents 1 and 2 and Non-Patent Document 1).
JP-A-8-87040 JP 2003-202533 A J. Opt. Soc. Am., B, 4, 968 (1987).

In order to use an EO material for a waveguide device, the light transmission loss must be small and strong against optical damage. However, the above example has not been verified for the light stability of the device.
Many organic nonlinear optical materials have a compound having a long π-conjugated electron system, and there is a particular concern about the stability to light. This is because a compound having a long π-conjugated electron system absorbs a relatively low energy photon and easily causes a chemical reaction. In particular, when there is a compound that is active against a photoreaction around an organic nonlinear optical material, such as a DAST crystal, it reacts with adjacent molecules by light, and the stability is likely to be further reduced. . A chemical reaction of the organic nonlinear material under light irradiation may cause a change in the refractive index of the material and weaken the confinement of the guided light, resulting in an increase in propagation loss.
Secondly, the concentration of EO molecules is also an important factor related to the optical properties of the device. In general, an EO material having a higher concentration of EO molecules has higher EO characteristics. However, if the EO material is dispersed in a polymer material or the like at a very high concentration, the homogeneity of the material is lost and the light transmission loss increases.
The present invention has been made in view of the above-described conventional problems, and an object thereof is to achieve the following object. That is, an object of the present invention is to provide a nonlinear optical material that achieves both high light transmittance and stability against light, and a waveguide device with high optical reliability using the nonlinear optical material.

Means for solving the above-mentioned problems are as follows. That is,
<1> A wavelength of 0.6 to 1.8 μm including a low molecular weight compound having a nonlinear optical property and having a molecular weight of 100 to 5000 and a compound inactive to a photoreaction in a mixed or chemically bonded state. The nonlinear optical material according to claim 1, wherein a transmission attenuation coefficient per 1 cm of light having a specific wavelength within the range is 0.5 or less.

<2> The mass ratio of the low-molecular compound to the total weight N (0 <N <1), the dipole moment of the low molecular compound mu (Debye), when the molecular weight was _{M W,} the following formula (1) The nonlinear optical material according to <1>, wherein the nonlinear optical material is satisfied.

<3> The nonlinear optical material according to <1> or <2>, wherein the compound inactive to the photoreaction is polycarbonate.

<4> The nonlinear optical material according to <1> or <2>, wherein the compound inactive to the photoreaction is polysulfone.

<5> The nonlinear optical material according to claim 1, wherein the compound inactive to the photoreaction is silicone.

<6> A waveguide device manufactured using the nonlinear optical material according to any one of <1> to <5>.

  According to the present invention, it is possible to provide a nonlinear optical material that achieves both high light transmittance and stability to light, and a waveguide device with high optical reliability using the nonlinear optical material.

The nonlinear optical material of the present invention includes a low molecular compound having a nonlinear optical property and having a molecular weight of 100 to 5000 and a compound inactive to a photoreaction in a mixed or chemically bonded state, and includes 0.6 to The transmission attenuation coefficient per 1 cm of light having a specific wavelength within a wavelength range of 1.8 μm is 0.5 or less.
The waveguide device of the present invention is manufactured using the nonlinear optical material of the present invention.
First, the nonlinear optical material of the present invention will be described.

<Nonlinear optical material>
The non-linear optical material of the present invention uses a low-molecular compound having non-linear optical properties in a mixed or chemically bonded state with an inert compound in order to ensure stability to light, and in order to ensure light transmission, The transmission attenuation coefficient per 1 cm of light having a specific wavelength within the wavelength range of 0.6 to 1.8 μm is set to 0.5 or less.
Here, the transmission attenuation coefficient A per 1 cm is defined as a coefficient expressed by the following equation (2) when the incident energy when transmitting light through a 1 cm sample is P _in and the output energy is P _out .

  In the present invention, as described above, the transmission attenuation coefficient is set to 0.5 or less. However, if it exceeds 0.5, high light transmittance cannot be ensured. The transmission attenuation coefficient is preferably 0.45 or less, and more preferably 0.4 or less.

  The specific wavelength within the wavelength range of 0.6 to 1.8 μm where the transmission attenuation coefficient is 0.5 or less is more preferably 1.3 to 1.6 μm in the wide-area communication field. In the communication between boards arranged in the above, 0.7 to 1 μm is preferable.

As described above, the nonlinear optical material of the present invention is a low molecular compound having nonlinear optical characteristics and having a molecular weight of 100 to 5,000 (hereinafter sometimes referred to simply as “low molecular compound”), and photoreaction. And an inactive compound (hereinafter sometimes simply referred to as “inactive compound”).
Each component of the nonlinear optical material of the present invention will be described below.

-Low molecular weight compounds-
The low molecular compound having nonlinear optical properties according to the present invention is a low molecular compound having a molecular weight of 100 to 5000, and in particular, a low molecular compound having a primary hyperpolarizability β of 10 × 10 ⁻³⁰ esu or more. It is preferable that Among them, a compound group in which an electron donating group and an electron withdrawing group are connected by a π electron system has a high first-order hyperpolarizability and is preferable.

  Specific examples that can be suitably used as the low molecular weight compound according to the present invention include azo dyes having an electron donating group and an electron withdrawing group, merocyanine dyes, and the like. Disperse Red 1 (DR1), 2-methyl-6- (4-N, N-dimethylaminobenzylidene) -4H-pyran-4-ylidenepropanedinitrile, 4-{[4- (dimethylamino) phenyl] Imino} -2,5-cyclohexadien-1-one and the like.

The nonlinear optical material of the present invention ensures light transmission, that is, a transmission attenuation coefficient per cm for light of a specific wavelength within a wavelength range of 0.6 to 1.8 μm is 0.5 or less. is the mass fraction of the low-molecular compound to the total weight N (0 <N <1), when a dipole moment μ of (Debye), the molecular weight was M _W, is set to satisfy the following formula (1) It is preferable. The molecular weight _Mw referred to here is the molecular weight of the low molecular weight compound itself when the low molecular weight compound and the inert compound are mixed and used, and the low molecular weight compound and the inert compound are chemically bonded. In this case, the molecular weight of a portion (part derived from a low molecular weight compound) exhibiting substantially nonlinear characteristics in the nonlinear optical material.

  By satisfying the formula (1), a thin film having high optical homogeneity can be formed without impairing the nonlinear optical characteristics of the nonlinear optical material. Further, if the value is less than the lower limit of the formula (1), the nonlinear optical characteristics may be deteriorated. If the upper limit of formula (1) is exceeded, aggregates and crystals may be generated and the transmission attenuation coefficient may not be 0.5 or less.

  On the other hand, when the wavelength used is short, the optical characteristics of the device deteriorate due to light absorption by the molecules, so it is preferable to keep the amount of the low molecular compound dispersed small.

-Inactive compounds-
As described above, the nonlinear optical material of the present invention imparts light stability to the low molecular weight compound exhibiting nonlinear optical characteristics by including an inert compound in a mixed or chemically bonded state.
Here, the light in the compound inactive to light is most preferable in terms of a wide wavelength range from ultraviolet to infrared, but if necessary, the wavelength range from ultraviolet to visible light, The wavelength range of visible light to infrared may be used. In addition, the intensity of the light is 6 to 10 mW as the intensity of light incident on the waveguide.

  As such an inactive compound, a polymer compound is easy to handle, and can be mentioned as a suitable example. However, it is necessary that the aromatic rings are not directly bonded, the aromatic rings are connected by a carbon-carbon double bond, or are not condensed ring aromatic compounds. Moreover, it is also necessary not to have a carbon-carbon double bond other than an aromatic ring or a photoreactive substituent. Specific examples of the polymer compound that is inappropriate for use include polymer compounds such as polythiophene, polypyrrole, polyacetylene, polybutadiene, polyarene, and a resist that is a photosensitive resin. Specific examples of the polymer compound suitable for use include polystyrene, polyimide, polyetherimide, polycarbonate, polyethylene terephthalate, polysulfone, polyethersulfone, polyphenylsulfone, polyurethane, polyamide, and silicone. Among these, polyimide, polyetherimide, polycarbonate, polysulfone, polyurethane, and silicone are preferable because they have a good balance between the solubility of the resin itself and the precursor compound that becomes the resin and the solvent resistance when thinned, and are easy to handle. In particular, polycarbonate and polysulfone are preferable.

  The nonlinear optical material of the present invention has an aspect in which the low molecular compound and the inert compound are used in combination and an aspect in which the low molecular compound and the inert compound are chemically bonded. Each aspect will be described below.

-Mode of using a mixture of a low molecular weight compound and an inert compound-
In this embodiment, a solvent is appropriately selected, and a low molecular compound and an inert compound are dissolved in the solvent and used as a solution. The obtained solution is used for coating to form a coating film, which will be described later.

-Aspect in which a low molecular weight compound and an inert compound are chemically bonded to each other-
Examples of the chemical bond herein include an ether bond, an ester bond, an amide bond, an imide bond, and a sulfide bond, and an ether bond and an ester bond are preferable from the viewpoint of light transmittance and chemical bond stability.
As a method of chemically bonding a low molecular weight compound and an inert compound, a nucleophilic substitution reaction between a hydroxyl group and a leaving group such as halogen, a dehydration condensation reaction between hydroxyl groups or between a hydroxyl group and a carboxyl group, What reacts an acid chloride and a hydroxyl group is mentioned.

  The nonlinear optical material of the present invention may be in any form, but is generally used in the form of a thin film when applied to a waveguide device. As a method for forming a thin film containing the nonlinear optical material of the present invention, known methods such as an injection molding method, a press molding method, a soft lithographic method, a nanoimprint method, a wet coating method, and the like can be used. From the viewpoints of properties, mass productivity, film quality (thickness uniformity, few defects such as bubbles), etc., at least the low molecular weight compound and the inert compound exhibiting the above nonlinear optical characteristics are combined with an organic solvent. A wet coating method is preferred in which the solution dissolved in is coated on an appropriate substrate by a spin coating method, blade coating method, dip coating method, ink jet method or the like.

  The organic solvent used in the wet coating method may be any organic solvent as long as it can dissolve the low-molecular compound and the inert compound to be used, but preferably has a boiling point in the range of 50 to 200 ° C. If an organic solvent with a boiling point of less than 50 ° C is used, solvent volatilization occurs when the coating solution is stored, and the viscosity of the coating solution changes (increases). There is a tendency for such problems to become prominent. On the other hand, when an organic solvent having a boiling point exceeding 200 ° C. is used, it is difficult to remove the solvent after coating, and the remaining organic solvent acts as a plasticizer for the inert compound and causes a decrease in the glass transition temperature. There is a case. Examples of preferred organic solvents include methanol, ethanol, 2-propanol, butanol, tetrahydrofuran, methyltetrahydrofuran, dioxane, diethylene glycol dimethyl ether, methyl ethyl ketone, cyclopentanone, cyclohexane, cyclohexanone, ethyl acetate, cyclohexanol, dichloroethane, toluene, xylene, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidin-2-one, dimethyl sulfoxide and the like can be mentioned. These organic solvents may be used alone or in combination.

  In addition to the low molecular weight compound and the inert compound, various additives can be added to the nonlinear optical material of the present invention as necessary. For example, known antioxidants such as 2,6-di-t-butyl-4-methylphenol and hydroquinone are used for the purpose of suppressing oxidative degradation of low molecular weight compounds and / or inactive compounds. For the purpose of suppressing the UV degradation of the inert compound, known UV absorbers such as 2,4-dihydroxybenzophenone and 2-hydroxy-4-methoxybenzophenone are used. When a known leveling agent such as silicone oil is used for the purpose of improving the surface smoothness of the coating film, or a low molecular weight compound and / or an inert compound having a crosslinkable curable functional group is used, the crosslink curing is promoted. For the purpose, a known curing catalyst or curing aid may be added.

<Waveguide device>
Next, the waveguide device of the present invention will be described. The waveguide device of the present invention is manufactured using the above-described nonlinear optical material of the present invention. Specifically, the waveguide layer is formed using the nonlinear optical material of the present invention. is there.
Hereinafter, the waveguide device of the present invention will be described through its manufacturing process. The process shown below is an example, and may be changed according to the structure of the device, the properties of the material to be used, and the like.

  1) to 5) in FIG. 1 are steps of manufacturing a waveguide device by forming a lower electrode 202, a lower cladding layer 203, a waveguide layer 204, an upper cladding layer 205, and an upper electrode 206 on a substrate 201. Shown sequentially. Below, a board | substrate and each layer are demonstrated.

[substrate]
Although the board | substrate used for this invention is not specifically limited, The thing excellent in flatness is preferable. For example, a metal substrate, a silicon substrate, a transparent substrate, etc. are mentioned, and can be appropriately selected depending on the form of the waveguide type light modulation element. Preferred examples of the metal substrate include gold, silver, copper, aluminum, and silicon substrates, and preferred examples of the transparent substrate include quartz, glass, and plastic substrates.

[Lower electrode]
First, the lower electrode 202 (electrical wiring) is formed on the outer surface of the substrate 201 or on the substrate (FIG. 1 (1)). The lower electrode can be, for example, a metal vapor deposition layer, a transparent electrode layer, or the like. Preferred examples of the metal to be deposited include gold, silver, copper, and aluminum. Moreover, as a preferable example of a transparent electrode layer, indium tin oxide (ITO), fluorine dope tin oxide (FTO), antimony dope tin oxide, etc. are mentioned. The substrate may also serve as the lower electrode.

[Lower cladding layer]
Next, a lower clad layer is formed on the substrate or the lower electrode. As a material for the lower cladding layer, a photocurable acrylic resin or epoxy resin can be cited as a preferred example in addition to polyimide and fluorinated polyimide. As a material application method, a well-known method such as curtain coating method, extrusion coating method, roll coating method, spin coating method, dip coating method, bar coating method, spray coating method, slide coating method, print coating method, etc. is adopted. In particular, the spin coating method is simple.

[Waveguide layer]
Subsequently, a waveguide layer 204 is formed on the lower cladding layer 203 (FIG. 1 (2)).
As the waveguide layer, the above-described nonlinear optical material of the present invention is used. At this time, it is necessary to select a nonlinear optical material having a refractive index higher than that of the lower cladding layer. The nonlinear optical material is applied on the lower clad in a state dissolved in an organic solvent or melted by heat. As a coating method, a well-known method such as curtain coating method, extrusion coating method, roll coating method, spin coating method, dip coating method, bar coating method, spray coating method, slide coating method, print coating method, etc. may be adopted. In particular, the spin coating method is simple.

[Waveguide]
After the waveguide layer 204 is formed, the waveguide layer is patterned by a known method using a semiconductor process technology such as reactive ion etching (RIE), photolithography, electron beam lithography, etc., and a channel-type waveguide or a ridge-type waveguide is formed. A waveguide can also be formed. Alternatively, a channel type or ridge type waveguide can be formed by patterning and irradiating a part of the core layer with UV light, an electron beam or the like to change the refractive index of the irradiated part (FIG. 1 (3)). )).

As waveguides, well-known waveguides described in light wave engineering (Corona, 1988), Chapter 107, page 204, for example, branched waveguide type, Mach-Zehnder type, directional coupler type, crossed waveguide, etc. A mold etc. can be adopted. Of course, the nonlinear optical material according to the present invention can be applied even to a waveguide not described in the document. One example is a multi-mode interferometer type waveguide device.
An example of a type of waveguide device will be specifically described. 2 (A) to (C), FIGS. 3 (D) to (G), and FIG. 4 are views of the respective waveguide devices as viewed from directly above. The same reference numerals are used for the same components as those in FIG. It is drawn so that the internal waveguide portion can be visually recognized. 2 (A) is a straight waveguide, (B) is a curved waveguide, (C) is a Y-shaped waveguide, FIG. 3 (D) is a directional coupler, (E) is a Mach-Zehnder type optical modulator, (F) is a mode converter, (G) is a branch switch, and FIG. 4 shows a multi-mode interferometer type waveguide device.

[Upper clad layer]
Next, the upper clad layer 205 is formed on the waveguide layer 204 (FIG. 1 (4)). Any material may be used as the upper cladding layer formed on the waveguide layer as long as it has a lower refractive index than that of the waveguide layer. Specific examples of the material for the upper clad layer include polyimide, fluorinated polyimide, photocurable acrylic resin, and epoxy resin. As a material application method, a well-known method such as curtain coating method, extrusion coating method, roll coating method, spin coating method, dip coating method, bar coating method, spray coating method, slide coating method, print coating method, etc. is adopted. In particular, the spin coating method is simple.

[Upper electrode]
An upper electrode 206 (electrical wiring) is provided on the entire surface or a part of the upper cladding layer 205 as required (FIG. 1 (5)). The material for forming the upper electrode is not particularly limited as is the case with the lower electrode. For example, if it is a metal, gold, silver, copper, aluminum, etc. can be used. The upper electrode is preferably an electrode on which these materials are deposited.

Although not described in the above-described process, it is necessary to perform polarization alignment processing in order to cause the waveguide device to exhibit a nonlinear optical effect. In the polarization orientation treatment, in the softened or fluidized state of the sample, an electrode can be attached to the sample and a DC electric field can be applied, or a charged charge by corona discharge can be used. The sample may be solidified by cooling or by thermosetting the polymer, but it is desirable to perform either in an electric field applied state or in a charged state. This step may be performed at any time after the formation of the waveguide layer. However, if heating is required in the subsequent step, the nonlinear optical effect is reduced, so that the polarization alignment treatment is performed as the final step. It is preferable to carry out as
The waveguide device thus manufactured is completed as a device by cutting a chip from the wafer by dicing or cleavage.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

[Example 1]
In this example, Disperse Red 1 (hereinafter abbreviated as “DR1”, dipole moment μ: 7.5 Debye, molecular weight M _W : 314) was used as the low molecular compound.
First, as the solution of the nonlinear optical material, cyclohexanone, tetrahydrofuran, polycarbonate, and DR1, and the total mass of all the materials as 100 parts by mass, from 68 parts by mass, 17 parts by mass, 12 parts by mass, and 3 parts by mass, respectively. A solution (hereinafter referred to as PC solution) was prepared. Nμ / _{M W} of the non-linear optical materials made from this solution was approximately 0.005. When the refractive index in the thin film of the nonlinear optical material was measured by the prism coupling method, it was confirmed to be 1.56.

  An acrylic ultraviolet curable resin having a refractive index of 1.54 was applied as a lower cladding layer on a silicon substrate on which gold was sputtered as the lower electrode, and an ultraviolet ray was irradiated to obtain a resin cured film having a thickness of 6 μm. Subsequently, the PC solution was applied and cured as a waveguide layer, and a waveguide was formed by etching following photolithography. The film thickness of the waveguide layer was 1.7 μm, the ridge height was 0.4 μm, and the width was 5 μm. The ultraviolet curable resin used for the lower clad layer was applied on the waveguide layer to produce an upper clad layer having a thickness of 6 μm. The upper electrode was fabricated by lift-off following photolithography, and a waveguide device was fabricated by cutting a chip from the wafer by dicing.

By aligning the straight waveguide and the single mode fiber of the manufactured waveguide device and measuring the insertion loss while shortening the device, the propagation loss in the light of 1.55 μm wavelength is 1.7 dB / cm. I confirmed that there was. In addition, it was confirmed by theoretical calculation that the device produced in this example has a scattering loss of 0.1 dB / cm or less on the waveguide wall surface and can be ignored. Therefore, the transmission attenuation coefficient per 1 cm derived from the absorption of the nonlinear optical material of the waveguide was 0.4.
Subsequently, in the manufactured waveguide device, a straight waveguide and a single mode fiber were aligned and connected using an acrylic ultraviolet curable resin. The device and the material were evaluated for light stability by storing the device in an oven and continuing to guide light at 70 ° C. FIG. 5 shows the change over time of the optical power at that time. As a result of the evaluation, there was almost no change in insertion loss due to the insertion of light, and it was confirmed that the waveguide device was stable to light.

[Example 2]
First, as the solution of the nonlinear optical material, cyclohexanone, tetrahydrofuran, polysulfone, and DR1, and the total mass of all the materials as 100 parts by mass, respectively from 77 parts by mass, 9 parts by mass, 10 parts by mass, and 4 parts by mass A solution (hereinafter referred to as PS solution) was prepared. Nμ / _{M W} of the non-linear optical materials made from this solution was approximately 0.007. When the refractive index in the thin film of this material was measured by the prism coupling method, it was confirmed to be 1.63.

An epoxy ultraviolet curable resin having a refractive index of 1.50 was applied as a lower clad layer on a silicon substrate on which gold was sputtered as a lower electrode, and an ultraviolet ray was irradiated to produce a resin cured film having a thickness of 4 μm. Subsequently, a PS solution was applied and cured as a waveguide layer, and a waveguide was formed by etching following photolithography. The film thickness of the waveguide layer was 3.3 μm, the ridge height was 0.6 μm, and the width was 5 μm. An acrylic ultraviolet curable resin having a refractive index of 1.50 serving as an upper clad layer was applied on the waveguide layer, and cured by irradiating with ultraviolet rays to produce a 4 μm thick upper clad layer. The upper electrode was fabricated by lift-off following photolithography, and a waveguide device was fabricated by cutting a chip from the wafer by dicing.
Propagation loss in light of 1.55 μm wavelength is 1.6 dB / cm by aligning the linear waveguide and single mode fiber of the fabricated device and measuring the insertion loss while shortening the device. It was confirmed. In addition, it was confirmed that the scattering loss on the waveguide wall surface is 0.1 dB / cm or less in the device manufactured in this example and can be ignored. Therefore, the transmission attenuation coefficient per 1 cm derived from the absorption of the nonlinear optical material of the waveguide was 0.4.

  Subsequently, the light stability of the device and the material was evaluated in the same manner as in Example 1. As a result of the evaluation, it was confirmed that there was almost no change in insertion loss due to the insertion of light, and that it was stable against light.

[Example 3]
First, as a solution of a nonlinear optical material, cyclohexanone, polysulfone, and [3-cyano-2-dicyanomethylidene-4- {trans, trans- [3- (2- (4-N, N-diethylaminophenyl) vinyl) Cyclohex-2-ethylidene] -1-propenyl} -5-methyl-5- (4-cyclohexylphenyl) -2,5-dihydrofuran (μ: 16 Debye, molecular weight M _w : 649) A solution (hereinafter referred to as a PSC solution) consisting of 85 parts by mass, 13 parts by mass, and 6 parts by mass was prepared with each mass being 100 parts by mass. Nμ / _{M W} of the non-linear optical materials made from this solution was approximately 0.0086. When the refractive index in the thin film of this material was measured by the prism coupling method, it was confirmed to be 1.64.

An epoxy ultraviolet curable resin having a refractive index of 1.50 was applied as a lower clad layer on a silicon substrate on which gold was sputtered as a lower electrode, and an ultraviolet ray was irradiated to produce a 4 μ thick resin cured film. Subsequently, a PSC solution was applied and cured as a waveguide layer, and a waveguide was formed by etching following photolithography. The film thickness of the waveguide layer was 3.3 μm, the ridge height was 0.6 μm, and the width was 5 μm. An epoxy-based ultraviolet curable resin having a refractive index of 1.50 was applied on the waveguiding layer and cured by irradiating with ultraviolet rays to produce a 4 μm thick upper cladding layer. The upper electrode was fabricated by lift-off following photolithography, and a waveguide device was fabricated by cutting a chip from the wafer by dicing.
Propagation loss in light with a wavelength of 1.55 μm is 2.0 dB / cm by aligning the straight waveguide and single mode fiber of the fabricated device and measuring the insertion loss while shortening the device. It was confirmed. In addition, it was confirmed that the scattering loss on the waveguide wall surface is 0.1 dB / cm or less in the device manufactured in this example and can be ignored. Therefore, the transmission attenuation coefficient per 1 cm derived from the absorption of the nonlinear optical material of the waveguide was 0.5.

  Subsequently, the light stability of the device and the material was evaluated in the same manner as in Example 1. As a result of the evaluation, it was confirmed that there was almost no change in insertion loss due to the insertion of light, and that it was stable against light.

[Example 4]
First, as a solution of the nonlinear optical material, cyclohexanone, tetrahydrofuran, methanol, distilled water, 1,6-bis (dimethoxymethylsilyl) hexane, and di {[2- (3-triethoxysilylpropyl) carbamoyloxy] ethyl}- 4- (4-nitro phenylazo) phenylamine (dipole moment μ: 7.5Debye, molecular weight _M W: 896), said respective 58 parts by 100 parts by total weight of all the materials, 6 parts by weight, 7 parts by mass, 4 parts by mass, 15 parts by mass, and 10 parts by mass were added, an ion exchange resin (Amberlyst 15E) was added as a solid catalyst, and the mixture was stirred at room temperature and reacted for 1 hour (hereinafter, Called “Solution A”). Subsequently, a solution in which aluminum acetylacetonate complex, acetylacetone, and cyclohexanone were mixed at a ratio of 5 parts by mass, 10 parts by mass, and 85 parts by mass, respectively, with the total mass of all the materials as 100 parts by mass was prepared (hereinafter referred to as “below”). , Referred to as “Solution B”). After filtering the ion exchange resin with a membrane filter, the solution A was mixed with the solution B at a ratio of 20: 1 and stirred for 10 minutes to prepare a solution of a nonlinear optical material (hereinafter referred to as Si solution). Nμ / _{M W} of the non-linear optical materials made from this solution was approximately 0.005. When the refractive index in the thin film of this material was measured by the prism coupling method, it was confirmed to be 1.53.

An epoxy ultraviolet curable resin having a refractive index of 1.50 was applied as a lower clad layer on a silicon substrate on which gold was sputtered as a lower electrode, and a resin film having a thickness of 5 μm was produced by irradiating with ultraviolet rays. Subsequently, a Si solution was applied and cured as a waveguide layer, and a waveguide was formed by etching following photolithography. The thickness of the waveguide layer was 1.6 μm, the ridge height was 1.0 μm, and the width was 4 μm. An epoxy-based ultraviolet curable resin having a refractive index of 1.50 serving as an upper clad layer was applied on the waveguide layer and irradiated with ultraviolet rays to produce a 7 μm thick cured film. The upper electrode was fabricated by lift-off following photolithography, and a waveguide device was fabricated by cutting a chip from the wafer by dicing. In addition, according to the theoretical calculation, the waveguide device manufactured in this example generates propagating light in a higher order mode, but it has been confirmed that there is almost no influence of these and there is no problem even if it is regarded as propagating in a single mode.
Propagation loss in light with a wavelength of 1.55 μm is 4.8 dB / cm by aligning the linear waveguide and single mode fiber of the fabricated device and measuring the insertion loss while shortening the device. It was confirmed. In the device manufactured in this example, surface roughness of about 250 nm occurred on the waveguide wall surface, and the scattering loss on the waveguide wall surface was 3.2 dB / cm. Therefore, the propagation loss derived from the absorption of the nonlinear optical material is 1.6 dB / cm, and is 0.4 when converted into a transmission attenuation coefficient per 1 cm.

  Subsequently, the light stability of the device and the material was evaluated in the same manner as in Example 1. As a result of the evaluation, it was confirmed that there was almost no change in insertion loss due to the insertion of light, and that it was stable against light.

[Comparative Example 1]
First, as the solution of the nonlinear optical material, cyclohexanone, tetrahydrofuran, polysulfone, and DR1, and the total mass of all the materials as 100 parts by mass, respectively from 75 parts by mass, 9 parts by mass, 8 parts by mass, and 8 parts by mass A solution (hereinafter referred to as PS solution) was prepared. Nμ / _{M W} of the non-linear optical materials made from this solution was approximately 0.011. When a thin film of the material was produced, defects such as cracks were found in the thin film, and the thin film could not be used for a waveguide device.

It is a figure explaining the manufacturing process of the waveguide device of this invention. It is a figure which shows the example of the type | mold of the waveguide which can apply the waveguide device of this invention. It is a figure which shows the example of the type | mold of the waveguide which can apply the waveguide device of this invention. It is a figure which shows the example of the type | mold of the waveguide which can apply the waveguide device of this invention. It is a figure which shows the time-dependent change of the optical power of the waveguide device produced in Example 1. FIG.

Explanation of symbols

201 Substrate 202 Lower electrode 203 Lower cladding layer 204 Waveguide layer 205 Upper cladding layer 206 Upper electrode

Claims (6)

A low molecular weight compound having a molecular weight of 100 to 5000, which exhibits nonlinear optical characteristics, and a compound inactive to a photoreaction, in a mixed or chemically bonded state,
The nonlinear optical material according to claim 1, wherein a transmission attenuation coefficient per 1 cm of light having a specific wavelength within a wavelength range of 0.6 to 1.8 μm is 0.5 or less. The mass ratio of the low-molecular compound to the total weight N (0 <N <1) , the dipole moment of the low molecular compound mu (Debye), when the molecular weight was M _W, satisfies the following formula (1) The nonlinear optical material according to claim 1.

  The nonlinear optical material according to claim 1, wherein the compound inactive to the photoreaction is polycarbonate.   The nonlinear optical material according to claim 1, wherein the compound inactive to the photoreaction is polysulfone.   The nonlinear optical material according to claim 1, wherein the compound inactive to the photoreaction is silicone.   A waveguide device manufactured using the nonlinear optical material according to claim 1.

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