JP2008039908A - Method for manufacturing optical waveguide module, and poling processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an optical waveguide module, with which disappearance of nonlinearity caused by heat evolution in module formation is suppressed, in the method for manufacturing the optical waveguide module having an optical waveguide element to manifest an electro-optic effect with poling processing. <P>SOLUTION: The method is characterized by including steps: of fabricating the optical waveguide element which at least includes a step of forming a lower cladding layer on a substrate, a step of forming a waveguide layer on the lower cladding layer, and a step of forming an upper cladding layer on the waveguide layer; and a step of fixing the optical waveguide element fabricated with the step of fabricating the optical waveguide element to a module casing, and having a step of aligning orientation of molecules with poling processing of the optical waveguide element subsequent to fixing of the optical waveguide element of the module casing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical waveguide module manufacturing method and a polling processing apparatus.

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.
One of the technologies that support high-capacity high-speed communication is optical communication technology. As an element used for optical communication, there are various optical waveguide elements such as an optical fiber, an optical switch element, an optical modulator, and a router.

In recent years, a waveguide type optical element that controls guided light by an electro-optic (hereinafter referred to as “EO”) effect has been actively developed. For optical waveguide devices, various types of waveguide structures have been studied, and various waveguide formation methods have been reported in the same manner.
Conventionally, as the material of the optical waveguide of the optical waveguide element, lithium niobate (LiNbO ₃ ) exhibiting a large EO effect, lanthanum-doped lead zirconate titanate ((Pb, La) (Zr, Ti) O ₃ , Inorganic materials such as “PLZT” are widely used. However, these materials have a low response speed due to a high dielectric constant, and therefore, applicable frequency bands are limited. In addition, since the manufacturing method is complicated and high temperature treatment is necessary, the cost of the element is high, and the applicable range is limited.

  On the other hand, polymers have a lower dielectric constant than inorganic materials and can greatly improve the problem of velocity mismatch with microwaves. In addition, thin films can be easily formed by spin coating, etc. I do not receive it. In addition, since it has excellent workability such as microfabrication and molding, it has a great advantage that it can be made into an element at a very low cost, and has attracted attention as an optical waveguide material.

  In such a polymer optical waveguide element, a polymer material or a polymer precursor compound that becomes a lower clad layer, a waveguide layer, and an upper clad layer is sequentially applied in a melted or dissolved state on a substrate made of silicon or the like. After the curing, the waveguide end face is mirrored by cutting or polishing. The waveguide is formed by combining known techniques such as photolithography and etching. In particular, when a device using a nonlinear optical effect such as an electro-optic effect is manufactured, an electrode is disposed on the substrate or the upper cladding layer. A light or thermosetting adhesive is generally used as the cladding material, and a solution obtained by dissolving a polymer compound in an organic solvent is generally used as the waveguide layer material.

  In a device that uses the electro-optic effect of such an organic material, the polarization of non-linear organic molecules randomly dispersed immediately after coating may be aligned in a certain direction in order to achieve a sufficient effect. is necessary. For this reason, after holding the element at a temperature equal to or higher than the glass transition point of the polymer, the step of applying an electric field, holding it for a certain period of time, and cooling it with the electric field applied to fix the orientation state of the organic molecules It is essential. This process is called polling.

  In recent years, it has been actively used as a material to realize high-speed, low-voltage driven waveguide elements because of the high nonlinearity of organic materials and the high speed matching with driving microwaves due to the low dielectric constant of polymers. (See, for example, Non-Patent Document 1).

However, in spite of active research activities in recent years, the actual situation is that a sufficient element for practical use has not been realized. In conventional R & D, materials and configurations for realizing organic waveguide devices have been studied, but most of the packaging, that is, modularization, which is indispensable for actual use of devices, has been studied. The current situation is that nothing has been done. In particular, in the case of modularization, in the step of fixing the element to the module housing, or in wire bonding performed when performing electrical wiring, a certain amount of heating is required. There has been a problem that the orientation state of is disturbed again. For this reason, although the element has a potential capable of being driven by a low voltage, it has not been possible to provide a module having sufficient performance that can withstand practical use.
Hua Zhang et al., Appl. Phys. Lett., Vol. 78, p. 3136 (2001) Vol. 78, p. 3136 (2001)

This invention is made | formed in view of the said conventional problem, and makes it a subject to achieve the following objectives. That is,
An object of the present invention is to provide an optical waveguide module manufacturing method that can suppress the disappearance of non-linearity due to heat during modularization in an optical waveguide module manufacturing method having an optical waveguide element that exhibits an electro-optical effect by a poling process. It is to provide.
Another object of the present invention is to provide a polling processing apparatus in which the module housing does not cause electrostatic breakdown due to a high voltage during the polling processing.

As a result of diligent research to solve the above-mentioned problems, the present invention, after modularizing the optical waveguide element, requires heating, and after performing the step of fixing the optical waveguide element to the module housing, By performing the polling treatment, it was found that it is possible to manufacture an optical waveguide module while avoiding the relaxation of the orientation of organic molecules, and the present invention has been achieved. That is, the present invention
<1> including at least a step of forming a lower cladding layer on the substrate, a step of forming a waveguide layer on the lower cladding layer, and a step of forming an upper cladding layer on the waveguide layer An optical waveguide device manufacturing process;
And a step of performing a poling process for aligning the molecular orientation of the optical waveguide element after fixing the optical waveguide element manufactured by the optical waveguide element manufacturing step to a module housing. Is the method.

<2> In the above <1>, the optical waveguide device manufacturing step further includes a step of forming a lower electrode on the substrate and / or a step of forming an upper electrode on the upper cladding layer. It is a manufacturing method of the described optical waveguide module.

<3> The method for producing an optical waveguide module according to <1> or <2>, wherein the waveguide layer is a waveguide layer having an electro-optic effect.

<4> The method according to any one of <1> to <3>, wherein in the optical waveguide element manufacturing step, after forming a waveguide layer, patterning is performed to process the structure into a ridge structure. It is a manufacturing method of an optical waveguide module.

<5> In the optical waveguide device manufacturing step, after forming the lower clad layer, patterning is performed, the lower clad layer is processed to form a trench, and a waveguide layer is formed on the lower clad layer. The method of manufacturing an optical waveguide module according to any one of <1> to <3>, wherein an inverted ridge structure is obtained by forming the structure.

<6> The steps <1> to <5>, wherein in the step of performing the polling process, the electrode on the side to which the polling voltage is applied and the wiring connected to the electrode facing the electrode are short-circuited. A method for manufacturing an optical waveguide module according to any one of the above.

<7> On the substrate, a means for fixing an optical waveguide element formed of at least a lower clad layer, a waveguide layer, and an upper clad layer to a module housing, and a polling voltage of the optical waveguide element are applied. A means for connecting and short-circuiting the electrode on the side and the electrode facing the electrode, and a polling processing means for applying a polling voltage to the optical waveguide element fixed to the module housing, A polling processing device.

<8> The polling processing device according to <7>, wherein the polling voltage is applied by corona polling.

<9> The polling processing device according to <7>, wherein the polling voltage is applied by electrode poling.

According to the present invention, in a method for manufacturing an optical waveguide module having an optical waveguide element that exhibits an electro-optic effect by polling processing, a method for manufacturing an optical waveguide module that can suppress the disappearance of nonlinearity due to heat during modularization. Can be provided.
In addition, according to the present invention, it is possible to provide a polling processing apparatus in which the module housing can perform the polling process without electrostatic breakdown due to the high voltage at the time of polling when performing the polling process.

Below, the manufacturing method of the optical waveguide module of this invention and a polling processing apparatus are demonstrated.
<Method for manufacturing optical waveguide module>
An optical waveguide module manufacturing method according to the present invention includes a step of forming a lower cladding layer on a substrate, a step of forming a waveguide layer on the lower cladding layer, and an upper cladding layer on the waveguide layer. An optical waveguide device manufacturing step including at least a forming step, and a poling process for aligning the molecular orientation of the optical waveguide device after fixing the optical waveguide device manufactured by the optical waveguide device manufacturing step to a module housing And a process.

First, a basic configuration of an optical waveguide device according to the present invention is shown in FIG. FIG. 1 is a schematic cross-sectional view of an example of an optical waveguide device according to the present invention as viewed from the input / output end face of light. An optical waveguide device 10 shown in FIG. 1 has a lower cladding layer 14, a waveguide layer 16, and an upper cladding layer 18 on a substrate 12.
Below, the manufacturing method of the optical waveguide module of this invention is demonstrated in order.

[Optical waveguide device fabrication process]
First, an optical waveguide element manufacturing process, which is a process of manufacturing an optical waveguide element, will be described.
First, a metal material is deposited on the surface of the substrate as a lower electrode as necessary. Examples of the substrate include various metal substrates (aluminum, gold, iron, nickel, chromium, stainless steel, etc.), various semiconductor substrates (silicon, silicon oxide, titanium oxide, zinc oxide, gallium-arsenide, etc.), glass substrates, plastic substrates ( PET (polyethylene terephthalate), polycarbonate, polyester, polyvinyl chloride, polyvinyl acetate, polymethyl acrylate, polymethyl methacrylate, polyurethane, polyimide, polystyrene, polyamide, etc.) can be used. These substrates may be thick and rigid, or thin and flexible. As described above, the lower electrode is formed on the surfaces of the semiconductor substrate, the glass substrate, and the plastic substrate.

  As materials for the lower electrode, various metals such as Au, Ti, TiN, Pt, Ir, Cu, Al, Al-Cu, Al-Si-Cu, W, and Mo, various oxides (NESA (tin oxide), oxidation) Indium, ITO (tin oxide-indium oxide composite oxide), various organic conductors (polythiophene, polyaniline, polyparaphenylene vinylene, polyacetylene), etc. These conductive films can be deposited, sputtered, applied or electroanalyzed. It may be formed by a method such as a protruding method, and a pattern may be formed as necessary.

  When the substrate is a metal substrate, it is not necessary to provide a lower electrode. Such a conductive substrate and the lower electrode can be used as an electrode when an electric field is applied to a nonlinear optical polymer described later. it can. The upper electrode formed on the surface of the upper clad layer as necessary is also made of the same material.

  Other layers may be formed between the substrate or the lower electrode and the lower clad layer, which will be described later, and between the upper clad layer and the upper electrode, as necessary. Adhesion for improving adhesion A layer, an undercoat layer for smoothing the unevenness of the surface, or some intermediate layer that provides these functions collectively may be formed.

  Materials for forming such layers include polyethylene, polypropylene, acrylic, methacrylic, polyamide, vinyl chloride, vinyl acetate, phenol, polycarbonate, polyurethane, polyimide, vinylidene chloride, polyvinyl acetal, vinyl chloride-vinyl acetate copolymer, Polyvinyl alcohol, polyester, nitrocellulose, casein, gelatin, polyglutamic acid, starch, starch acetate, amino starch, polyacrylic acid, polyacrylamide, zirconium chelate compound, titanyl chelate compound, titanyl alkoxide compound, organic titanyl compound, silane coupling agent A known material such as can be used.

It is better not to form an extra layer between the waveguide layer and the upper and lower cladding layers as much as possible. However, such a layer may be formed very thin so as not to affect the characteristics of the element. Alternatively, by treating the surface of the lower clad layer and the surface of the waveguide layer with a commercially available surfactant or the like, the adhesion to the upper layer, the wettability during coating, the film formability, etc. may be improved.
In the optical waveguide device according to the present invention, in addition to the function of the inherent electro-optical characteristics, in addition to the function as a waveguide layer that is a waveguide, the waveguide layer has a structure as shown in FIG. A lower cladding layer is formed between the substrate and the substrate.

As the lower cladding layer, a material having a refractive index lower than that of the waveguide layer is deposited. The material used for the lower cladding layer is preferably a material that does not cause intermixing during the formation of the waveguide layer, and is generally known as a thermosetting crosslinked resin, an ultraviolet curable crosslinked resin, an inorganic material, a conductive material. A functional polymer, a fluorinated polymer, or the like can be used.
Examples of the thermosetting crosslinked resin include polyimide, polyurethane, polybenzocyclobutene, and polyamide. Examples of the ultraviolet curable crosslinking resin include epoxy resin, acrylic resin, and silicone resin. .

As a means for forming the lower cladding layer, a general solution coating method such as a spin coating method or a dip method is used as long as it is a polymer material. For inorganic materials, electron beam evaporation, flash evaporation, ion plating, RF (radio frequency) -magnetron sputtering, DC (direct current) -magnetron sputtering, ion beam sputtering, Vapor deposition methods selected from laser ablation, MBE (molecular beam epitaxy), CVD (vapor deposition), plasma CVD, MOCVD (organic vapor deposition), or wet methods such as sol-gel and MOD・ Manufacturing is possible by the process, but it is not limited to these.
The film thickness of the lower cladding layer depends on the waveguide design guidelines such as the wavelength and mode of light to be used, but is preferably in the range of about 1 to 20 μm, and in the range of about 1.5 to 10.0 μm. Is more preferable. When the thickness of the lower cladding layer is thick, the effective voltage applied to the waveguide layer is low, so that a sufficient EO effect cannot be obtained, and when the thickness is thin, light absorption by the lower electrode increases. There may be a problem that optical loss increases.

  After forming the lower cladding layer, a polymer (nonlinear optical polymer) imparted with a nonlinear effect is laminated to form a waveguide layer. The waveguide layer preferably has an electro-optic effect. In the case of the ridge type, the ridge is formed by a dry etching method. Here, the nonlinear optical polymer is an organic nonlinear optical polymer obtained by adding an organic compound having nonlinear optical characteristics in a polymer matrix, or a structure having nonlinear optical characteristics in the main chain or side chain of the polymer (hereinafter referred to as “ Main chain organic nonlinear optical polymer or side chain organic nonlinear optical polymer into which a chromophore structure is sometimes introduced).

  As the material of the waveguide layer, an optical waveguide can be formed, and any material having a refractive index higher than that of the lower cladding layer does not detract from the intention of the present invention. However, the nonlinear optical polymer should be used. As described above, it is possible to use a polymer having a chromophore structure introduced on the side chain or main chain of the polymer for the purpose of imparting nonlinearity to the polymer.

  As the polymer material, acrylic resin, polyimide resin, epoxy resin, polycarbonate resin, polystyrene, polyurethane, polysilane, polybenzocyclobutene, or the like can be used.

Although the said chromophore structure will not be specifically limited if it is a well-known thing, What is represented by following Structural formula (1) is preferable.
D-P-A Structural formula (1)
In Structural Formula (1), D represents an atomic group having an electron donating property, P represents a bonding portion, and A represents an atomic group having an electron withdrawing property. In the structural formula (1), as the atomic group having an electron donating property represented by “D”, a known one can be used as long as it has an electron donating property, and it has an electron donating substituent. , An aliphatic unsaturated bond, an aromatic ring, a heteroaromatic ring, and a combination thereof. The electron donating substituent is not particularly limited as long as it has an electron donating property, but an alkyl group, an alkoxy group, an amino group, and the like are preferable. A part of the alkyl group may be substituted with an alkoxy group or a phenyl group, a part of the alkoxy group may be substituted with an alkoxy group or a phenyl group, and a part of the amino group is an alkyl group. It may be substituted with a group, an alkoxy group, or a phenyl group.

  On the other hand, as the atomic group having an electron-withdrawing property represented by “A”, any known group having an electron-withdrawing property may be used, but an aliphatic unsaturated bond having an electron-withdrawing substituent introduced therein. , Aromatic rings, heteroaromatic rings, and combinations thereof are desirable.

  As the electron-withdrawing substituent, a halogen atom, a halogen-substituted alkyl group, a cyano group, a nitro group, a carbonyl group, and the like are desirable.

  The bond represented by “P” may be any bond that connects “D” and “A” with a covalent bond, but has a conjugate bond that can delocalize electrons. For example, a material having a structure in which “D” and “A” are combined in a π-conjugated system is desirable. Specifically, aliphatic unsaturated bonds, aromatic rings, heteroaromatic rings, and those in which they are bonded to each other are desirable.

  The waveguide layer is formed by dissolving a polymer material having the chromophore structure or a mixture of an organic compound having a chromophore structure and a polymer material in a solvent that dissolves them to prepare a coating solution. The liquid is coated on the surface of the lower cladding layer or the like.

  The waveguide layer can be coated by a known method such as spin coating, spray coating, blade coating or dip coating. The removal of the solvent may be performed by heat drying with a blower dryer or the like, or may be dried with a reduced pressure (vacuum) dryer or the like.

  As the film thickness of the waveguide layer, in order to effectively apply an electric field to the action part of the polymer waveguide, the film thickness of the waveguide layer is preferably thin, preferably 5.0 μm or less, and more preferably 3.5 μm or less. . When the film thickness is thicker than 5.0 μm, application of an electric field to the action part of the polymer waveguide becomes large, and it may be impossible to achieve a target low driving voltage. The lower limit of the thickness of the waveguide layer is about 1.0 μm.

  Examples of the ridge pattern of the optical waveguide include a linear type, an S-shaped type, a Y-branch type, an X-crossing type, or a combination thereof. The ridge width and ridge height vary depending on the combination of the refractive index and the film thickness of the waveguide, but the ridge height (step) is generally preferably in the range of 50 to 3000 nm, more preferably in the range of 500 to 2000 nm. . If the step is less than 50 nm, a sufficient difference in refractive index may not be obtained and light may not be confined. If it exceeds 3000 nm, it may become a multi-mode and the function of the target element cannot be fully exhibited. Further, the ridge width is preferably in the range of 1 to 15 μm, and more preferably in the range of 3 to 10 μm.

  Furthermore, the lower cladding layer is patterned in advance by a known method using a semiconductor process technology such as reactive ion etching (RIE), wet etching, photolithography, electron beam lithography, and the lower cladding layer is processed. Thus, an inverted ridge-type waveguide can be formed by forming a trench and forming a waveguide layer thereon.

  By adopting the ridge type or reverse ridge type structure as described above, it is possible to obtain a large difference in refractive index between the upper and lower cladding layers. Therefore, the absorption loss due to the electrodes can be suppressed and the effective electric field of the element can be increased, so that the drive voltage can be reduced.

  After the ridge is formed, the waveguide layer is covered with a material having a refractive index lower than that of the waveguide layer as an upper cladding layer. The material used for the upper clad layer is preferably a material that does not intermix with the waveguide layer when the upper clad layer is formed, and the material used for the lower clad layer can be used. Further, as the means for forming the upper clad layer, the means used for forming the lower clad layer can be similarly used. In addition, as a film thickness of an upper clad layer, the range of 1-20 micrometers is preferable, and the range of 1.5-10.0 micrometers is more preferable.

  In an optical waveguide device, it is usually necessary to make the refractive index of the cladding layer smaller than the refractive index of the waveguide layer. In the present invention, the difference in refractive index between the waveguide layer and the clad layer differs depending on the type of element used. For example, when used as a single-mode waveguide, the waveguide layer and the clad layer The difference in refractive index is preferably in the range of 0.01 to 3%.

Next, a metal material is formed as an upper electrode on the surface of the upper cladding layer to form an optical waveguide element. As the material for the upper electrode, the materials used for the lower electrode can be used in the same manner.
These control electrodes (lower electrode, upper electrode) are known methods, for example, DC magnetron sputtering method, electron beam evaporation method, electrolytic plating method, flash evaporation method, ion plating method, RF magnetron sputtering method. The surface of the over clad layer by a vapor growth method selected from ion beam sputtering, laser ablation, MBE, CVD, plasma CVD, MOCVD, etc., or a wet process such as sol-gel, MOD, etc. Thin film growth can be performed.

  The manufacturing method of the optical waveguide device according to the present invention will be described with reference to the drawings. FIG. 2 is a diagram schematically showing the steps in the method of manufacturing an optical waveguide device according to the present invention. In FIG. 2, the lower electrode 13, the lower cladding layer 14, the waveguide layer 16, and the upper cladding are formed on the substrate 12. A method of manufacturing an optical waveguide element having the layer 18 and the upper electrode 20 in this order will be described. In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals (FIGS. 1 and 2 differ depending on the presence or absence of the upper and lower electrodes).

  First, the substrate 12 is prepared (FIG. 2A), and the lower electrode 13 is formed on the substrate 12 (FIG. 2B). Next, a lower cladding layer 14 is formed on the lower electrode 13 (FIG. 2C), and a waveguide layer material solution is applied on the lower cladding layer 14 to form a waveguide layer 16 (FIG. 2). 2 (D)). Next, the waveguide layer 16 is processed by dry etching or the like to form a ridge-type waveguide portion having the ridge portion 16A (FIG. 2E). Further, an upper clad layer 18 is formed on the waveguide layer 16 (FIG. 2F). Finally, the upper electrode 20 is formed above the ridge portion 16A of the waveguide layer 16 on the upper clad layer 18 (FIG. 2G).

  The optical waveguide element produced by the above process is processed into a chip shape (element shape) by cutting, thereby completing the element. A dicer or the like is used for cutting. The element shape generally refers to a rectangular shape, but includes a case of processing into a rhombus shape or a trapezoid shape for the purpose of reducing the return light at the light input / output end face.

Next, the optical waveguide device manufactured by the above optical waveguide manufacturing process is fixed to the module housing, and wire bonding is performed. For wire bonding, a general-purpose device used for electrical mounting of semiconductor ICs can be used. However, the bonding temperature should be 200 ° C. or lower because it is necessary to prevent the destruction and deterioration of the organic material used for the element. Is preferred.
And after that, a process of aligning the orientation of the molecules by poling treatment is performed. Thus, in the present invention, since the polling process is performed after the optical waveguide element is fixed to the module housing, in other words, the polling process is performed after the process involving heating is finished. It is possible to avoid such a problem that the alignment state is disturbed again thereafter.

  Here, the poling treatment has the polarization direction of the nonlinear optical polymer or the chromophore by applying an electric field in a state heated to a glass transition temperature (Tg) or higher after film formation, and performing orientation treatment. This refers to a process of removing the electric field after the temperature is lowered to Tg or less in a state where the chromophore part of the nonlinear optical polymer is oriented in the polarization direction and maintained.

  As such a poling process, as an electric field application method, a method of applying an electric field by directly sandwiching a nonlinear optical polymer between two or more electrodes (electrode poling), a medium such as a liquid between the nonlinear optical polymer and the electrode And a method of applying an electric field to the nonlinear optical polymer by an indirect method by corona discharge (corona poling).

  The poling temperature is preferably equal to or higher than the glass transition temperature. Specifically, it is desirable to maintain the poling temperature within a range of 100 to 200 ° C. for about 0.5 to 10 hours. When the polling temperature is raised stepwise from room temperature to the final temperature, the rising temperature of each step is preferably in the range of about 5 to 50 ° C., and the time of each step is preferably about 10 to 120 minutes. May be. The rate of temperature increase when the temperature is continuously increased is preferably about 0.1 to 20 ° C./minute, and may be combined with the step of increasing the temperature stepwise.

  In the corona discharge method, the positional relationship between the electrode, the grid, and the sample surface is arbitrary as long as it is in this order, but the shortest distance between the electrode and the sample surface is in the range of about 5 to 100 mm, and the shortest distance between the grid and the sample surface. Is preferably in the range of about 1 to 30 mm. In some cases, the use of a grid can stabilize the discharge, and since it is possible to prevent an unnecessary ion flow from flowing into the sample surface, it is considered that there is an effect of reducing damage to the surface.

  The voltage applied to the electrodes and the grid at the time of polling may be constant, may be changed continuously or stepwise, and may or may not match the timing of temperature rise or fall. For example, the voltage applied to the corona electrode is preferably in the range of about 1 to 20 kV, and the grid voltage when the grid is used is preferably in the range of about 0.1 to 2 kV.

  Moreover, it is preferable to set it as the range of about 0.1-2 kV as a voltage applied to the electrode of an electrode method. The polarity of the electrode may be either positive or negative. However, in the case of the corona discharge method, the positive voltage produces less ozone and nitrogen oxides, and the damage to the sample can be reduced. Note that the total polling time including the step of lowering the temperature is preferably within about 24 hours.

  In the above polling process, it is preferable to short-circuit between the wires connected to the electrode opposite to the electrode to which the polling voltage is applied. With this setting, no potential difference is generated between the electrodes, so that electrostatic breakdown due to a high voltage during poling can be prevented. FIG. 3 is a diagram conceptually showing the form. The optical waveguide device 10 shown in FIG. 3 includes a lower electrode 13, a lower cladding layer 14, a waveguide layer 16, an upper cladding layer 18, and an upper electrode 20 on a substrate 12. As shown in FIG. 3, a ground line is connected to the lower electrode 13, and the lower electrode 13 is grounded via the ground line. The upper electrode 20 is connected to a power source 22 through wiring, and the power source 22 is grounded through a ground line. That is, the upper electrode 20 that is an electrode to which a poling voltage is applied and the lower electrode 12 that is an electrode facing the upper electrode 20 are both grounded and both are short-circuited. In this state, a voltage is applied to the optical waveguide element to perform a polling process.

<Polling processing device>
The polling processing apparatus of the present invention comprises: a means for fixing an optical waveguide element formed on a substrate with at least a lower clad layer, a waveguide layer, and an upper clad layer to a module housing; A means for connecting and short-circuiting the electrode on the side to which the polling voltage is applied, an electrode facing the electrode, and a polling processing means for applying a polling voltage to the optical waveguide element fixed to the module housing; It is characterized by having.

  The polling processing apparatus of the present invention can execute a polling process on the optical waveguide element in the method for manufacturing an optical waveguide module of the present invention described above. That is, in the polling processing apparatus of the present invention, the optical waveguide element is fixed to the module housing, and the electrode on the side to which the polling voltage is applied and the opposite electrode are connected and short-circuited in the optical waveguide element as shown in FIG. The apparatus that performs the polling process in a state can suppress the disappearance of non-linearity due to heat at the time of modularization, and can execute the polling process without electrostatic damage of the module housing due to a high voltage.

  Hereinafter, the details of the invention will be described more specifically with reference to examples. Needless to say, the present invention is not limited to the following examples.

[Example 1]
As a material for the waveguide layer, a polycarbonate resin represented by the following structural formula was dissolved in a solvent in which 1 part by mass of THF and 4 parts by mass of cyclohexanone were mixed to prepare a 15% by mass resin solution. Next, Dispersed Red 1 was added and dissolved in this resin solution in an amount of 20% by mass as a solid content ratio to obtain a coating solution for a waveguide layer.

  A silicon substrate (diameter: 50.8 mm, thickness: 0.5 mm) having a natural oxide film provided with 0.3 μm of Au as a lower electrode by sputtering was used as the substrate. Next, a fluorinated polyimide raw material (manufactured by Hitachi Chemical Co., Ltd., OPI-N3405) was applied on the surface of the lower electrode by spin coating, and then imidized by heating to form a lower clad layer as a fluorinated polyimide film. The thickness of the lower cladding layer was 5.8 μm.

  Next, the previously prepared coating solution for the waveguide layer was dropped onto the surface of the lower cladding layer, a film was formed by spin coating, and the solvent was dried to obtain a waveguide layer. The thickness of the waveguide layer was 2.4 μm. A ridge type channel having a width of 4.1 μm and a step of 0.8 μm as a waveguide by dry etching after patterning a Mach-Zehnder type waveguide pattern on the waveguide layer using photolithography A waveguide was fabricated.

Furthermore, an upper clad layer was formed by applying an epoxy resin to the surface of the waveguide layer on which the waveguide was formed by spin coating. The thickness of the upper cladding layer was 5.0 μm.
The silicon wafer thus formed up to the upper cladding layer was cut into 5 mm × 20 mm by a dicer to obtain an optical waveguide element.

  The optical waveguide device manufactured as described above was fixed by heating at 150 ° C. for 30 minutes using a thermosetting adhesive on a module housing prepared in advance. Next, the module casing was set on a wire bonder and heated to 200 ° C., and then the module casing and the electrode pad of the waveguide element were electrically connected by wire bonding.

  In the optical waveguide module obtained in this way, the wiring is short-circuited so that a potential difference does not occur between the wires connected to the electrode opposite to the electrode to which the poling voltage is applied. After wiring, it was heated to 130 ° C., a voltage of +800 V was applied to the poling electrode and held for 60 minutes, and then the module was cooled to fix the orientation of the organic molecules.

Using this waveguide type Mach-Zehnder optical device, the insertion loss for a single mode optical fiber having a mode field diameter of 10.5 μm was evaluated by an optical insertion loss evaluation apparatus using a semiconductor laser having a wavelength of 1.55 μm as a light source. Was 9.8 dB.
Next, a voltage was applied to the waveguide type Mach-Zehnder optical device to evaluate the modulation characteristics. A half-wave voltage (Vπ) of 20 V was obtained, and it was confirmed that the half-wave voltage (Vπ) functions as a light modulation element.

[Comparative Example 1]
Before the optical waveguide device manufactured in the same manner as in Example 1 was fixed to the module housing, a polling process was performed in the same manner as in Example 1. Next, in the same manner as in Example 1, fixing to the module housing and electrical mounting by wire bonding were performed to produce an optical waveguide module.
Using this waveguide type Mach-Zehnder optical device, a voltage was applied to the waveguide type Mach-Zehnder optical device using a semiconductor laser having a wavelength of 1.55 μm as a light source, and the modulation characteristics were evaluated. The half-wave voltage (Vπ) was 100 V or more, and a sufficient function as a light modulation element could not be confirmed.

1 is a schematic cross-sectional view showing a basic configuration of an optical waveguide device according to the present invention. It is a figure which shows typically an optical waveguide element preparation process. It is a figure which shows the state which short-circuited the upper electrode and lower electrode of the optical waveguide element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical waveguide element 12 Substrate 13 Control electrode pattern 14 Lower clad layer 16 Waveguide layer 18 Upper clad layer 20 Upper electrode

Claims (9)

An optical waveguide device including at least a step of forming a lower cladding layer on a substrate, a step of forming a waveguide layer on the lower cladding layer, and a step of forming an upper cladding layer on the waveguide layer Production process;
And a step of performing a poling process for aligning the molecular orientation of the optical waveguide element after fixing the optical waveguide element manufactured by the optical waveguide element manufacturing step to a module housing. Method.   2. The optical waveguide according to claim 1, wherein the optical waveguide device manufacturing step further includes a step of forming a lower electrode on the substrate and / or a step of forming an upper electrode on the upper clad layer. Module manufacturing method.   The method for manufacturing an optical waveguide module according to claim 1, wherein the waveguide layer is a waveguide layer having an electro-optic effect.   4. The optical waveguide module according to claim 1, wherein, in the optical waveguide element manufacturing step, after forming a waveguide layer, patterning is performed to process into a ridge structure. 5. Production method.   In the optical waveguide device manufacturing process, after forming the lower cladding layer, patterning, processing the lower cladding layer to form a trench, and forming a waveguide layer on the lower cladding layer The method of manufacturing an optical waveguide module according to claim 1, wherein an inverted ridge structure is obtained by:   6. The method according to claim 1, wherein in the step of performing the polling process, an electrode on a side to which a polling voltage is applied and a wiring connected to an electrode facing the electrode are short-circuited. The manufacturing method of the optical waveguide module of description.   Means for fixing an optical waveguide element formed by forming at least a lower clad layer, a waveguide layer, and an upper clad layer on a substrate to a module housing, and an electrode on a side to which a polling voltage is applied of the optical waveguide element And polling processing means for applying a polling voltage to the optical waveguide element fixed to the module housing. apparatus.   The polling processing apparatus according to claim 7, wherein the polling voltage is applied by corona polling.   The polling processing apparatus according to claim 7, wherein the polling voltage is applied by electrode poling.

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