JP2011102919A - Optical transmitter module and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the cost of an optical transmitter module used for a head cymbal assembly of an information recording device, and to provide optical coupling between optical devices in a near-infrared wavelength of 600 to 900 nm without using advanced aligning equipment. <P>SOLUTION: One set of optical devices 502, 503 are optically coupled by an optical connection 510. The optical connector part is manufactured in a self-formed optical waveguide and includes a core 507 composed of a shaft-like curable composition component which is cured by the radiation of near-infrared light, and a clad 508 composed of a curable composition component which is provided at outside of the core and has a refractive index smaller than that of the core. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical transmission module applicable to a head gimbal assembly of a thermally assisted magnetic recording apparatus and a manufacturing method thereof.

In recent years, a heat-assisted magnetic recording system has been proposed as a recording system that achieves a recording density of 1 Tb / in ² or more (Non-Patent Document 1). In the conventional magnetic recording, when the recording density is 1 Tb / in ² or more, loss of recorded information due to thermal fluctuation becomes a problem. To prevent this, it is necessary to increase the coercive force of the magnetic recording medium, but since the magnitude of the magnetic field that can be generated from the recording head is limited, if the coercive force is increased too much, a recording bit is formed on the medium. It becomes impossible to do. In order to solve this problem, in the heat-assisted magnetic recording system, the medium is heated with light at the moment of recording to reduce the coercive force. As a result, recording on a high coercive force medium is possible, and a recording density of 1 Tb / in ² or more can be realized.

  In this heat-assisted magnetic recording, the spot diameter of the irradiated light needs to be the same size (several tens of nm) as the recording bit. This is because information on adjacent tracks is erased if the light spot diameter is larger than that. Near-field light is used to heat such a minute region. Near-field light is a localized electromagnetic field (light having wavenumber having an imaginary component) existing in the vicinity of a minute object having a wavelength equal to or less than the light wavelength, and is generated using a minute aperture or metal scatterer having a diameter equal to or less than the light wavelength. For example, it has been proposed to use a metal scatterer having a triangular shape as a highly efficient near-field light generator (Non-Patent Document 2). When light is incident on the metal scatterer, plasmon resonance is excited in the metal scatterer, and strong near-field light is generated at the apex of the triangle. By using this near-field light generator, light can be collected with high efficiency in a region of several tens of nm or less.

  For heat-assisted magnetic recording, it is necessary to heat the medium near the magnetic pole for applying a magnetic field with light. For this purpose, for example, an optical transmission module in which a waveguide is formed on the side of the magnetic pole and guides the light of the semiconductor laser as the light source to the vicinity of the tip of the magnetic pole is required. At this time, the semiconductor laser, for example, is placed at the base of the suspension and guides light using a waveguide such as an optical fiber from there to the flying slider (Non-Patent Document 3).

  For the manufacture of such an optical transmission module, it is possible to use the optical wiring technology used in optical communication. However, such an optical transmission module is expensive. The reason for this will be described in detail below. A part of the optical transmission module is connected to a pair of optical fibers. A curable composition that transmits light through these optical fibers is made of an extremely thin transparent material. The light propagation part of a general optical waveguide has a diameter of several μm to several hundreds of μm, and the propagation energy is concentrated in the center of the fiber, so the optical axis shift between the optical waveguides in the connection part is several μm. Must be kept within. The optical transmission module can use a lens, a semiconductor laser, a light emitting diode, a photodiode, a hologram, a prism, a mirror, a pinhole, or a slit, which is an optical element other than a waveguide, but is required for optical connection. The positioning accuracy is about several μm as in the case of an optical fiber, and connection of these optical devices requires extremely high three-dimensional positional accuracy. For this reason, the manufacture of the optical transmission module has a problem in that the connection cost increases because the connection work is performed manually or by a highly accurate alignment facility. In addition, in the trend of resource saving and space saving, miniaturization of the optical transmission module is strongly demanded.

  A conventional optical connection technique that has been used in the field of optical communication will be described. Non-Patent Document 4 discloses a method of improving two-dimensional positioning accuracy by forming a V-shaped or trapezoidal groove (hereinafter referred to as a V-groove) on a silicon single crystal and arranging each optical device on the V-groove. Proposed. Further, as described in Patent Document 1, positioning accuracy in the optical axis direction is improved by performing connector connection in addition to the V-groove.

  On the other hand, a self-forming optical waveguide technique as shown in Patent Document 2 has also been developed. This is because a connecting end face of an optical fiber or the like is immersed in a curable composition containing a photosensitive resin and the curable composition is gradually irradiated by irradiating the curable composition with light through the optical fiber or the like. It hardens | cures and forms an optical waveguide in the front-end | tip of a connection end surface. Patent Document 3 describes a method of forming an optical waveguide with high straightness from the tip of an optical fiber. A method of forming an optical waveguide by irradiating light from one end of such an optical fiber toward the photosensitive composition (hereinafter referred to as unidirectional incidence) is performed when the connection target is significantly separated in the optical axis direction. It is valid. When using a connector, the positioning accuracy depends on the machining accuracy of the connector, but the optical waveguide formed by unidirectional incidence is separated even if the distance between a pair of optical fibers is separated. Since the optical waveguide is self-formed according to the narrowed distance, stable optical coupling can be realized. The optical waveguide thus formed is referred to as a “straight forward self-forming optical waveguide” in this specification. That is, the self-forming optical waveguide eliminates the need for particularly expensive alignment equipment and connectors, and can form an optical waveguide in which optical fibers are completely coupled. In the present specification, this completely coupled optical waveguide is referred to as an “optical connection portion”.

  Non-Patent Document 5 describes an example in which when a set of optical devices is optically connected, light is incident on both sides of a photosensitive resin to form a self-forming optical waveguide. When light is incident from both sides, the light intensity increases in the region where the light overlaps. At this time, if a curable composition that can be photocured only at or above the light intensity of the light overlapping region is selected, an optical waveguide that connects both ends of a pair of optical devices to which light is incident can be self-formed. In such a method of forming an optical waveguide by irradiating light from one end of each different optical fiber to one end of the other optical fiber (hereinafter referred to as bi-directional incidence), a self-formed optical waveguide by unidirectional incidence is used. The optical connection portion can be formed more reliably not only when the ends of different optical fibers are remarkably separated as in the formation, but also when the optical axes of the different optical fibers are deviated. The optical waveguide formed in this way is referred to as “both end face coupled self-forming optical waveguide” in this specification.

JP 54-73061 A Japanese Patent Laid-Open No. 08-320422 JP 2005-257741 A JP 2009-150899 A

Jpn. J. Appl. Phys. 38, Part 1, p.1839 (1999) Technical Digest of 6th international conference on near field optics and related techniques, the Netherlands, Aug. 27-31, 2000, p.55 Jpn. J. Appl. Phys. Vol. 42, pp. 5102-5106 (2003) Proceeding of The IEEE Vol.57 No.9 September1969 “The Influence of Crystal Orientation Silicon Semiconductor Processing” JSR TECHNICAL REVIEW, No.111 / 2004, p.7

  Since the method of using a connector when connecting a pair of optical devices as in Patent Document 1 is a method of connecting by pressing and fixing a set of optical devices, the end face of the optical device is damaged at the time of connection. The connection part may be attached or the connection part may be deformed, and connection loss due to irregular reflection of transmitted light may occur in the connection part of a pair of optical devices. In addition to connectors, methods such as fusing optical fibers to various optical devices, and methods for adhering optical fibers and various optical devices with optical adhesives are used. This is a fixed and connected method, and there is no difference that connection loss may occur. Further, since the size is increased by using a connector or the like, it is difficult to use the optical transmission module for heat-assisted magnetic recording leading to the vicinity of the tip of the magnetic pole.

  In the self-forming optical waveguide disclosed in Patent Document 2, the calculation result is shown when the wavelength of light for forming the self-forming optical waveguide is 1.33 μm. Further, in the self-forming optical waveguide shown in Non-Patent Document 5, the self-forming optical waveguide is formed with a light wavelength of 405 nm. However, the wavelength of a semiconductor laser used for thermally assisted magnetic recording is a wavelength from red to near infrared (600 nm to 900 nm), and these documents do not show a specific configuration in the wavelength band.

  As shown in Patent Document 4, gold can be used as a metal for generating resonance plasmons in a near-field light generator of a thermally assisted magnetic head from the viewpoint of ease of processing and non-oxidation. On the other hand, in order to realize high light utilization efficiency, it is preferable that the wavelength of the light used is near infrared light of 500 nm to 800 nm. In addition, as a metal for realizing a near-field light generator with high light utilization efficiency in a wavelength band of 450 nm or less which is a curing wavelength of a conventional photocurable resin, Patent Document 4 also includes aluminum and magnesium. It has been. However, the material is less non-oxidizing than gold, and there are many problems in that the material used for the optical device has a lower transmittance in the same wavelength band.

  On the other hand, in the self-forming optical waveguide shown in Patent Document 3, an optical transmission module is produced at a wavelength of near infrared light (600 nm to 700 nm) by adding a pigment. Since the pigment remains in the optical transmission module even after the optical waveguide is manufactured, the optical loss of the optical transmission module increases.

  The present inventor paid attention to photopolymerization with near-infrared light by dye sensitization, and a combination of a near-infrared light absorbing cationic dye and a photo radical polymerization initiator containing a boron anion complex after light irradiation. The present inventors have found that the same ionic dye is decolored after irradiation with near-infrared light and completed the present invention. That is, the near-infrared dye having absorption in the near-infrared region used in the present invention is decolorized by irradiation with near-infrared light in the wavelength range of 600 nm to 900 nm. Radical generation is performed with a photoradical polymerization initiator containing a boron anion complex added together to obtain a radical polymerization compound. That is, when forming a core part made of a radical polymerization compound in an optical transmission module, it absorbs near-infrared light, but after the core part is formed, it is decolored and becomes transparent. The light absorption of the portion does not increase.

The curable composition used in the present invention is composed of the following components (A) to (D).
(A) 600 nm or more and 900 nm or less of near infrared light absorbing dye (B) which dissociates by irradiation with near infrared light (B) Component (A) is used in combination with a photosensitive wavelength of 600 nm or more and 900 nm or less. Radical polymerizable compound (D) component capable of forming a cured product upon irradiation with near infrared light of 600 nm or more and 900 nm or less by reacting with a radical generated by the photo radical polymerization initiator (C) component (B) having The polymerizable compound which can produce | generate the hardened | cured material which has a refractive index smaller than the hardened | cured material of (C) Moreover, the curable composition of this invention is a near-infrared in which a component (A) is shown by General formula (1). It is characterized by being a light-absorbing cationic dye-various anionic complexes.

General formula (1): D ⁺ A ⁻
(In the formula, D ⁺ is a cation having absorption in an arbitrary wavelength region up to near-infrared light, and A ⁻ represents various anions.)

  The curable composition of the present invention is characterized in that the component (B) is various cation complexes-boron anion complexes represented by the general formula (2).

Wherein R1, R2, R3 and R4 are independently alkyl, aryl, aralkyl, alkenyl, alicyclic group, heterocyclic group and silyl or substituted alkyl, substituted aryl, substituted aralkyl, substituted alkenyl and substituted heterocyclic group. , Substituted alicyclic group and substituted silyl, at least one of R1, R2, R3 and R4 is an alkyl group having 1 to 8 carbon atoms, and Z ⁺ represents various cationic complexes)

  The optical transmission module of the present invention is used for transmission of light of 600 nm or more and 900 nm or less, and has a set of optical devices and a light having a groove that can position each end face of the set of optical devices so as to face each other. A device holding portion and an optical connection portion for optically connecting a pair of optical devices, the optical connection portion including a core portion made of an axial photocurable composition, and a core portion outside the core portion; A core part is formed mainly of the component (C), and the cladding part is formed mainly of the component (D).

  In the optical transmission module of the present invention, the set of optical devices is individually selected from a lens, an optical waveguide, an optical fiber, a semiconductor laser, a light emitting diode, a photodiode, a hologram, a prism, a mirror, a pinhole, a slit, and a grating. The expression individual means that a set of optical devices may be the same type of optical device such as an optical fiber, or may be different types of optical devices such as an optical fiber and a semiconductor laser. In addition, a lens, an optical waveguide, an optical fiber, a hologram, a prism, a mirror, a pinhole, and a slit may be disposed in the light passage region in the light transmission module.

  According to the first method of manufacturing a light transmission module of the present invention, an uncured curable composition is disposed between end faces of a pair of optical devices facing each other, and light is transmitted to the curable composition via the optical device. By irradiating, the curable composition is changed into a photocurable composition to form an optical connection between a pair of optical devices, and one end face of each of the pair of optical devices is in the optical axis direction. A near-infrared light-absorbing dye and a near-infrared light-absorbing dye that dissociates when irradiated with near-infrared light of 600 nm to 900 nm. In combination with a radical photopolymerization initiator having a photosensitive wavelength of 600 nm or more and 900 nm or less and a radical generated by the photoradical polymerization initiator, and cured by irradiation with near infrared light of 600 nm or more and 900 nm or less. object An uncured curable composition comprising a radically polymerizable compound that can be formed and a polymerizable compound that can produce a cured product having a refractive index smaller than a cured product of the radically polymerizable compound, The step of arranging between the end faces facing each other, and irradiating the uncured curable composition with light having a wavelength of 600 nm or more and 900 nm or less through one of the set of optical devices, Forming an optical connection part by forming a core part made of an axial photocurable composition between the end faces facing each other.

  The manufacturing method of the second optical transmission module of the present invention is substantially the same as the first manufacturing method, but uncured light having a wavelength of 600 nm or more and 900 nm or less is transmitted through both of the pair of optical devices. It differs from a 1st manufacturing method by the point which forms the core part which consists of an axial photocuring composition between the end surface which faced the composition, and faced a pair of optical devices, and manufactured an optical connection part .

  The third method for manufacturing a light transmission module of the present invention used for transmission of light having a first wavelength of 600 nm or more and 900 nm or less includes the first wavelength of light and the first light device on the light irradiation side. A step of providing a light irradiation means capable of irradiating light having a second wavelength of 600 nm or more and 900 nm or less, which is different from the wavelength of 1, and a step of providing a reflection means for mainly reflecting the second wavelength in the other optical device. It has a different point from the first manufacturing method. And the light of the 2nd wavelength is irradiated to the other optical device through the uncured curable composition from one optical device, and the light irradiated from one optical device and the light reflected from the other optical device By irradiating light onto the uncured curable composition by the step, a core part made of an axial photocurable composition is formed between the end faces of a pair of optical devices facing each other to produce an optical connection part.

  In the third method for manufacturing an optical transmission module, the light irradiation means is preferably a two-wavelength laser module. The light reflecting means can be a fiber grating formed inside the optical device, or a dichroic mirror formed inside the optical device or on the end face of the optical device.

  Since the curable composition of the present invention can be photopolymerized with near-infrared light and decolorized after photopolymerization, it can be used in an optical transmission module to reduce light loss. The optical transmission module has a simple configuration in which an optical device holding unit and an optical connection unit are added to an optical device to be connected, and a connector or the like is unnecessary. In addition, since it is not necessary to perform advanced position adjustment of each optical device actively, an advanced alignment machine is not required, and cost reduction can be realized.

It is a schematic diagram for demonstrating an example of the manufacturing method of the optical transmission module by 1st Embodiment. It is a schematic diagram for demonstrating an example of the manufacturing method of the optical transmission module by the 1st Embodiment of this invention. It is a schematic diagram for demonstrating an example of the manufacturing method of the optical transmission module by the 1st Embodiment of this invention. It is a schematic diagram for demonstrating an example of the manufacturing method of the optical transmission module by the 2nd Embodiment of this invention. It is a schematic diagram for demonstrating an example of the manufacturing method of the optical transmission module by the 2nd Embodiment of this invention. It is a schematic diagram for demonstrating an example of the manufacturing method of the optical transmission module by the 2nd Embodiment of this invention. It is the schematic for demonstrating the conventional optical transmission module. It is a figure which shows the structure of the optical transmission module by the 1st and 2nd embodiment of this invention. It is a schematic diagram for demonstrating an example of the manufacturing method of the optical transmission module by the 3rd Embodiment of this invention. It is a schematic diagram for demonstrating an example of the manufacturing method of the optical transmission module by the 3rd Embodiment of this invention. It is a schematic diagram for demonstrating an example of the manufacturing method of the optical transmission module by the 3rd Embodiment of this invention. It is a schematic diagram for demonstrating an example of the manufacturing method of the optical transmission module by the 3rd Embodiment of this invention. It is a figure which shows the structure of the optical transmission module by the 3rd Embodiment of this invention. 2 is a graph showing a light absorption spectrum of the curable composition used in Example 1. FIG. 3 is a graph showing a light absorption spectrum of a curable composition used in Example 2. FIG. It is the graph which showed the light absorption spectrum of the curable composition used by the comparative example. It is a figure which shows the structure of the head gimbal assembly using an optical transmission module. It is a figure which shows the structure of the head gimbal assembly using an optical transmission module. It is a figure which shows the structure of the head gimbal assembly using an optical transmission module. FIG. 2 is a diagram illustrating a configuration of an entire recording apparatus using a head gimbal assembly.

  The curable composition of the present invention is composed of the following components (A) to (D).

The near-infrared light-absorbing dye component (A) has sensitivity to near-infrared light when it is contained in a support material such as a resin represented by the following component (C), and irradiates light in this region. By doing so, it is possible to obtain a photodecolorable composition that can be decolored and is stable to visible light. The near-infrared light absorbing dye used in the present invention is composed of a near-infrared light absorbing cationic dye-various anion complexes. Examples of near-infrared light-absorbing cationic dyes are cyanine, triarylmethane, aminium, and diimmonium dyes that absorb in the near-infrared region. Examples include chlorate ions, PF ₆ ⁻ , SbF ₆ ⁻ , OH ⁻ , sulfonate ions, BF ₄ ⁻ , or tetracoordinate boron anions similar to the anion portion of the organic boron compound of the general formula (2). A tetracoordinate boron anion is preferred. The near-infrared light-absorbing dye of the present invention is dissolved and mixed in the support material at a ratio of 0.01 to 90% by weight, particularly 0.1 to 50% by weight, or melt-mixed. Can be formed.

  By adding the radical photopolymerization initiator containing the boron anion complex as the component (B) together with the near-infrared light absorbing dye, it acts as a radical photopolymerization initiator when irradiated with near-infrared light.

  The alkyl group of R1, R2, R3, and R4 in the general formula (2) may have a substituent, specifically, a substituted or unsubstituted linear or branched alkyl group having 1 to 8 carbon atoms. For example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, cyanomethyl group, 4-chlorobutyl Group, 2-diethylaminoethyl group, methoxyethyl group and the like.

  The aryl group of R1, R2, R3, and R4 in the general formula (2) may have a substituent, specifically, a substituted or unsubstituted aryl group, such as a phenyl group, a tolyl group, or a xyl group. Group, mesityl group, 4-methylphenyl group, 2-methylphenyl group, 4-tert-butylphenyl group, naphthyl group, anthryl group, phenanthryl group, 4-nitrophenyl group, 4-trifluoromethylphenyl group, 4- A fluorophenyl group, 4-chlorophenyl group, 4-dimethylaminophenyl group and the like can be mentioned.

  The aralkyl group of R1, R2, R3, and R4 in the general formula (2) may have a substituent, specifically, a substituted or unsubstituted aralkyl group such as a benzyl group, a phenethyl group, 1 -A naphthylmethyl group, 2-naphthylmethyl group, 4-methoxybenzyl group, etc. can be mentioned.

  The alkenyl group of R1, R2, R3, and R4 in the general formula (2) may have a substituent, specifically, a substituted or unsubstituted alkenyl group such as a vinyl group, a propenyl group, and a butenyl group. Group, octenyl group and the like.

  The heterocyclic groups represented by R1, R2, R3, and R4 in the general formula (2) may have a substituent, specifically, a substituted or unsubstituted heterocyclic group such as a pyridyl group, 4- A methylpyridyl group, a quinolyl group, an indolyl group, etc. can be mentioned.

  The alicyclic group of R1, R2, R3, and R4 in the general formula (2) may have a substituent, specifically, a substituted or unsubstituted alicyclic group such as a cyclohexyl group, 4- Examples thereof include a methylcyclohexyl group, a cyclopentyl group, and a cycloheptyl group.

  The silyl group of R1, R2, R3 and R4 in the general formula (2) may have a substituent, specifically, a substituted or unsubstituted silyl group such as a trimethylsilyl group or a dimethylphenylsilyl group. , Dibutylphenylsilyl group, triphenylsilyl group and the like.

  Specific examples of the tetracoordinate boron anion of the organic boron compound of the general formula (2) include n-butyltriphenylboron ion, n-octyltriphenylboron ion, triphenylsilyltriphenylboron ion, and n-butyl. Trianisyl boron ion, n-butyltri (p-fluorophenyl) boron ion, n-butyltri (p-trifluoromethylphenyl) boron ion, n-butyltrinaphthylboron ion, n-butyltri (4-methylnaphthyl) boron ion , Di-n-dodecyldiphenylboron ion, tetraphenylboron ion, triphenylnaphthylboron ion, tetrabutylboron ion, tri-n-butyl (dimethylphenylsilyl) boron ion, and the like. No. 6-75374 Such anions as described are exemplified.

The cation (Z ⁺ ) in the general formula (2) is a quaternary ammonium cation, a quaternary pyridinium cation, a quaternary quinolinium cation, a diazonium cation, a tetrazolium cation, a phosphonium cation, or an (oxo) sulfonium cation. Ions, metal cations such as sodium, potassium, lithium, magnesium and calcium, organic oxygen cations such as flavilium and pyranium salts, carbon cations such as tropylium and cyclopropylium, halogenium cations such as iodonium, arsenic, cobalt, Examples thereof include cations of metal compounds such as palladium, chromium, titanium, tin, and antimony. Specific examples include cations described in JP-A-6-75374. These cationic dyes and organoboron compounds can be used alone or in admixture of two or more.

  Among these, a quaternary ammonium boron complex is desirable for the reaction with near infrared light. Specific examples of the quaternary ammonium boron complex include tetramethylammonium n-butyltriphenylboron, tetramethylammonium n-butyltrianisylboron, tetramethylammonium n-octyltriphenylboron, and tetramethylammonium n-octyltrianisyl. Boron, tetraethylammonium n-butyltriphenylboron, tetraethylammonium n-butyltrianisylboron, trimethylhydrogenammonium n-butyltriphenylboron, triethylhydrogenammonium n-butyltriphenylboron, tetrahydrogenammonium n-butyltriphenylboron, Tetramethylammonium tetrabutyl boron, tetraethyl ammonium tetrabutyl boron, tetramethyl ammonium Mutri-n-butyl (triphenylsilyl) boron, tetraethylammonium tri-n-butyl (triphenylsilyl) boron, tetrabutylammonium tri-n-butyl (triphenylsilyl) boron, tetramethylammonium tri-n-butyl (dimethylphenylsilyl) Boron, tetraethylammonium tri-n-butyl (dimethylphenylsilyl) boron, tetrabutylammonium tri-n-butyl (dimethylphenylsilyl) boron, tetramethylammonium n-octyldiphenyl (di-n-butylphenylsilyl) boron, tetraethylammonium n- Octyl diphenyl (di-n-butylphenylsilyl) boron, tetrabutylammonium n-octyldiphenyl (di-n-butylphenylsilyl) boron, tetramethyla Trimonium dimethylphenyl (trimethylsilyl) borate, tetraethylammonium dimethylphenyl (trimethylsilyl) boron, tetrabutyl ammonium dimethylphenyl (trimethylsilyl) borate and the like.

  It is necessary to add more radical photopolymerization initiator as a molar ratio than near-infrared light absorbing dyes. This is because radicals generated in the polymerization initiator are also used for the decoloring reaction of the near infrared light absorbing dye. Accordingly, the radical photopolymerization initiator is dissolved and mixed in the support material in a proportion of 0.01 to 90% by weight, particularly 0.1 to 50% by weight, or melt mixed based on the above conditions. Can be formed.

  The radically polymerizable compound as the component (C) is not particularly limited as long as it has transparency to light in a desired wavelength band after being cured by radical photopolymerization. Specifically, for example, an acrylic resin such as PMMA (polymethylmethacrylate) or an acrylate resin may contain various additives such as a monomer and a sensitizer, a solvent, and the like as necessary. If the refractive index of the resin material is adjusted in manufacturing the optical transmission module, the weighted hydrogenated PMMA in which the hydrogen part of the hydrocarbon is replaced with deuterium, and the fluorinated PMMA in which the hydrogen part of the hydrocarbon is replaced with fluorine. Etc. can be used. These substitutions not only reduce the refractive index compared to the original PMMA, but also reduce the influence of vibrational absorption in the carbon-hydrogen molecular chain, which is a problem on the longer wavelength side than the near infrared region. It is possible to keep the absorption loss of the transmission line module low.

  In addition, resin materials other than acrylic resins and acrylate resins include epoxy resins, fluorinated epoxy resins, polyolefin resins, and, if necessary, various additives such as monomers and sensitizers, solvents, etc. Also mentioned. The curable composition used in the method for manufacturing an optical transmission module of the present invention is desirably an organic composition as described above, but the curable composition is not limited to an organic composition, for example, silicon An inorganic composition made of a resin doped with Ge, P or the like may be used. In the present specification, the curable composition includes not only a polymer that undergoes a chemical reaction upon irradiation with light as described above, but also two or more types of resin components and / or monomers that are chemically exposed to light irradiation. Also included are those that cause a reaction to form a resin composite.

  If the polymerizable compound as the component (D) has a refractive index lower than that of the component (C) and does not have radical photopolymerizability, the acrylic resin or acrylate resin such as PMMA (polymethyl methacrylate) is used. In addition, various additives such as a monomer and a sensitizer, a solvent and the like can be included as necessary. At this time, since a reaction mechanism other than radical photopolymerization is required, it is desirable to add a thermal initiator or a cationic photopolymerization initiator that causes an ionic reaction as necessary.

  Examples of the thermal initiator include polyamines, carboxylic acids, carboxylic acid anhydrides, and polythiols. Of these, carboxylic acid anhydrides are desirable in terms of storage stability. Examples of the carboxylic acid anhydride include aromatic acid anhydrides such as phthalic acid anhydride, terephthalic acid anhydride, and pyromellitic acid anhydride, succinic acid anhydride, malonic acid anhydride, and glutaric acid anhydride. Any cationic photopolymerization system may be used as long as the curing reaction proceeds by irradiating light. For example, Lewis acid is irradiated by irradiating epoxy resin and aromatic diazonium salt, aromatic iodonium salt or the like. And a photoinitiator that is generated. Moreover, you may contain the photoinitiator which a strong acid liberates by irradiating light, such as chlorinated acetophenone and its derivative (s), and the resin component which superposition | polymerization advances with an acid. The polymerization initiator used in the polymerizable compound of the present invention is 0.01 to 90% by weight, particularly 0.1 to 50% by weight, based on the polymerizable compound, regardless of the thermal initiator or the photocationic polymerization initiator. It can be formed by dissolving and mixing using a solution in a proportion, or by melt mixing.

  Since the mixing ratio of the component (C) radical polymerizable compound and the component (D) polymerizable compound varies depending on the form of the optical transmission module to be manufactured, it will be described in detail after the description of the optical transmission module below.

  An optical transmission module of the present invention optically connects a set of optical devices, an optical device holding unit having a groove that can position each end face of the set of optical devices so as to face each other, and a set of optical devices. The optical connection part is composed of a core part made of an axial photocuring composition having a vertical cross section having a predetermined shape with respect to the optical axis, and a core outside the core part. And a clad portion made of a material having a refractive index smaller than that of the portion. Since the structure of the optical transmission module of the present invention can be established by any of the first to third different manufacturing methods, the configuration of the optical transmission module of the present invention will be described first, and then the first to third embodiments of the present invention will be described. The different manufacturing methods will be described with reference to the drawings.

  Optical devices include lenses, optical waveguides, optical fibers, semiconductor lasers, light emitting diodes, photodiodes, holograms, prisms, mirrors, pinholes, slits, and gratings. These optical devices can be classified into transmissive devices, reflective devices, and emission / incident devices according to their functions. Among these, the structure of the emission / incident type device is complicated, and the device is not disposed in the middle of the optical path, so the material constituting the device is not touched.

  Examples of the transmissive optical device include a lens, an optical waveguide, a fiber, a hologram, a prism, a pinhole, a slit, and a grating. The material used for the transmission optical device is not particularly limited as long as it is a material that transmits near-infrared light used in the present invention. As an inorganic material, for example, quartz glass is the main component. And multicomponent glass mainly composed of soda lime glass, borosilicate glass and the like. Examples of the polymer material (plastic) include acrylic resins such as PMMA (polymethyl methacrylate). On the other hand, examples of the reflective optical device include a mirror and an optical filter. The material used for the reflective optical device is not particularly limited as described above as long as it reflects the near infrared light used in the present invention, and the inorganic material includes a wide range represented by gold and aluminum. In addition to materials that reflect the wavelength of light, alloys typified by silver cadmium copper (AgCdCu) and the like, and glass materials and oxide dielectrics are also included. A multilayer film formed by laminating a glass material and an oxide dielectric such as tantalum oxide having a refractive index different from that of the glass material can function as a reflective film for an arbitrary wavelength by adjusting the film thickness of each layer.

  The optical device holding unit is formed by forming V-grooves or irregularities according to the outer shape of the optical device on a silicon single crystal. By removing the [100] crystal plane of the silicon single crystal in the [111] crystal direction by etching, a V-shaped groove having a certain shape can be obtained on the silicon wafer. This technique is characterized in that it can be processed extremely finely and accurately by a photoetching technique as seen in the manufacture of LSI, and its finish is far superior to that obtained by ordinary machining. In addition, as long as there is a margin in positioning accuracy, instead of a silicon single crystal plate, a low cost material such as aluminum plate processing or plastic injection molding may be used. Two-dimensional high positioning accuracy can be realized by arranging each optical device on such V-grooves and irregularities.

  An optical connection part is comprised by the core part which is a photocurable composition, and the clad part with a smaller refractive index than a core part. The photocurable composition which comprises a core part is manufactured by irradiating light to a curable composition. On the other hand, the clad part can also be obtained by photocuring the curable composition in the same manner as the core part, but the residue is removed after the core part is formed, and the refractive index of the clad part is smaller than that of the core part. The material may be filled. Further, even in the case of air, a gas atmosphere close thereto, or a vacuum after removing the residue, the refractive index of these gases or vacuum is smaller than that of the core portion, so that it can function as a cladding portion. That is, in the present invention, light irradiation is essential for forming the core part, but light irradiation is not essential if there is a means for forming the cladding part.

  In the method for manufacturing an optical waveguide according to the present invention, the core portion is sequentially formed from the optical waveguide side according to the path of the irradiated light. Therefore, it is desirable that the curable composition has a higher refractive index after curing than before curing. This is because the refractive index increases after curing, so that the light irradiated through the optical wiring is confined in the core portion where it is formed, and the light is concentrated from the tip, and the light according to the light path. This is because the waveguide can be formed more reliably. As described above, in the production method of the present invention, it is desirable to select and use a curable composition that satisfies the above-described refractive index conditions, but even a curable composition having a refractive index outside the above-described range. The refractive index can be adjusted and used.

  As a method for adjusting the refractive index, the curable composition for forming the core part and the clad part may be composed of two kinds of materials. At this time, the refractive index before photocuring can be defined by the refractive index of two kinds of mixed solutions, and the refractive index can be adjusted by changing the mixing ratio of the two kinds of materials. Even when one kind of material is selected, the refractive index can be adjusted by designing and controlling the molecular structure.

  In general, since the refractive index of a polymer increases as the ratio of molecular refraction to molecular volume (molecular refraction / molecular volume) increases, the refractive index of the polymer can be adjusted by adjusting the molecular refraction and / or molecular volume. Can be adjusted. Specifically, a method of adjusting molecular refraction, which is the sum of atomic refractions of individual groups constituting a polymer folding unit, is known. For example, when a group having a large polarizability such as chlorine or sulfur is introduced. Since atomic refraction increases, molecular refraction can be increased. Further, even when a double bond group or an aromatic ring group is introduced to lower the symmetry of the molecule, the polarizability increases and the atomic refraction increases, so that the molecular refraction can be increased. In addition, when adjusting the molecular volume (molecular weight / density), for example, the density may be adjusted. In this case, for example, the density can be increased by reducing the molecular weight between cross-linking points. For example, since fluorine has a larger volume than the polarizability, the density can be increased also by introducing a group containing fluorine.

  First, the manufacturing method of the optical transmission module in Embodiment 1 and Embodiment 2 of this invention is demonstrated. Embodiment 1 of the present invention shows an example using a rectilinear self-forming optical waveguide by unidirectional incidence, and Embodiment 2 of the present invention uses an end-face connected self-forming optical waveguide by bidirectional incidence. Show.

  1A to 1C are schematic views for explaining an example of a method for manufacturing an optical transmission module according to the first embodiment of the present invention.

  As shown to FIG. 1A, the 1st optical device (optical fiber) 1 and the 2nd optical device (optical fiber) 2 are arrange | positioned, and the curable composition 3 is arrange | positioned between optical devices. Specifically, the first optical device (optical fiber) 1 and the second light are arranged so that the end faces of the first optical device (optical fiber) 1 and the second optical device (optical fiber) 2 face each other. A device (optical fiber) 2 is arranged. Furthermore, the emitted light 4 is transmitted through the curable composition 3 from the first optical device side by a light irradiation means (not shown). At this time, the distance between the end faces facing different optical devices is not particularly limited, but it is necessary to consider the composition of the curable composition, the intensity of the emitted light, and the like. In the first embodiment of the present invention, since the straight type self-forming optical waveguide is used, the optical axes 5 in different optical devices must be matched.

  The light irradiation means is not particularly limited as long as it is a means capable of irradiating light from one end of the optical device toward one end of the other optical device and curing the curable composition. The means for irradiating light capable of curing the curable composition may be appropriately selected in consideration of the composition of the curable composition, for example, a composition having photosensitivity in the near infrared region. For example, a means for irradiating light having a wavelength in the ultraviolet region may be provided. For example, a semiconductor laser or the like can be used as means for irradiating light having a wavelength in the near infrared region. A metal halide lamp, a xenon lamp, a laser, or the like can also be used. Examples of the light-emitting element that can be used as the light irradiation means include DFB-LD (distributed feedback type-semiconductor laser), LED (light-emitting diode), and the like. Moreover, as a method of making light incident on the first optical device 1 using the light irradiating means, light is incident on an end surface of the first optical device 1 that does not face the second optical device 2. If possible, the method is not limited to a method in which light is directly incident on an end surface of the first optical device 1 that does not face the end surface of the second optical device 2. It is also possible to use a method via a reflective optical device such as a guide, a method via a transmissive optical device such as a lens or a slit, or the like.

  As shown in FIG. 1B, by introducing the outgoing light 4 into the curable composition 3, only the portion with high light intensity in the light irradiated portion is photocured, and the core portion is formed along the optical axis 5. 6 can be formed.

  In the method for manufacturing an optical transmission module of the present invention, an optical waveguide including a core portion 6 and an uncured cladding portion 7 that is a residue of the curable composition 3 is manufactured as an optical connection portion for connecting different optical devices. be able to. However, the uncured clad portion 7 is usually a liquid, and in this state, the core portion 6 tends to flow and is very unstable as an optical waveguide. Therefore, it is desirable to form the solid clad part 7 by forming the core part 6 and then subjecting the uncured clad part 7 to a curing process. Therefore, after forming the core portion 6, the entire system can be solidified by irradiating light to the uncured cladding portion 7.

  However, when a curable composition containing only one type of photosensitive resin is used, the core 6 and the clad 7 have substantially the same refractive index due to the curing of the clad 7. Since the light cannot be confined in the core 6, it does not function as an optical waveguide. That is, a resin for forming the clad portion 6 is mixed in advance in the curable composition for forming the core portion 6. Here, as the resin for the cladding part, a resin having a photoreaction mechanism different from that for the core part may be selected. For example, the resin for the core part is selected to react by radical photopolymerization, and the resin for the clad part is selected from cationic photopolymerization. In general photopolymerization, a small amount of initiator necessary for photopolymerization is added. However, radical photopolymerization in which the reaction mechanism is performed by radicals reacts with light in a longer wavelength band than ionic cationic photopolymerization. There are possible initiators. In other words, the core portion and the cladding portion can be selectively synthesized by performing light irradiation in the long wavelength region when forming the core portion and performing light irradiation in the short wavelength region when forming the cladding portion.

  Further, a material whose refractive index before and after curing is smaller than the refractive index of the core part is selected. By selecting such a material and changing the light irradiation means, the resin for core formation can selectively start polymerization. Among the curable compositions containing the core forming resin and the clad forming resin, when the core forming resin starts to be polymerized, the uncured clad forming resin maintains its fluidity and thus hardens. It will be removed from the core forming resin. In addition, since the refractive index of the core portion is larger than the refractive index of the uncured clad forming resin, the light irradiated through the optical wiring is concentrated on the tip while being confined in the formed core portion. . As a result, the light irradiated from one end of the optical device preferentially cures the core forming resin according to the light path, and forms the core portion according to the light path, and the surroundings are uncured. The curable composition is surrounded.

  In addition, instead of the curable composition having the above-described characteristics, a resin composition in which polymerization proceeds only by performing heat treatment is selected as the clad forming resin, and the core is irradiated with light in a long wavelength region. After forming the part, instead of the method of irradiating the entire uncured curable composition with light irradiation in the short wavelength region, a stable clad part is formed using a method of heat curing the uncured resin, It may be an optical waveguide. In addition, when using what contains 2 or more types of curable compositions (for example, resin for core formation, and resin for clad formation), the mixing ratio is not specifically limited. By using such a manufacturing method, it is possible to form an optical waveguide that is excellent in connectivity with the optical wiring and is solidified and excellent in stability.

  As shown in FIG. 1C, when the light irradiation unit is continued, the core portion 6 is formed along the optical axis 5 up to the end surface of the second optical device 2, and the optical connection portion can be manufactured.

  2A to 2C are schematic views for explaining an example of a method of manufacturing an optical transmission module according to the second embodiment of the present invention. Since the optical device used for optical connection and the curable composition are not different from the first embodiment, only differences from the first embodiment will be described.

  As shown in FIG. 2A, the optical axis 5 of the first optical device 1 and the optical axis 8 of the second optical device 2 do not coincide as shown in FIG. 1A. Further, light is incident from both end faces of different devices 1 and 2. That is, in the second embodiment of the present invention, the emitted light 4 from the first optical device side and the emitted light 9 from the second optical device side are incident on the photocurable resin 3.

  As shown in FIG. 2B, since light is incident from both end faces of different devices, the optical connecting portion core section 6 is simultaneously formed from the both end faces toward the central portion of the photocurable resin. However, unlike FIG. 1B, the self-forming optical waveguide does not grow linearly in the direction along the optical axis, and the emitted light 4 from the first optical device side and the emitted light from the second optical device side An optical waveguide is formed in a region where the intensity of the light 9 overlaps is high.

  As shown in FIG. 2C, when the light irradiation is continued, the curved core portion 6 is formed so as to connect the end face of the first optical device 1 and the end face of the second optical device 2, and the optical connecting portion is Can be manufactured.

  FIG. 3 is a schematic diagram for explaining a conventional optical transmission module, and shows an example in which a connecting optical fiber 10 is inserted into an optical connecting portion. Since the refractive index is different between the optical fiber material and air, reflection occurs at the end face. Therefore, end face reflection can be suppressed by using the refractive index adjusting optical adhesive 11 that matches the refractive index of each optical device and the connecting optical fiber 10. In Embodiments 1 and 2 of the present invention and the conventional example, the materials constituting the optical transmission module are substantially the same, but in FIG. 1C, which is Embodiment 1 of the present invention, and Embodiment 2 of the present invention. In FIG. 2C, the end face of the optical device is directly connected to the core part of the optical connecting part, whereas in FIG. 3 showing the conventional example, the connecting optical fiber 10 corresponding to the optical connecting part is separated from the end face of the optical device. They are connected only via the refractive index adjusting optical adhesive 11.

  FIG. 4 is a diagram showing the configuration of the optical transmission module according to the first and second embodiments of the present invention. In the first and second embodiments of the present invention, although there is a slight optical axis misalignment between optical devices and a difference in light incident method (one-way incidence or two-way incidence), the configuration of the optical transmission module There is almost no difference. The optical transmission module of the present invention includes a first optical device (optical fiber) 402 and a second optical device (optical fiber) 403 that form a pair of optical devices on an optical device holding unit 401 having a V-groove. Each of the end faces is positioned and arranged so as to face each other. Between the optical devices, an optical connecting portion 406 having a core portion 404 formed by the method of the present invention and a cladding portion 405 made of a material having a refractive index smaller than that of the core portion is formed. The aperture changes in the optical axis direction. Note that the change in the optical axis direction of the diameter of the core portion, which is a feature of the present invention, is different between the first and second embodiments of the present invention, and will be described in detail in Example 1 below. In this embodiment, a semiconductor laser (LD) is used as the near infrared light emitting element. Many semiconductor lasers are used in the field of optical discs, and are extremely excellent in wavelength selectivity, size, and cost.

  In Embodiment 1 and Embodiment 2 of the present invention, one end of a different optical fiber is immersed in the curable composition, and a straight-advance self-forming optical waveguide by one-way incidence or a double-sided connection self-forming optical waveguide by two-way incidence In this case, instead of the first optical fiber, an optical component such as a light emitting element is used, and the light emitting surface is immersed in the curable composition, or the light emitting surface is curable. By applying the composition, a core part directly attached to the light emitting surface of the optical component can be formed. In this case, as described above, the light-emitting element needs to emit light that can cure the curable composition. Further, instead of the second optical fiber, using an optical component such as a light receiving element, immersing the light receiving surface in the curable composition, or applying the curable composition to the light receiving surface, A core portion directly attached to the light receiving surface of the optical component can be formed. Furthermore, in place of different optical fibers, by using a light emitting element that emits light that can cure the curable composition, and a light receiving element, the light emitting surface of the light emitting element and the light receiving surface of another optical component It is also possible to form a core part connecting the two.

  As described above, various types of optical devices can be used in the present invention, and the optical transmission module in which the core portion is formed as the optical connection portion does not require alignment between the optical devices constituting the optical transmission module.

  Then, the manufacturing method of the optical transmission module in Embodiment 3 of this invention is demonstrated. Embodiment 3 of the present invention shows an example in which a reflection means is provided in an optical device so that a double-sided surface connection type self-forming optical waveguide can be configured even when incident in one direction.

  5A to 5D are schematic views for explaining an example of a method for manufacturing an optical transmission module according to the third embodiment of the present invention. In the present embodiment, a two-wavelength laser module is used as a light irradiation unit that can irradiate light of the first wavelength and light of the second wavelength, and light of only the first wavelength in the optical device end face or the optical device. An optical fiber grating was used as the reflecting means. Since these two-wavelength laser module and optical fiber grating serve as the first optical device and the second optical device, respectively, it is not necessary to remove the reflecting means or replace the irradiating means. Miniaturization can be realized.

  As shown in FIG. 5A, a first optical device (dual wavelength laser module) 502 and a second optical device (a set of optical devices) are formed on an optical device holding unit 501 in which V grooves and irregularities are engraved. Optical fibers) 503 are arranged so that the respective end faces thereof are substantially opposed to each other. The first optical device (dual wavelength laser module) 502 is a light emitting element including light irradiation means for irradiating light having a first wavelength and a second wavelength. The dual wavelength laser module is used in a CD / DVD compatible optical disk drive apparatus in the field of optical disks. Optical discs such as CDs and DVDs are recorded and reproduced with light of different wavelengths, and in such optical disc compatible drives, adopting different optical systems at two different wavelengths increases the size of the optical disc drive and increases the number of parts. I will invite you. Thus, a dual wavelength laser module has been put to practical use as an optical device that can use a common optical system even at different wavelengths.

  In the second optical device (optical fiber) 503, an optical fiber grating 504 is formed as light reflecting means capable of reflecting only light of the first wavelength. Between these different optical devices, the aforementioned photo-curable resin 505 is filled. A fiber grating is an optical device that can reflect only light of a specific wavelength corresponding to the grating interval by forming a diffraction grating called a Bragg grating in the optical axis direction in the optical fiber wiring. These fiber gratings use a chemical reaction in which the refractive index is permanently changed only in the region irradiated with strong UV light on a silica-based optical fiber doped with Ge or the like, and a coherent UV light source with high coherence is used. By forming the interference fringes on the optical fiber, it is possible to manufacture a diffraction grating in which the shade portion of the interference fringes has a refractive index change. A dichroic mirror may be used as the light reflecting means. The dichroic mirror is a dielectric multilayer film that acts as a mirror only at a certain wavelength. For example, a commercially available dielectric multilayer filter such as a filter in which thin films of silica, titania or the like are laminated in multiple layers on a substrate such as quartz glass can be used. Such a dielectric multilayer filter can also be directly formed, for example, by depositing a thin film of silica, titania or the like as a set on the end face of an optical device such as an optical fiber.

  As shown in FIG. 5B, light having a first wavelength is emitted from a first optical device (dual wavelength laser module) 502. As shown in the traveling direction 506 of the light of the first wavelength, the light of the first wavelength is partially transmitted through the photocurable resin 505 and formed in the second optical device (optical fiber) 503. Then, the light is reflected by the optical fiber grating 504 and re-enters the photo-curing resin 505 by changing its direction. That is, bi-directional incidence is realized by the optical fiber grating 504, and the core portion 507 is formed as a double-sided coupled self-forming optical waveguide.

  As shown in FIG. 5C, the residue of the curable composition 505 on which the core part 507 was formed was irradiated with light from an ultraviolet lamp to form a clad part 508. Note that the residue functions as a cladding even in a solution state in which the light of the ultraviolet lamp is not cured.

  As shown in FIG. 5D, when the optical transmission module is used, light having the second wavelength is emitted from the first optical device (dual wavelength laser module) 502. At this time, as shown in the traveling direction 509 of the second wavelength light, the second wavelength light is not reflected by the optical fiber grating 504 formed in the second optical device (optical fiber) 503. Optical transmission is possible.

  FIG. 6 is a diagram showing a configuration of an optical transmission module according to the third embodiment of the present invention. The optical transmission module of the present invention includes a first optical device (two-wavelength laser module) 502 and a second optical device (which are a set of optical devices) on the optical device holding portion 501 in which V grooves and irregularities are engraved. The optical fibers 503 are positioned and arranged so that the end faces of the optical fibers 503 face each other. The first optical device (dual wavelength laser) 502 also serves as light irradiation means that can irradiate the first and second wavelengths. In addition, an optical fiber grating that reflects only light of the first wavelength is formed inside the second optical device (optical fiber) 503. Between the optical devices, an optical connecting portion 510 having a core portion 507 formed by the method of the present invention and a clad portion 508 made of a material having a refractive index smaller than that of the core portion is provided. It changes in the optical axis direction. The change in the optical axis direction of the core portion, which is a feature of the present invention, will be described in detail in Example 2 below.

  As described in the plurality of embodiments of the optical transmission module, the structure of the self-forming optical waveguide (that is, the size of the core portion and the cladding portion) differs depending on the optical transmission module. Therefore, the mixing ratio of the radically polymerizable compound as the component (C) and the polymerizable compound as the component (D) should be approximately equal to the volume ratio of the core part to the cladding part in the region where light irradiation is performed. Is preferred. The region where no light is irradiated is finally the solution removal or the clad part, but considering the mixing ratio up to the clad part in this region, the component (C) constituting the core part may be insufficient at the time of photopolymerization. .

  In the connection between optical fibers in Example 1, when a single mode fiber is used, the component (C) is preferably 0.01 to 10% by volume, particularly preferably 0.1 to 5% by volume with respect to the component (D). Further, when LD connection is performed as in Example 2 or when a multimode fiber having a large core diameter is used, the ratio of the core portion increases, so the component (C) is 0.05 to 50% by volume, particularly 0.5 to 25% by volume is preferred. Although the description is given here in terms of volume%, the above numerical values may be regarded as weight% as long as the densities before the reaction of the polymerization compound of component (C) and component (D) are approximately the same.

  First, the results of examining the compositions and light absorption characteristics of the curable composition 1 and the curable composition 2 used in Example 1 and Example 2 together with Comparative Example 1 will be described. Next, the optical transmission module manufacturing method according to the first and second embodiments will be described, and finally the head cymbal assembly and the information recording apparatus using the optical transmission module manufactured in the first and second embodiments will be described.

  The following components were used for curable composition 1, curable composition 2, and comparative example 1. The curable composition 1, the curable composition 2, and the comparative example 1 differ only in the component (A), and the same component (B), component (C), and component (D) were used. Table 1 shows the composition of each component. Furthermore, about a component (A) and a component (B), a chemical structural formula and the chemical reaction formula at the time of light irradiation are shown below.

Component (A):
[Curable composition 1] Near infrared light absorbing dye "IRT13F" (manufactured by Showa Denko KK, infrared absorbing dye)
[Curable composition 2] Near infrared light absorbing dye "IRT" (manufactured by Showa Denko KK, red / infrared absorbing dye)

[Comparative Example 1] Pigment LIONOL GREEN "6Y-503" (manufactured by Toyo Ink Co., Ltd., red absorbing pigment)
Component (B): Photoradical polymerization initiator “P3B” (manufactured by Showa Denko KK, organoboron compound)
Component (C): radical photopolymerization resin “M-208” (manufactured by Toa Gosei Co., Ltd., phenol-modified acrylate)
Component (D): Cationic photopolymerization resin “2021P” (Daicel, decyclic epoxy)
Cationic photopolymerization initiator “PHOTO INITIATOR2074” (manufactured by RHODORSIL)

<Chemical structural formula: IRT13F>

<Chemical structural formula: IRT>

<Chemical structural formula: 6Y-503>

<Chemical structural formula: P3B>

<Chemical reaction formula>
The organoboron compound that acts as a photoradical polymerization initiator is decomposed by light to form a radical, as shown by the following formula.

  Further, when a cationic dye coexists, electron transfer occurs between dye molecules excited by light absorption of the cationic dye, and radical generation efficiency increases. Therefore, the selection of the cationic dye and the organoboron compound is sensitive in the visible to near-infrared light region, and becomes a radical source with high sensitivity.

  That is, since the curable composition of the present invention contains a combination of a near-infrared absorbing dye as component (A) and a photopolymerization initiator based on an organoboron compound as component (B), the conventional UV Sensitization can be performed with higher sensitivity in a longer wavelength region (visible light region of 400 nm or more) than the initiator. In the following chemical reaction formula, the functional groups R1 to R3 that do not contribute to the chemical reaction in the above formula are not described, and the reactive group R4 that generates a radical at the time of decomposition is expressed as R for convenience.

light
^{D + A - + B - Z} + → D · + R · + B + A - Z +
(In the above formula, D ⁺ A ⁻ represents a near-infrared light absorbing dye, D ⁺ represents a near infrared absorbing dye group, A ⁻ represents various anions, and B ⁻ Z ⁺ represents the initiation of radical photopolymerization. B ^- represents a boron anion complex, Z ⁺ represents various cation complexes, and A ^- Z ⁺ represents various cation-various anion complexes formed after light irradiation.)

At this time, the radical photopolymerization reaction formula is as follows: R · + M → RM ·
RM ・ + M → RMn ・
(In the above formula, M is a monomer, M · is a radical added to the end of the monomer, n is the number of consecutive M (monomer), and RMn · is a radical added to the end of continuous n monomers. Shows the status

In parallel with the above chemical reaction, a decoloring reaction represented by the following chemical formula occurs.
R ・ + D ・ → D−R ・
(In the above formula, R is a reactive group of a photopolymerization initiator, D is a near-infrared absorbing dye group,. Is a photoradical, D-R is a state in which D and R are reactively bonded. External reactivity is lost (discolors))

  FIG. 7 shows the light absorption rate of the curable composition 1, FIG. 8 shows the curable composition 2, and FIG. By combining the infrared light-absorbing dye of the present invention with a radical photopolymerization initiator, decolorization after photopolymerization, that is, the absorption rate can be suppressed to several percent or less at the wavelength of near-infrared light. By using the curable composition 1 and the curable composition 2, an optical transmission module having high transparency at the wavelength of near infrared light shown in Examples 1 and 2 below can be realized.

[Example 1] Production of optical transmission module according to Embodiments 1 and 2 (see FIG. 7)
(1) Using a fiber cutter, two quartz single-mode optical fibers having a length of about 1 m (manufactured by Suruga Seiki Co., Ltd., core diameter: 10 μm) were prepared. Further, the end faces of these two optical fibers were polished.

(2) The emission conditions of the semiconductor laser for forming the self-forming optical waveguide were confirmed. Specifically, light with a wavelength of 780 nm was incident from one end face of the optical fiber using a semiconductor laser, and the light intensity was measured at the end face on the emission side. The light intensity at this time was 1.25 μW. The light intensity measurement was performed using a light intensity meter (ADC230, 8230, sensor unit model number 8314A). Similarly, the light emission conditions of the semiconductor laser in which the light intensity at the end face on the emission side is 0.1 μW were also confirmed by the method in order to evaluate the connection loss.

(3) Next, an optical fiber V-groove substrate (Mortex Co., Ltd., quartz V-groove) is disposed so that the gap (hereinafter referred to as a gap) between the two end faces of the two optical fibers is 100 μm. did.

(4) Light with a wavelength of 405 nm for connection loss evaluation confirmed in (2) and a light intensity of 0.1 μW at the end face on the emission side was incident on the end face of the optical fiber that was not attached. At this time, when the optical output emitted from the other optical fiber entrance end that was not attached was measured using a light intensity meter, the loss of optical output of 4 dB was measured.

(5) The curable composition 1 was filled in the entire attached portion where the optical fiber was disposed in (3). Thereafter, the curable composition and the optical fiber were sandwiched so as not to move on the V-groove in such a manner that the filling portion was covered with transparent glass as a V-groove pressing plate.

(6) When the connection loss was measured in the same manner as (4) with the curable composition filled, a loss of light output of 2.8 dB was measured. At this point, when the curable composition was observed using a microscope (VH-7000 manufactured by Keyence Corporation), no optical waveguide was formed.

(7) An optical transmission module was manufactured by the method of the first embodiment. Light having a wavelength of 780 nm for forming a self-formed optical waveguide confirmed in (2) and a light intensity of 1.25 μW at the end face on the exit side was incident on an end face of one optical fiber that was not attached to each other for 30 seconds. . Thereafter, the entire curable composition was cured by irradiating with a high-pressure mercury lamp having an illuminance of 70 mW / cm ² for 90 seconds. When the connection loss was measured in the same manner as in (4), a 1.6 dB optical output loss was measured. At this point, when the photocured composition was observed using a microscope (VH-7000 manufactured by Keyence Corporation), the diameter of the core portion was 10.0 μm at the incident side end face and gradually 11.2 μm at the output side end face. A tapered optical waveguide with a large aperture was formed.

(8) Next, an optical transmission module was manufactured by the method of Embodiment 2. Steps (1) to (6) are not changed at all, and the end face where both optical fibers are not attached to each other is formed with a wavelength of 780 nm for self-forming optical waveguide formation confirmed in (2) above, and the end face on the emission side Light having an optical intensity of 1.25 μW was incident for 30 seconds. Thereafter, the entire curable composition was cured by irradiating with a high-pressure mercury lamp having an illuminance of 70 mW / cm ² for 90 seconds. When the connection loss was measured in the same manner as in (4) above, a loss of 1.2 dB optical output was measured. At this time, when the photocurable composition was observed using a microscope (VH-7000 manufactured by Keyence Corporation), the diameter of the core portion was 10.0 μm at both end faces, and the diameter was 10.8 μm at the center portion. The largest optical waveguide was formed.

  According to the first embodiment, the 2.8 dB coupling loss of the optical transmission module before the formation of the self-forming optical waveguide shown in the above (6) is reduced to 1 in the optical transmission module according to the first embodiment as shown in the above (7). The optical transmission module according to Embodiment 2 can be improved to 1.2 dB as shown in (8) above. Further, the diameter of the core portion of the optical connecting portion in the first and second embodiments is different from that in the case of using the connecting optical fiber as in the conventional example, so that it varies depending on the embodiment from 10.0 μm to 11.2 μm. Had changed.

[Example 2] Production of optical transmission module according to Embodiment 3 (see FIG. 8)
(1) Using a fiber cutter, a quartz single mode mode optical fiber (core diameter: 10 μm) having a length of about 1 m on which a fiber grating that reflects 95% of light having a wavelength of 661 nm as a first wavelength was formed was prepared. . In addition, the reflectance of 785 nm light used as the second wavelength is 5% or less. The fiber grating was fabricated by irradiating the optical fiber core with interference fringes using an ion excimer laser as a vacuum ultraviolet coherent light source.

(2) The light emission conditions of the two-wavelength laser module for forming the self-forming optical waveguide were confirmed. Specifically, light intensity measurement with an emission power of 661 nm wavelength was performed from one end face of the optical fiber using a two-wavelength laser module. The light intensity at this time was 50 mW. The light intensity measurement was performed using a light intensity meter (ADC230, 8230, sensor unit model number 8314A). Further, in the same way, in order to evaluate the connection loss, the light emission condition of the two-wavelength laser module in which the light intensity as the emission power at the wavelength of 785 nm is 1 mW was also confirmed. Unlike Example 1, the order of light intensity in Example 2 was as large as mW because Example 1 shows light intensity including coupling loss emitted from the other end face after fiber coupling. is there.

(3) A gap between a two-wavelength laser module (LNCT16PF manufactured by Panasonic Corporation) that can emit light having a wavelength of 661 nm as the first wavelength and light having a wavelength of 785 nm as the second wavelength, and the above-described optical fiber on which the fiber grating is formed. The Si substrate was fixed on the Si substrate with the V-grooves and irregularities on the holder substrate (see FIG. 5A).

(4) Light having a connection loss confirmed in (2) having an evaluation wavelength of 785 nm and an output power intensity of 1 mW was incident on the end face of the optical fiber attached using the two-wavelength laser module. At this time, when the optical output emitted from the other optical fiber exit end that was not attached was measured using a light intensity meter, a loss of optical output of 6 dB was measured.

(5) The curable composition 2 was filled in the entire abutting portion where the two-wavelength laser module and the optical fiber were disposed in (3). Thereafter, the curable composition and both optical devices were sandwiched so as not to move in a form in which the filling portion was covered with transparent glass as a V-groove and an uneven pressing plate.

(6) When the connection loss was measured in the same manner as (4) with the curable composition filled, a loss of light output of 4.8 dB was measured. At this point, when the curable composition was observed using a microscope (VH-7000 manufactured by Keyence Corporation), no optical waveguide was formed.

(7) Light having a wavelength of 661 nm for forming the self-formed optical waveguide confirmed in the above (2) and a light intensity of 50 mW at the end face on the emission side was incident on the end face of the optical fiber thus attached for 30 seconds. Thereafter, the entire curable composition was cured by irradiating with a high-pressure mercury lamp having an illuminance of 70 mW / cm ² for 90 seconds. When the connection loss was measured in the same manner as in (4) above, a loss of optical output of 2.1 dB was measured. At this point, when the photocured composition was observed using a microscope (VH-7000 manufactured by Keyence Corporation), the core diameter of the optical connection portion, which was approximately 0 μm at the emission point of the two-wavelength laser module, was the end point of the optical connection portion. An optical waveguide having a diameter gradually increasing to 10 μm was formed at the end face on the optical fiber input side.

  According to Example 2, the 4.8 dB coupling loss of the optical transmission module before forming the self-forming optical waveguide shown in (6) above is reduced to 2 by the optical transmission module according to Embodiment 3 as shown in (7) above. It was improved to 1 dB. Moreover, it confirmed that the aperture of the core part of the optical connection part in Embodiment 3 was changing from 0 micrometer to 10.0 micrometers.

  FIG. 10A to FIG. 10C show an HGA (Head Gimbal Assembly) unit mounted on the heat-assisted magnetic recording apparatus. In this specification, the HGA is referred to as a head gimbal assembly. FIG. 10A is a view of the flying slider 1001 using the optical waveguide connecting part manufactured by the method of Example 1 as viewed from the air bearing surface side, and FIG. 10B uses the light source module manufactured by the method of Example 2 in addition to that. FIG. 10C is a side view of the flying slider 1001 that is a common part of the first embodiment and the second embodiment. FIG.

  The base part of the waveguide coupler of the present invention was fixed to the flexure part 1005 of the suspension 1004. The waveguide 1003 passes through the center of the suspension 1004 in the width direction. At this time, if the position of the waveguide 1003 is shifted from the center of the suspension 1004, a force that rotates in the direction parallel to the recording medium surface is applied to the flying slider 1001. In order to prevent this force, it is preferable that the waveguide 1003 is always located at the center of the suspension 1004. Therefore, in this embodiment, light is guided to the center of the suspension 1004 by passing the plurality of waveguides 1003 through the optical waveguide connection portion 1006.

  Note that the waveguide 1003 is preferably disposed so as to be horizontal to the surface of the recording medium 1002. That is, the distance L2 from the surface of the recording medium 1002 to the waveguide 1003 is always constant. This is because, when the waveguide 1003 is arranged to be inclined with respect to the surface of the recording medium 1002, a force having a component in a direction perpendicular to the surface of the recording medium 1002 is applied from the waveguide 1003 to the flying slider 1001. This is because levitation becomes unstable. In order to arrange the waveguide 1003 in this way, the distance from the suspension 1004 to the surface of the recording medium 1002 is L1, and the waveguide 1003 from the surface of the recording medium 1002 when arranged so as to be horizontal to the surface of the recording medium 1002. The distance L3 from the suspension 1004 to the center of the optical waveguide connector 1006 is preferably L3 = L1−L2, where L2 is the distance to the center of the optical fiber. In this example, L1 = 0.5 mm and L2 = 0.3 m, so that L3 = 0.2 mm.

  In Example 1, a semiconductor laser 1007 was used as a light source, and this semiconductor laser 1007 was placed on an arm 1008 as shown in FIG. 10A. A coupling lens 1009 is disposed between the semiconductor laser 1007 and the waveguide 1003, and light from the semiconductor laser 1007 is coupled to the waveguide 1003. The semiconductor laser 1007 and the coupling lens 1009 are formed in a thin package 1010. In this embodiment, the semiconductor laser is disposed on the arm 1008, but may be disposed on the suspension 1004.

  In the second embodiment shown in FIG. 10B, the light source module 1011 in which the two-wavelength semiconductor laser is directly connected to the optical waveguide by the self-forming optical waveguide is used as the light source unit, and other configurations are the same as the first embodiment. By using the light source unit 1011, the coupling lens 1009 is not necessary, so that the optical transmission module can be further reduced in size.

  FIG. 11 shows an overall view of a heat-assisted magnetic recording apparatus using the head gimbal assembly of the present invention. The flying slider 1001 was fixed to the suspension 1004 and positioned at a desired track position on the magnetic disk 1013 by an actuator including a voice coil motor 1012. A flying pad was formed on the head surface and floated on the magnetic disk 1013 with a flying height of 10 nm or less. The recording disk 1013 was fixed and rotated on a spindle 1014 that was rotationally driven by a motor. The semiconductor laser 1007 was fixed on the submount with solder, and then the submount was placed at the base of the arm to which the suspension was attached (the part called e-block). The driver of the semiconductor laser 1007 is arranged on a circuit board arranged beside the e-block. The circuit board was also equipped with a driver for the magnetic head. The submount on which the semiconductor laser 1007 is mounted may be disposed directly on the e-block or may be disposed on the driver circuit board. The light emitted from the semiconductor laser 1007 is coupled to the waveguide 1003 by directly joining the waveguide 1003 to the semiconductor laser or by inserting a lens between the waveguide 1003 and the semiconductor laser. At this time, the waveguide 1003, the semiconductor laser 1007, and the elements and components for coupling the waveguide 1003 may be integrated as a module and disposed on the e-block or a circuit board next to the e-block. . Further, in order to extend the life of the semiconductor laser 1007, the inside of the module may be hermetically sealed.

  The recording signal was generated by the signal processing LSI 1015, and the recording signal and the power for the semiconductor laser were supplied to the driver for the semiconductor laser through an FPC (flexible printed circuit). At the moment of recording, a magnetic field was generated by a coil provided in the flying slider 1001, and at the same time, a semiconductor laser was emitted to form a recording mark. Data recorded on the magnetic disk 1013 was reproduced by a magnetic reproducing element (GMR or TMR element) formed in the flying slider 1001. The signal processing of the reproduction signal was performed by a signal processing circuit.

  In this embodiment, the GMR or TMR element is used to reproduce the recorded information. However, the information may be reproduced using light. By detecting the rotation of the polarization of the return light from the recording bit, the magnetization direction of the recording bit can be detected.

1 First optical device (optical fiber)
2 Second optical device (optical fiber)
3 Curable composition 4 Emission light 5 (from the first optical device side) (first optical device or common to first and second optical devices) Optical axis 6 (optical connection portion) Core portion 7 (optical connection) Part) cladding part 8 (second optical device) optical axis 9 outgoing light 10 (from the first optical device side) connecting optical fiber 11 refractive index adjusting optical adhesive 401 optical device holding part 402 first light Device (optical fiber)
403 Second optical device (optical fiber)
404 Core unit 405 Clad unit 406 Optical connection unit 501 Optical device holding unit 502 First optical device (dual wavelength laser module)
503 Second optical device (optical fiber)
504 Reflection means (optical fiber grating)
505 Photo-curing resin 506 First light traveling direction 507 Core portion 508 Cladding portion 509 Second light traveling direction 510 Optical connecting portion 1001 Flying slider 1002 Recording medium 1003 Conduction connecting semiconductor laser and flying slider Waveguide 1004 Suspension 1005 (Suspension) flexure section 1006 Optical waveguide connection section 1007 Semiconductor laser 1008 Arm 1009 Light source coupling lens 1010 Thin package 1011 Light source module 1012 Voice coil motor 1013 Magnetic disk 1014 Spindle 1015 Signal processing LSI

Claims (11)

Light having a set of optical devices, an optical device holding portion having a groove that can position each end face of the set of optical devices so as to face each other, and an optical connection portion that optically connects the set of optical devices. A transmission module,
The optical connection part has a core part composed of an axial photocuring composition, and a clad part having a refractive index smaller than that of the core part arranged outside the core part,
By using the component (A) in combination with the component (A), a near-infrared light-absorbing dye that discolors the component (A) by irradiation with near-infrared light of 600 nm or more and 900 nm or less. A photo-radical polymerization initiator having a photosensitive wavelength below, the component (C) reacts with the radical generated by the component (B), and a cured product can be formed by irradiation with near infrared light of 600 nm or more and 900 nm or less. When the radical polymerizable compound, component (D) is a polymerizable compound capable of producing a cured product having a smaller refractive index than the cured product of component (C),
The optical transmission module, wherein the core part is formed mainly of the component (C), and the cladding part is formed mainly of the component (D).   2. The optical transmission module according to claim 1, wherein the set of optical devices is selected from a lens, an optical waveguide, an optical fiber, a semiconductor laser, a light emitting diode, a photodiode, a hologram, a prism, a mirror, a pinhole, a slit, and a grating. An optical transmission module comprising the same or different optical devices.   2. The optical transmission module according to claim 1, wherein a lens, an optical waveguide, an optical fiber, a hologram, a prism, a mirror, a pinhole, or a slit is disposed in the light passage region. An uncured curable composition is disposed between the end faces of a pair of optical devices facing each other, and the curable composition is irradiated with light through the optical device, whereby the curable composition is irradiated with light. A method for producing an optical transmission module, wherein an optical connection part is formed between the set of optical devices by changing into a cured composition,
Positioning the set of optical devices such that one end face of each of the set of optical devices substantially faces in the optical axis direction;
By using in combination with a near-infrared light-absorbing dye that can be resolved by irradiation with near-infrared light of 600 nm or more and 900 nm or less and the near-infrared light-absorbing dye, the photosensitive wavelength is 600 nm or more and 900 nm or less. A radically polymerizable compound capable of reacting with a radical generated by the radical photopolymerization initiator and a radical generated by the radical photopolymerization initiator to form a cured product upon irradiation with near infrared light of 600 nm or more and 900 nm or less, and the radical polymerization An uncured curable composition comprising a polymerizable compound capable of producing a cured product having a smaller refractive index than a cured product of the curable compound is disposed between the facing end faces of the set of optical devices. And a process of
The uncured curable composition is irradiated with light having a wavelength of 600 nm or more and 900 nm or less through one of the set of optical devices, and an axis is formed between the facing end faces of the set of optical devices. Forming a core part made of a photo-curing composition in the form of producing the optical connection part,
A method of manufacturing an optical transmission module, comprising: An uncured curable composition is disposed between the end faces of a pair of optical devices facing each other, and the curable composition is irradiated with light through the optical device, whereby the curable composition is irradiated with light. A method for producing an optical transmission module, wherein an optical connection part is formed between the set of optical devices by changing into a cured composition,
Positioning the set of optical devices such that one end face of each of the set of optical devices substantially faces in the optical axis direction;
By using in combination with a near-infrared light-absorbing dye that can be resolved by irradiation with near-infrared light of 600 nm or more and 900 nm or less and the near-infrared light-absorbing dye, the photosensitive wavelength is 600 nm or more and 900 nm or less. A radically polymerizable compound capable of reacting with a radical generated by the radical photopolymerization initiator and a radical generated by the radical photopolymerization initiator to form a cured product upon irradiation with near infrared light of 600 nm or more and 900 nm or less, and the radical polymerization An uncured curable composition comprising a polymerizable compound capable of producing a cured product having a smaller refractive index than a cured product of the curable compound is disposed between the facing end faces of the set of optical devices. And a process of
The uncured curable composition is irradiated with light having a wavelength of 600 nm or more and 900 nm or less through both of the pair of optical devices, and an axis is formed between the facing end faces of the pair of optical devices. Forming a core part made of a photo-curing composition in the form of producing the optical connection part,
A method of manufacturing an optical transmission module, comprising: An uncured curable composition is disposed between the end faces of a pair of optical devices facing each other, and the curable composition is irradiated with light through the optical device, whereby the curable composition is irradiated with light. A method for producing an optical transmission module used for transmission of light having a first wavelength of 600 nm or more and 900 nm or less, wherein the optical connection is formed between the set of optical devices by changing to a cured composition,
Providing a light irradiating means capable of irradiating light having the first wavelength and light having a second wavelength of not less than 600 nm and not more than 900 nm different from the first wavelength in one of the light devices on the light irradiation side; ,
Providing the other optical device with reflecting means for mainly reflecting the second wavelength;
Positioning the set of optical devices such that one end face of each of the set of optical devices substantially faces in the optical axis direction;
A radical photopolymerization having a photosensitive wavelength at the second wavelength when used in combination with the near-infrared light-absorbing dye and the near-infrared light-absorbing dye, which are resolved by irradiation with light of the second wavelength. An initiator, a radical polymerizable compound capable of reacting with radicals generated by the photo radical polymerization initiator to form a cured product upon irradiation with light of the second wavelength, and a cured product of the radical polymerizable compound Placing an uncured curable composition comprising a polymerizable compound capable of producing a cured product having a small refractive index between the opposed end faces of the set of optical devices;
The second optical device is irradiated with light of the second wavelength from the one optical device via the uncured curable composition, and the light irradiation from the one optical device and the other optical device are irradiated. By irradiating light to the uncured curable composition by reflected light, a core portion made of an axial photocured composition is formed between the facing end surfaces of the pair of optical devices, A step of manufacturing an optical connection part;
A method of manufacturing an optical transmission module, comprising:   7. The method of manufacturing an optical transmission module according to claim 6, wherein the light irradiation means is a two-wavelength laser module.   7. The method of manufacturing an optical transmission module according to claim 6, wherein the reflecting means is a fiber grating formed inside the other optical device.   7. The method of manufacturing an optical transmission module according to claim 6, wherein the reflecting means is a dichroic mirror formed inside or on an end face of the other optical device. 10. The method of manufacturing an optical transmission module according to claim 4, wherein the near-infrared light absorbing dye has a general formula D ⁺ A ⁻ (where D ⁺ is an arbitrary light up to near-infrared light). shows a cation having an absorption in the wavelength region, a ^- near-infrared light absorbing cationic dye represented by showing a variety of anions) - a method of manufacturing an optical transmission module, wherein it is various anionic complex . In the manufacturing method of the optical transmission module of any one of Claims 4-9, the said radical photopolymerization initiator is various cation complexes-boron anion complex shown by the following general formula, It is characterized by the above-mentioned. Manufacturing method of optical transmission module.
Wherein R1, R2, R3 and R4 are independently alkyl, aryl, aralkyl, alkenyl, alicyclic group, heterocyclic group and silyl or substituted alkyl, substituted aryl, substituted aralkyl, substituted alkenyl and substituted heterocyclic group. , Substituted alicyclic group and substituted silyl, wherein at least one of R1, R2, R3 and R4 is an alkyl group having 1 to 8 carbon atoms, and Z ⁺ represents various cationic complexes)