JPH08304639A - Optical transmission system - Google Patents

Abstract

PURPOSE: To obtain high transmission range over a wide wavelength region in one plastic optical fiber by using a refractive index distribution type optical fiber consisting of a noncrystalline fluorine-contg. polymer matrix having no C-H bonds. CONSTITUTION: A refractive index distribution type optical fiber obtd. by distributing a material (b) which gives the distribution of refractive index of a matrix in a noncrystalline fluorine-contg. polymer (fluorine-contg. polymer (a)) having substantially no C-H bonds is used as an optical fiber. As for the fluorine-contg. polymer (a), a fluorine-contg. polymer having a cyclic structure in the main chain is preferable, and a fluorine-contg. polymer having a fluorine-contg. alicyclic structure or fluorine-contg. imide ring structure is preferable. The material (b) has a refractive index different by >=0.001 from that of the fluorine-contg. polymer (a), and it may have a higher or lower refractive index. Usually, a material having a higher refractive index is used for an optical fiber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission system using a graded index optical fiber having a low transmission loss and a high transmission band, which is excellent in heat resistance, flame retardancy and solvent resistance.

[0002]

2. Description of the Related Art As an optical fiber, an inorganic glass-based optical fiber having an excellent light transmission property over a wide wavelength range is known. However, it is not only poor in workability and weak in bending stress, but also expensive, so that a plastic is used. An optical fiber as a base material has been developed and put into practical use. This plastic optical fiber consists of a core layer based on a polymer such as polymethylmethacrylate, polycarbonate, polystyrene, etc., which has a good light transmittance, and a polymer such as a fluoropolymer which has a smaller refractive index and is substantially transparent. Is used as a basic constituent unit. Further, JP-A-2-244007 proposes using a fluorine-containing resin for the core and the clad.

As an optical fiber, a graded index type (GI type) optical fiber is known as well as a graded index optical fiber consisting of a core and a clad. The refractive index distribution of a gradient index optical fiber is one in which the refractive index decreases from the center in the radial direction in a curve close to a parabola (for details, see the following document). Examples of gradient index plastic optical fibers include, for example, “Chemicals and Industry”, No. 4
Volume 5 No. 7 (1992) 1261-1264, JP-A-5
-173026, WO94 / 04949, WO9
4/15005 and the like are known.

As the product form of these optical fibers (optical fiber strands), an optical fiber cable in which the optical fiber strands are covered with a coating material, a bundle fiber in which the optical fiber cords are bundled, a bundle fiber or the like is combined with a tension member, etc. And so on.

[0005]

As described above, the plastic optical fiber has a characteristic that the inorganic glass-based optical fiber does not have, but the conventional refractive index stepped plastic optical fiber has a narrow transmission band. A graded-index plastic optical fiber, which is the main component, has a large transmission loss in the near-infrared light, and thus no practical optical fiber has been obtained as a communication optical fiber.

The present invention is based on polymethylmethacrylate,
It has mechanical strength, heat resistance, moisture resistance, chemical resistance, and incombustibility required for automobiles, office automation (OA), home appliances, etc. that could not be achieved with polystyrene-based or polycarbonate-based optical transmission materials. In addition, visible light (500 to 700) that cannot be achieved by an acrylic, polycarbonate, norbornene, or other optical transmission material.
(nm) and near-infrared light (700 to 1600 nm) can be used. Furthermore, it has low optical transmission loss in a wide range of transmission area and enables wavelength division multiplexing transmission using gradient index plastic optical fiber with high transmission band. The present invention aims to provide a new optical transmission system.

[0007]

Means for Solving the Problems As a result of intensive studies based on the recognition of the above problems, the present inventor has imparted heat resistance, moisture resistance, chemical resistance and nonflammability, and has a near infrared light. In order to eliminate the C—H bond (that is, carbon-hydrogen bond) in which light absorption occurs, a fluoropolymer in which the C—H bond is converted to a C—F bond (that is, carbon-fluorine bond) is optimal. I got the knowledge that there is.

In the case of a graded index optical fiber,
Multi-mode light propagates while being reflected at the interface between the core and the clad, so that mode dispersion occurs and the transmission band decreases. However, in the graded index optical fiber, mode dispersion hardly occurs and the transmission band increases. Therefore, C-
By incorporating a refractive index distribution type optical fiber into an optical transmission system using a matrix of an amorphous fluorine-containing polymer having no H-bond, it has low transmission loss and high transmission band and enables wavelength division multiplexing transmission. The present invention has been accomplished by finding that an optical transmission system for

That is, the present invention is the following (1) to (4).

(1) In an optical transmission system comprising a light source, an optical fiber which is an optical transmission section from the light source, and a photodetector, the optical fiber comprises an amorphous fluorine-containing polymer having substantially no C--H bond. An optical transmission system, which is a gradient index optical fiber used as a matrix.

(2) The optical transmission system as described in (1) above, wherein the non-crystalline fluoropolymer is a fluoropolymer having a ring structure in its main chain.

(3) The optical transmission system according to (1), wherein the fluoropolymer having a ring structure in the main chain has a repeating unit selected from the following (I) to (IV).

[0013]

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[In the above formulas (I) to (IV), 1 is 0 to 5, m is 0 to 4, n is 0 to 1, and l + m + n is 1 to
6, o, p and q are 0 to 5, respectively, and o + p + q is 1 to
6, R ³ and R ⁴ are F or CF ₃ , R ⁵ is F or CF ₃ ,
R ⁶ is F or CF ₃ , X ¹ is F or Cl, and X ² is F or Cl. (4) The above (1) characterized by performing wavelength division multiplexing transmission
The optical transmission system described.

Since the optical fiber in the optical transmission system of the present invention does not scatter light because the matrix is an amorphous resin and has high transparency in a wide wavelength band from visible light to near infrared light, it has various wavelengths. It can be effectively used for optical systems. Especially, it is the wavelength used for trunk quartz single-mode optical fiber in the communication field.
An optical fiber having a low loss at 300 nm and 1550 nm is provided, and an optical transmission system capable of wavelength division multiplexing transmission is provided by utilizing the low loss in the wide wavelength region.

Further, the optical fiber in the optical transmission system of the present invention has heat resistance, chemical resistance, moisture resistance, and nonflammability, which can withstand severe usage conditions.

The gradient index plastic optical fiber in the optical transmission system of the present invention has a non-crystalline fluoropolymer (hereinafter referred to as fluoropolymer (a)) matrix refraction having substantially no C—H bond. It is obtained by distributing a substance that gives a distribution of the rate (hereinafter referred to as substance (b)).

The fluoropolymer (a) in the present invention is not particularly limited as long as it is a non-crystalline fluoropolymer having no C--H bond, but a fluoropolymer having a ring structure in its main chain. Is preferred. As the fluorine-containing polymer having a ring structure in the main chain, a fluorine-containing polymer having a fluorine-containing aliphatic ring structure, a fluorine-containing imide ring structure, a fluorine-containing triazine ring structure or a fluorine-containing aromatic ring structure is preferable. Among the fluoropolymers having a fluorinated aliphatic ring structure, those having a fluorinated aliphatic ether ring structure are more preferable.
As the fluorinated polymer (a), a fluorinated polymer having a fluorinated polyimide ring structure and a fluorinated polymer having a fluorinated alicyclic structure are preferable, and the latter is particularly preferable.

The fluorine-containing polymer having a fluorine-containing alicyclic structure has a thermal stretching or melting property which will be described later in comparison with a fluorine-containing polymer having a fluorine-containing imide ring structure, a fluorine-containing triazine ring structure or a fluorine-containing aromatic ring structure. It is a more preferable polymer because it is difficult for the polymer molecules to be oriented even when it is made into fibers by spinning, and as a result, light is not scattered.

The viscosity of the fluoropolymer (a) in the molten state is from 10 ^{3 at} a melting temperature of 200 ° C. to 300 ° C.
10 ⁵ poise is preferred. If the melt viscosity is too high, not only melt spinning is difficult, but also necessary for forming the refractive index distribution,
Diffusion of the substance (b) is less likely to occur, making it difficult to form a refractive index distribution. In addition, if the melt viscosity is too low, there will be a practical problem. That is, when it is used as an optical transmitter in electronic devices, automobiles, etc., it is exposed to high temperatures and softens, and the optical transmission performance deteriorates.

The number average molecular weight of the fluoropolymer (a) is
It is preferably 10,000 to 5,000,000, more preferably 50,000 to 1,000,000. If the molecular weight is too small, heat resistance may be impaired, and if it is too large, it becomes difficult to form an optical transmission medium having a refractive index distribution, which is not preferable.

The polymer having a fluorinated alicyclic structure is obtained by polymerizing a monomer having a fluorinated cyclic structure, or a fluorinated monomer having at least two polymerizable double bonds is cyclopolymerized. A polymer having a fluorinated alicyclic structure in the main chain obtained as described above is suitable.

A polymer having a fluorinated alicyclic structure in its main chain obtained by polymerizing a monomer having a fluorinated alicyclic structure is known from Japanese Patent Publication No. 63-18964. That is, perfluoro (2,2-dimethyl-
1,3-dioxole) and other monomers having a fluorine-containing alicyclic structure are homopolymerized, and this monomer is also radical-polymerizable monomer such as tetrafluoroethylene, chlorotrifluoroethylene, and perfluoro (methyl vinyl ether). A polymer having a fluorinated alicyclic structure in its main chain can be obtained by copolymerizing with. Examples of repeating units of such a polymer are shown in (IV) above.

Further, a polymer having a fluorinated alicyclic structure in its main chain obtained by cyclopolymerization of a fluorinated monomer having at least two polymerizable double bonds is disclosed in JP-A-63-
It is known from JP-A-238111 and JP-A-63-238115. That is, perfluoro (allyl vinyl ether), perfluoro (butenyl vinyl _{ether), CF 2 = CF-CF} 2 -CFCl-CF 2 -CF =
By cyclopolymerizing a monomer such as CF ₂ or by copolymerizing such a monomer with a radical polymerizable monomer such as tetrafluoroethylene, chlorotrifluoroethylene, perfluoro (methyl vinyl ether), the main chain is formed. A polymer having a fluorinated alicyclic structure is obtained. Examples of repeating units of such a polymer are shown in the above (I) to (III).

Further, perfluoro (2,2-dimethyl-
Monomers having a fluorinated alicyclic structure such as 1,3-dioxole) and perfluoro (allyl vinyl ether)
A polymer having a fluorinated alicyclic structure in its main chain can also be obtained by copolymerizing a fluorinated monomer having at least two polymerizable double bonds such as or perfluoro (butenyl vinyl ether).

The polymer having a fluorinated alicyclic structure is
A polymer having a ring structure in the main chain is suitable, but a polymer containing 20 mol% or more, preferably 40 mol% or more of polymerized units having a ring structure is preferable in terms of transparency, mechanical properties and the like.

The polymer having a fluorinated alicyclic structure is
A polymer having a ring structure in the main chain is preferable, but the repeating unit having a ring structure is 20 mol% or more, preferably 40
Those containing more than mol% are preferable in terms of transparency, mechanical properties and the like.

The method for producing the fluorine-containing polyimide is not particularly limited. For example, perfluoropyromellitic anhydride, an aromatic tetracarboxylic acid anhydride in which all hydrogen atoms are replaced by fluorine atoms, and perfluorop, p '. A polyamic acid is produced by a reaction of an aromatic diamine in which all hydrogen atoms such as diaminodiphenyl ether are substituted with fluorine atoms, and this is further heated to give a fluorine-containing polyimide.

Specific examples of the fluorine-containing polyimide include those having a repeating unit selected from the following formula (V). The fluorine atoms in these fluoropolymers (a) may be partially substituted with chlorine atoms in order to increase the refractive index.

[0030]

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[In the above formula (V), R ¹ is

[0032]

[Chemical 4]

R ² is selected from

[0034]

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Is selected from Here, R _f is selected from a fluorine atom, a perfluoroalkyl group, a perfluoroaryl group, a perfluoroalkoxy group, and a perfluorophenoxy group, and these may be the same or different. Y is

[0036]

[Chemical 6]

Is selected from Here, _R'f is selected from a perfluoroalkylene group and a perfluoroarylene group, and these may be the same or different.
r is 1-10. Further, Y and two R _f's may sandwich a carbon to form a ring, in which case the ring may be a saturated ring or an unsaturated ring. The substance (b) is at least one substance having a difference in refractive index of 0.001 or more in comparison with the fluoropolymer (a), and has a higher refractive index than that of the fluoropolymer (a). It may have a low refractive index. In optical fibers and the like, a substance having a higher refractive index than the fluoropolymer (a) is usually used.

The substance (b) is preferably a low molecular compound, an oligomer or a polymer containing an aromatic ring such as a benzene ring, a halogen atom such as chlorine, bromine or iodine, and a bonding group such as an ether bond. Further, the substance (b) is preferably a substance which does not substantially have a C—H bond for the same reason as the fluoropolymer (a). The difference in refractive index with the fluoropolymer (a) is preferably 0.005 or more.

The substance (b) which is an oligomer or polymer is a polymer of the monomer forming the above-mentioned fluoropolymer (a), and has a refractive index in comparison with the fluoropolymer (a). It may be an oligomer or a polymer having a difference of 0.001 or more. As a monomer,
It is selected from those which form a polymer having a difference in refractive index of 0.001 or more in comparison with the fluoropolymer (a). For example, two kinds of fluoropolymers (a) having different refractive indexes can be used, and one polymer (a) can be distributed as the substance (b) in the other polymer (a).

These substances (b) have a solubility parameter difference of 7 (cal) in comparison with the above matrix.
/ Cm ³ ) ^1/2 is preferable. Here, the solubility parameter is a characteristic value that is a measure of the mixing property between substances, and the solubility parameter is δ, the molecular cohesive energy of the substance is E, and the molecular volume is V. The equation δ = (E / V) ¹ Expressed as ^{/ 2} .

Examples of the low molecular weight compound include halogenated aromatic hydrocarbons containing no hydrogen atoms bonded to carbon atoms, particularly halogenated aromatic hydrocarbons containing only fluorine atoms as halogen atoms, fluorine atoms and others. The halogenated aromatic hydrocarbon containing a halogen atom is preferable in terms of compatibility with the fluoropolymer (a). It is more preferable that these halogenated aromatic hydrocarbons do not have a functional group such as a carbonyl group or a cyano group.

Examples of such halogenated aromatic hydrocarbons include those represented by the formula Φ _r -Z _b [Φ _r is a b-valent fluorinated aromatic ring residue in which all hydrogen atoms are replaced by fluorine atoms, and Z is fluorine. Or a halogen atom other than fluorine, -Rf, -CO
-Rf, -O-Rf, or -CN. However, Rf is a perfluoroalkyl group, a polyfluoroperhaloalkyl group, or a monovalent Φ _r . b is 0 or an integer of 1 or more. ] There is a compound represented by. The aromatic ring includes a benzene ring and a naphthalene ring. The perfluoroalkyl group or polyfluoroperhaloalkyl group which is Rf preferably has 5 or less carbon atoms. As a halogen atom other than fluorine, a chlorine atom or a bromine atom is preferable.

Specific compounds include, for example, 1,3-
Dibromotetrafluorobenzene, 1,4-dibromotetrafluorobenzene, 2-bromotetrafluorobenzotrifluoride, chloropentafluorobenzene,
Examples include bromopentafluorobenzene, iodopentafluorobenzene, decafluorobenzophenone, perfluoroacetophenone, perfluorobiphenyl, chloroheptafluoronaphthalene, and bromoheptafluoronaphthalene.

As the substance (b) which is a polymer or oligomer, among the substances having the repeating units (I) to (V), a fluorine-containing polymer having a refractive index different from that of the fluoropolymer (a) to be combined is used. Combined (for example, a combination of a fluoropolymer containing only fluorine atoms as halogen atoms and a fluoropolymer containing fluorine atoms and chlorine atoms, obtained by polymerizing two or more monomers of different types and different ratios) Combinations of different fluoropolymers) are preferred.

In addition to the fluorine-containing polymers having a ring structure in the main chain as described above, hydrogen atoms such as tetrafluoroethylene, chlorotrifluoroethylene, dichlorodifluoroethylene, hexafluoropropylene and perfluoroalkyl vinyl ether are not contained. Oligomers composed of monomers, copolymerized oligomers of two or more of those monomers, and the like can also be used as the substance (b). Also, -CF
₂ CF (CF ₃₎ O- or _{- (CF 2) n O- (} n is an integer of 1 to 3) such as perfluoropolyether having structural units of can be used. The molecular weight of these oligomers is selected from the range of molecular weight that makes them amorphous, and the number average molecular weight is 300 to
10,000 is preferred. Considering the ease of diffusion, a number average molecular weight of 300 to 5000 is more preferable.

The particularly preferred substance (b) is a chlorotrifluoroethylene oligomer because of its good compatibility with the fluoropolymer (a), especially the fluoropolymer having a ring structure in its main chain. Since the compatibility is good, the fluoropolymer (a), particularly the fluoropolymer having a ring structure in the main chain, and the chlorotrifluoroethylene oligomer are easily mixed by heating and melting at 200 to 300 ° C. be able to. Well, both can be mixed uniformly by dissolving in a fluorine-containing solvent and mixing and then removing the solvent. A preferred molecular weight of the chlorotrifluoroethylene oligomer is a number average molecular weight of 500 to 1
500.

In the gradient index optical fiber of the present invention, the substance (b) is distributed in the fluoropolymer (a) with a concentration gradient from the center to the peripheral direction.
Preferably, the substance (b) is a substance having a higher refractive index than the fluoropolymer (a), and the substance (b) has a concentration gradient in which the concentration decreases from the center of the optical fiber to the peripheral direction. It is a distributed optical fiber. In some cases, the substance (b) is a substance having a lower refractive index than the fluoropolymer (a), and this substance is distributed with a concentration gradient in which the concentration decreases from the periphery of the optical fiber toward the center. Fiber optics are also useful. The former optical fiber can be usually manufactured by arranging the substance (b) at the center and diffusing it toward the peripheral direction. The latter optical fiber can be manufactured by diffusing the substance (b) from the periphery toward the center.

The optical fiber of the present invention has a wavelength of 700 to
The transmission loss of 100 m at 1,600 nm can be 100 db or less. Particularly, in a fluoropolymer having an alicyclic structure in its main chain, the transmission loss at 100 m can be 50 db or less at the same wavelength. Wavelength 700-1,
At relatively long wavelengths of 600 nm, such low level transmission loss is highly advantageous. That is, since the same wavelength as that of the quartz optical fiber can be used, connection with the quartz optical fiber is easy, and it is a cheaper light source than the conventional plastic optical fiber which has to use a wavelength shorter than 700 to 1,600 nm. It has the advantage of being completed.

In the optical fiber of the present invention, molding of the resin and formation of the refractive index distribution may be performed simultaneously or separately. For example, it can be manufactured by forming a refractive index distribution at the same time as forming a refractive index distribution by spinning or extrusion molding. Further, the refractive index distribution can be formed after molding the resin by spinning or extrusion molding. Further, a preform (base material) having a refractive index distribution can be manufactured, and this preform can be molded (for example, spun) to manufacture an optical fiber.

Examples of the method for producing an optical fiber in the present invention include the following methods (1) to (7). However, the method (1) is not limited to these and a particularly preferable method is (1).

(1) The fluoropolymer (a) is melted to contain the substance (b) or the substance (b) in the center of the melt of the fluoropolymer (a). And molding the compound (b) while diffusing the substance (b) or after diffusing the substance (b).

In this case, in order to inject the substance (b), not only the case of injecting the substance (b) in only one layer in the central portion,
The substance (b) may be injected in multiple layers in the central portion. The molding includes extrusion melt molding suitable for molding a rod-shaped base material such as an optical fiber preform, and melt spinning molding suitable for molding an optical fiber. (2) Fluorine-containing polymer (a) obtained by melt spinning or drawing
A method of repeatedly dip-coating a substance (b) or a fluoropolymer (a) containing the substance (b) on a core material made of

(3) A hollow glass tube made of a fluoropolymer (a) is formed by using a rotating glass tube or the like, and the substance (b) or the substance (b) is contained inside the polymer tube. A method in which the monomer phase forming the fluoropolymer (a) is sealed and polymerized while rotating at a low speed.

In the case of this interfacial gel copolymerization, in the polymerization process, the tube made of the fluoropolymer (a) swells in the monomer phase to form a gel phase, and the monomer molecules selectively diffuse into the gel phase. While being polymerized.

(4) By using two kinds of monomers which are a monomer forming the fluoropolymer (a) and a monomer forming the substance (b) and the reactivity of the monomers is different,
A method of advancing the polymerization reaction so that the composition ratio of the resulting fluoropolymer (a) and the substance (b) continuously changes from the peripheral portion toward the center.

(5) Fluorine-containing polymer (a) and substance (b)
Is mixed uniformly or in a solvent, and then the mixture obtained by volatilizing and removing only the solvent is made into a fiber by hot drawing or melt extrusion, and then (or immediately after being made into a fiber) in a heated state. A method of forming a refractive index profile by contacting with an active gas to volatilize the substance (b) from the surface. Alternatively, after forming the fiber, the fiber is immersed in a solvent that dissolves only the substance (b) without dissolving the fluoropolymer (a), and the substance (b) is eluted from the surface of the fiber to obtain a refractive index. How to form a distribution.

(6) The rod or fiber made of the fluoropolymer (a) is coated only with the substance (b) having a smaller refractive index than the fluoropolymer (a), or the fluoropolymer (a) ) And the substance (b) are coated, and then the substance (b) is diffused by heating to form a refractive index profile.

(7) The high-refractive-index polymer and the low-refractive-index polymer are melted by heating or mixed in a solution containing a solvent, and while multi-layer extrusion is performed (or after extrusion) under different mixing ratios. A method in which both are diffused to obtain a fiber with a final refractive index distribution. In this case, the high refractive index polymer may be the fluoropolymer (a) and the low refractive index polymer may be the substance (b), the high refractive index polymer may be the substance (b) and the low refractive index polymer may be the substance (b). ) Is okay.

In the optical fiber of the present invention, a protective coating layer is formed as an outer layer, if desired. Further, in the present invention, after coating each optical fiber to form a cord, a plurality of bundles can be bundled into a bundle fiber.

Since the optical transmission system using the graded index optical fiber of the present invention has low loss in a wide wavelength range of 200 to 1600 nm, a plurality of lights of different wavelengths selected from this wavelength range are used to Multiplex transmission is possible. For example, 16 gigabits of different wavelengths are each loaded with 2 gigabit information, and a single fiber can transmit a large capacity of 32 gigabit in total. Furthermore, if a bundle fiber made up of 10 fibers is used, a large capacity transmission of 320 Gbit is possible.

Further, a high performance modulator is used for the transmitter, and
It is also possible to realize high-speed modulation of 2 gigabits per wave and install a dispersion compensating fiber in the receiver to collectively recover the distortion of 16 wave signals.

According to the present invention, one plastic optical fiber enables transmission about 320 times as much as television transmission, and it is possible to cope with the expected multi-channels of information, communication and broadcasting services in the future, and it is possible to obtain high-quality images with clear images. It is expected to be applicable to remote medical care and distance education, especially for short distances up to about 1 km.

The optical fiber of the present invention may be provided with a protective coating layer. The polymer constituting the coating layer is composed of a polymer other than the fluoropolymer (a) of the matrix. The type of polymer constituting this coating layer is not particularly limited, and at least one selected from those used for coating conventional inorganic or plastic optical fiber strands, or at least one of the fluoropolymers listed below can be used. Can be used. For example, as the non-fluorine-based polymer, low-density polyethylene, ethylene-vinyl acetate copolymer, (water) cross-linkable polyolefin, polyolefin-based polymer such as polyolefin elastomer, polyester-based polymer such as polyethylene terephthalate, soft vinyl chloride resin Vinyl resin such as, vinyl polymer such as polyvinyl chloride,
Silicone-based polymers such as dimethylpolysiloxane polymer and polyfluoroalkylmethylpolysiloxane polymer, polyamide, (foamed) polystyrene, polycarbonate, polyetherimide, polyphenylene oxide, polysulfone, poly-4-methylpentene-1, polyamideimide Etc. Examples of the fluoropolymer include fluororubber, trifluoroethylene polymer, chlorotrifluoroethylene polymer, tetrafluoroethylene polymer, tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-ethylene- (perfluoroalkyl) The following (such as ethylene copolymer, tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride polymer, vinylidene fluoride-hexafluoropropylene copolymer) ( V
Examples thereof include fluoropolymers having repeating units selected from I) to (X).

[0064]

[Chemical 7]

In addition to the above polymer coating, a curable resin such as an ultraviolet curable resin, an electron beam curable resin or a thermosetting resin may be coated on the optical fiber and cured to form a coating layer. it can. When an ultraviolet curable resin or an electron beam curable resin is used, there is an advantage that the optical fiber element wire is less damaged because the coating can be performed at a relatively low temperature. Examples of ultraviolet curable resins and electron beam curable resins include curable resins such as urethane acrylate-based, epoxy acrylate-based, silicon acrylate-based, polyester acrylate-based, polybutadiene acrylate-based, and polyfluoroalkyl acrylate-based resins. When these curable resins are used, a method of applying a liquid resin having an appropriate viscosity to the surface of the gradient index optical fiber and then curing the resin is applied. On the other hand, when polyamide or polyimide resin is used, the tensile strength of the fiber cord is increased and the mechanical durability is dramatically improved.

If desired, a plasticizer, a pigment, a cross-linking agent, an adhesive agent, etc. may be added to the above-mentioned polymer constituting the coating material.

The production of the optical fiber having the coating layer of the present invention is not particularly limited. For example, the target optical fiber can be obtained by forming a coating material on the outside of the optical fiber manufactured by the above-mentioned method by extrusion coating or solvent coating. Further, in the present invention, after coating each optical fiber to form a cord, a plurality of bundles can be bundled into a bundle fiber. The bundle fiber includes a multi-core tape core wire formed by arranging cords in parallel. It is also possible to make a cable by coating the optical fiber with a plastic or metal reinforced with aromatic polyamide, glass or carbon fiber. Use the thread, string, paper, plastic,
It may be filled with various cushioning materials or grooved spacers.

The plastic optical fiber in the present invention can be directly connected to not only a quartz single mode optical fiber, but also an optical waveguide such as an optical waveguide, an optical branching device, an optical coupler, an optical multiplexer, an optical demultiplexer, etc. Blanching device, optical switch, optical attenuator, optical isolator, polarizer, optical integrated circuit, optical transmitter module,
It can be directly connected to optical components such as an optical receiver module, and signals can be transmitted without impairing their low loss and high bandwidth.

The optical transmission system of the present invention is applicable to subscriber communication lines, LANs in factories, LANs in hospitals, LANs in public facilities such as school LANs, floor cables, power line monitoring communication lines, automobile applications, and trains. Image transmission of high-speed, high-bandwidth, high image quality such as monitor image transmission of operating conditions, communication in large vessels on the open sea route, data transmission in aircraft, amusement relations such as arcade game machines It can be used in various fields such as transmission of moving images and stereoscopic images, wiring inside devices such as computers and automatic exchanges, general indoor communication networks, various sensor fields, lighting fields, illumination fields, energy transmission and the like.

[0070]

EXAMPLES Next, examples of the present invention will be described more specifically, but it goes without saying that the description does not limit the present invention.

Synthetic Example 30 g of perfluoro (butenyl vinyl ether), 120 g of ion-exchanged water, 4.8 g of methanol and 76 mg of ((CH ₃ ) ₂ CHOCOO) ₂ as a polymerization initiator were used, and the internal volume was 200 ml.
It was placed in a pressure-resistant glass autoclave. After purging the system with nitrogen three times, suspension polymerization was carried out at 40 ° C. for 22 hours.
After the obtained polymer was isolated, it was heat-treated at 300 ° C. and washed with water.
As a result, a colorless and transparent polymer (hereinafter referred to as polymer A)
Was obtained. The intrinsic viscosity [η] of this polymer A was 0.34 at 30 ° C. in perfluoro (2-butyltetrahydrofuran). The glass transition point of the polymer was 108 ° C., and the refractive index was 1.34.

Production Example The polymer A obtained in the above synthesis example was dissolved in a solvent of perfluoro (2-butyltetrahydrofuran), and a chlorotrifluoroethylene oligomer having a refractive index of 1.42 (Daifloyl # 20; Daikin) was added in an amount of 15% by weight to obtain a mixed solution. The solution was desolvated to obtain a transparent mixed polymer (hereinafter referred to as mixed polymer B). The polymer A was melted and melt-spun by two-color extrusion at 300 ° C. while pouring the mixed polymer B of the melt into the center, whereby the refractive index at the center was 1.36 and 1. Three
An optical fiber having an outer diameter of 500 μm was obtained, which was gradually parabolicly decreased to a refractive index of 4. Then, a vinylidene fluoride / hexafluoropropylene 96/4 mol% copolymer was coated on the outside by extrusion coating at 180 ° C. to obtain an optical fiber having an outer diameter of 2.0 mm (hereinafter referred to as optical fiber C). The optical transmission loss of the optical fiber C thus obtained is 300 dB / km at 780 nm, 1
It was 130 dB / km at 550 nm, and it was confirmed to be an optical fiber capable of favorably transmitting light up to near infrared light. The transmission band obtained from the baseband frequency characteristic of the optical fiber C was 2.0 GHz.

Example A semiconductor laser was used as a light source, and an optical multiplexer (optical multiplexer) for multiplexing optical signals of eight different wavelengths within a range of 650 to 1550 nm into one optical fiber was produced in a manufacturing example. It was attached to a gradient index optical fiber C having an outer diameter of 2.0 mm and a length of 100 m, and at the other end of the fiber, one optical fiber was split into optical signals of the original wavelength by utilizing the difference in wavelength. An optical demultiplexer (optical demultiplexer) was installed for wave generation, and a photodetector was installed at the end. As a result of wavelength division multiplexing transmission using this system, it was confirmed that transmission of about 2.0 gigabits / sec. For each wavelength and 8 waves, totaling about 16 gigabits / sec. For 100 m.

Comparative Example Wavelength division multiplex transmission was carried out by using a system similar to that of the example using 100 m of an acrylic type gradient index plastic optical fiber commercially available from Nippon Petrochemical Co., Ltd. 6
At a wavelength of 50 nm, we could confirm a transmission rate of 1 Gbit / sec, but at other wavelengths, the acrylic C
Since the vibration of -H is absorbed, the loss is extremely large and 100m
The optical signal after transmission could not be detected.

[0075]

According to the present invention, in an optical transmission system provided with a light source, an optical fiber which is an optical transmission section from the light source, and a photodetector, the optical fiber contains an amorphous material having substantially no C--H bond. It becomes possible to provide an optical transmission system having a low transmission loss and a high transmission band over a wide wavelength range with a single plastic optical fiber by using a gradient index optical fiber having a fluoropolymer matrix. It was Furthermore, by performing wavelength division multiplex transmission using this system, it has become possible to transmit large amounts of information at high speed, which could not be achieved with conventional plastics. In particular, this graded-index plastic optical fiber is flexible and easy to branch and connect despite its large fiber diameter.
Provided is a plastic optical fiber having heat resistance, chemical resistance, moisture resistance, and nonflammability that can be used for wiring of OA equipment and the like.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08L 29/10 LGZ C08L 29/10 LGZ G02B 6/18 G02B 6/18 H04B 10/14 H04B 9 / 00 Q 10/135 G08C 23/00 A 10/13 10/12 // G08C 23/04 (72) Inventor Haruhisa Miyake 1150 Hazawa-machi, Kanagawa-ku, Yokohama, Kanagawa Prefecture Asahi Glass Co., Ltd. Central Research Laboratory

Claims (4)

[Claims] 1. An optical transmission system comprising a light source, an optical fiber which is an optical transmission part from the light source, and a photodetector, wherein the optical fiber has a matrix of a non-crystalline fluoropolymer having substantially no C—H bond. An optical transmission system characterized by being a graded index optical fiber. 2. The optical transmission system according to claim 1, wherein the non-crystalline fluoropolymer is a fluoropolymer having a ring structure in its main chain. 3. The optical transmission system according to claim 1, wherein the fluoropolymer having a ring structure in the main chain has repeating units selected from the following (I) to (IV). Embedded image [In the above formulas (I) to (IV), 1 is 0 to 5, m is 0 to 4, n is 0 to 1, l + m + n is 1 to 6, o, p, q
Is 0 to 5, o + p + q is 1 to 6, R ³ and R ⁴ are F, respectively.
Or CF ₃ , R ⁵ is F or CF ₃ , and R ⁶ is F or CF
₃ , X ¹ is F or Cl, and X ² is F or Cl. ] 4. The optical transmission system according to claim 1, wherein wavelength division multiplexing transmission is performed.