WO2003091772A1

WO2003091772A1 - Plastic optical fiber

Info

Publication number: WO2003091772A1
Application number: PCT/JP2003/005356
Authority: WO
Inventors: Koji Koganezawa; Chikafumi Tanaka; Tsuyoshi Onishi
Original assignee: Asahi Glass Company, Limited
Priority date: 2002-04-25
Filing date: 2003-04-25
Publication date: 2003-11-06
Also published as: JPWO2003091772A1; AU2003235143A1

Abstract

A plastic optical fiber which has three or more cores in a clad, wherein the core consists substantially of an amorphous fluorine-containing polymer (a) having no C-H bond and the clad comprises a fluorine-containing polymer (b) having a refractive index lower than that of the core by 0.001 or more. The plastic optical fiber allows the achievement of a combination of low transmission loss, a high band, and a low bending loss in a broad wavelength region.

Description

Specification

Plastic optical fiber

The present invention relates to a plastic optical fiber having excellent heat resistance, flame retardancy, chemical resistance, and solvent resistance, having a low transmission loss and a high transmission band. More specifically, heat resistance and flame retardancy

The present invention relates to a plastic multi-core optical fiber having excellent chemical resistance and solvent resistance, having three or more cores, and suppressing transmission loss due to bending. Background art

A plastic multi-core optical fiber having three or more cores is a communication plastic optical fiber in which the transmission loss due to bending (hereinafter referred to as “bending loss”) is suppressed while increasing the light coupling efficiency. There are known techniques disclosed in Japanese Patent Application Laid-Open No. 3411147, Japanese Patent Application Laid-Open No. 9-33737, Japanese Patent Application Laid-Open No. 2001-166157, and the like.

However, in any case, since a resin having a C-H bond (carbon-hydrogen bond) such as an acrylic resin or a polycarbonate resin is used as a core, an essential loss due to the C-H bond is generated. It was large and could be used only at a limited wavelength, and the transmission distance was limited to a short distance. Further, in the above-mentioned conventional example, although the use of a fluorine-containing resin for the core itself was proposed, no specific example was described, and the effect was not clear.

The present invention provides a plastic optical fiber that eliminates the essential transmission loss based on the C—H bond and that can use a light source in a wide range from 500 to 160 nm from visible to near infrared. The purpose is to do. Also, due to the heat resistance, flame retardancy, chemical resistance, and solvent resistance of the fluororesin, there is provided a plastic optical fiber that does not deteriorate even in a severe environment and is suitable as a sensor for medical use. With the goal. Disclosure of the invention The present invention relates to a fluorine-containing polymer (a) in which the core comprises a non-crystalline fluorine-containing polymer (a) having substantially no C—H bond, and the clad has a refractive index lower than that of the core by 0.001 or more ( b) A plastic optical fiber comprising: a core; and 3 or more cores provided in the same clad. The use of a material having no C—H bond as the core of the optical fiber of the present invention is necessary to ensure transparency over a wide range of 500 to 1600 nm, that is, low transmission loss. In addition, it is essential to use the above-mentioned fluoropolymer (a) as the core and the above-mentioned fluoropolymer (b) as the clad in order to obtain a plastic optical fiber with low transmission loss. In addition, by using a fluoropolymer for both the core and the clad, characteristics such as heat resistance, flame retardancy, chemical resistance, and solvent resistance can be obtained. By providing three or more cores in the same clad, bending loss can be suppressed as compared with a single-core fiber having the same outer diameter.

In the present invention, the fluorinated polymer (a) is preferably a fluorinated polymer having a fluorinated aliphatic ring structure in the main chain, and more preferably the fluorinated polymer (a) and the fluorinated polymer ( b) is preferably a fluoropolymer having a fluorinated aliphatic ring structure in the main chain. According to this embodiment, a plastic optical fiber with small scattering loss can be obtained.

Further, in the present invention, the core is preferably of a refractive index distribution type. In this embodiment, the refractive index distribution type core is preferably made of a fluorinated polymer (a) containing a refractive index adjusting agent (a 2), and in each core, the refractive index adjusting agent (a 2) It is preferable that the fluorine-containing polymer (a) is contained with a concentration distribution. These modes are preferable because a wide band transmission rate with a small mode dispersion can be secured while suppressing bending loss.

Further, in the present invention, it is preferable that the core is of a single mode type, and the core further comprises a fluoropolymer composition of the fluoropolymer (a) and the refractive index adjuster (a2). It is preferable that the clad be made of only the fluoropolymer (a) and the clad be made of the fluoropolymer (b). This mode is preferable because bending loss can be suppressed to a very low level. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a sectional view of an example of the plastic optical fiber of the present invention.

FIG. 2 is a cross-sectional view of one example of the plastic optical fiber of the present invention.

1: Clad, 2: Core assembly, 3: Clad, 4: Core Best mode for carrying out the invention

In the plastic optical fiber of the present invention, the core is made of an amorphous fluoropolymer having substantially no C—H bond (a), and the clad has a refractive index of 0.001 or more as compared with the core. A plastic optical fiber made of a low fluoropolymer (b), wherein three or more cores are provided in the same clad.

In the present invention, the phrase “the core or the clad is made of a fluoropolymer” means that the fluoropolymer contains a refractive index adjusting agent in addition to the case where the core or clad is made of only the fluoropolymer. It also refers to the case where the composition comprises a fluoropolymer composition with an agent. Further, when the polymer has substantially no C—H bond, it means that when a polymer film (thickness to be measured is preferably about 0.2) is prepared and the infrared absorption spectrum is measured, — No absorption due to H bond is observed. The term “non-crystalline” refers to a diagram in which the X-ray diffraction (XRD) of a polymer or a polymer composition is measured with 20 (unit: degree) on the horizontal axis and intensity (cps) on the vertical axis. Means that no clear peak with a half width of 2 degrees or less is observed. The refractive index means a refractive index for sodium D line. The core is the part of the optical fiber in which most of the optical power is transmitted while being confined, and the cladding is the part made of a substance having a lower refractive index than the core surrounding the core. In addition, the core aggregate refers to a region where a plurality of cores exist in close proximity. The difference in the refractive index between the core and the clad is the difference between the refractive index of the core having the highest refractive index and the refractive index of the clad having the lowest refractive index. The core diameter refers to the diameter of a region showing a light amount of 5% or more of the light amount at the center of the core.

In the plastic optical fiber of the present invention, the core is made of an amorphous fluoropolymer (a) having substantially no C—H bond. As the fluorinated polymer (a), The material is not particularly limited as long as it is non-crystalline and has substantially no C—H bond in which light is absorbed by near-infrared light. As the fluorinated polymer (a), a fluorinated polymer having a fluorinated aliphatic ring structure in the main chain is preferable.

Having a fluorinated aliphatic ring structure in the main chain means that at least one of the carbon atoms constituting the aliphatic ring is a carbon atom in the carbon chain constituting the main chain, and that the carbon atom constituting the aliphatic ring is present. Has a structure in which a fluorine atom or a fluorine-containing group is bonded to at least a part thereof. As the fluorinated aliphatic ring structure, a fluorinated aliphatic ether ring structure is more preferable.

The viscosity of the fluorine-containing polymer (a) in the molten state is preferably 100 to 100,000 Pa · S, more preferably 300 to 10,000 Pa * S at a melting temperature of 200 to 300 ° C, and 500 to 500 Pa. 3,000 Pa · S is particularly preferred. If the melt viscosity is too high, melt spinning is difficult, and if the melt viscosity is too low, it is exposed to high temperatures and softened when a protective coating is applied to make a cable, and the light transmission performance is reduced. The number average molecular weight of the fluoropolymer (a) is preferably ^{1 X 10 4 ~ 5 X 10} 6, 5X 10 4 ~1 X 10 6 are more preferred. If the molecular weight is too small, heat resistance may be impaired, and if it is too large, molding or melt extrusion of the base material becomes difficult. When this molecular weight is represented by an intrinsic viscosity [77], it is preferably 0.1 to 0.1 in 30 of perfluoro (2-butyltetrahydrofuran) [hereinafter referred to as “PBTHF”]; It is preferably from 2 to 0.5 d 1 / g.

Examples of the polymer having a fluorinated aliphatic ring structure include a monomer having a fluorinated ring structure (a monomer having a polymerizable double bond between a carbon atom constituting the ring and a carbon atom not constituting the ring). Or a monomer having a polymerizable double bond between two carbon atoms constituting the ring) or a polymer obtained by polymerizing (Ml), or a fluorine-containing monomer having two or more polymerizable double bonds. Polymers having a fluorinated aliphatic ring structure in the main chain obtained by cyclopolymerization of the monomer (M2) are preferred.

Polymers having a fluorine-containing aliphatic ring structure in the main chain obtained by polymerizing a monomer (Ml) having a fluorine-containing aliphatic ring structure include perfluoro (2,2-dimethyl-1,3 dioxol), Fluorinated fats such as perfluoro (4-methyl-2-methylene-1,3-dioxolane) and perfluoro (2-methyl-1,4-dioxin) It can be obtained by homopolymerizing a monomer (Ml) having an aliphatic ring structure. Further, a polymer having a fluorinated aliphatic ring structure in the main chain obtained by copolymerizing this monomer (Ml) and a radical polymerizable monomer (M3) containing no C_H bond is also used. However, a homopolymer of the monomer (Ml) is preferable because the light transmittance may decrease. Examples of the radical polymerizable monomer (M3) containing no C-H bond include tetrafluoroethylene, trifluoromethyl ethylene, perfluoro (methyl vinyl ether), and the like.

Further, a polymer having a fluorinated aliphatic ring structure in the main chain obtained by cyclopolymerization of a fluorinated monomer (M2) having two or more polymerizable double bonds is disclosed in No. 2,381,111 and JP-A-63-238115. That is, perfluoro (aryl vinyl ether) [CF ₂ = CF—CF ₂ _0_CF = CF ₂ ], perfluoro (butenyl vinyl ether) [CF ₂ = CF—CF ₂ _CF ₂ -0-CF = CF ₂ ], and Perfluoro (4-pentene-2-ylvinyl ether) [CF ₂ = CF_CF ₂ —CF (CF ₃ ) —0_CF = CF ₂ ] can be obtained by polymerization of a monomer (M2). Here, these monomers (M2) may be homopolymerized, or two or more monomers may be copolymerized. Further, by copolymerizing such a monomer (M2) and a radical polymerizable monomer (M3) containing no C—H bond, a polymer having a fluorinated aliphatic ring structure in the main chain can be obtained. However, a polymer of only the monomer (M2) is preferable because a light transmittance may decrease, and a homopolymer of the monomer (M2) is particularly preferable.

In addition, a monomer having a fluorinated aliphatic ring structure (Ml) and a fluorinated monomer having two or more polymerizable double bonds (M2) are copolymerized into a main chain. A polymer having a fluoroaliphatic ring structure is obtained, and is used as the fluorinated polymer (a). In this case, a homopolymer is preferred because the light transmittance may be reduced depending on the combination.

In the polymer having a fluorinated alicyclic structure, the polymer units having a fluorinated alicyclic structure are at least 20 mol%, particularly 40 mol%, based on all the polymer units of the polymer having a fluorinated alicyclic structure. Those containing above are preferred in terms of transparency, mechanical properties, and the like. In the present invention, the fluoropolymer (a) may be composed of only the fluoropolymer (a) or may be composed of the fluoropolymer (a) containing the refractive index adjuster (a2). May be. Particularly, when the core of the plastic optical fiber of the present invention is of a refractive index distribution type, the fluoropolymer (a) preferably contains a refractive index adjusting agent (a2). It is preferable that the refractive index adjusting agent (a 2) has a concentric and continuously varying concentration distribution in the fluoropolymer (a), and the concentration distribution is parabolic. Is preferred. That is, a distribution in which the concentration is high at the center of the core and decreases toward the periphery is preferable. In particular, when the core of the plastic optical fiber of the present invention is of a single mode type, the fluorinated polymer (a) contains only the fluorinated polymer (a) or the fluorinated polymer (a) And a refractive index adjusting agent (a2).

In the present invention, as the refractive index adjusting agent (a2), a compound having excellent compatibility with the fluoropolymer (a) and having substantially no C—H bond is preferable. That is, in the fluorinated polymer composition of the fluorinated polymer (a) and the refractive index adjusting agent (a2), the refractive index adjusting agent (a2) is dissolved in the fluorinated polymer (a). It is preferable that you do. Here, “dissolved” means that phase separation does not occur even when the fluoropolymer composition is heated to the glass transition point and then slowly cooled (for example, cooled at 5 / hr). .

Further, as compared with the fluoropolymer (a), the refractive index of the refractive index adjusting agent (a2) is preferably higher. That is, the refractive index adjuster 2) is preferably a high refractive index agent for the fluoropolymer (a). As the refractive index adjuster (a2), a compound having a chlorine atom and / or an aromatic compound is preferable because of its high refractive index. Examples of the compound having a chlorine atom include a trifluoroethylene oligomer. Examples of the aromatic compound include perfluoro (1,3,5-triphenylbenzene) and perfluoro (2,4,6_triphenyl_1,3,5-triazine).

In the present invention, the fluoropolymer (b) is a fluoropolymer having a refractive index lower than that of the core by 0.001 or more. That is, the fluoropolymer serving as the core (a) Since it is necessary to have a lower refractive index, a fluorine-containing polymer having substantially no C—H bond is preferred. From the viewpoint of moldability and the like, the fluoropolymer (b) is preferably a fluoropolymer (b) having a fluorinated aliphatic ring structure in the main chain. In particular, it is particularly preferable that the clad is only composed of the fluoropolymer (b) in the present invention. Here, as the fluorinated polymer (b), when the fluorinated polymer (a) contains a refractive index adjuster (a2) having a higher refractive index than the fluorinated polymer (a), Only the fluoropolymer (a) containing no agent (a2) may be used.

As a specific combination, when the combination of the fluoropolymer (a) and the fluoropolymer (b) is represented by (a) / (b), (i) the fluoropolymer ( a-1) / fluorine-containing polymer (a-1) a combination of a fluorinated polymer (a_2) having a lower refractive index by a predetermined amount or more than (a-1); (ii) a fluorinated polymer (a) and a refractive index adjuster (a The combination of the composition Z fluoropolymer (a) comprising 2) is preferred. In particular, when the core of the plastic optical fiber of the present invention is of a refractive index distribution type, the combination of (i) or (ii) is preferable, and the combination of (ii) is particularly preferable. Similarly, when the core is a single mode type, the combination of (i) is preferable.

In the present invention, a low transmission loss of 50 dB / km or less can be achieved in the wavelength region of 700 to 1600 nm by the combination of the fluoropolymer (a) and the fluoropolymer (b). It is preferable in that the degree of freedom in selecting a light source is improved.

In the plastic optical fiber according to the present invention, three or more cores are provided in the same clad. That is, a sea-island structure is formed in which the clad is the sea and the core is the island. At this time, the plurality of cores are separated from each other by a continuous cladding. The number of cores provided in the same clad may be three or more, preferably seven or more, and more preferably ten or more. The upper limit is not particularly limited, but is preferably 3000 or less.

The core diameters of the provided cores may be the same or different. In particular, it is preferable to arrange a core with a large core diameter at the center (inside) of the core assembly, and to arrange a core with a smaller core diameter on the concentric circle of the outer periphery than the center. This is plastic It is considered that the optical energy leaked from the core at the center when the optical fiber is bent reenters the core at the outer periphery and the increase in bending loss can be suppressed. Is suitable. However, when disposing cores of different diameters and the core is of a single mode type, it is necessary to satisfy the conditions described below.Also, the disposition of the core in the cladding is not particularly limited. Since it is difficult to make a difference depending on the bending direction, it is preferable to arrange the points symmetrically. In addition, the close-packed arrangement is preferable from the viewpoint of improving the coupling efficiency when light enters the core assembly.

The core of the plastic optical fiber in the present invention is preferably of a refractive index distribution type or a single mode type. When the core is of a refractive index distribution type, the refractive index of the core preferably changes continuously without any step, and the refractive index distribution preferably has a parabolic shape. That is, a distribution in which the refractive index is high at the center of the core and the refractive index decreases toward the periphery is preferable. This distribution shape can be obtained, for example, by preparing a high-concentration portion of the refractive index adjusting agent in the center and diffusing it by thermal diffusion to give a refractive index distribution.

Next, a case where the core is a single mode type will be described. The single mode type means that only the lowest mode is propagated at the wavelength of interest. The condition for a single mode is expressed by equation (1) using a parameter called the normalized frequency V.

2πα

V = — ⁿ i ~ ⁿ 2 ² 2.405 (1) where a is the core radius, is the refractive index of the core center, n ₂ is the refractive index of the cladding, and λ is the wavelength. In this case, regarding the relationship between the refractive index and η ₂ required to satisfy the expression (1), Δ η ^ ι ^ — η ₂ is in the range of 0.0 1 ≤Δ η <0.03. Desirably. If Δη is smaller than this, light cannot be confined and bending loss tends to increase.On the other hand, if it is large, the core diameter needs to be very small to satisfy the condition of single mode, which makes manufacturing difficult. Prone. By making the core a single mode type, it is possible to realize a large transmission capacity and a low transmission loss in a high band. As the method for producing the plastic optical fiber in the present invention, (S1) a method of forming a base material (preform) and then hot drawing the same, or (S2) a method of melt-spinning using an extruder is adopted. Is done. In any case, it is also possible to form directly from a polymer or to mold while polymerizing a monomer. Further, a method in which the method (S1) and the method (S2) are combined, that is, a method in which a base material is manufactured by an extrusion method and then hot-stretched may be employed. In particular, when the core of the plastic optical fiber of the present invention is of a refractive index distribution type, the method (S1) is preferable. Similarly, when the core is a single mode type, the method of (S2) is used. Is preferred.

Examples of the method (S1) include the following examples. First, a predetermined number of core materials formed in a strand shape are inserted into a separately formed porous clad material, and this is used as a base material. The obtained preform is thermally drawn to obtain a plastic optical fiber. The stretching ratio at this time is preferably from 20 to 1000 times, more preferably from 50 to 300 times. This method is suitable when the core is of a refractive index distribution type. An example of a specific molding method is shown below. First, a hollow tube of the fluoropolymer (a) is prepared, a refractive index adjuster (a2) is injected into the center of the hollow tube, and the refractive index adjuster (a2) is thermally diffused to form a core base material. obtain. Next, the core base material is thermally stretched to obtain a core material formed into the above-mentioned strand shape. A predetermined number of the core materials are inserted into a multi-hole clad material obtained by extruding the fluoropolymer (b) to form a base material. The obtained preform is thermally drawn to obtain a plastic optical fiber.

Other specific examples are shown below. A strand of the fluoropolymer (a) comprising the fluoropolymer (a) and the refractive index adjuster (a2) is formed. Next, the fluoropolymer (a) is extruded to form a porous clad material. After a strand is introduced into the clad material, thermal diffusion is performed to obtain a base material having a refractive index distribution type core. The preform is thermally drawn to obtain a plastic optical fiber.

Examples of the method (S2) include the following examples. First, the homogeneously melted core material is split in the die of the extruder, and after being subdivided, the clad material is supplied to the periphery. These are extruded from the same nozzle to obtain a plastic optical fiber. This method is suitable when the core is of a single mode type. In addition, a base material consisting of a core material and a porous clad material was obtained by extrusion molding of two colors, and this was obtained. There is also a method of obtaining a plastic optical fiber by hot stretching.

The plastic optical fiber of the present invention is not affected by acidic chemicals such as sulfuric acid and hydrochloric acid or alkaline chemicals such as sodium hydroxide. It is not affected by organic solvents such as toluene, benzene, and acetone. Due to its chemical and solvent resistance, it can be used in poor environments, such as in sewer pipes and in factories where hydraulic oil scatters. Also, by having three or more cores, bending loss is improved, and it can be used for movable parts such as robots that are frequently bent.

The fluorine-containing plastic multi-core optical fiber of the present invention is a communication line for a subscriber system; a communication line used for a LAN in a public facility such as a LAN in a factory, a LAN in a hospital, a LAN in a school, and a LAN in a sewer pipe; Power line monitoring communication line; suitable for applications requiring high speed and high bandwidth, such as communication lines for data transmission of automobiles, aircraft, trains, ships, etc. Particularly, it is suitable for wiring to a narrow place where bending loss tends to be large. It is also safe because it is made of plastic, so it is hard to break and hard to stick when broken.

(Example)

Hereinafter, examples of the present invention will be specifically described.

(Example 1)

As the fluoropolymer (a), a perfluoro (butenyl vinyl ether) cyclic polymer (refractive index: 1.342) (hereinafter referred to as polymer API) was selected, and a refractive index modifier (a2) was used. Fluoroethylene (CTFE) oligomer was selected as the target. The CTFE oligomer was added to the polymer API to obtain a polymer composition AC1 having a CTFE oligomer concentration of 15% by mass and a refractive index of 1.355.

A hollow tube with an outer diameter of 40 mm, an inner diameter of 20.5 mm and a length of 500 mm is made using the polymer API. In addition, a cylinder having an outer diameter of 20 mm and a length of 500 mm is prepared using the polymer composition AC1. A cylindrical column of the polymer composition AC 1 was introduced into the hollow tube of the polymer AP 1 and melt-spun in a heating furnace heated to 220 ° C to have an outer diameter of 0.26 mm and a core diameter of 0.26 mm. Get a 13mm strand.

20mm outer diameter, 10mm inner diameter, 500mm length using polymer AP1 Create a new hollow tube. One hundred and three hundred and thirty strands cut into a length of 480 mm are inserted into this hollow part to prepare a base material. The preform is melt spun in a heating furnace heated to 220 ° C to produce a plastic optical fiber with an outer diameter of 0.5 mm. The plastic optical fiber has a core having a core diameter of 3.25 βΐη. The core has a standard frequency of 2.25 for light with a wavelength of 850 nm, and this core is a single mode type.

FIG. 1 shows a cross-sectional view of an example of the plastic optical fiber of the present invention obtained by the present embodiment. The core assembly 2 is arranged at the center of the clad 1. In the core assembly part 2, the above-mentioned single mode type cores are arranged so as to form a sea-island structure.

A 200 m transmission test was performed on the manufactured plastic optical fiber using a laser beam with a numerical aperture (NA) of 0.1 and a wavelength of 850 nm, and the transmission loss was 19 dB / km, bandwidth is 4GHz · km. When a bending test was performed using this plastic optical fiber with a radius of 10 mm and a bending angle of 180 degrees, the bending loss was less than 0.010 dB.

(Example 2)

Polymer API was selected as the fluoropolymer (a), and perfluoro (1,3,5-triphenylbenzene) (TPB) was selected as the refractive index adjuster (a2). Using polymer AP1, a hollow tube with an outer diameter of 20 mm, an inner diameter of 5 mm, and a length of 300 mm is made. The TPB is injected into the hollow tube in a molten state, and the hollow tube into which the TPB has been injected is heated while rotating in the sealed tube. Heat at 240 ° C for 10 hours to obtain a hollow tube with TPB diffused. The inner tube has a refractive index of 1.355, and the outer tube has a refractive index of 1.342. This hollow tube is melt-spun in a heating furnace heated to 220 ° C. while reducing the pressure in the hollow portion to obtain a strand having an outer diameter of 2 mm.

One glass tube a with an outer diameter of 46 mm, an inner diameter of 40 mm, and a length of 350 mm, and three glass tubes b with both outer diameters of 2.1 mm, an inner diameter of 0.5 mm, and a length of 3 30 mm sealed at both ends Prepare 0 bottles. Place glass tube b at approximately the center of glass tube a, fix it, and seal one side of glass tube a with a cylindrical resin block made of polytetrafluoroethylene. I do. The polymer AP1 is poured into the glass tube a in a molten state, defoamed under reduced pressure, then gradually cooled, and cooled to room temperature. Thereafter, the solution is poured into a 50% by mass aqueous solution of hydrofluoric acid, and the aqueous solution of hydrofluoric acid is circulated to completely dissolve and remove the glass tubes a and b. This is washed with water and dried to obtain a porous clad material having an outer diameter of 40 mm and a length of 300 mm having 30 holes. A strand is inserted into each hole of the porous clad material to serve as a base material, which is melt-spun in a heating furnace heated to 230 ° C to produce a plastic optical fiber having an outer diameter of 0.5 mm. The plastic optical fiber has 30 graded index cores having a core diameter of 23 m.

FIG. 2 shows a cross-sectional view of an example of the plastic optical fiber of the present invention obtained by the present embodiment. At the approximate center of the clad 3, 30 refractive index distribution type cores 4 are arranged. A 500m transmission test was performed on the manufactured plastic optical fiber using a laser beam with a NA of 0.25 and a wavelength of 130 Onm.The transmission loss was 17 dBZkm and the bandwidth was 1 GHzkm. . When a bending test was performed using this plastic optical fiber with a radius of 10 mm and a bending angle of 180 °, the bending loss was 0.1 dB.

(Example 3)

As a fluoropolymer (a), a polymer API was used, and as a polymer having a lower refractive index than the polymer AP1, perfluoro (butenyl vinyl ether) and perfluoro (2,2-dimethyl-1,3-dioxole) were used. (Refractive index: 1.338) (hereinafter, referred to as polymer AP 2) was selected.

Prepare two 15 mm plunger-type extruders with corrosion-resistant specifications, and use them as Extruder 1 and Extruder 2, respectively. Extruder 1 is loaded with polymer API, and extruder 2 is loaded with polymer AP2. Extruder 1 and Extruder 2 are connected via a crosshead. The flow path from the extruder 1 is divided into 200 lines in the crosshead. The resin is guided from the crosshead to the nozzle, where a 10 mm diameter clad material (Polymer AP2) is extruded, into which a 0.12 mm diameter core material (Polymer API) is extruded. I do. Set extruder 1 at 220 ° C and extruder 2 at 240 ° C and extrude. The resin coming out of the nozzle is stretched in the molten state to obtain a plastic optical fiber with an outer diameter of 5 mm. Plastic The optical fiber has 200 cores with a core diameter of 6 im. The normalized frequency of this core for light with a wavelength of 850 nm is 2.30, and this core is a single mode type.

A 200-m transmission test was performed on a manufactured plastic optical fiber using a laser with a NA of 0.1 and a wavelength of 850 nm.The transmission loss was 24 dB / km and the bandwidth was 3 GHzkm. is there. When a bending test was performed using this plastic optical fiber with a radius of 10 mm and a bending angle of 180 degrees, the bending loss was 0.01 dB or less.

(Example 4)

As a fluoropolymer (a), a polymer API is used. As a polymer having a lower refractive index than polymer AP1, a perfluoro (4-pentene-2-ylvinyl ether) cyclized polymer (refractive index: 1.326) ) (Hereinafter referred to as polymer AP 3).

The same two extruders as in Example 3 are used, and the clad material is set to AP3 and the core material is set to AP1. Extrusion is performed in the same manner as in Example 3, and the resin discharged from the nozzle is stretched in a molten state to obtain a plastic optical fiber having an outer diameter of 0.25 mm. The plastic optical fiber has 200 cores with a core diameter of 3 m. The standard frequency of this core for light with a wavelength of 850 nm is 2.29, and this core is a single mode type.

A 20 Om transmission test was performed on a manufactured plastic optical fiber using a laser with a NA of 0.1 and a wavelength of 850 nm.The transmission loss was 24 dB Zkm and the bandwidth was 3 GHz. km. When a bending test was performed using this plastic optical fiber with a radius of 10 mm and a bending angle of 180 degrees, the bending loss was 0.01 dB or less. Industrial applicability

According to the present invention, low transmission loss and high bandwidth can be achieved in a wide wavelength range, which cannot be achieved by a conventional plastic optical fiber using a material such as polymethyl methacrylate resin, and Low bending losses can be achieved.

Claims

The scope of the claims

1. The core is composed of a non-crystalline fluoropolymer having substantially no C—H bond (a), and the cladding is a fluoropolymer having a refractive index lower than that of the core by 0.001 or more (b) A plastic optical fiber, comprising: three or more cores provided in the same clad.

2. The plastic optical fiber according to claim 1, wherein the fluoropolymer (a) is a fluoropolymer having a fluorinated aliphatic ring structure in the main chain.

3. The process according to claim 1, wherein the fluoropolymer (a) and the fluoropolymer (b) are both fluoropolymers having a fluoroaliphatic ring structure in the main chain. Plastic optical fiber.

4. The plastic optical fiber according to claim 1, 2 or 3, wherein the core is of a gradient index type.

5. The plastic optical fiber according to claim 4, wherein the refractive index distribution type core is made of a fluoropolymer (a) containing a refractive index adjuster (a2).

6. The plastic optical fiber according to claim 5, wherein in each core, the refractive index adjusting agent (a2) is contained in the fluoropolymer (a) with a concentration distribution.

7. The plastic optical fiber according to claim 1, 2 or 3, wherein the core is of a single mode type.

8. The method according to claim 7, wherein the core comprises a fluoropolymer composition of the fluoropolymer (a) and the refractive index adjusting agent (a2), and the cladding comprises the fluoropolymer (b) alone. Plastic optical fiber.

9. The plastic optical fiber according to claim 7, wherein the core comprises only the fluoropolymer (a) and the cladding comprises only the fluoropolymer (b).