JP3848597B2 - Manufacturing method of plastic holey fiber - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a manufacturing method for a plastic Horley Fiber having a large number of pores in the cladding of the core near.
[0002]
[Prior art]
An optical fiber that enables high-capacity and high-speed communication is indispensable for constructing an optical communication network. However, in recent and future optical communication networks, optical signals have been increased in speed and information. Along with this, an optical fiber having a larger capacity has been demanded, and an optical fiber called a so-called photonic crystal fiber (hereinafter referred to as a PCF) is attracting attention as a new optical fiber that satisfies this demand. Has been.
[0003]
This photonic crystal optical fiber is provided with a photonic structure, which is a periodic structure of refractive index, in a clad covering a core, and specifically, a honeycomb structure space such as a honeycomb so as to surround the core. Is provided in the cladding to generate a photonic band gap (hereinafter referred to as PBG) which is a forbidden band of light. For example, Knight et al. Reported a PCF based on the PBG structure in Science 282, 1476, (1998), and Cregan et al., Based on the PBG structure in Science 285, 1537, (1999). We report on hollow core PCF. This hollow-core PCF shows the possibility of an ultra-low loss fiber in which Rayleigh scattering, which is a main factor of loss, is extremely small because there is no quartz medium in the core through which light propagates. Japanese Patent No. 3072842 also mentions a hollow core PCF and there is a description that a reduction in loss of about 0.01 dB / km can be expected.
[0004]
However, in these conventional PCFs, if there is a slight structural fluctuation in the PBG structure, the light propagation condition cannot be maintained, and so-called structural loss is generated. Therefore, it is necessary to precisely configure the PBG structure. Yes, there are still many challenges for realization.
[0005]
On the other hand, recently, although it does not have a complete PBG structure like the above PCF, there is a void in the cladding near the core of the optical fiber having a relative refractive index difference due to the difference in the conventional glass composition, An optical fiber referred to as a so-called holey fiber has been proposed which has a characteristic not conventionally obtained by lowering the effective refractive index of the clad and increasing the relative refractive index between the core and the clad. For example, in OFC2001PD5-1, Hasegawa et al. Used a holey fiber with four holes in the cladding near the core of a fiber having a normal single-mode fiber structure. Has been reported to realize a fiber with zero dispersion and single mode operation in the 0.8 μm band.
[0006]
[Problems to be solved by the invention]
By the way, such a conventional holey fiber has a problem that the manufacturing cost is high and the flexibility is inferior because quartz glass is used as a material.
[0007]
In other words, a conventional holey fiber is manufactured by manufacturing a glass rod made of quartz glass, then mechanically perforating the glass rod, and drawing it to a predetermined diameter while heating and melting in the same way as a normal glass fiber. It can be obtained by spinning and spinning. However, the length of the quartz glass rod is limited in order to perform this mechanical drilling process, and the material is also a difficult-to-cut material, so at present, the maximum is about 200 mm. If the outer diameter is φ50 mm, only about 20 km can be obtained by one spinning, and the manufacturing cost becomes very high. Further, there are no particular problems if the number of holes is several, but if the number is further increased to several tens or more in the future, the work takes a lot of time and the production cost increases. Furthermore, conventional holey fibers based on quartz glass have poor flexibility, and are difficult to use when the bending diameter is, for example, φ60 mm or less.
[0008]
The present invention has been made to effectively solve the above problems, its object is a method for producing a novel plastic Horley Fiber manufacturing cost with excellent inexpensive flexible It is to provide.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a method for extruding a core resin in a method for producing a plastic holey fiber having a plurality of holes extending in a longitudinal direction in a cladding near a core, as shown in claim 1. For the core extruded from the nozzle tip of the core extruder using an extrusion device in which the nozzle tips of the core extruder and the clad extruder for extruding the clad resin are combined and combined at the nozzle part Hole molding extending in the extrusion direction so as to extrude the resin for clad from the nozzle tip of the extruder for clad around the resin and to surround the injection port of the nozzle tip at the nozzle tip of the core extruder. For this purpose, a plurality of pins are provided, whereby holes are continuously formed in the cladding. According to a second aspect of the present invention, polymethyl methacrylate is used as the core resin, and a fluorine-based resin is used as the cladding resin.
[0010]
That is, by using the resin instead of the glass material of the conventional quartz glass or the like, it is possible to efficiently obtain the push-out molding, and mass productivity is improved, it becomes possible to greatly reduce the manufacturing cost. Further, since the whole is made of resin, the flexibility is greatly improved as compared with the conventional fiber made of glass.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, a preferred embodiment for carrying out the present invention will be described with reference to the accompanying drawings.
[0013]
FIG. 1 shows an embodiment of a plastic holey fiber 1 manufactured by the manufacturing method according to the present invention.
[0014]
As shown in the figure, this plastic holey fiber 1 is provided with a core 3 having a diameter of about 0.2 mm along the longitudinal direction at the axial center of a clad 2 having a diameter of about 1.0 mm. A plurality of holes 4 (eight in the present embodiment) having a diameter of about 30 μm are formed in the vicinity of 3 in the vicinity of 3 in the longitudinal direction.
[0015]
The core 3 is made of polymethyl methacrylate which is a resin (plastic) excellent in optical properties, particularly transparency, and the clad 2 is made of a fluorine-based resin in order to lower the refractive index than the core 3. Has been.
[0016]
Then, in order to produce the plus tics holey fiber 1 having such a structure, a composite extrusion device in the configuration shown in FIGS. This extrusion apparatus extrudes the core extruder 5 for extruding the core resin (polymethyl methacrylate in this embodiment) and the clad resin (fluorine resin in this embodiment). The nozzles 5a and 6a of the clad extruder 6 are combined at the tip of the nozzle 7 and the core resin is extruded from the core extruder 5 and at the same time the core resin is extruded around the core resin. 3 and the clad 2 are extruded at the same time. Further, as shown in the drawing, a plurality of pins 8 extending in the pushing direction so as to surround the injection port are provided at the tip of the nozzle 5a of the core extruder of the nozzle portion 7 (in this embodiment, eight pins at regular intervals). ) Is provided. Therefore, when the core 3 and the clad 2 are simultaneously extruded, the clad resin is not filled only in the downstream portion of the tip of the pins 8, 8,..., Thereby enclosing the core 3 in the clad 2 simultaneously with the extrusion of the clad resin. As a result, holes 4, 4... Continuous in the longitudinal direction are formed.
[0017]
Therefore, since it is possible to form the core 3 and the cladding 2, and the pore 4, 4 by such a manufacturing method simultaneously and continuously, Ku such that each resin is suspended over long distances as long as continues to be supplied it is possible to manufacture the plus tick holey fiber 1, it is possible to exhibit an excellent mass production. Further, since the resin can be used as the material and can be used for the extrusion molding as described above, the conventional troublesome mechanical drilling process becomes unnecessary.
[0018]
Also, by forming the whole with resin, the flexibility is greatly improved and the fiber can be bent and installed with a small radius, so it can be installed in optical processing with a complicated structure, or even in a narrow space It can be easily installed.
[0019]
It should be noted that the installation position and the number of the holes 4 can be easily changed by changing the arrangement and the number of the pins 8. Further, a jacket may be formed around the cladding 2 to protect the cladding 2 and the like.
[0020]
【The invention's effect】
In short, according to the present invention, by using a resin instead of a conventional glass raw material such as quartz glass, it can be efficiently obtained by extrusion molding, so that mass productivity is improved and manufacturing cost is greatly reduced. Is possible. In addition, since the whole is made of resin, the flexibility is greatly improved compared to the conventional fiber made of glass, and it can be installed easily and reliably even in narrow and complex spaces. Excellent effects such as become.
[Brief description of the drawings]
FIG. 1 is an enlarged cross-sectional view showing an embodiment of a plastic holey fiber manufactured by a manufacturing method according to the present invention.
FIG. 2 is a configuration diagram showing a composite extrusion apparatus for obtaining the plastic holey fiber of FIG . 1 ;
3 is a cross-sectional view showing a configuration of a nozzle portion of a composite extrusion apparatus for obtaining the plastic holey fiber of FIG . 1 ;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Plastic holey fiber 2 Clad 3 Core 4 Hole 5 Core extruder 6 Clad extruder 7 Nozzle part 8 Pin

Claims (2)

In the manufacturing method of the plastic holey fiber having a plurality of holes extending in the longitudinal direction in the cladding near the core,
Using an extrusion apparatus in which the nozzle tips of the core extruder for extruding the core resin and the clad extruder for extruding the clad resin are combined and combined at the nozzle part,
While extruding the cladding resin from the nozzle tip of the clad extruder around the core resin extruded from the nozzle tip of the core extruder,
A plurality of hole forming pins extending in the extruding direction are provided at the nozzle tip of the core extruder so as to surround the injection port at the nozzle tip, whereby the holes are continuously formed in the cladding. A method for producing a plastic holey fiber, comprising: forming a plastic holey fiber.   2. The method for producing a plastic holey fiber according to claim 1, wherein polymethyl methacrylate is used as the core resin, and a fluorine-based resin is used as the cladding resin.

Images