JP2003294969A - Photonic crystal fiber and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a PCF having barrier walls in optional positions and to provide a method for economically manufacturing the PCF. <P>SOLUTION: The photonic crystal fiber having a plurality of tubular hollow holes 2 formed in the internal part thereof along an axial center is characterized in that the barrier walls 3 between adjacent hollow holes are provided in optional positions. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a photonic crystal fiber and a method for manufacturing the same. More specifically, the present invention relates to a highly reliable method for manufacturing a photonic crystal fiber that can be used even in an underwater environment.

[0002]

BACKGROUND ART Photonic crystal fiber (PC) has been used as a broadband transmission medium replacing conventional optical fibers for communication.
F: Another name, hole fiber) has been proposed. These have holes that are continuous in the longitudinal direction of the optical fiber, but for the purpose of preventing deterioration in transmission characteristics and strength when this fiber is used in an underwater environment, a partition wall that blocks the holes. A PCF provided with is proposed (Japanese Patent Application No. 2002-20).
04).

As shown in FIG. 2, the appearance of this PCF is one in which a plurality of holes are provided in the longitudinal direction of a cylindrical fiber made of an optical transmission medium. Etc. have been proposed. That is, a plurality of holes 2 are continuously formed along the longitudinal direction of the quartz rod 1 which is a cylindrical fiber, and the holes 2 are closed by the partition walls 3 to be closed by the partition walls 3. Hole 4
It is said that. The diameter of the holes 2 is on the order of wavelength, and the cutoff wavelength and dispersion characteristics are determined by structural parameters such as diameter, arrangement, number, and fiber outer diameter.

[0004]

[Patent Document 1] Japanese Patent Application No. 2002-2
In No. 004, the method proposed as an example of the method for manufacturing the PCF has a disadvantage that the partition walls 3 can be manufactured only at the same location in the adjacent holes 2. An object of the present invention is to provide a PCF having a partition wall at an arbitrary position and a method for economically manufacturing the PCF.

[0005]

The photonic crystal fiber according to claim 1 of the present invention for solving the above-mentioned problems is a photonic crystal fiber having a plurality of tubular holes formed inside along an axis thereof. A partition wall is provided at an arbitrary position of the holes adjacent to each other.

A method of manufacturing a photonic crystal fiber according to a second aspect of the present invention which solves the above-mentioned problems is a method of drawing a photonic crystal fiber base material made of quartz from a hole opening portion of the base material in a melt drawing step. The feature is that quartz powder is supplied at any time.

A method of manufacturing a photonic crystal fiber according to a third aspect of the present invention which solves the above-mentioned problems is a quartz powder supply tube inserted from a hole opening of a photonic crystal fiber base material made of quartz. Is intermittently enclosed in the inner wall of the hole, and a step of pulling out the supply pipe and a step of melting and drawing the base material.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to the embodiments shown in the drawings. This embodiment is a PC
Production of a photonic crystal fiber consisting of three steps: a step of forming a partition wall on the core portion of F, a step of coating the core produced in the step with a jacket tube, and a step of drawing the preform produced in the step Is the way.

The manufacturing process of this embodiment is shown in FIG. still,
The PCF fiber preform 10 is shown in cross section for the purpose of explaining the steps. As shown in FIG. 3, a PCF fiber preform 10 having a through hole 2 is placed in a heating furnace 12, and upper and lower parts thereof are held by preform gripping parts 13 and 14, respectively. The powder supply pipe attached to the quartz powder intermittent supply device 11 is inserted into the upper end opening of the.

Here, the PCF fiber preform 10
The heated portion of the preform 10 is stretched by heating the portion to be stretched in the central portion of the preform 10 by the heating furnace 12 and applying a constant tension to the preform 10 by the preform gripping portions 13 and 14. At the same time, PCF
Quartz powder is intermittently and intermittently supplied to the pores 2 of the preform 10 from the silica powder intermittent supply device 11 to the opening at the upper end of the fiber preform 10. When the required amount of powder has been supplied, the supply is stopped.

The powder supplied to the pores 2 is clogged and then heated and melted to fill the pores. After that, when the temperature of the heating portion is lowered, the voids 2 are solidified while being closed in the process of cooling and solidification, so that the filled quartz powder becomes the partition walls 3. Since it is possible to supply and stop the supply of quartz powder by an arbitrary amount at any time during the drawing process of the PCF fiber preform 10, a series of continuous fibers in which the closed positions of the holes 2 are arbitrarily distributed in the fiber longitudinal direction. Can be manufactured.

In FIG. 3, in order to simplify the description of the drawing,
Although the quartz powder intermittent supply device 11 was connected to only one of the plurality of holes 2 in the PCF fiber preform 10, it goes without saying that the quartz powder can be supplied to all the holes 2. Therefore, a plurality of quartz powder intermittent supply devices 11 may be prepared or may be moved.

Further, by continuously moving the heated portion of the PCF fiber preform 10 from the lower part to the upper part of the preform, it is possible to produce a PCF core preform with a partition wall having an arbitrary length. The heating furnace 12 may be of a fixed type as shown in the figure, or may be of a type that can move in parallel as the preform heating portion changes upward.

When a plurality of quartz powder intermittent supply devices 11 corresponding to the number of holes 2 are prepared, the partition 3 can be formed at the same position in the longitudinal direction of the PCF as shown in FIG. on the other hand,
When the quartz powder intermittent feeding device 11 is moved in parallel, the PCF core portion in which the positions of the partition walls between the adjacent holes are different as shown in FIG. 1 is manufactured. The preform created by this step is referred to as a partition-attached PCF core preform in the following description.

The steps of this embodiment are shown in FIG. First, as shown in FIG. 4, there is prepared a PCF jacket tube 16 having a through hole slightly larger than the outer diameter of the core preform 15 with a partition formed in the step and having one through hole at the center. By inserting the PCF core preform 15 with a partition into the hole of the jacket tube 16, a PCF preform 20 having a jacket around the core is obtained.

The steps of this embodiment are shown in FIG. The process is a drawing process using the drawing device 22. That is, the PCF preform 20 is heated and melted in the heating furnace 21,
A PCF with a partition wall having a constant outer diameter is obtained by drawing a wire downward with a constant tension, passing it through a resin coating die 23 to coat the resin, curing the resin in a resin curing furnace 24, and further winding it with a winding bobbin 25. Can be obtained. A cross-sectional view of a PCF with a partition formed in this step is shown in FIG.

In the conventional manufacturing method, as shown in FIG. 2, the partition wall 3 had to be formed in the same place in all the holes 2, whereas in the present manufacturing method, the partition wall position was arbitrarily set for each hole. It became possible to set. That is, in the photonic crystal fiber according to the present embodiment, a plurality of holes 2 are continuously formed along the longitudinal direction of the quartz rod 1 which is a cylindrical fiber, and these holes 2 are blocked by the partition wall 3. In addition, the positions of the partition walls 3 between the adjacent holes 2 are different.

[Example] In the process, the outer diameter of synthetic quartz is about 11 mm and the length is 35 mm (the length of the grip portion 13,
PCF corepliform 10 of 14 gripping margins is not included. The inner diameter of the holes is about 1 mm. This P
By stretching the CF core preform 10 in the process, the outer diameter of the parallel part is about 6 mm and the length is about 100 mm.
A PCF core preform 15 with a partition wall was prepared.

Since the hole has an inner diameter of 1 mm, a quartz powder supply pipe having an outer diameter of 0.7 mm can be easily inserted into the inside by about 30 mm, and the controllability of supplying quartz powder is excellent. The heating temperature of the stretched portion is about 1650 ° C. As the PCF jacket tube preform 16 used in the process,
Outer diameter about 18mm, inner diameter of the central hole that penetrates about 6.1m
m, 100mm long synthetic quartz preform prepared,
Insert the PCF core preform 15 with the partition,
A PCF preform 20 was created.

This preform 20 is drawn by a process, and a PCF with a partition having an outer diameter of 125 microns is about 15 k.
created m. The inner diameter of the hole 2 is about 1 micron, the thickness of the partition wall is about 130 microns, and the distance between adjacent partition walls in one hole 2 is about 1 km. The loss of the obtained PCF is about 2d per km at a wavelength of 1.55 microns.
B, the cutoff wavelength was 1 micron, and it was confirmed to have excellent low loss characteristics.

When this fiber was held in a hydrogen tank having a hydrogen partial pressure of 4 atm and a temperature of about 25 ° C., and loss change at a wavelength of 1.24 μm was measured, a saturation loss of about 20 dB per km was reached. It took about 170 hours. As a result, it was confirmed that it had an extremely excellent hydrogen resistance loss as expected. From this result, by providing the partition wall, even if a crack occurs due to an accident or obstacle when the PCF is laid in water such as the seabed, the movement of moisture propagating along the longitudinal direction of the hole is restricted. Therefore, it can be inferred that the moisture can be propagated only locally, so that the strength deterioration of the PCF can be significantly suppressed.

As described above, in this embodiment, by dividing the manufacturing process of the preform into steps and steps, the inner diameter of the PCF core preform 10 can be increased to about 1 mm. It has become possible.
As a result, it becomes easy to insert the powder supply pipe of the quartz powder intermittent supply device 11 into the inside of the hole, and it becomes possible for the first time to form the quartz partition wall 3 at an arbitrary position as shown in FIG. Furthermore, it becomes possible to disperse the unstable phenomenon of the transmission characteristics concentrated in the vicinity of the partition wall 3 in the longitudinal direction of the fiber, and it becomes possible to manufacture a PCF having stable transmission characteristics over the entire length.

[0023]

As described above in detail based on the embodiments, according to the present invention, in the photonic crystal fiber mainly laid in a long distance section such as the seabed, the holes 2 inside the optical fiber are formed. A structure of an optical fiber and a manufacturing method thereof, characterized in that a partition is provided at an arbitrary position. Therefore, according to the present invention, since the partition wall can be provided at an arbitrary position of the hole inside the optical fiber, it is possible to disperse the deterioration of the transmission characteristics concentrated in the vicinity of the conventional partition wall in the longitudinal direction of the optical fiber. Therefore, it becomes possible to manufacture a PCF having stable transmission characteristics over the entire length.

[Brief description of drawings]

FIG. 1 is a sectional view of a PCF with a partition according to the present invention.

FIG. 2 is a sectional view of a conventional PCF with a partition wall.

FIG. 3 is an explanatory diagram of a PCF manufacturing method (process) of the present invention.

FIG. 4 is an explanatory diagram of a PCF manufacturing method (process) of the present invention.

FIG. 5 is an explanatory diagram of a PCF manufacturing method (process) of the present invention.

[Explanation of symbols]

1 quartz rod 2 holes 3 partitions 4 Holes closed by partition walls 10 PCF core application form 11 Quartz powder intermittent supply device 12 heating furnace 13,14 Preform grip 15 PCF core app form with bulkhead 16 PCF jacket tube preform 20 PCF preform 21 heating furnace 22 Wire drawing device 23 Resin-coated dies 24 Resin curing furnace 25 winding bobbin

Claims (3)

[Claims] 1. A photonic crystal fiber having a plurality of tubular holes formed inside along an axis, wherein a partition is provided at an arbitrary position of the holes adjacent to each other. fiber. 2. A method for producing a photonic crystal fiber, characterized in that, in a step of drawing a photonic crystal fiber preform made of quartz, quartz powder is supplied from a hole opening portion of the preform at any time. 3. A step of pulling out the supply tube while intermittently enclosing the quartz powder in the inner wall of the hole by a quartz powder supply tube inserted through a hole opening of a photonic crystal fiber preform made of quartz, and A method for producing a photonic crystal fiber, comprising a step of melting and drawing the base material.