# US 2014/0193128 A1 · Holey fiber and method of producing the same

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- Number: US 2014/0193128 A1
- Document ID: US20140193128A1
- Status: Published application
- Kind: A1
- Application number: 14/203,019
- Filed: 2014-03-10
- Published: 2014-07-10
- Earliest claimed: 2012-05-24
- Assignees: Furukawa Electric Co., Ltd.
- Applicants: Furukawa Electric Co., Ltd.
- Inventors: Kazunori MUKASA
- Web page: https://patentgrep.com/patent/US20140193128A1

## CPC

- G02B 6/02357: {Property of longitudinal structures or background material varies radially and/or azimuthally in the cladding, e.g. size, spacing, periodicity, shape, refractive index, graded index, quasiperiodic, quasicrystals}
- G02B 6/02338: {Structured core, e.g. core contains more than one material, non-constant refractive index distribution in core, asymmetric or non-circular elements in core unit, multiple cores, insertions between core and clad}
- G02B 6/02347: {Longitudinal structures arranged to form a regular periodic lattice, e.g. triangular, square, honeycomb unit cell repeated throughout cladding}
- G02B 6/02385: {Comprising liquid, e.g. fluid filled holes}
- G01N 21/3504: for analysing gases, e.g. multi-gas analysis
- G01N 2021/0346: {Capillary cells; Microcells}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

A holey fiber includes: a core portion; an inner-cladding portion positioned at an outer periphery of the core portion, the inner-cladding portion having a plurality of inner holes formed in a layered structure around the core portion; and an outer-cladding portion positioned at an outer periphery of the inner-cladding portion, the outer-cladding portion having a plurality of outer holes formed in a layered structure around the inner-cladding portion. The inner holes are disposed to form a triangular lattice of which lattice constant Λ1 is equal to or smaller than 2.0 μm and to form equal to or greater than two layers. The outer holes are disposed to form a triangular lattice of which lattice constant Λ2 is greater than the Λ1 and equal to or larger than 3.0 μm and to form equal to or greater than two layers. The overlap index is equal to or greater than 2.0%.

## Claims

### Claim 1

A holey fiber comprising:
a core portion;
an inner-cladding portion positioned at an outer periphery of the core portion, the inner-cladding portion having a plurality of inner holes formed in a layered structure around the core portion; and
an outer-cladding portion positioned at an outer periphery of the inner-cladding portion, the outer-cladding portion having a plurality of outer holes formed in a layered structure around the inner-cladding portion, wherein
the inner holes are disposed to form a triangular lattice of which lattice constant Λ1 is equal to or smaller than 2.0 μm and to form equal to or greater than two layers,
the outer holes are disposed to form a triangular lattice of which lattice constant Λ2 is greater than the Λ1 and equal to or larger than 3.0 μm and to form equal to or greater than two layers, and
the overlap index is equal to or greater than 2.0%.

### Claim 2 (depends on 1)

The holey fiber according to claim 1, wherein number of the layers of the inner holes is equal to or greater than three.

### Claim 3 (depends on 2)

The holey fiber according to claim 2, wherein the number of the layers of the inner holes is equal to or greater than four.

### Claim 4 (depends on 1)

The holey fiber according to claim 1, wherein number of the layers of the outer holes is equal to or greater than three.

### Claim 5 (depends on 4)

The holey fiber according to claim 4, wherein the number of the layers of the outer holes is equal to or greater than four.

### Claim 6 (depends on 1)

The holey fiber according to claim 1, wherein confinement loss is equal to or lower than 1 dB/m.

### Claim 7 (depends on 6)

The holey fiber according to claim 6, wherein the confinement loss is equal to or lower than 1 dB/km.

### Claim 8 (depends on 1)

The holey fiber according to claim 1, wherein d1/Λ1 and d2/Λ2 are equal to or smaller than 0.6 where d1 [μm] indicates diameter of the inner holes and d2 [μm] indicates diameter of the outer holes.

### Claim 9

A method of producing a holey fiber by using a stack-and-draw method, the holey fiber comprising:
a core portion;
an inner-cladding portion positioned at an outer periphery of the core portion, the inner-cladding portion having a plurality of inner holes formed in a layered structure around the core portion; and
an outer-cladding portion positioned at an outer periphery of the inner-cladding portion, the outer-cladding portion having a plurality of outer holes formed in a layered structure around the inner-cladding portion, wherein
the inner holes are disposed to form a triangular lattice of which lattice constant Λ1 is equal to or smaller than 2.0 μm and to form equal to or greater than two layers, the outer holes are disposed to form a triangular lattice of which lattice constant Λ2 is greater than the Λ1 and equal to or larger than 3.0 μm and to form equal to or greater than two layers, and
the overlap index is equal to or greater than 2.0%.

### Claim 10 (depends on 9)

The method of producing the holey fiber according to claim 9, comprising:
forming a first preform to form the core portion and the inner-cladding portion by using the stack-and-draw method;
forming a second preform to form the outer-cladding portion having the outer holes by disposing a glass tube at an outer periphery of the first preform; and
drawing the holey fiber from the second preform.