Triple-sheathed monomode optical fiber

• US 9,256,025 B2
• Filed: 04/24/2012
• Issued: 02/09/2016
• Est. Priority Date: 04/26/2011
• Status: Active Grant

• Current Assignee: Centre National De La Recherche Scientifique, Universite de Limoges
• Original Assignee: Centre National De La Recherche Scientifique, Universite de Limoges
• Inventors: Roy, Philippe, Schuster, Kay, Grimm, Stephan
• Primary Examiner(s): Le, Uyen Chau N
• Assistant Examiner(s): Smith, Chad
• Application Number:
  US14/113,663
• Publication Number:
  US 20140193127A1
• Time in Patent Office: 1,386 Days
• US Class Current: 1/1
• CPC Class Codes: G02B 6/02 Optical fibres with cladding with or without a coating
• CPC Class Codes: G02B 6/02314 Plurality of longitudinal structures extending along optical fibre axis, e.g. holes
• CPC Class Codes: G02B 6/02333 Core having higher refractive index than cladding, e.g. solid core, effective index guiding
• CPC Class Codes: 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
• CPC Class Codes: G02B 6/02352 Complex periodic lattices or multiple interpenetrating periodic lattices, e.g. unit cell having more than two materials, partially internally coated holes, for multiple bandgaps
• CPC Class Codes: 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
• CPC Class Codes: G02B 6/02361 Longitudinal structures forming multiple layers around the core, e.g. arranged in multiple rings with each ring having longitudinal elements at substantially the same radial distance from the core, having rotational symmetry about the fibre axis
• CPC Class Codes: G02B 6/03638 having 3 layers only
• CPC Class Codes: H01S 3/06733 Fibre having more than one cladding
• CPC Class Codes: H01S 3/06741 Photonic crystal fibre, i.e. the fibre having a photonic bandgap

Abstract

According to the invention, the intermediate sheath (13) is formed by assembling longitudinal elements (13A) and includes: a first optical material, the refractive index of which differs from the refractive index of the monomode core by at most 10⁻³; and a second optical material, the refractive index of which is lower than the refractive index of said monomode core and differs therefrom by at least 10⁻³.

Claims

1. Monomode optical fiber comprising, from center to periphery:

a monomode core doped at least partly with a rare earth,

an optically inactive intermediate sheath,

a multimode pumping sheath, and

an outer sheath,

wherein the intermediate sheath is formed by an assembly of solid bars, and

said assembly of solid bars comprises first solid bars made of a first optical material with a refractive index that differs from the refractive index of said monomode core by at most 10.sup.-3, and second solid bars made of a second optical material with a refractive index that differs from the refractive index of said monomode core by at least 10.sup.-3.

2. Monomode optical fiber according to claim 1, wherein

the refractive index of said first optical material is equal or as close as possible to the refractive index of said monomode core, and

intermediate sheath has an effective refractive index lower than the refractive index of the monomode core, the refractive index of said second optical material being much lower than the refractive index of said monomode core.

3. Monomode optical fiber according to claim 1, wherein

the refractive index of said first optical material is equal or as close as possible to the refractive index of said monomode core, and

the intermediate sheath has an effective refractive index higher than the refractive index of the monomode core, the refractive index of said second optical material being much higher than the refractive index of said monomode core.

4. Monomode optical fiber according to claim 1, wherein, in said assembly, said solid bars of the intermediate sheath are arranged in a matrix arrangement.

5. Monomode optical fiber according to claim 1, wherein the solid bars of the intermediate sheath have a transverse dimension greater than the monomode emission wavelength of said monomode optical fiber by a factor of at least 10.

6. Monomode optical fiber according to claim 1, wherein the solid bars of the intermediate sheath have a transverse dimension less than the monomode emission wavelength of said monomode optical fiber.

7. Monomode optical fiber according to claim 1, wherein modal filtering means are arranged at the monomode core and/or the intermediate sheath.

8. Monomode optical fiber according to claim 1, wherein the intermediate sheath has an effective refractive index that differs from the refractive index of the monomode core by 10.sup.-4 at most.