Optical waveguide

Patent metadata

Field	Value
Publication number	US-12032201-B2
Application number	US-202017616720-A
Country	US
Kind code	B2
Filing date	Jun 4, 2020
Priority date	Jun 4, 2019
Publication date	Jul 9, 2024
Grant date	Jul 9, 2024

Abstract

The invention relates to an optical waveguide with two or more light-guiding cores ( 1 a - 1 e ) extending continuously along the longitudinal extension of the optical waveguide, parallel to one another and spaced apart from one another, from one end of the optical waveguide to the other, and with a first cladding ( 2 ) enclosing the cores ( 1 a - 1 e ). It is an object of the invention to provide a multicore optical waveguide for high-power operation with reduced system complexity compared to the prior art. This object is achieved by the invention in that the cores ( 1 a - 1 e ) are arranged relative to one another and are spaced apart from one another in such a way that the propagation modes of the light propagating in the optical waveguide at a working wavelength couple to one another, the length of the optical waveguide being selected such that the light coupled into only a single one of the cores ( 1 a - 1 e ) at one end of the optical waveguide first spreads to the other cores ( 1 a - 1 e ) during propagation through the optical waveguide and, after passing through the optical waveguide, leaves the optical waveguide again at the other end from a single core ( 1 a ) with at least 60%, preferably at least 75%, of the total light power propagating in the optical waveguide. The invention also relates to a laser system with such an optical waveguide as an optical amplifier, and a method for guiding light in an optical waveguide.

First claim

The invention claimed is:

1. An optical waveguide with:
two or more light-guiding cores extending continuously along the longitudinal extension of the optical waveguide, parallel to one another and spaced apart from one another, from one end of the optical waveguide to the other, and
with a first cladding enclosing the cores,
wherein the cores are arranged relative to one another and are spaced apart from one another in such a way that the propagation modes of the light propagating in the optical waveguide at a working wavelength couple to one another, the length of the optical waveguide being selected such that the light coupled into a single one of the cores at one end of the optical waveguide first spreads to the other cores during propagation through the optical waveguide and, after passing through the optical waveguide, leaves the optical waveguide again at the other end from a single core with at least 60% of the total light power propagating in the optical waveguide;
wherein at least one of the cores is at least one doped core doped with rare earth ions;
wherein at least one of the other cores is at least one not doped core not doped with rare earth ions;
wherein an intensity of the light power propagating in the optical waveguide oscillates in the at least one doped core and in the at least one not doped core over a propagation distance while the light transfers back and forth between the cores,
wherein a length of the optical waveguide is set such that at least a majority of the light power propagating in the optical waveguide leaves the optical waveguide via the at least one not doped core.

2. The optical waveguide according to claim 1 , wherein the optical waveguide has a lower refractive index in the region forming the first cladding than in the regions forming the cores.

3. The optical waveguide according to claim 2 , wherein the regions forming the cores of the optical waveguide have refractive indices that differ from one another.

4. The optical waveguide according to claim 1 , wherein a refractive index in the region forming at least one of the cores varies along the longitudinal extension of the optical waveguide as a function of the propagation distance.

5. The optical waveguide according to claim 1 , further comprising a second cladding, which, as viewed in the cross-section of the optical waveguide, encloses the first cladding, wherein the optical waveguide has a lower refractive index in the region forming the second cladding than in the region of the first cladding.

6. The optical waveguide of claim 1 , wherein the length of the optical waveguide being selected such that, utilizing the Talbot effect, after the light has passed through the optical waveguide, it leaves the optical waveguide again at the other end from the single core with at least 75%.

7. The optical waveguide according to claim 1 , wherein all except one of the cores are doped with rare earth ions.

8. The optical waveguide according to claim 1 , comprising by a central core, arranged centrally as viewed in the cross-section of the optical waveguide, which is surrounded by at least four further cores in a cross-shaped arrangement.

9. The optical waveguide according to claim 1 , comprising a central core, arranged centrally as viewed in the cross-section of the optical waveguide, which is surrounded by further cores in a concentric, annular arrangement relative to the central core.

10. The optical waveguide according to claim 1 , wherein the cores have identical or different diameters and/or identical or different refractive index profiles.

11. A laser system with a laser light source and an optical amplifier coupled thereto, wherein the optical amplifier is formed by an optical waveguide according to claim 1 , wherein the optical waveguide is optically coupled to a pump light source.

12. A method for guiding light in an optical waveguide having two or more light-guiding cores extending continuously along the longitudinal extension of the optical waveguide, parallel to one another and spaced apart from one another, from one end of the optical waveguide to the other, and having a first cladding enclosing the cores, wherein the light is coupled into a single core at one end of the optical waveguide, the cores being arranged relative to one another and spaced apart from one another in such a way that the propagation modes of the light propagating in the optical waveguide at a working wavelength couple to one another, and the light initially spreads from the one core into the other cores, the length of the optical waveguide being selected such that, utilizing the Talbot effect, after the light has passed through the optical waveguide, it leaves the optical waveguide again at the other end from a single core with at least 60% of the total light power propagating in the optical waveguide;
wherein at least one of the cores is at least one doped core doped with rare earth ions;
wherein at least one of the other cores is at least one not doped core not doped with rare earth ions;
wherein an intensity of the light power propagating in the optical waveguide oscillates in the at least one doped core and in the at least one not doped core over a propagation distance while the light transfers back and forth between the cores,
wherein a length of the optical waveguide is set such that at least a majority of the light power propagating in the optical waveguide leaves the optical waveguide via the at least one not doped core.

13. The method of claim 12 , wherein the length of the optical waveguide being selected such that, utilizing the Talbot effect, after the light has passed through the optical waveguide, it leaves the optical waveguide again at the other end from the single core with at least 75%.

Assignees

• Fraunhofer Ges Forschung
• Univ Jena Friedrich Schiller

Inventors

• Jáuregui Misas César
• Limpert Jens
• Tünnermann Andreas

Classifications

• G02B6/021

  characterised by the core or cladding or coating, e.g. materials, radial refractive index profiles, cladding shape · CPC title

• H01S3/09415

  the pumping beam being parallel to the lasing mode of the pumped medium, e.g. end-pumping · CPC title

• H01S3/06733

  Fibre having more than one cladding · CPC title

• H01S3/094007

  Cladding pumping, i.e. pump light propagating in a clad surrounding the active core · CPC title

• H01S3/06754

  Fibre amplifiers (H01S3/06708 takes precedence) · CPC title