Photonic crystal fiber, a method of production thereof and a supercontinuum light source

Patent metadata

Field	Value
Publication number	US-10228510-B2
Application number	US-201515537005-A
Country	US
Kind code	B2
Filing date	Dec 15, 2015
Priority date	Dec 18, 2014
Publication date	Mar 12, 2019
Grant date	Mar 12, 2019

Abstract

The invention concerns a Photonic Crystal Fiber (PCF) a method of its production and a supercontinuum light source comprising such PCF. The PCF has a longitudinal axis and comprises a core extending along the length of said longitudinal axis and a cladding region surrounding the core. At least the cladding region comprises a plurality of microstructures in the form of inclusions extending along the longitudinal axis of the PCF in at least a microstructured length section. In at least a degradation resistant length section of the microstructured length section the PCF comprises hydrogen and/or deuterium. In at least the degradation resistant length section the PCF further comprises a main coating surrounding the cladding region, which main coating is hermetic for the hydrogen and/or deuterium at a temperature below Th, wherein Th is at least about 50° C., preferably 50° C.<Th<250° C.

First claim

The invention claimed is:

1. A microstructured fiber (MSF) comprising:
a solid core extending along a longitudinal axis of the MSF,
a cladding region surrounding the core,
wherein at least the cladding region comprises a plurality of inclusions extending along the longitudinal axis of the MSF in at least a length section,
wherein the MSF, in at least a selected length section of said length section, comprises hydrogen and/or deuterium,
wherein the MSF, in at least said selected length section, further comprises a coating surrounding the cladding region, wherein the coating is hermetic for said hydrogen and/or deuterium at a temperature below T h , wherein T h is 50° C.<T h <250° C.,
wherein the cladding region in at least said selected length section comprises an inner cladding region comprising the plurality of inclusions and an outer cladding region surrounding the inner cladding region and wherein the radial distance between an outermost inclusion of the inner cladding region and the coating is at least about 10 μm.

2. The MSF of claim 1 , wherein the plurality of inclusions is arranged in a pattern comprising at least two rings of inclusions surrounding the core.

3. The MSF of claim 1 , wherein the plurality of inclusions comprise gas inclusions.

4. The MSF of claim 1 , wherein said selected length section is the whole length of the MSF with an exception of any closed ends of the MSF, wherein a closed ends can have a length along the longitudinal axis of the MSF of up to about 3 mm.

5. The MSF of claim 1 , further comprising inclusions located in the outer cladding region (“outer inclusion”), wherein said inclusions located in the inner cladding region (“inner inclusions”) are larger than the outer inclusions.

6. The MSF of claim 1 , wherein material between the inner cladding region and the main coating forms a reservoir for hydrogen and/or deuterium.

7. The MSF of claim 1 , wherein the core in at least said selected length section has a core diameter of about 10 μm or less.

8. The MSF of claim 1 , wherein an innermost inclusion in at least said selected length section has a center-to-center distance to the core of less than about 50 μm.

9. The MSF of claim 1 , wherein the MSF has anomalous dispersion for at least one wavelength between 1000 nm and 1100 nm.

10. The MSF of claim 1 , wherein the core of the MSF is spatially single mode at 1064 nm.

11. The MSF of claim 1 , wherein the core of the MSF is single mode at 1030 nm.

12. The MSF of claim 1 , wherein at least the core of the MSF is essentially free of Germanium.

13. The MSF of claim 1 , wherein at least the core of the MSF is essentially free of active material.

14. The MSF of claim 1 , wherein the coating comprises nitride, carbon, aluminum, gold, copper, nickel, metallic glass or a combination or an alloy comprising one or more of the before mentioned.

15. The MSF of claim 1 , wherein the main coating has a thickness of about 5 nm to about 25 μm.

16. The MSF of claim 1 , wherein the coating is diffusion open for hydrogen and/or deuterium at a temperature above T o , where T o is larger than T h .

17. The MSF of claim 1 , wherein the MSF comprises at least one additional coating for mechanical protection outside said coating.

18. The MSF of claim 1 , wherein the MSF comprises at least one tapered length section wherein said core in a first end of the tapered length section has a core diameter D 1 and said core in a second end of the tapered length section has a core diameter D 2 , wherein D 1 is larger than D 2 .

19. The MSF of claim 18 , wherein the first end of the tapered length section is at a launching end of the fiber or up to 5 cm along the length from the launching end of the fiber.

20. The MSF of claim 1 , wherein the MSF comprises at least two spliced fiber length sections, wherein at least one spliced fiber length section is or comprises said selected length section.

21. The MSF of claim 1 , wherein the MSF comprises:
a first length section with a first length L 1 , wherein the inclusions of said MSF at least at a first cross-section through the first length section perpendicularly to the longitudinal axis have
a first pitch Λ 1 ,
a first inclusion diameter d 1 , and
a first relative size d 1 /Λ 1 of inclusions,

a second length section with a second length L 2 , wherein the inclusions of said MSF at least at a second cross-section through the second length section perpendicularly to the longitudinal axis have
a second pitch Λ 2 ,
a second inclusion diameter d 2 , and
a second relative size d 2 /Λ 2 of inclusions, and

wherein at least one of said first length L 1 and said second length L 2 comprises said selected length section.

22. The MSF of claim 1 , wherein the MSF comprises a mode-adaptor extending along the length of the MSF in at least a mode-field adapting length section extending from a launching end of the MSF up to 5 cm from the launching end of the MSF, wherein said mode-field adapting length section has a length of at least about 5 cm.

23. A method of producing the MSF as claimed in claim 1 , wherein the method comprises
producing a preform comprising a preform structure for the core and the cladding region of the MSF,
drawing the preform to obtain the core and cladding region of the MSF,
subjecting at least the selected length section of the MSF to hydrogen and/or deuterium loading, and
applying the coating to at least said selected length section of the MSF.

24. The method of claim 23 , wherein the method comprises subjecting the MSF to hydrogen and/or deuterium loading prior to application of the coating.

25. The method of claim 24 , wherein the hydrogen and/or deuterium loading comprises placing the MSF in a chamber containing hydrogen and/or deuterium at a pressure of at least about P 1 and temperature of at least about T 1 for a duration of at least t 1 .

26. The method of claim 23 , wherein the method comprises subjecting the MSF to hydrogen and/or deuterium loading after application of the coating.

27. The method of claim 26 , wherein the method comprises
subjecting the MSF to hydrogen and/or deuterium at a temperature of at least about T o , and
cooling the MSF to T h or less.

28. The method of claim 26 , wherein the hydrogen and/or deuterium loading comprises placing the MSF in a chamber containing hydrogen and/or deuterium at a pressure of at least about P 2 and temperature of at least about T 2 >T o for a duration of at least t 2 .

29. The method of claim 23 , wherein the inclusions comprise gas and the method comprises closing said inclusions on either side of said selected length section.

30. The method of claim 29 , wherein the inclusions are closed prior to subjecting the MSF to hydrogen and/or deuterium loading.

31. The method of claim 23 , wherein the method comprises application of at least one additional coating outside said coating.

32. The method of claim 23 , wherein the coating is a carbon coating, said method comprises applying said carbon coating by a chemical vapor deposition process comprising pulling the fiber through a reactor chamber of a reactor and subjecting the fiber in the reactor chamber to a reactor gas at a temperature of at least about 700° C., wherein the reactor gas comprises a carbonaceous composition.

Assignees

• Nkt Photonics As

Inventors

• Alkeskjold Thomas Tanggaard
• Byg Casper Laur
• Jakobsen Christian
• Lyngsøe Jens Kristian
• Jespersen Kim G
• Johansen Jeppe
• Maack Martin Dybendal
• Pedersen Martin Erland Vestergaard
• Thomsen Carsten L

Classifications

• C03B37/0279

  Photonic crystal fibres or microstructured optical fibres other than holey optical fibres · CPC title

• G02F1/365

  in an optical waveguide structure (G02F1/377, {G02F1/395} take precedence) · CPC title

• C03C25/607

  in the gaseous phase · CPC title

• C03B2201/12

  doped with fluorine (C03B2201/14 takes precedence) · CPC title

• C03B2203/14

  Non-solid, i.e. hollow products, e.g. hollow clad or with core-clad interface · CPC title