Method of laser modification of an optical fibre

Patent metadata

Field	Value
Publication number	US-11467337-B2
Application number	US-201816636364-A
Country	US
Kind code	B2
Filing date	Aug 7, 2018
Priority date	Aug 7, 2017
Publication date	Oct 11, 2022
Grant date	Oct 11, 2022

Abstract

Method of laser modifying an optical fibre to form a modified region at a target location within the fibre, comprising positioning at least a portion of an optical fibre in a laser system for modification by a laser, applying a correction to an active optical element of the laser system to modify wavefront properties of the laser to counteract an effect of aberration on laser focus, and laser modifying the optical fibre at the target location using the laser with the corrected wavefront properties to produce the modified region.

First claim

The invention claimed is:

1. A method of laser modifying an optical fibre to form a modified region at a target location within the fibre, comprising:
positioning at least a portion of an optical fibre in a laser system for modification by a laser;
determining a correction to be applied to an active optical element of the laser system based at least upon characteristics of the optical fibre;
applying the correction to the active optical element of the laser system to modify wavefront properties of the laser to counteract an effect of aberration of the fibre on laser focus, wherein applying the correction to the active optical element comprises applying the correction to the active optical element to modify wavefront properties of the laser to counteract an effect of spherical aberration on laser focus or of coma on laser focus or both spherical aberration and coma on laser focus; and
laser modifying the optical fibre at the target location using the laser with the corrected wavefront properties to produce the modified region.

2. A method as claimed in claim 1 , wherein the step of determining the correction comprises determining the correction based upon the position of the target location within the fibre.

3. A method as claimed in claim 1 wherein the step of applying the correction to the active optical element comprises applying the correction to the active optical element to modify wavefront properties of the laser to counteract an effect of astigmatic aberration on laser focus.

4. A method as claimed in claim 1 , comprising determining at least one characteristics of the optical fibre and determining the correction based at least upon said at least one characteristic.

5. A method as claimed in claim 1 , comprising changing the correction based upon a change of the target location within the optical fibre.

6. A method as claimed in claim 1 , comprising modifying a plurality of regions which are spatially separated from one another within a transverse cross-section of the fibre.

7. A method as claimed in claim 1 , wherein the correction counteracts an effect of aberration on laser focus caused by refraction at a plurality of optical interfaces of the fibre.

8. A method as claimed in claim 1 , wherein the correction counteracts an effect of astigmatic aberration on laser focus caused by the outer surface of the fibre, and/or an effect of astigmatic aberration on laser focus caused by an interface between a fibre core and cladding surrounding the fibre core.

9. A method as claimed in claim 1 , wherein the correction counteracts an effect of coma on laser focus caused by the outer surface of the fibre, and/or an effect of coma on laser focus caused by an interface between a fibre core and cladding surrounding the fibre core.

10. A method as claimed in claim 1 , comprising modifying a region of the fibre proximate a channel within the fibre.

11. A method as claimed in claim 1 , wherein the correction is a phase field comprising a discontinuity for applying different corrections to rays incident on different parts of the fibre.

12. A method as claimed in claim 1 , comprising using a dry objective lens.

13. A method as claimed in claim 1 , comprising etching the laser modified region to form a micro-channel.

14. A method of laser modifying an optical fibre to form a modified region at a target location within the fibre, comprising:
positioning at least a portion of an optical fibre in a laser system for modification by a laser;
determining a correction to be applied to an active optical element of the laser system based at least upon characteristics of the optical fibre;
applying the correction to the active optical element of the laser system to modify wavefront properties of the laser to counteract an effect of aberration of the fibre on laser focus; and
laser modifying the optical fibre at the target location using the laser with the corrected wavefront properties to produce the modified region;
wherein the focus of the corrected laser has a Strehl ratio of at least 0.5.

15. A method of laser modifying an optical fibre to form a modified region at a target location within the fibre, comprising:
positioning at least a portion of an optical fibre in a laser system for modification by a laser;
determining a correction to be applied to an active optical element of the laser system based at least upon characteristics of the optical fibre;
applying the correction to the active optical element of the laser system to modify wavefront properties of the laser to counteract an effect of aberration of the fibre on laser focus;
laser modifying the optical fibre at the target location using the laser with the corrected wavefront properties to produce the modified region;
measuring the laser focus within the optical fibre and determining the correction based at least upon that measurement.

16. A method of laser modifying an optical fibre to form a modified region at a target location within the fibre, comprising:
positioning at least a portion of an optical fibre in a laser system for modification by a laser;
determining a correction to be applied to an active optical element of the laser system based at least upon characteristics of the optical fibre;
applying the correction to the active optical element of the laser system to modify wavefront properties of the laser to counteract an effect of aberration of the fibre on laser focus; and
laser modifying the optical fibre at the target location using the laser with the corrected wavefront properties to produce the modified region;
wherein producing the modified region comprises forming at least a section of an optical core of the fibre; and/or wherein the method comprises forming a plurality of sections of optical cores.

17. A method of laser modifying an optical fibre to form a modified region at a target location within the fibre, comprising:
positioning at least a portion of an optical fibre in a laser system for modification by a laser;
determining a correction to be applied to an active optical element of the laser system based at least upon characteristics of the optical fibre;
applying the correction to the active optical element of the laser system to modify wavefront properties of the laser to counteract an effect of aberration of the fibre on laser focus;
laser modifying the optical fibre at the target location using the laser with the corrected wavefront properties to produce the modified region; and
forming the modified region within an optical core of the optical fibre.

18. A method as claimed in claim 17 , comprising translating the optical fibre during modification thereof; and/or comprising rotating the optical fibre about its longitudinal axis.

19. A method as claimed in claim 17 , comprising forming a fibre Bragg grating within the fibre.

20. A method as claimed in claim 17 , wherein the optical fibre comprises at least one of a sapphire fibre, a photonic crystal fibre, a polymer fibre, a silica fibre, a hydrogel fibre, a high refractive index optical fibre, a non-cylindrical optical fibre, a multimode fibre, a polarisation maintaining fibre, an air-hole fibre, or a multi-core fibre.

21. A method of laser modifying an optical fibre to form a modified region at a target location within the fibre, comprising:
positioning at least a portion of an optical fibre in a laser system for modification by a laser;
determining a correction to be applied to an active optical element of the laser system based at least upon characteri

Assignees

• Univ Oxford Innovation Ltd

Inventors

• Fells Julian
• Booth Martin
• Salter Patrick

Classifications

• G02B2006/02161

  Grating written by radiation passing through the protective fibre coating · CPC title

• G02B6/02123 Primary

  characterised by the method of manufacture of the grating (photolithography G03F7/0005) · CPC title

• G02B6/02147 Primary

  Point by point fabrication, i.e. grating elements induced one step at a time along the fibre, e.g. by scanning a laser beam, arc discharge scanning (G02B6/02133 and G02B6/02142 take precedence) · CPC title

• G02B6/02333

  Core having higher refractive index than cladding, e.g. solid core, effective index guiding · CPC title

• G02B6/02314

  Plurality of longitudinal structures extending along optical fibre axis, e.g. holes · CPC title