Input coupler with features to divert stray light from a waveguide

Patent metadata

Field	Value
Publication number	US-10614843-B2
Application number	US-201916446882-A
Country	US
Kind code	B2
Filing date	Jun 20, 2019
Priority date	Jul 17, 2018
Publication date	Apr 7, 2020
Grant date	Apr 7, 2020

Abstract

A recording head has a waveguide core with an input end proximate an energy source at an input surface of the recording head. The waveguide core couples light from the energy source to a near-field transducer that heats a recording medium in response to the light. An input coupler extends along the waveguide core from the input end to a termination region that is away from the input end in a light propagation direction. The input coupler has a first refractive index between that of the waveguide core and a surrounding material. The input coupler is wider than the waveguide core and has a slanted edge at the termination region. The slanted edge crosses the waveguide core such that the input coupler narrows to a neck away from the waveguide core in a crosstrack direction.

First claim

What is claimed is:

1. A recording head comprising:
a waveguide core comprising an input end proximate an energy source at an input surface of the recording head, the waveguide core coupling light from the energy source to a near-field transducer that heats a recording medium in response to the light; and
an input coupler extending along the waveguide core from the input end to a termination region that is away from the input end in a light propagation direction, the input coupler comprising a first refractive index between that of the waveguide core and a surrounding material; the input coupler being wider than the waveguide core and having a slanted edge at the termination region, the slanted edge crossing the waveguide core such that the input coupler narrows to a neck away from the waveguide core in a crosstrack direction.

2. The recording head of claim 1 , wherein the neck diverts stray light away from the waveguide core.

3. The recording head of claim 1 , further comprising an escape slab having an edge joined with the neck of the input coupler.

4. The recording head of claim 3 , wherein the escape slab dissipates light coupled from the neck of the input coupler.

5. The recording head of claim 3 ; wherein the escape slab comprises:
an opaque coating on one edge of the escape slab; and
an aperture formed within the opaque coating, the aperture allowing light to exit the escape slab.

6. The recording head of claim 5 , further comprises a sensor that detects the light that exits the escape slab, the sensor used to determine alignment of the energy source with the waveguide core based on the light that exits the slab being at a minimum value.

7. The recording head of claim 1 , wherein the slanted edge of the input coupler reflects stray light that is not coupled into the waveguide core away from the light source.

8. The recording head of claim 1 , wherein the slanted edge is at an angle relative to a light propagation direction of the waveguide, the angle being less than 15 degrees.

9. The recording head of claim 1 , wherein the input coupler comprises a second slanted edge that does not cross the waveguide core, the second slanted edge being at a different angle relative to a light propagation direction of the waveguide than the slanted edge.

10. A recording head, comprising:
a waveguide core extending from a light source to a near-field transducer;
an input coupler extending along the waveguide core, the input coupler having a first end at the light source and a second end with a tapered neck that terminates off-center from the waveguide core in a crosstrack direction, the second end located between the light source and the near-field transducer; and
an escape slab joined with the neck of the input coupler, stray light from the input coupler being coupled into the escape slab via the neck.

11. The recording head of claim 10 , wherein the escape slab dissipates light coupled from the neck of the input coupler.

12. The recording head of claim 10 , wherein the escape slab comprises:
an opaque coating on one edge of the escape slab; and
an aperture formed within the opaque coating, the aperture allowing light to exit the escape slab.

13. The recording head of claim 12 , further comprises a sensor that detects the light that exits the escape slab, the sensor used to determine alignment of the energy source with the waveguide core based on the light that exits the slab being at a minimum value.

14. The recording head of claim 10 , wherein the neck of the input coupler comprises a slanted edge that crosses over the waveguide core; slanted edge reflecting stray light that is not coupled into the waveguide core away from the light source.

15. The recording head of claim 14 , wherein the slanted edge is at an angle relative to a light propagation direction of the waveguide, the angle being less than 15 degrees.

16. The recording head of claim 14 , wherein the input coupler comprises a second slanted edge that does not cross the waveguide core, the second slanted edge being at a different angle relative to a light propagation direction of the waveguide than the slanted edge.

17. A method comprising:
coupling light from an energy source into an input coupler of a recording head;
directing a first part of the light from the input coupler to a waveguide core, the waveguide core delivering the first part of the light to a near-field transducer that heats a magnetic recording medium; and
directing a second part of the light to a tapered neck of the input coupler, the tapered neck terminating off-center from the waveguide core in a crosstrack direction and reducing reflections of the second part of the light back towards the energy source.

18. The method of claim 17 , further comprising directing the second part of the light into an escape slab.

19. The method of claim 18 , wherein the second part of the light is dissipated in the escape slab.

20. The method of claim 18 , wherein the escape slab comprises:
an opaque coating on one edge of the escape slab; and
an aperture formed within the opaque coating, the aperture allowing light to exit the escape slab, the method further comprises measuring the second part of the light via the aperture to assist in aligning the energy source with the recording head.

Assignees

• Seagate Technology Llc

Inventors

• Harvey Christopher Neil
• Callan Kelly Elizabeth
• Goggin Aidan Dominic
• Mcgurk John Bernard
• Mehfuz Reyad
• Ward Christopher Gerwyn

Classifications

• G11B5/3133 Primary

  including layers not usually being a part of the electromagnetic transducer structure and providing additional features, e.g. for improving heat radiation, reduction of power dissipation, adaptations for measurement or indication of gap depth or other properties of the structure (G11B5/3106 takes precedence) · CPC title

• G02B6/305 Primary

  and having an integrated mode-size expanding section, e.g. tapered waveguide · CPC title

• G11B2005/0021

  Thermally assisted recording using an auxiliary energy source for heating the recording layer locally to assist the magnetization reversal · CPC title

• G11B5/4866 Primary

  the arm comprising an optical waveguide, e.g. for thermally-assisted recording · CPC title