Heat-assisted magnetic recording device having external cavity laser with slot waveguide

• US 9,960,570 B1
• Filed: 05/22/2017
• Issued: 05/01/2018
• Est. Priority Date: 05/26/2016
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Goggin, Aidan Dominic, Gubbins, Mark Anthony, Hardy, Michael James, Hamilton, Kelly Elizabeth
• Primary Examiner(s): Dinh, Tan X
• Application Number:
  US15/601,024
• Time in Patent Office: 344 Days
• Field of Search: None
• CPC Class Codes: G11B 2005/0021 Thermally assisted recording using an auxiliary energy source for heating the recording layer locally to assist the magnetization reversal
• CPC Class Codes: G11B 5/6088 Optical waveguide in or on flying head
• CPC Class Codes: G11B 7/126 Circuits, methods or arrangements for laser control or stabilisation
• CPC Class Codes: H01S 3/08045 Single-mode emission
• CPC Class Codes: H01S 3/0805 by apertures, e.g. pin-holes or knife-edges
• CPC Class Codes: H01S 3/08068 Holes; Stepped surface; Special cross-section
• CPC Class Codes: H01S 5/14 External cavity lasers H01S5/18 takes precedence; mode locking H01S5/065

Abstract

A slider includes a slot waveguide configured to receive energy from an input surface. The slot waveguide has first and second high-index regions surrounding a middle region that extends along a light propagation direction. The middle region has a refractive index less than that of the first and second high index regions. A near-field transducer is at an output portion of the middle region at media-facing surface. The near-field transducer has first and second plates parallel to the media-facing surface with a gap therebetween. An active laser region has a front facet optically coupled to the input surface of the slider. A reflective back facet of the laser and the near-field transducer define a single optical resonator.

Claims

1. An apparatus comprising:

a slider comprising;

a slot waveguide configured to receive energy from an input surface, the slot waveguide comprising first and second high-index regions surrounding a middle region that extends along a light propagation direction, the middle region having a refractive index less than that of the first and second high index regions; and

a near-field transducer at an output portion of the middle region at media-facing surface, the near-field transducer comprising first and second plates parallel to the media-facing surface with a gap therebetween; and

an active laser region with a reflective back facet and a front facet, the front facet optically coupled to the input surface of the slider, the reflective back facet and the near-field transducer defining a single optical resonator.

2. The apparatus of claim 1, wherein the first and second high-index regions have angled portions that result in a reduced cross-track width in the middle region as it approaches the media facing surface.

3. The apparatus of claim 2, wherein the first and second high-index regions have input regions of constant cross-track width near the input surface, the angled portions extending from the input regions to the media-facing surface.

4. The apparatus of claim 2, wherein the angled portions comprise tapers that result in respective first and second reduced cross-track widths in the first and second high-index regions as they approach the media-facing surface.

5. The apparatus of claim 1, wherein the first and second high-index regions are surrounded on three-sides by an intermediate-index layer and on fourth sides by a low-index layer, the intermediate-index layer forming the middle region and having an intermediate refractive index that is less than that of the high-index layer and more than that of the low-index layer.

6. The apparatus of claim 5, wherein a side of the intermediate-index layer facing away from the first and second high-index regions is covered by a second low-index layer, the intermediate refractive index being more than that of the low-index layer.

7. The apparatus of claim 1, wherein the first and second plates have an area that is larger than a corresponding cross-section of the first and second high index regions at the output portion.

8. The apparatus of claim 1, wherein the first and second plates are rectangular.

9. The apparatus of claim 1, further comprising a magnetic write pole and a heat-assisted, magnetic recording medium that is heated by surface plasmon emissions of the near-field transducer while the magnetic write pole applies a changing field to the magnetic recording medium, the surface plasmon emissions caused by a portion of the energy passing through the gap of the near-field transducer.

10. A method comprising:

applying current to an active laser region with a reflective back facet and a front facet externally coupled to an input surface of a slider, the application of the current causing energy to be emitted into the input surface;

receiving the energy from the input surface at a slot waveguide comprising first and second high-index regions surrounding a middle region that extends along a light propagation direction, the middle region having a refractive index less than that of the first and second high index regions, the energy being coupled into the middle region;

directing the energy from an output portion of the middle region to a near-field transducer at a media-facing surface, the near-field transducer comprising first and second plates parallel to the media-facing surface with a gap therebetween; and

reflecting the energy from the near-field transducer to the reflective back facet such that the reflective back facet and the near-field transducer define a single resonator.

11. The method of claim 10, wherein the first and second high-index regions have angled portions that result in a reduced cross-track width in the middle region as it approaches the media facing surface.

12. The method of claim 11, wherein the first and second high-index regions have input regions of constant cross-track width near the input surface, the angled portions extending from the input regions to the media-facing surface.

13. The method of claim 11, wherein the angled portions comprise tapers that result in respective first and second reduced cross-track widths in the first and second high-index regions as they approach the media-facing surface.

14. The method of claim 10, wherein the first and second high-index regions are surrounded on three-sides by an intermediate-index layer and on fourth sides by a low-index layer, the intermediate-index layer forming the middle region and having an intermediate refractive index that is less than that of the high-index layer and more than that of the low-index layer.

15. The method of claim 14, wherein a side of the intermediate-index layer facing away from the first and second high-index regions is covered by a second low-index layer, the intermediate refractive index being more than that of the low-index layer.

16. The method of claim 10, wherein the first and second plates have an area that is larger than a corresponding cross-section of the first and second high index regions at the output portion.

17. The method of claim 10, wherein the first and second plates are rectangular.

18. The method of claim 10, further comprising:

heating a heat-assisted, magnetic recording medium via surface plasmon emissions of the near-field transducer caused by a portion of the energy passing through the gap of the near-field transducer; and

applying a changing field to the magnetic recording medium while it is being heated.

19. A slider comprising:

a magnetic write pole near a media-facing surface; and

an external cavity resonator comprising;

an active laser region with a reflective back facet and a front facet, the front facet optically coupled to an input surface of the slider;

a slot waveguide configured to receive energy from the input surface, the slot waveguide comprising first and second tapered high-index regions surrounding a tapered middle region that extends along a light propagation direction, the middle region having a refractive index less than that of the first and second high index regions; and

a near-field transducer at an output portion of the middle region near the write pole, the near-field transducer comprising first and second plates parallel to the media-facing surface with a gap therebetween, wherein the energy reflects between the reflective back facet of the active laser region and the first and second plate to amplify the energy, a portion of the energy causing surface plasmons to resonate in the gap, the surface plasmons directed out of the media-facing surface to form a hot spot on a recording medium while the write pole applies a magnetic field to the hotspot.

20. The slider of claim 19, wherein the first and second high-index regions are surrounded on three-sides by an intermediate-index layer and on fourth sides by a low-index layer, the intermediate-index layer forming the middle region and having an intermediate refractive index that is less than that of the high-index layer and more than that of the low-index layer.