Multi-ridged subwavelength aperture for optical transmission and thermally assisted magnetic recording

• US 20070230010A1
• Filed: 04/04/2006
• Published: 10/04/2007
• Est. Priority Date: 04/04/2006
• Status: Active Grant

• Current Assignee: JP Morgan Chase Bank, N.A. (JP Morgan Chase & Co)
• Original Assignee: Hitachi Global Storage Technologies Netherlands BV (Western Digital Corporation)
• Inventors: Jin, Xuhui, Strand, Timothy, Yang, Henry, Poon, Chie
• Granted Patent: US 7,649,677 B2
• Time in Patent Office: Days
• US Class Current: 360/69
• CPC Class Codes: G11B 2005/0005 Arrangements, methods or circuits
• 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 5/02 Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
• CPC Class Codes: G11B 5/314 where the layers are extra layers normally not provided in the transducing structure, e.g. optical layers G11B5/3196 takes precedence

Abstract

A subwavelength aperture includes a plurality of ridges that project from an aperture sidewall into the aperture opening. The ridges may be closely spaced such that the hot spots associated with the ridges are likewise closely spaced and create an elongated hot spot. The subwavelength aperture of the present invention may be adapted for use in a magnetic head of a hard disk drive for improved thermally assisted recording (TAR) of magnetic data bits. Such a magnetic head may include an optical resonant cavity that is fabricated within the magnetic head structure.

Claims

1. A subwavelength aperture for transmitting optical energy, comprising:

a thin film of metallic material being disposed upon a substrate including an optically transparent material;

an aperture of optical subwavelength dimensions being disposed within said thin film, and wherein at least two ridges project from a first side of said aperture into said aperture towards an oppositely disposed second side of said aperture.

2. A subwavelength aperture as described in claim 1 wherein said aperture has a shape that is selected from the group consisting of circular, oval, square and rectangular.

3. A subwavelength aperture as described in claim 1 wherein said aperture has a longer width axis and a shorter height axis, and wherein said at least two ridges project from a first longer side of said aperture into said aperture towards an oppositely disposed second longer side of said aperture.

4. A subwavelength aperture as described in claim 3 wherein two said ridges project from said first side, and wherein said two ridges are spaced apart from each other by a central gap distance of from approximately 5 nm to approximately 100 nm.

5. A subwavelength aperture as described in claim 4 wherein each of said two ridges is generally rectangular in shape.

6. A subwavelength aperture as described in claim 5 wherein said ridges are spaced apart from said oppositely disposed second longer side by a distance of from approximately 5 nm to approximately 150 nm.

7. A subwavelength aperture as described in claim 5 wherein said ridges have length and width dimensions of from approximately 5 nm to approximately 100 nm.

8. A subwavelength aperture as described in claim 1 wherein said thin film is comprised of a nonferrous metal.

9. A subwavelength aperture as described in claim 1 wherein said thin film is comprised of a metal taken from the group consisting of silver, gold, aluminum, rhodium, platinum and chromium.

10. A subwavelength aperture as described in claim 3 wherein three said ridges project from said first side.

11. A subwavelength aperture as described in claim 10 wherein said ridges are spaced apart from each other by gap distances of from approximately 5 nm to approximately 100 nm.

12. A subwavelength aperture as described in claim 10 wherein each of said ridges is generally rectangular in shape.

13. A subwavelength aperture as described in claim 12 wherein said ridges are spaced apart from said oppositely disposed second longer side by a distance of from approximately 5 nm to approximately 150 nm.

14. A subwavelength aperture as described in claim 12 wherein said ridges have length and width dimensions of from approximately 5 nm to approximately 100 nm.

15. A subwavelength aperture as described in claim 1 wherein said aperture is formed with an E shape.

16. A subwavelength aperture as described in claim 1 wherein at least one further ridge projects into said aperture from said second side.

17. A subwavelength aperture as described in claim 1 wherein at least two further ridges project into said aperture from said second side, and wherein said further ridges are spaced apart by gap distances of from approximately 5 nm to approximately 100 nm.

18. A magnetic head, comprising:

a write head portion including a write pole tip and having an air bearing surface thereof;

a light transmitting device being disposed proximate said write pole tip;

a subwavelength aperture being disposed proximate said air bearing surface and said light transmitting device, whereby optical energy from said light transmitting device projects through said subwavelength aperture generally perpendicularly to said air bearing surface; and

wherein said subwavelength aperture includes an aperture of optical subwavelength dimensions being disposed within a thin metallic film, and wherein at least two ridges project from a first side of said aperture into said aperture towards an oppositely disposed second side of said aperture.

19. A magnetic head as described in claim 18 wherein said aperture has a shape that is selected from the group consisting of circular, oval, square and rectangular.

20. A magnetic head as described in claim 18 wherein said aperture has a longer width axis and a shorter height axis, and wherein at least two ridges project from a first longer side of said aperture into said aperture towards an oppositely disposed second longer side of said aperture.

21. A magnetic head as described in claim 20 wherein two said ridges project from said first side and wherein said two ridges are spaced apart by a central gap distance of from approximately 5 nm to approximately 100 nm.

22. A magnetic head as described in claim 21 wherein each of said two ridges is generally rectangular in shape.

23. A magnetic head as described in claim 18 wherein said thin film is comprised of a nonferrous metal.

24. A magnetic head as described in claim 20 wherein three said ridges project from said first side.

25. A magnetic head as described in claim 24 wherein said three ridges are spaced apart from each other by gap distances of from approximately 5 nm to approximately 100 nm.

26. A magnetic head as described in claim 18 wherein at least one further ridge projects into said aperture from said second side.

27. A magnetic head as described in claim 18 wherein at least two further ridges project into said aperture from said second side, and wherein said further ridges are spaced apart by gap distances of from approximately 5 nm to approximately 100 nm.

28. A magnetic head as described in claim 18 wherein said light transmitting device includes an optical waveguide being disposed proximate said write pole tip;

and

an optical energy source and an optical energy transfer means to couple optical energy from the source to said optical waveguide.

29. A magnetic head as described in claim 28 wherein said subwavelength aperture provides a heating spot having dimensions on a magnetic disk medium that have approximately the same aspect ratio as data bits formed on said disk medium.

30. A hard disk drive, comprising:

at least one hard disk being fabricated for rotary motion upon a disk drive;

at least one magnetic head adapted to fly over said hard disk for writing data on said hard disk, said magnetic head including;

a write head portion including a write pole tip and having an air bearing surface thereof;

a light transmitting device being disposed proximate said write pole tip;

a subwavelength aperture being disposed proximate said air bearing surface and said light transmitting device, whereby optical energy from said light transmitting device projects through said subwavelength aperture generally perpendicularly to said air bearing surface; and

wherein said subwavelength aperture includes an aperture of optical subwavelength dimensions being disposed within a thin metallic film, and wherein at least two ridges project from a first side of said aperture into said aperture towards an oppositely disposed second side of said aperture.

31. A hard disk drive as described in claim 30 wherein said aperture has a shape that is selected from the group consisting of circular, oval, square and rectangular.

32. A hard disk drive as described in claim 30 wherein said aperture has a longer width axis and a shorter height axis, and wherein at least two ridges project from a first longer side of said aperture into said aperture towards an oppositely disposed second longer side of said aperture.

33. A hard disk drive as described in claim 30 wherein said thin film is comprised of a nonferrous metal.

34. A hard disk drive as described in claim 30 wherein at least one further ridge projects into said aperture from said second side.

35. A hard disk drive as described in claim 30 wherein said light transmitting device includes an optical resonant cavity being disposed proximate said write pole tip;

and

an optical energy source and an optical energy transfer means to couple optical energy from the source to said resonant cavity.

36. A hard disk drive as described in claim 30 wherein said subwavelength aperture provides a heating spot having aspect ratio and dimensions on a magnetic disk medium that are approximately the same as data bits formed on said disk medium.