Compact mode converter having first and second straight portions for heat-assisted magnetic recording device

Patent metadata

Field	Value
Publication number	US-11443765-B2
Application number	US-202117221945-A
Country	US
Kind code	B2
Filing date	Apr 5, 2021
Priority date	Apr 25, 2018
Publication date	Sep 13, 2022
Grant date	Sep 13, 2022

Abstract

A write head includes an input coupler configured to receive light excited by a light source. A waveguide core is configured to receive light from the input coupler at a fundamental transverse electric (TE00) mode. The waveguide core has a first straight portion. The waveguide core has a mode converter portion comprising a branched portion extending from the first straight portion. The mode converter portion is configured to convert the light to a higher-order (TE10) mode, the mode converter portion spaced apart from the input coupler. The waveguide core has a second straight portion between the mode converter portion and a media-facing surface. The write head has a near-field transducer at the media-facing surface, the near-field transducer receiving the light at the TE10 mode from the waveguide and directing surface plasmons to a recording medium in response thereto.

First claim

What is claimed is:

1. A write head comprising:
an input coupler configured to receive light excited by a light source;
a waveguide core configured to receive light from the input coupler at a fundamental transverse electric (TE 00 ) mode, the waveguide core comprising:
a first straight portion extending from the input coupler;
a mode converter portion comprising a branched portion extending from the first straight portion, the mode converter portion configured to convert the light to a higher-order (TE 10 ) mode, the mode converter portion separated from the input coupler by the first straight portion such that the mode converter is moved out of the input coupler; and
a second straight portion between the mode converter portion and a media-facing surface, wherein the first straight portion has a length greater than that of the second straight portion; and

a near-field transducer at the media-facing surface, the near-field transducer configured to receive the light at the TE 10 mode from the waveguide and direct surface plasmons to a recording medium in response thereto.

2. The write head of claim 1 , wherein the branched portion is separated from at least part of the first straight portion by a gap for a predetermined length.

3. The write head of claim 2 , wherein the gap has a substantially constant cross-sectional width.

4. The write head of claim 1 , wherein the branched portion comprises a taper.

5. The write head of claim 1 , wherein the second straight portion and the branched portion combine to form a predetermined combined width.

6. The write head of claim 5 , wherein one or both of the second straight portion and the branched portion has a taper to accommodate the difference in the combined width.

7. The write head of claim 6 , wherein the taper has a length in a range of about 2 μm to about 8 μm.

8. The write head of claim 1 , wherein the mode converter portion has a length in a range of about 15 μm to about 24 μm.

9. The write head of claim 1 , wherein the mode converter portion has a length of about 17 μm.

10. The write head of claim 1 , wherein the light source comprises an active region formed a non-self supporting, crystalline layer transfer printed to a substrate of the write head.

11. The write head of claim 1 , wherein the waveguide core is configured to receive the light emitted in a crosstrack direction from the light source.

12. The write head of claim 11 , wherein the waveguide core comprises:
a first turn that receives the light in the crosstrack direction redirects the light to an opposite crosstrack direction;
a second turn that redirects the light to a direction normal to a media-facing surface of the write head;
a first straight portion coupling the first and second turns; and
a second straight portion between the second turn and the media-facing surface.

13. A write head comprising:
an input coupler configured to receive light excited by a light source;
a waveguide core configured to receive light from the input coupler at a fundamental transverse electric (TE 00 ) mode, the waveguide core comprising:
an input portion extending from the input coupler and configured to receive light from the input coupler;
a mode converter portion comprising a branched portion extending from the input portion, the mode converter portion configured to convert the light to a higher-order (TE 10 ) mode, the mode converter potion separated from the input coupler by the input portion such that the mode converter is moved out of the input coupler; and
an output portion between the mode converter portion and a media-facing surface, wherein the input portion has a length greater than that of the output portion; and

a near-field transducer at the media-facing surface, the near-field transducer configured to receive the light at the TE 10 to mode from the waveguide and direct surface plasmons to a recording medium in response thereto.

14. The write head of claim 13 , wherein the mode converter portion comprises a main branch and a secondary branch, the main branch at least partially separated from the secondary branch by a by a gap for a predetermined length.

15. The write head of claim 14 , wherein the gap has a substantially constant cross-sectional width.

16. The write head of claim 14 , wherein the main branch and the secondary branch combine to form a predetermined combined width.

17. The write head of claim 16 , wherein one or both of the main branch and the secondary branch has a taper to accommodate the difference in the combined width.

18. The write head of claim 17 , wherein the taper has a length in a range of about 2 μm to about 8 μm.

19. The write head of claim 13 , wherein the mode converter portion has a length in a range of about 15 μm to about 24 μm.

20. The write head of claim 13 , wherein the mode converter portion has a length of about 17 μm.

21. The write head of claim 1 , wherein the first straight portion has a length at least twice that of the second straight portion.

22. The write head of claim 13 , wherein the input portion has a length at least twice that of the output portion.

Assignees

• Seagate Technology Llc

Inventors

• Mehfuz Reyad
• Goggin Aidan Dominic
• Asselin Pierre
• Harvey Christopher Neil

Classifications

• G02B6/1228

  Tapered waveguides, e.g. integrated spot-size transformers (for coupling with fibres G02B6/305) · 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

• G02B6/1226 Primary

  involving surface plasmon interaction · CPC title

• G11B5/6088

  Optical waveguide in or on flying head · CPC title