Curved-edge optical mode converter for heat-assisted magnetic recording

Patent metadata

Field	Value
Publication number	US-10734019-B1
Application number	US-201916528174-A
Country	US
Kind code	B1
Filing date	Jul 31, 2019
Priority date	Sep 20, 2017
Publication date	Aug 4, 2020
Grant date	Aug 4, 2020

Abstract

An apparatus includes an input coupler configured to receive light excited by a light source. A near-field transducer (NFT) is positioned at a media-facing surface of a write head. A layered waveguide is positioned between the input coupler and the NFT and configured to receive the light output from the input coupler in a transverse electric (TE) mode and deliver the light to the NFT in a transverse magnetic (TM) mode. The layered waveguide comprises a first layer extending along a light-propagation direction. The first layer is configured to receive light from the input coupler. The first layer tapers from a first cross track width to a second cross track width where the second cross track width is narrower than the first cross track width. The layered waveguide includes a second layer that is disposed on the first layer. The second layer has a cross sectional area in a plane perpendicular to the light propagation direction that increases along the light propagation direction. The cross sectional area of the second layer is smaller proximate to the input coupler and larger proximate to the NFT. The layered waveguide includes an interface between the first layer and the second layer, the interface comprises a curve.

First claim

What is claimed is:

1. A method for forming a write head, comprising:
depositing a first waveguide layer;
depositing a second waveguide layer adjacent to the first waveguide layer;
applying a first mask to a substrate parallel surface of the second waveguide layer creating a masked portion and an exposed portion of the second waveguide layer;
etching the exposed portion of the second waveguide layer;
applying a second mask to the substrate parallel surface of the second waveguide layer creating masked sections and exposed sections of the first and second waveguide layers; and
milling the exposed sections of both the first and the second waveguide layers, wherein the second layer has a cross sectional area in a plane perpendicular to the light propagation direction that increases along the light propagation direction, the cross sectional area being smaller proximate to an input coupler and larger proximate to a near field transducer (NFT) and wherein an interface between the first layer and the second layer comprises a curve.

2. The method of claim 1 , further comprising forming a stop layer on the first waveguide layer before depositing the second waveguide layer.

3. The method of claim 1 , wherein the curve is based on a cubic Bezier curve.

4. The method of claim 1 , further comprising after the etching, filling the etched portion with a cladding material.

5. The method of claim 1 , further comprising, after the milling, filling the milled sections with a cladding material.

6. The method of claim 1 , wherein at least one of the first waveguide layer and the second waveguide layer comprises NbO x .

7. The method of claim 1 , wherein at least one of the first mask and the second mask is applied with a tolerance of 50 nm.

8. A method for forming a write head, comprising:
depositing a first waveguide layer;
depositing a second waveguide layer adjacent to the first waveguide layer;
applying a first mask to a substrate parallel surface of the second waveguide layer creating masked portions and exposed portions of the first and second waveguide layers;
etching the exposed portions of the first and second waveguide layers;
applying a second mask to the substrate parallel surface of the second waveguide layer, the second mask creating a masked section and an exposed section of the second waveguide layer; and
milling the exposed section of the second waveguide layer, wherein the second layer has a cross sectional area in a plane perpendicular to the light propagation direction that increases along the light propagation direction, the cross sectional area being smaller proximate to an input coupler and larger proximate to a near field transducer (NFT) and wherein an interface between the first layer and the second layer comprises a curve.

9. The method of claim 8 , further comprising, after the milling, filling the milled section with a cladding material.

10. The method of claim 8 , further comprising, after the etching, filling the etched portion with a cladding material.

11. The method of claim 8 , wherein at least one of the first mask and the second mask is applied with a tolerance of 50 nm.

12. A method for forming a write head, comprising:
depositing a waveguide layer;
applying a first mask to a substrate parallel surface of the waveguide layer creating a first masked portion and a first exposed portion of the waveguide layer;
etching the first exposed portion of the waveguide layer;
applying a second mask to the substrate parallel surface of the waveguide layer, the second mask creating a second masked portion and a second exposed portion; and
milling the second exposed portion of the waveguide layer, wherein the waveguide layer has a cross sectional area in a plane perpendicular to the light propagation direction that increases along the light propagation direction, the cross sectional area being smaller proximate to an input coupler and larger proximate to a near field transducer (NFT) and wherein an interface between the first layer and the second layer comprises a curve.

13. The method of claim 12 , wherein etching the first exposed portion of the waveguide layer comprises etching the first exposed portion of the waveguide layer to a predetermined thickness.

14. The method of claim 13 , wherein the predetermined thickness is about half of a total thickness of the waveguide layer.

15. The method of claim 13 , wherein milling the second exposed portion of the waveguide layer comprises milling the second exposed portion to a total thickness of the waveguide layer.

16. The method of claim 12 , wherein etching the first exposed portion of the waveguide layer comprises etching the first exposed portion of the waveguide layer to a total thickness of the waveguide layer.

17. The method of claim 16 , wherein milling the second exposed portion of the waveguide layer comprises milling the second exposed portion to a predetermined thickness of the waveguide layer.

18. The method of claim 17 , wherein the predetermined thickness is about half of the total thickness of the waveguide layer.

19. The method of claim 12 , further comprising, after the etching, filling the milled portion with a cladding material.

20. The method of claim 12 , after the etching, filling the etched portion with a cladding material.

Assignees

• Seagate Technology Llc

Inventors

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

Classifications

• G11B5/6088 Primary

  Optical waveguide in or on flying head · 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

• G02B6/1228

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

• G02B6/126

  using polarisation effects {(G02B6/1226 takes precedence)} · CPC title

• G11B11/1051

  by modulating both the magnetic field and the light beam at the transducers · CPC title