US 8,787,129 B1Granted

Polarization rotator for thermally assisted magnetic recording

AssigneeHeadway Technologies, Inc.

InventorsXuhui Jin, Hiroyuki Ito, Yoshitaka Sasaki, Shigeki Tanemura

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Abstract

A waveguide structure with a light polarization rotator section for converting transverse electric light from a TE light source to transverse magnetic light which is subsequently coupled to a plasmon generator (PG) is disclosed. Wavelengths above 800 nm are advantageously used to reduce resistive heating in the PG, and in adjacent cladding and write pole layers to improve the thermally assisted magnetic recording head lifetime. The light polarization rotator section has a length determined by TE LD light wavelength, and the effective mode index of the two orthogonal fundamental modes, and preferably has a symmetric structure including a sloped side with a 45 degree angle with respect to a bottom surface. A vertical side of the light polarization rotator section may be coplanar with sides of adjacent waveguide sections. Offsets to the cross-track width are used to improve symmetry for higher TE to TM polarization conversion efficiency.

Claims25

Dependent claims

A waveguide in a thermally assisted magnetic recording (TAMR) head comprising:

(a) a first section with a first width and a first end at a back end of a slider, the first end receives transverse electric (TE) light from an adjoining laser diode (LD), and a second end that is connected to the first end by two parallel sides which are aligned in a first axis direction that is perpendicular to an air bearing surface (ABS);
(b) a tapered section having a first width in a cross-track direction at a first end that adjoins the second end of the first section, and a second width in a cross-track direction at a second end that faces the ABS wherein the second width is less than the first width, the tapered section narrows a beam of TE light that is propagated toward the ABS;
(c) a first sub-section that has the second width in a cross-track direction between two sides that are aligned in the first axis direction, and a first end adjoining the second end of the tapered section;
(d) a second sub-section that has the second width between two sides that are aligned perpendicular to the ABS, and a first end adjoining the ABS, light propagated through the second sub-section is coupled to an adjacent plasmon generator (PG);
and
(e) a light polarization rotator section for converting TE light from the first sub-section into transverse magnetic (TM) light which enters the second sub-section and is then coupled to the PG, comprising;
(1) a first end adjoining a second end of the first sub-section;
(2) a second end adjoining an end of the second sub-section that faces away from the ABS;
(3) a vertical side formed between a top surface and a bottom surface;
and
(4) a sloped side formed between the top surface and the bottom surface wherein the top and bottom surfaces are coplanar with a top and a bottom surface of each of the first section, tapered section, and first and second sub-sections.

8 more elements

A thermally assisted magnetic recording (TAMR) head comprising:

(a) a waveguide formed between an air bearing surface (ABS) and a back end of a slider, comprising:
(1) a first section with a first width and a first end at a back end of the slider, the first end receives a beam of TE light from an adjoining laser diode (LD), and a second end that is connected to the first end by two parallel sides which are aligned in a first axis direction that is perpendicular to the ABS;
(2) a tapered section having a first width in a cross-track direction at a first end that adjoins the second end of the first section, and a second width in a cross-track direction at a second end that faces the ABS wherein the second width is less than the first width, the tapered section narrows the LD light beam as the light propagates toward the ABS through the waveguide;
(3) a first sub-section that has the second width in a cross-track direction between two sides that are aligned perpendicular to the ABS, and a first end adjoining the second end of the tapered section;
(4) a second sub-section that has the second width between two sides that are aligned perpendicular to the ABS, and a first end adjoining the ABS, light propagated through the second sub-section is coupled to an adjacent plasmon generator (PG);
and
(5) a light polarization rotator section for converting TE light entering from the first sub-section into TM light that exits into the second sub-section, the light polarization rotator section has a vertical side that connects a top surface to a bottom surface, and a sloped side which is formed between the top and bottom surfaces;
and
(b) the PG which couples TM light from the second sub-section to a plasmon mode that is propagated along a PG surface to an end of the PG at the ABS and then onto a magnetic medium to enable a weaker magnetic field from a write pole to switch a bit in the magnetic medium during a write process;
and
(c) the write pole that adjoins the PG and has a lengthwise dimension along the first axis direction.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 13/785,280Filed 5 Mar 2013
Granted: 22 Jul 2014
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

G02B 6/105
Of the optical waveguide type: having optical polarisation effects
G11B 5/314
Including layers not usually being a part of the electromagnetic transducer structure and providing additional features, e.g. for improving heat…:…
G11B 5/4866
Specially adapted for disk drive assemblies, e.g. assembly prior to operation, hard or flexible disk drives: the arm comprising an optical…
G11B 5/6088
Specially adapted for spacing from a rotating disc using a fluid cushion: optical waveguide in or on flying head

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