# US 2014/0153861 A1 · Polarization rotator

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- Number: US 2014/0153861 A1
- Document ID: US20140153861A1
- Status: Published application
- Kind: A1
- Application number: 13/872,447
- Filed: 2013-04-29
- Published: 2014-06-05
- Earliest claimed: 2012-12-04
- Assignees: Seagate Technology LLC
- Applicants: Seagate Technology LLC
- Inventors: Chubing Peng; Yongjun Zhao
- Web page: https://patentgrep.com/patent/US20140153861A1

## CPC

- G11B 5/4866: {the arm comprising an optical waveguide, e.g. for thermally-assisted recording}
- G02B 6/126: using polarisation effects {(G02B6/1226 takes precedence)}
- G02B 6/2726: {in or on light guides, e.g. polarisation means assembled in a light guide}
- G11B 5/314: {where the layers are extra layers normally not provided in the transducing structure, e.g. optical layers (G11B5/3196 takes precedence)}
- G02B 6/274: {based on light guide birefringence, e.g. due to coupling between light guides (G02B6/105, G02B6/024 take precedence; mechanically induced birefringence G02F1/0134)}
- G11B 2005/0021: {Thermally assisted recording using an auxiliary energy source for heating the recording layer locally to assist the magnetization reversal}
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A polarization rotator comprises a first waveguide configured to be coupled to an input coupler at a first end and a second waveguide, wherein the first waveguide is offset from the second waveguide and a second end of the first waveguide is coupled to a second end of the second waveguide.

## Claims

### Claim 1

An apparatus comprising:
an input coupler configured to couple light energy from a light source; and
a polarization rotator coupled to the input coupler, wherein the polarization rotator is configured to rotate polarization state of the light energy orthogonally.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein polarization state of the light energy entering the polarization rotator is transverse electric (TE) polarization.

### Claim 3 (depends on 2)

The apparatus of claim 2, wherein the polarization rotator rotates the polarization state of the light energy from transverse electric (TE) polarization state to transverse magnetic (TM) polarization state.

### Claim 4 (depends on 1)

The apparatus of claim 1, further comprising a near-field transducer (NFT) adapter, wherein the NFT adapter is configured to couple the light energy output from the polarization rotator to an NFT.

### Claim 5 (depends on 4)

The apparatus of claim 4 wherein the NFT adapter is configured to have expanded waveguide propagation mode compared to propagation mode of the polarization rotator.

### Claim 6 (depends on 4)

The apparatus of claim 4 wherein the NFT adapter is configured to have reduced waveguide propagation mode compared to propagation mode of the polarization rotator.

### Claim 7 (depends on 1)

The apparatus of claim 1 wherein the light source is a laser diode.

### Claim 8 (depends on 1)

The apparatus of claim 1 wherein the polarization rotator comprises an overlay structure comprising a first waveguide and a second waveguide, wherein the first waveguide is offset from the second waveguide.

### Claim 9 (depends on 8)

The apparatus of claim 8, wherein the first waveguide is attached at a first end to the input coupler and at the second end to an NFT adapter.

### Claim 10 (depends on 9)

The apparatus of claim 9 wherein the second end of the first waveguide is also coupled to a second end of the second waveguide.

### Claim 11 (depends on 9)

The apparatus of claim 9 wherein a cross-section of the first end of the first waveguide has a width that is substantially twice the thickness of the cross-section.

### Claim 12 (depends on 8)

The apparatus of claim 8 wherein a cross-section of the second end of the first waveguide is substantially similar to cross-section of the second end of the second waveguide.

### Claim 13

A polarization rotator comprising:
a first waveguide configured to be coupled to an input coupler at a first end; and
a second waveguide, wherein the first waveguide is offset from the second waveguide and a second end of the first waveguide is coupled to a second end of the second waveguide.

### Claim 14 (depends on 13)

The polarization rotator of claim 13, wherein the cross-section of the first end of the first waveguide has a width that is substantially twice the thickness of the cross-section.

### Claim 15 (depends on 13)

The polarization rotator of claim 13, wherein a cross-section of the second end of the first waveguide is substantially similar to cross-section of the second end of the second waveguide.

### Claim 16 (depends on 13)

The polarization rotator of claim 13, wherein the second end of the first waveguide and the second end of the second waveguide are coupled to an NFT adapter.

### Claim 17

A method comprising:
coupling light energy output from a light source to an input coupler;
rotating polarization status of the light energy output from the input coupler using a polarization rotator; and
coupling light energy output from the polarization rotator to an NFT adapter.

### Claim 18 (depends on 17)

The method of claim 17, wherein polarization of the light energy output from a light source is transverse electric (TE) polarization.

### Claim 19 (depends on 17)

The method of claim 17, wherein rotating polarization status further comprises rotating the polarization state of the light energy from transverse electric (TE) polarization state to transverse magnetic (TM) polarization state.

### Claim 20 (depends on 17)

The method of claim 17, further comprising coupling the light energy output from the NFT adapter to an NFT located on a transducer head of a disc drive.