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

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;

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 spaced apart from the input coupler, the branched portion separated from at least a part of the first straight portion by a gap having a substantially constant cross-sectional width along an entire length of the gap; and

a second straight portion between the mode converter portion and a media-facing surface; and

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

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

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

4. The write head of claim 3 , wherein one or both of the second straight portion and the branched portion has a taper to accommodate the difference in the combined width.

5. The write head of claim 4 , wherein the taper has a length in a range of about 2 μm to about 8 μm.

6. 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.

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

8. 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.

9. 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.

10. The write head of claim 9 , 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.

11. A method comprising:

receiving light from a light source at a fundamental transverse electric (TE 00 ) mode;

converting the light to a higher-order (TE 10 ) mode via a mode converter spaced apart from an input coupler, the mode converter comprising a branched portion extending from a straight portion, the branched portion separated from at least a part of the straight portion by a gap having a substantially constant cross-sectional width along an entire length of the gap;

delivering the converted light to a near-field transducer (NFT) at a media-facing surface of a write head; and

heating a magnetic recording medium in response to delivering the light.

12. The method of claim 11 , wherein the mode converter portion has a length in a range of about 15 μm to about 24 μm.

13. The method of claim 11 , wherein the mode converter portion has a length of about 17 μm.

14. The method of claim 11 , wherein receiving light from a light source comprises receiving the light emitted in a crosstrack direction from the light source.