Waveguide with blocking layer

1. An apparatus comprising:

a write pole;

a waveguide adjacent to the write pole, the waveguide having a truncated end and an interior surface that converges optical light to a focal point that is axially centered with respect to an aperture at the truncated end; and

a blocking layer positioned adjacent the truncated end and extending from a single side of the waveguide across a portion of the aperture at the truncated end to output a non-uniform beam from the waveguide.

2. The apparatus of claim 1 , wherein the blocking layer comprises a linear edge that extends across the aperture adjacent the focal point to provide a substantially D-shaped opening for the beam.

3. The apparatus of claim 1 , wherein the interior surface is substantially parabolically shaped.

4. The apparatus of claim 1 , wherein the planar waveguide includes a core layer having a thickness in the range of about 100 nm to about 1500 nm.

5. The apparatus of claim 1 , wherein the waveguide is a channel waveguide.

6. The apparatus of claim 1 , wherein an edge of the blocking layer is positioned from a center line of the waveguide at a distance up to one half of the wavelength of light in the waveguide.

7. The apparatus of claim 1 , wherein an edge of the blocking layer is positioned from a center line of the waveguide at a distance in the range from 0 nm to about 415 nm.

8. The apparatus of claim 1 , wherein a distance between opposing sides of the aperture at the truncated end of the waveguide is in a range from about 120 nm to about 9000 nm.

9. The apparatus of claim 1 , wherein the blocking layer has a thickness of about 5 nm to about 50 nm.

10. The apparatus of claim 1 , wherein the blocking layer covers less than 180 degrees of the circumferential edge of the aperture.

11. An apparatus comprising:

a recording medium;

a recording head comprising a waveguide adjacent to a write pole and an offset blocking layer positioned adjacent a truncated end of the waveguide and extending from only one side of the waveguide across a portion of an aperture at the truncated end that outputs a beam with a flattened, non-uniform cross-sectional shape onto the recording medium; and

a positioning device for positioning the recording head adjacent to the recording medium.

12. The apparatus of claim 11 , wherein the waveguide is a planar waveguide having an interior surface shaped to direct an electromagnetic wave to a focal point axially centered in the aperture defined by the truncated end of the waveguide, and the blocking layer extends from a single side of the waveguide to partially cover the aperture to form a substantially D-shaped opening through which the beam passes to the recording medium, wherein the focal point is offset within the aperture.

13. The apparatus of claim 12 , wherein the interior surface is substantially parabolically shaped.

14. The apparatus of claim 12 , wherein the planar waveguide includes a core layer having a thickness in the range of about 100 nm to about 1500 nm.

15. The apparatus of claim 11 , wherein the waveguide is a channel waveguide.

16. The apparatus of claim 11 , wherein an edge of the blocking layer is positioned from a center line of the waveguide at a distance up to one half of the wavelength of light in the waveguide.

17. An apparatus comprising:

a write pole adapted to impart a magnetic field to an adjacent recording medium to write data thereto; and

a waveguide adjacent the write pole adapted to impart a flattened, non-circular optical heating beam to the recording medium, the waveguide comprising a non-symmetric opening offset with respect to a central axis of the waveguide along which the beam extends; and

an offset blocking layer positioned adjacent the waveguide, the offset blocking layer extending from only one side of the waveguide across a portion of an aperture provided by the waveguide.

18. The apparatus of claim 17 , in which the waveguide comprises a body portion with an interior parabolic channel which terminates at the aperture symmetrically about the central axis, and the offset blocking layer affixed to the body portion which partially covers the first aperture to provide a substantially D-shape.

19. The apparatus of claim 17 , in which the waveguide comprises a body portion with an interior annular channel with a rectangular cross-sectional shape in a plane perpendicular to the central axis and which terminates at a rectangular aperture with opposing first and second sides and opposing third and fourth sides, and the offset blocking layer which partially covers the respective first and second sides and fully covers the third side, the fourth side remaining uncovered to form the non-symmetric opening.

20. The apparatus of claim 17 , characterized as a servo-writer transducer adapted to write a servo pattern to the recording medium to facilitate subsequent positioning of a data transducer adjacent the recording medium.