Planar optical waveguide for heat assisted magnetic recording
An optical waveguide includes a core guiding layer, a cladding layer adjacent to the core guiding layer, a reflective layer, and a multiple layer stack on the reflective layer. The multiple layer stack includes a periodic arrangement of dielectric bilayers that each include a first dielectric layer and a second dielectric layer. An index of refraction n 1 of the first dielectric layer is greater than an index of refraction n 2 the second dielectric layer.
1. An optical waveguide comprising:
a core guiding layer;
a grating adjacent to the core guiding layer to launch light rays into the core layer, wherein light rays received by the grating include a first portion incident to the grating and a second portion to pass through the grating;
a cladding layer for the second portion of light rays to pass through; and
a reflective structure including a reflective layer and a multiple layer stack on the reflective layer, wherein the multiple layer stack includes a periodic arrangement of dielectric bilayers that each include a first dielectric layer and a second dielectric layer, wherein an index of refraction n 1 of the first dielectric layer is greater than an index of refraction n 2 of the second dielectric layer.
2. An optical waveguide, comprising:
a core guiding layer;
a cladding layer adjacent to the core guiding layer;
a reflective layer; and
a multiple layer stack between the reflective layer and the cladding layer, wherein the multiple layer stack includes a periodic arrangement of dielectric bilayers that each include a first dielectric layer and a second dielectric layer, wherein an index of refraction n 1 of the first dielectric layer is greater than an index of refraction n 2 of the second dielectric layer; and
wherein, for all layers of the multiple layer stack except a layer adjacent the reflective layer, the first dielectric layer has a thickness of
0.5
λ
2
n
1
2
-
n
0
2
sin
2
θ
i
and the second dielectric layer has a thickness of
0.5
λ
2
n
2
2
-
n
0
2
sin
2
θ
i
for light having a wavelength λ that is incident on a planar upper surface of the optical waveguide at an angle θ i through a medium of incidence having an index of refraction n 0 .
3. The optical waveguide of claim 1 , wherein the first dielectric layer is comprised of the same material as the core guiding layer.
4. The optical waveguide of claim 1 , wherein the second dielectric layer is comprised of the same material as the cladding layer.
5. The optical waveguide of claim 1 , wherein the periodic arrangement of dielectric bilayers comprises between one and ten dielectric bilayers.
6. The optical waveguide of claim 1 , wherein the grating comprises a plurality of rectangular grooves in the core guiding layer.
7. The optical waveguide of claim 1 , and further comprising:
an overcoat layer adjacent to the core guiding layer on a side opposite the cladding layer.
8. A magnetic recording apparatus comprising:
a write element for generating a write field; and
an optical device configured to deliver optical energy proximate the write field, wherein the optical device comprises a core guiding layer for providing light in an excited waveguide mode, a cladding layer adjacent to the core guiding layer, a reflective structure with a reflective layer, and a multiple layer stack between the reflective layer and the cladding layer, wherein the multiple layer stack includes a periodic arrangement of dielectric bilayers that each include a first dielectric layer and a second dielectric layer, wherein an index of refraction n 1 of the first dielectric layer is greater than an index of refraction n 2 of the second dielectric layer, and a grating to launch light into the core guiding layer by coupling a first portion of light received that is incident to the grating with a second portion of light received that passes through the grating and is reflected by the reflective structure.
9. A magnetic recording apparatus comprising:
a write element for generating a write field; and
an optical device configured to deliver optical energy proximate the write field, wherein the optical device comprises a core guiding layer, a cladding layer adjacent to the core guiding layer, a reflective layer, and a multiple layer stack between the reflective layer and the cladding layer, wherein the multiple layer stack includes a periodic arrangement of dielectric bilayers that each include a first dielectric layer and a second dielectric layer, wherein an index of refraction n 1 of the first dielectric layer is greater than an index of refraction n 2 of the second dielectric layer;
wherein, for all layers of the multiple layer stack except a layer adjacent the reflective layer, the first dielectric layer has a thickness of
0.5
λ
2
n
1
2
-
n
0
2
sin
2
θ
i
and the second dielectric layer has a thickness of
0.5
λ
2
n
2
2
-
n
0
2
sin
2
θ
i
for light having a wavelength λ that is incident on a planar upper surface of the optical waveguide at an angle θ i through a medium of incidence having an index of refraction n 0 .
10. The magnetic recording apparatus of claim 8 , wherein the first dielectric layer is comprised of the same material as the core guiding layer.
11. The magnetic recording apparatus of claim 8 , wherein the second dielectric layer is comprised of the same material as the cladding layer.
12. The magnetic recording apparatus of claim 8 , wherein the periodic arrangement of dielectric bilayers comprises between one and ten dielectric bilayers.
13. The magnetic recording apparatus of claim 8 , wherein the grating comprises a plurality of rectangular grooves in the core guiding layer.
14. The magnetic recording apparatus of claim 8 , and further comprising:
an overcoat layer adjacent to the core guiding layer on a side opposite the cladding layer.
15. A magnetic recording system comprising:
a magnetic medium;
a write element for generating a write field at the magnetic medium; and
an optical waveguide for delivering optical energy to heat a portion of the magnetic medium proximate the write field, wherein the optical waveguide comprises a core guiding layer for providing light in an excited waveguide mode, a cladding layer adjacent to the core guiding layer, a reflective structure with a reflective layer and a multiple layer stack between the reflective layer and the cladding layer, wherein the multiple layer stack includes a periodic arrangement of dielectric bilayers that each include a first dielectric layer and a second dielectric layer, wherein an index of refraction n 1 of the first dielectric layer is greater than an index of refraction n 2 of the second dielectric layer, and a grating to launch light into the core guiding layer by coupling a first portion of light received that is incident to the grating with a second portion of light received that passes through the grating and is reflected by the reflective structure.
16. A magnetic recording system comprising:
a magnetic medium;
a write element for generating a write field at the magnetic medium; and
an optical waveguide for delivering optical energy to heat a portion of the magnetic medium proximate the write field, wherein the optical waveguide comprises a core guiding layer, a cladding layer adjacent to the core guiding layer, a reflective layer, and a multiple layer stack between the cladding layer and the reflective layer, wherein the multiple layer stack includes a periodic arrangement of dielectric bilayers that each include a first dielectric layer and a second dielectric layer, wherein an index of refraction n 1 of the first dielectric layer is greater than an index of refraction n 2 of the second dielectric layer;
wherein, for all layers of the multiple layer stack except a layer adjacent the reflective layer, the first dielectric layer has a thickness of
0.5
λ
2
n
1
2
-
n
0
2
sin
2
θ
i
and the second dielectric layer has a thickness of
0.5
λ
2
n
2
2
-
n
0
2
sin
2
θ
i
for light having a wavelength λ that is incident on a planar upper surface the optical waveguide at an angle θ i through a medium of incidence having an index of refraction n 0 .
17. The magnetic recording system of claim 15 , wherein the first dielectric layer is comprised of the same material as the core guiding layer.
18. The magnetic recording system of claim 15 , wherein the second dielectric layer is comprised of the same material as the cladding layer.
19. The magnetic recording system of claim 15 , wherein the periodic arrangement of dielectric bilayers comprises between one and ten dielectric bilayers.