90°-bent metallic waveguide having tapered c-shaped aperture, method of fabricating the waveguide, light delivery module including the waveguide, and heat assisted magnetic recording head having the waveguide

1. A metallic waveguide comprising a metal body that is formed of conductive metal, and comprises an aperture whose input end and output end are formed through the metal body, wherein the aperture comprises:

a bent portion that changes a light traveling direction between the input and output ends; and

a tapered portion between the bent portion and the output end,

wherein the tapered portion has a width that is gradually reduced toward the output end, and the aperture is formed in a C-shape by a ridge formed on an inner surface of the metal body.

2. The metallic waveguide of claim 1 , wherein, when a thickness of the metallic waveguide is defined in a direction where the light travels, a thickness t out of the metallic waveguide from the bent portion of the aperture to the tapered portion of the aperture is greater than a thickness t in of the metallic waveguide from the input end to a before-bent portion.

3. The metallic waveguide of claim 2 , wherein the thickness t in is determined such that a frequency of an incident beam coincides with a thickness resonance frequency through a thickness resonance analysis with respect to a portion of the metallic waveguide from the input end to the before-bent portion.

4. The metallic waveguide of claim 3 , wherein the thickness t in satisfies an equation:

t in =0.25λ±Δ t res,α

where λ is a wavelength of the light and Δt res,α is a thickness deviation related to front scattering and resonance.

5. The metallic waveguide of claim 3 , wherein a thickness t tp of the metallic waveguide at the tapered portion is determined such that the frequency of the incident beam coincides with the thickness resonance frequency through a thickness resonance analysis with respect to the tapered portion of the metallic waveguide.

6. The metallic waveguide of claim 5 , wherein the thickness t tp satisfies an equation:

t tp =0.25λ±Δ t res,γ

where, λ is a wavelength of the light and Δt res,γ is a thickness deviation related to rear scattering and resonance.

7. The metallic waveguide of claim 5 , wherein the thickness t out is determined such that the frequency of the incident beam coincides with the thickness resonance frequency through a thickness resonance analysis with respect to the overall metallic waveguide in a state where the thickness t in and the thickness t tp are fixed.

8. The metallic waveguide of claim 7 , wherein the thickness t out satisfies an equation:

t out =0.5λ±Δ t res,β

where, λ is a wavelength of the light and t res,β is a thickness deviation related to scattering at the bent portion of the aperture and resonance.

9. The metallic waveguide of claim 1 , wherein each of the metal body and the aperture formed through the metal body has a width and a height that is less than the width.

10. The metallic waveguide of claim 1 , wherein the aperture is filled with air or a dielectric.

11. The metallic waveguide of claim 1 , wherein a width and a height of the ridge are uniformly maintained.

12. A method of fabricating the metallic waveguide of claim 1 , the method comprising:

forming a metal layer on a substrate;

forming the ridge in a bent shape by etching a portion of the metallic layer such that the ridge has a predetermined width and thickness;

depositing an ultraviolet (UV)-curable resin on the ridge and the rest of the metal layer;

forming the aperture bent surrounding the ridge and having a tapered structure whose width is gradually reduced at an end by partly hardening the UV-curable resin;

removing an unhardened portion of the UV-curable resin; and

forming another metal layer surrounding the aperture.

13. A light delivery module comprising:

a first metallic waveguide that is formed of a conductive metal body and provided with an aperture therein; and

a second waveguide that delivers light from a light source to the first metallic waveguide,

wherein the aperture comprises:

a bent portion that changes a light traveling direction between an input end and an output end; and

a tapered portion between the bent portion and the output end,

wherein the tapered portion has a width that is gradually reduced toward the output end, and the aperture is formed in a C-shape by a ridge formed on an inner surface of the first metallic waveguide.

14. The light delivery module of claim 13 , wherein, when a thickness of the first metallic waveguide is defined in a direction where the light travels, a thickness t out of the first metallic waveguide from the bent portion of the aperture to the tapered portion of the aperture is greater than a thickness t in of the first metallic waveguide from the input end to a before-bent portion.

15. The light delivery module of claim 14 , wherein the thickness t in is determined such that a frequency of an incident beam coincides with a thickness resonance frequency through a thickness resonance analysis with respect to a portion of the first metallic waveguide from the input end to the before-bent portion.

16. The light delivery module of claim 15 , wherein a thickness t tp of the first metallic waveguide at the tapered portion is determined such that the frequency of the incident beam coincides with the thickness resonance frequency through a thickness resonance analysis with respect to the tapered portion of the first metallic waveguide.

17. The light delivery module of claim 16 , wherein the thickness t out is determined such that the frequency of the incident beam coincides with the thickness resonance frequency through a thickness resonance analysis with respect to the overall first metallic waveguide in a state where the thickness t in and the thickness t tp are fixed.

18. The light delivery module of claim 13 , wherein the second waveguide is formed in a flat shape where a width is greater than a height, and a width of an input end is greater than a width of an output end.

19. The light delivery module of claim 18 , wherein each of the first metallic waveguide and the aperture has a width and a height that is less than the width to realize a profile matching with the second waveguide;

20. A heat assisted magnetic recording head comprising:

a magnetic recording unit which forms a magnetic field that records information on a magnetic recording medium;

a light delivery module which emits light to heat a recording region of the magnetic recording medium,

wherein the light delivery module comprises:

a first metallic waveguide that is formed of a conductive metal body and provided with an aperture therein; and

a second waveguide that delivers light from a light source to the first metallic waveguide,

wherein, the aperture comprises:

a bent portion that changes a light traveling direction between an input end and an output end; and

a tapered portion between the bent portion and the output end, and

wherein the tapered portion has a width that is gradually reduced toward the output end, and the aperture is formed in a C-shape by a ridge formed on an inner surface of first metallic waveguide.

21. The heat assisted magnetic recording head of claim 20 , wherein, when a thickness of the first metallic waveguide is defined in a direction where the light travels, a thickness t out of the first metallic waveguide from the bent portion of the aperture to the tapered portion of the aperture is greater than a thickness t in of the first metallic waveguide from the input end to a before-bent portion.

22. The heat assisted magnetic recording head of claim 21 , wherein the thickness t in is determined such that a frequency of an incident beam coincides with a thickness resonance frequency through a thickness resonance analysis with respect to a portion of the first metallic waveguide from the input end to the before-bent portion.

23. The heat assisted magnetic recording head of claim 22 , wherein a thickness t tp of the first metallic waveguide at the tapered portion is determined such that the frequency of the incident beam coincides with the thickness resonance frequency through a thickness resonance analysis with respect to the tapered portion of the first metallic waveguide.

24. The heat assisted magnetic recording head of claim 23 , wherein the thickness t out is determined such that the frequency of the incident beam coincides with the thickness resonance frequency through a thickness resonance analysis with respect to the overall first metallic waveguide in a state where the thickness t in and the thickness t tp are fixed.

25. The heat assisted magnetic recording head of claim 20 , wherein the magnetic recording unit comprises:

a main pole forming a magnetic field magnetizing the magnetic recording medium;

a return pole disposed facing a surface of the main pole and magnetically connected to the main pole to form a magnetic path;

an inductive coil for inducing the magnetic field to the main pole;

a sub-yoke disposed on the other surface of the main pole to assist the focusing of magnetic flux on an extreme end of the main pole.