Optical structure on an optical fiber and method of fabrication

1. A method of fabricating an optical structure on an optical fiber, the method comprising:

preparing an end of an optical fiber;

forming a layer onto the fiber end; and

subsequent to the forming, patterning the layer to form the optical structure, wherein the optical structure comprises a photonic crystal structure.

2. The method of claim 1 , wherein preparing the end comprises cleaving the optical fiber to form the end.

3. The method of claim 1 , wherein forming the layer comprises depositing the layer onto the fiber end by e-beam evaporation, sputtering, or chemical vapor deposition.

4. The method of claim 1 , wherein patterning the layer comprises ion-milling the layer using a focused ion beam.

5. The method of claim 1 , wherein the optical structure comprises a periodic array of holes that extend either partially or completely through the layer.

6. The method of claim 1 , wherein the layer comprises a dielectric material and the method further comprising covering the dielectric material with one or more metal layers prior to patterning the layer.

7. The method of claim 1 , wherein the optical structure covers at least part of the area of a core region of the optical fiber.

8. The method of claim 1 , wherein the optical structure comprises a sub-wavelength grating.

9. A method of fabricating a photonic crystal structure, the method comprising:

forming a first dielectric layer on an end of an optical fiber;

forming a sacrificial layer over at least a portion of the first dielectric layer;

forming a second dielectric layer over the sacrificial layer;

subsequent to the forming of the first dielectric layer, patterning the first dielectric layer to form a first photonic crystal slab;

patterning the second dielectric layer to form a second photonic crystal slab; and

removing the sacrificial layer.

10. The method of claim 9 , wherein the sacrificial layer comprises chrome and forming the sacrificial layer comprises:

forming a chrome layer over at least a portion of the first dielectric layer;

forming a gold layer over the chrome layer;

removing a portion of the chrome layer; and

removing the gold layer.

11. The method of claim 9 , wherein patterning the first dielectric layer and patterning the second dielectric layer are performed concurrently.

12. An optical apparatus comprising:

an end of an optical fiber; and

a layer comprising material deposited onto the end of the optical fiber, the layer comprising one or more first portions having a first optical pathlength in a direction perpendicular to the layer and one or more second portions having a second optical pathlength in the direction perpendicular to the layer, the second optical pathlength different from the first optical pathlength, wherein the layer comprises a photonic crystal structure.

13. The optical apparatus of claim 12 , wherein the one or more first portions have a first refractive index and the one or more second portions have a second refractive index different from the first refractive index.

14. The optical apparatus of claim 12 , wherein the one or more first portions have a first thickness in the direction perpendicular to the layer and the one or more second portions have a second thickness in the direction perpendicular to the layer, the second thickness different from the first thickness.

15. The optical apparatus of claim 12 , wherein the end of the optical fiber is cleaved.

16. The optical apparatus of claim 12 , wherein the layer comprises amorphous silicon, silicon dioxide, silicon nitride, magnesium fluoride, or silicon monoxide.

17. The optical apparatus of claim 12 , wherein the layer comprises metal.

18. The optical apparatus of claim 12 , wherein the one or more first portions comprise a dielectric material and the one or more second portions comprise a periodic array of holes that extend at least partially through the layer.

19. The optical apparatus of claim 18 , wherein the periodic array of holes covers at least part of the area of a core region of the optical fiber.

20. The optical apparatus of claim 12 , wherein the photonic crystal structure forms one end of a fiber Fabry-Perot cavity.

21. The optical apparatus of claim 12 , wherein the optical fiber is coupled to another optical fiber such that the layer is between the two optical fibers.

22. The optical apparatus of claim 12 , wherein the layer comprises a subwavelength grating.

23. The optical apparatus of claim 12 , wherein the layer comprises a holographic waveplate.

24. The optical apparatus of claim 12 , wherein the layer comprises a wire-grid polarizer.

25. The method of claim 9 , wherein the patterning the second dielectric layer is subsequent to the forming of the second dielectric layer over the sacrificial layer.