Illumination device

1. A structure comprising:

a semiconductor light emitting device for emitting a first light at a first wavelength;

a wavelength conversion medium arranged to convert at least part of the first light into a second light at a second wavelength; and

a periodic antenna array comprising a plurality of antennas, wherein the periodic antenna array supports surface lattice resonances arising from diffractive coupling of localized surface plasmon resonances in at least one of the antennas;

wherein the wavelength conversion medium is disposed between the periodic antenna array and the semiconductor light emitting device.

2. The structure of claim 1 wherein the periodic antenna array supports surface lattice resonances at least at one of the first wavelength and the second wavelength.

3. The structure of claim 1 wherein the wavelength conversion medium is disposed on a transparent substrate.

4. The structure of claim 1 wherein each antenna in the plurality of antennas comprises two metal layers, a lower metal layer for adhesive purposes, and an upper metal layer, the upper metal layer being thicker than the lower metal layer.

5. The structure of claim 1 wherein the plurality of antennas are embedded in an optically homogeneous medium.

6. The structure of claim 1 wherein the wavelength conversion medium is a doped ceramic slab.

7. The structure of claim 6 wherein the periodic antenna array is deposited on an undoped ceramic slab and is sandwiched between the undoped ceramic slab and the doped ceramic slab.

8. The structure of claim 7 wherein the doped ceramic slab and the undoped ceramic slab have the same index of refraction.

9. The structure of claim 7 wherein a space between the doped ceramic slab and the undoped ceramic slab is filled with a material having an index of refraction matching an index of refraction of the doped ceramic slab and the undoped ceramic slab.

10. The structure of claim 1 wherein the wavelength conversion medium is a first wavelength conversion medium, the structure further comprising a second wavelength conversion medium.

11. The structure of claim 10 wherein:

the first wavelength conversion medium is a first doped ceramic slab on which the periodic antenna array is deposited; and

the second wavelength conversion medium is a second doped ceramic slab.

12. The structure of claim 10 wherein:

the first wavelength conversion medium is a doped ceramic slab on which the periodic antenna array is deposited; and

the second wavelength conversion medium is quantum dots spin-coated over the periodic antenna array.

13. The structure of claim 10 wherein the first and second wavelength conversion media have different emission spectra.

14. The structure of claim 1 further comprising a collimating optic disposed between the semiconductor light emitting device and the periodic antenna array.

15. The structure of claim 1 further comprising a polarizer disposed between the semiconductor light emitting device and the periodic antenna array.

16. The structure of claim 1 wherein:

the periodic antenna array is a first periodic antenna array;

the first periodic antenna array has a long axis;

the structure further comprises a second periodic antenna array having a long axis; and

the long axis of the first periodic antenna array is rotated with respect to the long axis of the second periodic antenna array.

17. The structure of claim 16 wherein the structure emits light in a donut pattern.

18. The structure of claim 1 wherein the periodic antenna array is immersed in a coating of Si 3 N 4 .

19. The structure of claim 18 wherein the coating of Si 3 N 4 has a thickness between 5 nm and 50 nm.