Optical device capable of providing at least two different optical functions
An optical device forming an outgoing electromagnetic wave from an incident electromagnetic wave comprises at least one unit cell (UC), comprising: at least two subwavelength optical elements ( 1, 2 ), each of them belonging to a different set (MSI, MS 2 ) of subwavelength optical elements, a set of subwavelength optical elements being characterized by a type of optical response to an incident electromagnetic wave; means ( 21 ) enabling selective excitation of all subwavelength optical elements belonging to a given set, in response to an electromagnetic wave ( 20 ) incident on said unit cell.
1. An optical device forming an outgoing electromagnetic wave from an incident electromagnetic wave, wherein the optical device comprises at least one unit cell (UC; UC 1 , UC 2 ),
said unit cell comprising:
at least two subwavelength optical elements (1, 2, . . . , N), each of them belonging to a different set (MS 1 , MS 2 , . . . , MS n ) of subwavelength optical elements, a set of subwavelength optical elements being characterized by a type of optical response to an incident electromagnetic wave; and
a nanojet microlens ( 21 ) enabling selective excitation of the subwavelength optical elements belonging to a given set, in response to said electromagnetic wave ( 20 ) incident on said unit cell.
2. The optical device of claim 1 , wherein the type of optical response belongs to the group comprising:
a phase shift applied to said incident electromagnetic wave and,
an amplitude change of at least part of a spectrum of said incident electromagnetic wave.
3. The optical device of claim 1 , wherein said subwavelength optical elements (NP) belong to the group comprising:
metallic particles;
dielectric particles;
semiconductor particles;
optical resonators; and
optical antennas.
4. The optical device of claim 1 , wherein said subwavelength optical elements are assembled on or inside a dielectric substrate ( 10 ).
5. The optical device of claim 4 , wherein said nanojet microlens is a nanojet microlens embedded in said substrate and made of a dielectric material with refractive index higher than that of said substrate.
6. The optical device of claim 4 , wherein said nanojet microlens is placed at a distance below a surface of said substrate on which said subwavelength optical elements are assembled.
7. The optical device of claim 4 , wherein said substrate comprises at least one cavity filled with a medium with refractive index lower than that of said substrate and wherein said nanojet microlens is formed in the same material as said substrate and has a focusing function enabled by a step of refractive index induced by an edge of said cavity.
8. The optical device of claim 4 , wherein said nanojet microlens is attached to a surface of said substrate opposite to a surface of said substrate on which said subwavelength optical elements are assembled, and wherein said optical device comprises a host medium surrounding said nanojet microlens and having a refractive index lower than that of said nanojet microlens.
9. The optical device of claim 4 , wherein said nanojet microlens forms said substrate on a surface of which said subwavelength optical elements are assembled.
10. The optical device of claim 1 , wherein the optical device comprises a one-dimensional or two-dimensional array of unit cells.
11. The optical device of claim 8 , wherein said unit cells of said array of unit cells comprise subwavelength optical elements belonging to the same sets of subwavelength optical elements but which are not identical.
12. The optical device of claim 1 , wherein the optical device belongs to an eyewear optical device or a display device.
13. The optical device of claim 1 , wherein said subwavelength optical elements are in a focal plane of said nanojet microlens.
14. The optical device of claim 1 , wherein the nanojet microlens enables selective excitation of all subwavelength optical elements belonging to a given set, in response to said electromagnetic wave incident on said unit cell.
15. An apparatus comprising:
a plurality of nanojet microlenses; and
for each of the nanojet microlenses, at least a first subwavelength optical element and a second subwavelength optical element, the second subwavelength optical element being different from the first subwavelength optical element;
wherein the first and second subwavelength optical elements are arranged such that the first subwavelength optical elements are selectively illuminated for a first incident angle of an incident electromagnetic wave and the second subwavelength optical elements are selectively illuminated for a second incident angle of the incident electromagnetic wave.
16. The apparatus of claim 15 , wherein the plurality of nanoj et microlenses and the first and second subwavelength optical elements are provided on a common substrate.
17. The apparatus of claim 15 , wherein the second subwavelength optical element differs from the first subwavelength optical element in an amount of phase shift applied to the incident electromagnetic wave.
18. The apparatus of claim 15 , wherein the second subwavelength optical element differs from the first subwavelength optical element in an amount of amplitude change of at least part of a spectrum of the incident electromagnetic wave.
19. The apparatus of claim 15 , wherein the first and second subwavelength optical elements comprise nanoparticles.
20. The apparatus of claim 15 , wherein the first subwavelength optical element comprises a first nanoparticle and the second subwavelength optical element comprises a second nanoparticle having a size different from the first nanoparticle.