BROADBAND MULTIFUNCTIONAL EFFICIENT META-GRATINGS BASED ON DIELECTRIC WAVEGUIDE PHASE SHIFTERS

• US 20180210147A1
• Filed: 08/18/2016
• Published: 07/26/2018
• Est. Priority Date: 08/19/2015
• Status: Active Grant

• Current Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Original Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Inventors: KHORASANINEJAD, Mohammadreza, CAPASSO, Federico
• Granted Patent: US 10,866,360 B2
• Time in Patent Office: Days
• CPC Class Codes: G02B 2006/12061 Silicon
• CPC Class Codes: G02B 2006/12078 Gallium arsenide or alloys (GaAs, GaAlAs, GaAsP, GaInAs)
• CPC Class Codes: G02B 5/18 Diffraction gratings holographic optical elements G02B5/32, G03H; integrally combined with optical fibres G02B6/02057; for coupling light guides G02B6/34; integrally combined with optical integrated light guides G02B6/12; grating systems G02B27/44
• CPC Class Codes: G02B 6/107 Subwavelength-diameter waveguides, e.g. nanowires
• CPC Class Codes: G02B 6/124 Geodesic lenses or integrated gratings

Abstract

A phase shift element includes a substrate and a dielectric ridge waveguide (DRW) disposed on the substrate. The DRW includes a dielectric material, and a width of the DRW is less than 500 nanometers (nm). A meta-grating includes a substrate and multiple dielectric ridge wave-guides (DRWs) disposed on the substrate.

Claims

1. A phase shift element, comprising:

a substrate; and

a dielectric ridge waveguide (DRW) disposed on the substrate, the DRW comprising a dielectric material;

wherein a width of the DRW is less than 500 nanometers (nm).

2. The phase shift element of claim 1, wherein the DRW is configured to bend incident electromagnetic energy and direct the electromagnetic energy in one direction.

3. The phase shift element of claim 2, wherein the width of the DRW is about 50 nm to about 150 nm.

4. The phase shift element of claim 2, wherein the width of the DRW is less than one half of a minimum wavelength of incident electromagnetic energy in a predefined energy spectrum.

5. The phase shift element of claim 1, further comprising a plurality of DRWs of which the DRW is one, wherein the plurality of DRWs are disposed on the substrate, and wherein the phase shift element is configured to split incident electromagnetic energy and direct the electromagnetic energy in two directions.

6. The meta-grating of claim 1, wherein the DRW comprises a material with a refractive index greater than 1.5.

7. The meta-grating of claim 6, wherein the DRW comprises one of amorphous silicon, gallium phosphide, a titanium oxide, or silicon nitride.

8. A meta-surface, comprising:

a substrate; and

an array of periodic unit cells, where each periodic unit cell includes two dielectric ridge waveguides (DRWs) disposed on the substrate and configured to change a direction of incident electromagnetic energy in a predefined energy spectrum;

wherein, in each unit cell, a width of a first of the DRWs is greater than a width of a second of the DRWs, and a center-to-center distance between the two DRWs is less than a minimum wavelength of electromagnetic energy in the predefined energy spectrum.

9. The meta-grating of claim 8, wherein the width of the first DRW and the width of the second DRW are each less than one half of a minimum wavelength of the incident electromagnetic energy in the predefined energy spectrum.

10. The meta-grating of claim 8, wherein the first DRW and the second DRW each comprise a material with a refractive index greater than 1.5.

11. The meta-grating of claim 10, wherein the first DRW and the second DRW each comprise one of amorphous silicon, gallium phosphide, a titanium oxide, or silicon nitride.

12. The meta-grating of claim 10, wherein at least one of the first DRW and the second DRW comprises amorphous silicon.

13. A meta-grating, comprising:

a substrate; and

a plurality of dielectric ridge waveguides (DRWs) disposed on the substrate.

14. The meta-grating of claim 13, configured to change a direction of incident electromagnetic energy in a predefined energy spectrum, wherein the DRWs are arranged in pairs, and in each pair:

a width of a first of the DRWs is greater than a width of a second of the DRWs; and

a center-to-center distance between the pair of DRWs is less than a minimum wavelength of electromagnetic energy in the predefined energy spectrum.

15. The meta-grating of claim 13, wherein a width of each of the DRWs is less than one half of a minimum wavelength of incident electromagnetic energy in a predefined energy spectrum.

16. The meta-grating of claim 13, configured to split incident electromagnetic energy to electromagnetic energy directed in two directions, wherein the DRWs are arranged in unit cells of three DRWs, and the three DRWs in a unit cell have substantially a same width and a same length.

17. The meta-grating of claim 13, wherein the DRWs each comprise a material with a refractive index greater than 1.5.

18. The meta-grating of claim 17, at least one of the DRWs comprising amorphous silicon.

19. The meta-grating of claim 17, the DRWs each comprising one of amorphous silicon, gallium phosphide, a titanium oxide, or silicon nitride.

20. The meta-grating of claim 13, wherein the meta-grating is configured to disperse the incident light and act as a grating.

21. The meta-grating of claim 13, wherein the meta-grating is configured to spatially separate two orthogonal polarizations of incident light.

22. The meta-grating of claim 13, wherein the DRWs are configured to redirect one polarization of incident light and allow other polarizations of incident light to pass through undisturbed.

23. The meta-grating of claim 13, further comprising an embedding material disposed on the substrate, wherein the DRWs are embedded in the embedding material, and the embedding material is a low refractive index material with refractive index less than 1.7.

24. The meta-grating of claim 13, further comprising an embedding material disposed on the substrate, wherein the DRWs are embedded in the embedding material, and the embedding material is a dielectric material or in a polymer.

25. The meta-grating of claim 13, wherein the meta-grating is configured as a polarization beam splitter.

26. The meta-grating of claim 25, wherein the meta-grating is incorporated into an optical isolator.