Electrically-reconfigurable optical device structures with phase change materials

Patent metadata

Field	Value
Publication number	US-12130507-B1
Application number	US-202318204158-A
Country	US
Kind code	B1
Filing date	May 31, 2023
Priority date	May 31, 2023
Publication date	Oct 29, 2024
Grant date	Oct 29, 2024

Abstract

A reconfigurable optical frequency selective structure having embedded therein:
(a) an array of optical antennas for picking up propagating radiation in a visible or infrared frequency region and achieving preferential absorption of electromagnetic energy at a target wavelength k within the region, (b) an array of optical mesa structures of sub-wavelength scale including a phase-change material, the array of optical antennas being disposed atop the array of optical mesa structures respectively; (c) a metal ground plane disposed beneath the array of optical mesa structures, the array of optical mesa structures standing above the ground plane or an interfacial layer and being separated from one another to inhibit parasitic capacitance coupling therebetween; and (d) a plurality of heaters for selectively heating any one of the array of optical mesa structures to cause the phase change material in the selected optical mesa structure to change from an amorphous state, wherein the antenna atop the selected mesa structure is capacitively coupled to the metal ground plane, to a crystalline state wherein the antenna atop the selected mesa structure is electrically shunted to the ground plane via the selected mesa structure.

First claim

What is claimed is:

1. A reconfigurable optical frequency selective structure comprising embedded therein:
(a) an array of optical antennas for picking up propagating radiation in a visible or infrared frequency region and achieving preferential absorption of electromagnetic energy at a target wavelength k within the region, the array of optical antennas being of sub-wavelength scale and being separated from one another at a predetermined pitch or pitches;
(b) an array of optical mesa structures of sub-wavelength scale, including at least first and second optical mesa structures, each optical mesa structure in the array of optical mesa structures comprising a phase-change material, the phase change material comprising a chalcogenide-containing alloy, the array of optical antennas being disposed atop the array of optical mesa structures respectively;
(c) a metal ground plane disposed beneath the array of optical mesa structures or, optionally, beneath an interfacial layer disposed between the metal ground plane and the array of optical mesa structures, the array of optical mesa structures standing above the ground plane or the interfacial layer and being separated from one another to inhibit parasitic capacitance coupling therebetween; and
(d) means for selectively heating any selected one of the array of optical mesa structures to cause the phase change material in the selected optical mesa structure to change from an amorphous state in which the antenna atop the selected optical mesa structure is capacitively coupled to the metal ground plane to a crystalline state in which the antenna atop the selected optical mesa structure is electrically shunted to the metal ground plane via the selected optical mesa structure:

wherein, with the antenna atop the selected optical mesa structure capacitively coupled to the metal ground plane the selected optical mesa structure provides the optical frequency selective structure with an optical response and, with the antenna atop the selected optical mesa structure electrically shunted to the ground plane the selected optical mesa structure does not provide the optical frequency selective structure with an optical response; and
wherein components (a), (b), (c) and (d) are configured and arranged such that the optical frequency selective structure is reconfigurable in at least four (4) different optical configurations, including a configuration in which the first and second optical mesa structures provide the optical frequency selective structure with first and second optical responses respectively, a configuration in which neither of the first and second optical mesa structures provides the optical frequency selective structure with an optical response and configurations in which only one or the other of the first and second optical mesa structures provides the optical frequency selective structure with an optical response.

2. The reconfigurable optical frequency selective structure according to claim 1 , wherein the means for selectively heating comprises a plurality of heater blocks of sub-wavelength scale embedded in a dielectric material and disposed beneath the metal ground plane or within openings in the metal ground plane with each of the plurality of heater blocks aligned beneath respective of the optical mesa structures.

3. The reconfigurable optical frequency selective structure according to claim 2 , wherein each of the plurality of heater blocks comprises a TiW heater.

4. The reconfigurable optical frequency selective structure according to claim 1 , wherein the array of optical antennas atop respective of the optical mesa structures are embedded in a first dielectric layer.

5. The reconfigurable optical frequency selective structure according to claim 1 , further comprising a substrate under the metal ground plane, a second dielectric layer being disposed between the substrate layer and the plurality of heaters to isolate the substrate from the plurality of heaters.

6. The reconfigurable optical frequency selective structure according to claim 5 , wherein the substrate comprises silicon and the second dielectric layer comprises SiO 2 .

7. The reconfigurable optical frequency selective structure according to claim 1 , wherein the array of optical antennas are metallic optical antennas.

8. The reconfigurable optical frequency selective structure according to claim 7 , wherein the array of optical antennas comprise a metal selected from the group consisting of Au, Al, Pt, Cr, and Cu.

9. The reconfigurable optical frequency selective structure according to claim 1 wherein the array of optical antennas are dielectric optical antennas.

10. The reconfigurable optical frequency selective structure according to claim 9 , wherein the array of optical antennas comprise a dielectric material selected from the group consisting of Ge, Si and TiO 2 .

11. The reconfigurable optical frequency selective structure according to claim 1 , wherein the phase change material is an alloy comprising a chalcogenide selected from the group consisting of SbTe and doped-SbTe.

12. The reconfigurable optical frequency selective structure according to claim 1 , which comprises the interfacial layer disposed between the metal ground plane and the array of optical mesa structures.

13. The reconfigurable optical frequency selective structure according to claim 1 , wherein the array of optical antennas is arranged periodically at the predetermined pitch.

14. An apparatus comprising the reconfigurable optical frequency selective structure according to claim 1 , and means for applying electrical pulse signals selectively to each of the plurality of heater blocks to activate and inactivate them.

15. A reconfigurable optical filter comprising the reconfigurable optical frequency selective structure of claim 1 .

16. The reconfigurable optical filter according to claim 15 , wherein the optical filter is a notch filter or a bandpass filter.

17. The reconfigurable optical frequency selective structure according to claim 1 , wherein the array of optical antennas comprises at least a first optical antenna for picking up and preferentially absorbing radiation at a first target wavelength λ 1 and a second optical antenna for picking up and preferentially absorbing radiation at a second target wavelength λ 2 , the second target wavelength being different from the first target wavelength such that the array of optical antennas pick up and preferentially absorb radiation comprising wavelengths of a plurality of different colors, including a first color and a second color.

18. The reconfigurable optical frequency selective structure according to claim 17 , wherein the first optical antenna is disposed atop the first optical mesa structure and the second optical antenna is disposed atop the second optical mesa structure, the first and second optical mesa structures being separated from one another to inhibit parasitic capacitance coupling therebetween and to enable selective heating of each of the first and second optical mesa structures individually such that the first optical mesa structure, the second optical mesa structure or both can be selectively heated to cause the phase change material in the selectively heated optical mesa structure or structures to change from an amorphous state, wherein the antenna atop the selected mesa structure is capacitively coupled to the metal ground plane, to a crystalline state, wherein the antenna atop the selectively mesa structure is electrically shunted to the metal ground plane.

19. The reconfigurable

Assignees

• Hrl Lab Llc

Inventors

• Chow David
• Jensen Joseph
• Moon Jeong-Sun
• Son Kyung-Ah
• Quarfoth Ryan

Classifications

• G02F1/17

  based on variable-absorption elements not provided for in groups G02F1/015 - G02F1/169 · CPC title

• G02F1/0147 Primary

  based on thermo-optic effects (G02F1/132 takes precedence) · CPC title

• G01J1/0407 Primary

  Optical elements not provided otherwise, e.g. manifolds, windows, holograms, gratings · CPC title