Actively Tunable Polar-Dielectric Optical Devices

• US 20150063739A1
• Filed: 10/24/2014
• Published: 03/05/2015
• Est. Priority Date: 02/14/2013
• Status: Active Grant

• Current Assignee: The Government Of The United States Of America, As Represented By The Secretary Of The Navy
• Original Assignee: Naval Research Laboratory (U.S. Department Of Defense)
• Inventors: Long, James Peter, Caldwell, Joshua D., Owrutsky, Jeffrey C., Glembocki, Orest J.
• Granted Patent: US 9,274,352 B2
• Time in Patent Office: Days
• US Class Current: 385/1
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G01J 2003/1213 Filters in general, e.g. dichroic, band
• CPC Class Codes: G01J 3/12 Generating the spectrum; Monochromators
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• CPC Class Codes: G02B 6/1225 comprising photonic band-gap structures or photonic lattices
• CPC Class Codes: G02F 1/009 Thermal properties
• CPC Class Codes: G02F 1/011 in optical waveguides, not otherwise provided for in this subclass
• CPC Class Codes: G02F 1/0126 Opto-optical modulation, i.e. control of one light beam by another light beam, not otherwise provided for in this subclass
• CPC Class Codes: G02F 1/0136 for the control of polarisation, e.g. state of polarisation [SOP] control, polarisation scrambling, TE-TM mode conversion or separation G02F1/0353 takes precedence
• CPC Class Codes: G02F 1/0333 addressed by a beam of charged particles G02F1/05 takes precedence
• CPC Class Codes: G02F 1/29 for the control of the position or the direction of light beams, i.e. deflection
• CPC Class Codes: G02F 1/292 by controlled diffraction or phased-array beam steering controlled diffraction for optical switching G02F1/31
• CPC Class Codes: G02F 2202/10 semiconductor
• CPC Class Codes: G02F 2202/30 Metamaterials
• CPC Class Codes: G02F 2202/32 Photonic crystals
• CPC Class Codes: G02F 2203/10 plasmon
• CPC Class Codes: G02F 2203/11 involving infrared radiation
• CPC Class Codes: G02F 2203/13 involving THZ radiation
• CPC Class Codes: G02F 2203/15 involving resonance effects, e.g. resonantly enhanced interaction
• CPC Class Codes: Y10S 977/932 for electronic or optoelectronic application

Abstract

Optical devices that include one or more structures fabricated from polar-dielectric materials that exhibit surface phonon polaritons (SPhPs), where the SPhPs alter the optical properties of the structure. The optical properties lent to these structures by the SPhPs are altered by introducing charge carriers directly into the structures. The carriers can be introduced into these structures, and the carrier concentration thereby controlled, through optical pumping or the application of an appropriate electrical bias.

Claims

1. An actively tunable polar-dielectric optical device, comprising:

at least one polar-dielectric structure fabricated from a plurality of polar-dielectric materials, each of the materials being configured to exhibit surface phonon polaritons (SPhPs) when it is exposed to a corresponding incident infrared optical beam having at least one wavelength within a Reststrahlen band of that polar-dielectric material, a presence of SPhPs in each of the polar-dielectric materials affecting at least one optical property of the device, a value of the at least one optical property of the structure being dependent on a concentration of charge carriers in the polar-dielectric materials; and

a controllable source of charge carriers configured to inject additional charge carriers into at least one of the polar-dielectric materials;

wherein the value of the at least one optical property of the device can be actively tuned by controllably injecting charge carriers from the charge carrier source directly into the at least one of the polar-dielectric materials.

2. The actively tunable polar-dielectric optical device according to claim 1, wherein the source of charge carriers is configured to produce a first concentration of charge carriers in a first one of the polar-dielectric materials and to produce a second concentration of charge carriers in a second one of the polar-dielectric materials, the first and second concentrations of charge carriers producing a desired value of the at least one optical property of the device.

3. The actively tunable polar-dielectric optical device according to claim 1;

wherein the polar-dielectric structure comprises a plurality of polar-dielectric SPhP nanoantennas fabricated from a plurality of polar-dielectric materials in a stacked structure.

4. The actively tunable polar-dielectric optical device according to claim 1;

wherein the polar-dielectric structure comprises a plurality of polar-dielectric SPhP nanoantennas fabricated from a plurality of polar-dielectric materials configured as a plurality of discrete conformally overgrown layers.

5. The actively tunable polar-dielectric optical device according to claim 1;

wherein the polar-dielectric structure comprises a plurality of polar-dielectric SPhP nanoantennas fabricated from a plurality of polar-dielectric materials wherein the second polar-dielectric material is embedded within a structure formed from the first polar-dielectric material.

6. The actively tunable polar-dielectric optical device according to claim 1;

wherein the polar-dielectric structure comprises a plurality of polar-dielectric SPhP nanoantennas fabricated from a plurality of polar-dielectric materials, a first portion of each nanoantenna being fabricated from a first polar-dielectric material and a second portion of each nanoantenna being fabricated from a second polar-dielectric material;

wherein the at least one optical property is a resonant wavelength λ

_res in the first polar-dielectric material; and

wherein the resonant wavelength λ

_res in the first polar-dielectric material in the nanoantennas is actively tuned by controllably injecting charge carriers into the first polar-dielectric material.

7. The actively tunable polar-dielectric optical device according to claim 1;

wherein the polar-dielectric structure comprises a plurality of polar-dielectric SPhP nanoantennas fabricated from a plurality of polar-dielectric materials, a first portion of each nanoantenna being fabricated from a first polar-dielectric material and a second portion of each nanoantenna being fabricated from a second polar-dielectric material;

wherein the at least one optical property is a resonant wavelength λ

_res in the first polar-dielectric material;

wherein a first injection of charge carriers into the first polar-dielectric material is configured to produce a desired permittivity ∈

₁ in the first polar-dielectric material; and

wherein a second injection of charge carriers into the second polar-dielectric material is configured to produce a desired index of refraction n₂ in the second polar-dielectric material; and

wherein the first and second injections of charge carriers are further configured to produce a desired resonant wavelength λ

_res(∈

₁,n₂) in the first polar-dielectric material.

8. The actively tunable polar-dielectric optical device according to claim 1;

wherein the polar-dielectric structure comprises a plurality of polar-dielectric SPhP nanoantennas fabricated from a plurality of polar-dielectric materials, a first portion of each nanoantenna being fabricated from a first polar-dielectric material and a second portion of each nanoantenna being fabricated from a second polar-dielectric material;

wherein a first injection of charge carriers into the first polar-dielectric material is configured to produce a desired permittivity ∈

₁ and a desired index of refraction n₁ in the first polar-dielectric material; and

wherein a second injection of charge carriers into the second polar-dielectric material is configured to produce a desired permittivity ∈

₂ and desired index of refraction n₂ in the second polar-dielectric material; and

wherein the first and second injections of charge carriers are further configured to produce a desired resonant wavelength λ

_res(∈

₁,n₂) in the first polar-dielectric material and a desired resonant wavelength λ

_res(∈

₂,n₁) in the second polar-dielectric material.

9. The actively tunable polar-dielectric optical device according to claim 1;

wherein the polar-dielectric structure comprises an SPhP waveguide fabricated from a plurality of polar-dielectric materials, a first portion of the waveguide being fabricated from a first polar-dielectric material and a second portion of the waveguide being fabricated from a second polar-dielectric material;

wherein the at least one optical property is an index of refraction n_r of the waveguide;

wherein the index of refraction n_r is actively tuned by controllably injecting a first plurality of charge carriers into the first polar-dielectric material and controllably injecting a second plurality of charge carriers into the second polar-dielectric material.

10. The actively tunable polar-dielectric optical device according to claim 1;

wherein the charge carrier source is a controllable optical pump beam incident on the structure; and

wherein the injection of charge carriers into the at least one the polar-dielectric materials is controlled by controlling an intensity of the pump beam incident on that polar-dielectric material.

11. The actively tunable polar-dielectric optical device according to claim 1;

wherein at least one of the polar-dielectric materials is situated adjacent to a doped substrate and wherein the charge carrier source is a controllable electrical source operatively connected to the substrate and the at least one polar-dielectric material, the controllable electrical source being configured to controllably inject charge carriers from the substrate into at the at least one polar-dielectric material;

wherein the injection of charge carriers into the at least one polar-dielectric materials is controlled by controlling an electrical signal from the electrical source.

12. The actively tunable polar-dielectric optical device according to claim 1;

wherein at least one of the polar-dielectric materials is in contact with a highly doped substrate, metallic film or a van der Waals film situated and wherein the charge carrier source is a controllable electrical source operatively connected to the contact layer and the at least one polar-dielectric material, the controllable electrical source being configured to controllably inject charge carriers from the substrate into at the at least one polar-dielectric material;

wherein the injection of charge carriers into the at least one polar-dielectric materials is controlled by controlling an electrical signal from the electrical source.

13. The actively tunable polar-dielectric optical device according to claim 1;

wherein at least one of the polar-dielectric materials is situated between both an adjacent doped substrate and is in contact with a highly doped substrate, metallic film or a van der Waals film and wherein the charge carrier source is a controllable electrical source operatively connected to the substrate and the contact layer, the controllable electrical source being configured to controllably inject charge carriers of one polarity (electron or hole) from the substrate and of the opposite polarity from the contact layer into at the at least one polar-dielectric material;

wherein the injection of charge carriers into the at least one polar-dielectric materials is controlled by controlling an electrical signal from the electrical source.

14. The actively tunable polar-dielectric device according to claim 1, wherein at least one of the polar-dielectric materials comprises SiC, GaN, BN, BC, AlN, Al₂O₃, SiO₂, or AlGaN.

15. The actively tunable polar-dielectric device according to claim 1,

wherein at least one of a corresponding extraordinary and a corresponding ordinary permittivity of at least one of the polar-dielectric materials is actively tuned by controlling the number of charge carriers injected into the device.

16. The actively tunable polar-dielectric optical device according to claim 1, wherein a birefringence of at least one of the polar-dielectric materials is actively tuned by controlling the number of charge carriers injected into the device.

17. An actively tunable polar-dielectric optical device, comprising:

a plurality of local surface phonon-polariton (LSPhP) resonators situated on a substrate, the LSPhP resonators being fabricated from a polar-dielectric material configured to thermally excite LSPhPs that will emit photons when the material is at a higher temperature than its surroundings, a value of a thermal emission spectrum of the polar-dielectric material being dependent on a concentration of charge carriers in the polar-dielectric materials; and

a controllable source of charge carriers coupled to the polar-dielectric materials;

wherein the thermal emission spectrum from at least some of the LSPhP resonators can be actively tuned by controllably injecting charge carriers from the charge carrier source directly into the at least some of the resonators.

18. An actively tunable polar-dielectric optical device, comprising:

at least one polar-dielectric structure fabricated from a polar-dielectric metamaterial configured to exhibit surface polar phonon polaritons (SPhPs) affecting at least one optical property of the device when the metamaterial is subjected to an external stimulation, a value of the at least one optical property of the structure being dependent on a concentration of charge carriers in the metamaterial; and

a source of charge carriers controllably coupled to the device;

wherein the value of the at least one optical property is actively tuned by controllably injecting charge carriers from the charge carrier source directly into the polar-dielectric device.

19. The actively tunable polar-dielectric optical device according to claim 18, wherein the at least one optical property of the structure is an effective index of refraction of the metamaterial;

and;

wherein an output angle of an optical beam incident onto the device can be actively tuned by controlling the number of charge carriers injected into the device.

20. The actively tunable polar-dielectric optical device according to claim 18, wherein at the at least one optical property of the structure is at least one of a corresponding ordinary and a corresponding extraordinary permittivity of an anisotropic lattice of the polar dielectric material;

wherein a value of the at least one of the corresponding ordinary permittivity and extraordinary permittivity can be actively tuned by controlling the number of charge carriers injected into the device.

21. The actively tunable polar-dielectric optical device according to claim 18, wherein at the at least one optical property of the structure is at least one of a corresponding ordinary and a corresponding extraordinary permittivity of an anisotropic structure of a metamaterial;

wherein a value of the at least one of the corresponding ordinary permittivity and extraordinary permittivity can be actively tuned by controlling the number of charge carriers injected into the device.

22. The actively tunable polar-dielectric optical device according to claim 18, wherein the at least one optical property of the structure is a birefringence of the polar dielectric material;

wherein a value of the birefringence of the polar dielectric material can be actively tuned by controlling the number of charge carriers injected into the device.

23. The actively tunable polar-dielectric optical device according to claim 18, wherein the at least one optical property of the structure is a birefringence of an anisotropic structure of the metamaterial;

wherein a value of the birefringence of the anisotropic structure of the metamaterial can be actively tuned by controlling the number of charge carriers injected into the device.

24. The actively tunable polar-dielectric optical device according to claim 18, wherein the metamaterial exhibits simultaneous positive and negative real permittivities from orthogonal crystal axes in the metamaterial;

and

wherein a value of a least one of the positive and negative real permittivities can be actively tuned by controlling the number of charge carriers injected into the device.

25. The optical device according to claim 18, wherein the charge carrier source is a controllable optical pump beam incident on the device;

and

wherein the injection of charge carriers into the device is controlled by controlling an intensity of the pump beam.

26. The optical device according to claim 18, wherein the device is situated on a doped substrate and the charge carrier source is a controllable electrical source connected to the substrate and the device, the electrical source being configured to cause charge carriers from the substrate to be injected into the metamaterial;

wherein the injection of charge carriers into the metamaterial is controlled by controlling an electrical signal from the electrical source.