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US 9,195,052 B2Granted
Actively tunable polar-dielectric optical devices
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorsJames Peter Long, Joshua D. Caldwell, Jeffrey C. Owrutsky, Orest J. Glembocki
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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.
Claims23
An actively tunable polar-dielectric optical device, comprising:
- a waveguide having an active arm and an inactive arm, the waveguide being fabricated from a polar-dielectric material and, being configured to propagate a surface phonon polariton (SPhP) beam travelling along a surface thereof when the polar-dielectric material is exposed to an incident infrared optical beam having at least one wavelength within a Reststrahlen band of the polar-dielectric material;
- and
- a controllable source of charge carriers configured to controllably inject additional charge carriers directly into the active arm such that the active arm has a index of refraction nr(N,λ), N being the concentration of injected carriers, while the inactive arm has an index of refraction of nr(0,λ), at least one characteristic of the SPhP beam being affected by the index of refraction nr(N,λ) of the waveguide;
- wherein an input SPhP beam entering the waveguide is split into beam SPhP1 travelling along the inactive arm and beam SPhP2 traveling along the active arm, SPhP1 and SPhP2 being rejoined into a single output SPhP beam before exiting the waveguide, the beam SPhP1 having phase Φ1 and the beam SPhP2 beam having phase Φ2 as a result of the injection of charge carriers N into the active arm, a difference between phase Φ1 and phase Φ2 producing an interference between SPhP1 and SPhP2 when they are rejoined before exiting the waveguide, the interference producing a change in an amplitude of the output SPhP beam relative to an amplitude of the input SPhP beam;
- wherein the phase Φ2 and the amplitude of the output SPhP beam can be actively tuned by controlling the concentration of charge carriers injected into active arm of the waveguide.
2 more elements
An actively tunable polar-dielectric optical device, comprising:
- a waveguide fabricated from a polar-dielectric material, the waveguide including a cavity formed by a pair of parallel reflective features fabricated into the polar-dielectric material and being configured to propagate a surface phonon polariton (SPhP) beam travelling along a surface thereof when the material is exposed to an incident infrared optical beam having at least one wavelength within a Reststrahlen band of the polar-dielectric material;
- and
- a controllable source of charge carriers configured to controllably inject additional charge carriers directly into one or more portions of the waveguide;
- wherein the waveguide has a first index of refraction nr(0,λ) a first time when additional charge carriers are not injected into the waveguide and a second index of refraction nr(N,λ) at a second time when additional charge carriers are injected into the waveguide, N being a concentration of injected charge carriers,
- a transmission of the SPhP beam across the cavity being dependent on an index of refraction nr(N,λ) of the polar-dielectric material comprising the cavity;
- wherein the transmission of the SPhP beam across the cavity can be actively tuned by controlling the concentration of charge carriers injected into the waveguide.
3 more elements
An actively tunable polar-dielectric optical device, comprising:
- a waveguide fabricated from a polar-dielectric material, the waveguide being configured to propagate a surface phonon polariton (SPhP) beam travelling along a surface thereof when the material is exposed to an incident infrared optical beam having at least one wavelength within a Reststrahlen band of the polar-dielectric material;
- and
- a controllable source of charge carriers configured to controllably inject additional charge carriers directly into one or more portions of the waveguide;
- wherein the source of charge carriers is configured to form a patterned distribution of injected charge carriers in only a patterned portion of the waveguide, wherein the patterned portion of the waveguide has an index of refraction nr(N,λ) while the remainder of the waveguide not having additional charge carriers injected therein has a different index of refraction nr(0,λ);
- wherein the SPhP beam travelling through the waveguide enters the patterned portion of the waveguide at a first angle θ1 with respect to a first edge of the patterned portion and exits the patterned portion of the waveguide at a second angle θ2 with respect to the first edge of the patterned portion, a difference between θ2 and θ1 being a result of a difference between the index of refraction nr(N,λ) and the index of refraction nr(0,λ);
- wherein a refraction of the SPhP beam into the second angle θ2 can be actively tuned to steer the SPhP beam in a desired direction by controlling the concentration of injected charge carriers in the patterned portion of the waveguide.
3 more elements
An actively tunable polar-dielectric optical device, comprising:
- a polar-dielectric material having a real part of its permittivity near zero (∈1(λ)˜0) when the device operates at an “epsilon near zero” (ENZ) free-space wavelength λ of the polar-dielectric material, the polar-dielectric material being configured to surround a waveguide comprising a channel or trench fabricated from an optically denser material having a real part of its permittivity greater than zero (∈1(λ)>0) at the ENZ wavelength λ;
- and
- a controllable source of charge carriers configured to controllably inject additional charge carriers directly into the surrounding polar-dielectric material;
- wherein the real part of the permittivity ∈1(λ) of the device is actively tuned by controlling a concentration N of additional charge carriers injected into the polar-dielectric material.
1 more element
Dependencies are inferred from the claim text.