Reconfigurable thermally actuated transmissive and reflective metasurfaces

1 . A panel comprising:

a substrate;

a metallization layer formed on a first surface of the substrate, wherein the metallization layer is configured to be resonant at an operating frequency or an operating frequency range, the metallization layer including a plurality of unit cells;

a switch layer formed on a second surface of the substrate, wherein the switch layer is in a metallic state when a temperature of the switch layer is above a transition temperature and is in an insulator state when the temperature of the switch layer is below the transition temperature; and

a refractory heater layer configured to generate heat such that the temperature of the switch layer is controlled,

wherein the panel operates in a reflective mode when the switch layer is in the metallic state and operates in a transmission mode when the switch layer is in the insulator state,

an insulator layer positioned between the switch layer and the refractory heater layer, wherein the insulator layer is thermally conductive,

wherein the unit cells of the metallization layer are configured to have a phase profile such that an incident signal is reflected in a specific direction when operating in the reflective mode;

a cover layer formed over the metallization layer;

a bottom cover layer formed below the refractory heater layer; and

wherein:

the refractory heater layer is transparent at least to the operating frequency or range of operating frequencies,

the refractory heater layer comprises a strip having a meandering shape disposed at or near a periphery of the panel to reduce radio frequency interference on the metallization layer,

wherein the refractory heater layer has a resistance and wherein a shape of the refractory heater layer is configured to avoid temperature gradients.

2 . The panel of claim 1 , further comprising contact points extending through the bottom cover layer and connecting with the refractory heater layer, wherein a voltage is applied to the refractory heater layer via the contact points.

3 . The panel of claim 1 , wherein at least one of:

the meandering shape comprises transitions such that different portions of the strip are oriented in different orientations;

the meandering shape includes curved portions and straight portions; and

the strip does not overlap with the unit cells of the metallization layer in a depth direction or at least partially overlaps with the unit cells in the depth direction.

4 . The panel of claim 1 , wherein ends of the refractory heater layer terminate at contact points.

5 . The panel of claim 1 , wherein the refractory heater layer comprises tungsten and the switch layer comprises vanadium dioxide (VO 2 ).

6 . The panel of claim 1 , further comprising configuring a shape, width, and thickness of the refractory heater layer.

7 . The panel of claim 1 , further comprising a controller configured to connect and disconnect a power source to the refractory heater layer.

8 . The panel of claim 7 , wherein the controller is controlled wirelessly.

9 . The panel of claim 1 , wherein the substrate comprises at least one of silicon, FR4, glass, sapphire, quartz or a dielectric material and wherein the insulator layer comprises a dielectric material and wherein the panel is transparent to radio frequencies in the transmission mode.

10 . A system comprising:

panels that are placed in an environment to provide network coverage in the environment,

wherein each panel comprises:

a substrate;

a metallization layer formed on a first surface of the substrate, wherein the metallization layer is configured to be resonant at an operating frequency or an operating frequency range;

a switch layer formed on a second surface of the substrate, wherein the switch layer is in a metallic state when a temperature of the switch layer is above a transition temperature and is in an insulator state when the temperature of the switch layer is below the transition temperature; and

a refractory heater layer configured to generate heat such that the temperature of the switch layer is controlled,

wherein the panel operates in a reflective mode when the switch layer is in the metallic state and operates in a transmission mode when the switch layer is in the insulator state,

an insulator layer positioned between the switch layer and the refractory heater layer, wherein the insulator layer is thermally conductive,

wherein the metallization layer comprises a plurality of unit cells that are configured to have a phase profile such that an incident signal is reflected in a specific direction when operating in the reflective mode;

a cover layer formed over the metallization layer;

a bottom cover layer formed below the refractory heater layer; and

wherein:

the refractory heater layer is transparent at least to the operating frequency or range of operating frequencies,

the refractory heater layer comprises a meandering strip disposed at or near a periphery of the panel to reduce radio frequency interference on the metallization layer,

wherein the refractory heater layer has a resistance and wherein a shape of the refractory heater layer is configured to avoid temperature gradients.

11 . The system of claim 10 , wherein at least one of the panels operates in the reflective mode and at least one of the panels operates in the transmission mode.

12 . The system of claim 10 , wherein a first panel included in the panels is configured to reflect an incident signal to a second panel included in the panels.

13 . The system of claim 10 , wherein each of the panels further comprises:

contact points extending through the bottom cover layer and connecting with the refractory heater layer, wherein a voltage is applied to the refractory heater layer via the contact points, wherein the refractory heater layer comprises tungsten and the switch layer comprises vanadium dioxide (VO 2 ).