Isotropically-etched cavities for evanescent-mode electromagnetic-wave cavity resonators

1. A device comprising:

an evanescent-mode electromagnetic-wave cavity resonator including:

a first dielectric cavity portion including a cavity operable to support at least one evanescent electromagnetic wave mode, the first cavity portion including an inner cavity surface defining the cavity;

a first conductive layer on the inner cavity surface;

a second cavity portion adjacent the first cavity portion, the second cavity portion including a cavity ceiling surface defining a ceiling of the cavity;

a dielectric post structure extending distally away from a central region of the inner cavity surface towards the cavity ceiling surface, a distal surface of the post structure being separated from the cavity ceiling surface by a gap distance, a resonant frequency of the at least one evanescent electromagnetic wave mode being dependent at least partially on the gap distance;

a second conductive layer on the post structure;

at least one dielectric spacer in a first region between the distal surface of the post structure and the cavity ceiling surface, the at least one dielectric spacer defining a static portion of the gap distance; and

at least one tuning element between the distal surface of the post structure and the cavity ceiling surface, the at least one tuning element including:

a first portion or first tuning element that physically couples the cavity ceiling surface with the at least one dielectric spacer in the first region, and

a second portion or second tuning element that includes at least one microelectromechanical systems (MEMS) structure actuatable to adjust a capacitance across the gap distance in a second region outside of the first region to effect a change in the resonant frequency of the at least one evanescent electromagnetic wave mode.

2. The device of claim 1 , wherein the cavity is substantially hemispheric.

3. The device of claim 1 , wherein the cavity is of a shape that is characteristically like a half of an ellipsoid wherein a mating surface of the isotropically-etched cavity is coplanar with a plane parallel to both the major axis and the minor axis of the half of the ellipsoid.

4. The device of claim 1 , wherein:

the inner cavity surface of the cavity has a first approximately planar inner bottom surface parallel to a mating surface of the cavity; and

the inner cavity surface of the cavity has a second curved inner side surface that connects the mating surface of the isotropically-etched cavity with the first planar inner bottom surface.

5. The device of claim 1 , wherein the cavity includes a first cavity and a second cavity having a mating surface that is coplanar with a mating surface of the first cavity, a circumference of the first cavity overlapping a circumference of the second cavity.

6. The device of claim 1 , wherein the post structure has a circular or elliptical cross-section.

7. The device of claim 1 , wherein the post structure is integrally connected with the first cavity portion.

8. The device of claim 1 , the post structure including a post and a post top at the distal end of the post, the post top being concentric with the post and having a radius or width larger than a corresponding radius or width of the post.

9. The device of claim 8 , wherein:

the post structure has a height in the range of approximately 100 microns (μm) to approximately 1000 μm;

the post has a width or diameter in the range of approximately 0.1 millimeters (mm) to approximately 1 mm; and

the post top has a width or diameter in the range of approximately 0.2 mm to approximately 5.0 mm.

10. The device of claim 1 , wherein the at least one MEMS structure includes at least two MEMS structures, each of the at least two MEMS structure being selectively actuatable.

11. The device of claim 1 , wherein the at least MEMS structure is electrostatically-actuatable.

12. The device of claim 1 , wherein the at least MEMS structure element is piezoelectrically-actuatable.

13. The device of claim 1 , further including:

a display;

a processor configured to communicate with the display, the processor being configured to process image data; and

a memory device configured to communicate with the processor.

14. The device of claim 13 , further including:

a driver circuit configured to send at least one signal to the display; and

a controller configured to send at least a portion of the image data to the driver circuit.

15. The device of claim 1 , wherein the gap distance is fixed in length.

16. The device of claim 1 , wherein the at least one MEMS structure is actuatable to adjust a length of the gap distance to adjust the capacitance across the gap distance.

17. A device comprising:

an evanescent-mode electromagnetic-wave cavity resonating means including:

a first dielectric cavity means operable to support at least one evanescent electromagnetic wave mode, the first cavity means including an inner cavity surface defining the cavity;

a first conductive means on the inner cavity surface;

a second cavity means adjacent the first cavity means, the second cavity means including a cavity ceiling surface defining a ceiling of the cavity;

a dielectric capacitive tuning means extending distally away from a central region of the inner cavity surface towards the cavity ceiling surface, a distal surface of the capacitive tuning means being separated from the cavity ceiling surface by a gap distance, a resonant frequency of the at least one evanescent electromagnetic wave mode being dependent at least partially on the gap distance;

a second conductive means on the capacitive tuning means;

at least one dielectric spacer means in a first region between the distal surface of the capacitive tuning means and the cavity ceiling surface, the at least one dielectric spacer means defining a static portion of the gap distance; and

at least one actuatable tuning means between the distal surface of the capacitive tuning means and the cavity ceiling surface, the at least one actuatable tuning means including:

a first portion or first tuning element that physically couples the cavity ceiling surface with the at least one dielectric spacer means in the first region, and

a second portion or second tuning element that includes at least one microelectromechanical systems (MEMS) structure actuatable to adjust a capacitance across the gap distance in a second region outside of the first region to effect a change in the resonant frequency of the at least one evanescent electromagnetic wave mode.

18. The device of claim 17 , wherein the capacitive tuning means is integrally connected with the first cavity means.

19. The device of claim 17 , the capacitive tuning means including a post and a post top at the distal end of the post, the post top being concentric with the post and having a radius or width larger than a corresponding radius or width of the post.

20. The device of claim 17 , wherein the capacitive tuning means has a circular or elliptical cross-section.

21. The device of claim 17 , wherein the at least one MEMS structure includes at least two MEMS structures, each of the at least two MEMS structures being selectively actuatable.

22. The device of claim 17 , wherein the at least one MEMS structure is electrostatically-actuatable.

23. The device of claim 17 , wherein the at least one MEMS structure is piezoelectrically-actuatable.

24. The device of claim 17 , wherein the gap distance is fixed in length.

25. The device of claim 17 , wherein the at least one MEMS structure is actuatable to adjust a length of the gap distance to adjust the capacitance across the gap distance.