Device and method for generating stimulated emission of microwave or radio frequency radiation

1. A device for generating stimulated emission of microwave or radio frequency electromagnetic radiation, the device comprising:

a resonator structure comprising a resonant element and a gain medium;

an input source of microwave or radio frequency electromagnetic radiation to he amplified; and

an input of energy arranged to pump the resonator structure and thereby cause amplification of the electromagnetic radiation;

wherein the resonant element comprises an electrically inductive metallic loop structure having one or more half-turns, and an electrically capacitive structure.

2. A device as claimed in claim 1 , wherein the resonant element comprises a split-ring, hairpin or LC resonator; and wherein the electrically capacitive structure comprises a gap, a slot, or parallel plates.

3. A device as claimed in claim 1 , wherein the electrically inductive metallic loop structure is formed of gold, silver, or copper.

4. A device as claimed in claim 1 , wherein the electrically inductive metallic loop structure is formed as a metallic layer.

5. A device as claimed in claim 4 , wherein the metallic layer is disposed on a substrate, the substrate comprising a material having a relative permittivity greater than 10.

6. A device as claimed in claim 4 , wherein the metallic layer is disposed on a substrate, the substrate comprising a material having a relative permittivity greater than 20.

7. A device as claimed in claim 4 , wherein the metallic layer is disposed on a substrate, the substrate comprising a material selected from a group comprising: a dielectric medium; a single crystal material; a single crystal ceramic; a sintered oxide polycrystalline ceramic; a polymer; a polymer composite material; a metal; a metallodielectric structure; and a printed circuit board material.

8. A device as claimed in claim 1 , wherein the electrically inductive metallic loop structure is a first electrically inductive metallic loop structure, the resonant element further comprising a second electrically inductive metallic loop structure arranged within the first electrically inductive metallic loop structure; wherein the first and second electrically inductive loop structures are arranged concentrically and each comprises a respective gap or slot, the respective gaps or slots being arranged on mutually opposing sides of the resonant element.

9. A device as claimed in claim 1 , wherein the gain medium is disposed within the resonant element in one or more regions of relatively high magnetic field density within the resonant element.

10. A device as claimed in claim 1 , wherein the gain medium contains a polyaromatic hydrocarbon.

11. A device as claimed in claim 10 , wherein the gain medium contains p-terphenyl doped with pentacene.

12. A device as claimed in claim 1 , wherein the resonator structure has a magnetic Purcell factor of the order of 10 7 cm −3 .

13. A device for generating stimulated emission of microwave or radio frequency electromagnetic radiation, the device comprising:

a resonator structure comprising a gain medium disposed within a resonant element;

an input source of microwave or radio frequency electromagnetic radiation to be amplified; and

an input of energy arranged to pump the gain medium and thereby cause amplification of the electromagnetic radiation;

wherein the resonant element comprises a material having a relative permittivity greater than 13.

14. A device as claimed in claim 1 , wherein the stimulated emission of electromagnetic radiation is at a frequency in the range of 1 kHz to 300 GHz.

15. A device as claimed in claim 14 , wherein the stimulated emission of electromagnetic radiation is at a microwave frequency.

16. A device as claimed in claim 14 , wherein the stimulated emission of electromagnetic radiation is at a radio frequency.

17. A device as claimed in claim 1 , further comprising a temperature stabilization or thermal management apparatus.

18. A device as claimed in claim 17 , wherein the temperature stabilization or thermal management apparatus is selected from a group comprising: a Peltier element; a Stirling cycle cooler; a pulse tube cooler; forced air or gas cooling; and a Gifford-McMahon cooler.

19. A device as claimed in claim 1 , having no outer casing around the resonant element.

20. A device as claimed in claim 1 , further comprising apparatus for applying a magnetic field to the gain medium.

21. A device as claimed in claim 20 , wherein said apparatus for applying the magnetic field is selected from a group comprising: a permanent magnet; and a coil through which an electric current may be passed.

22. A device as claimed in claim 1 , further comprising apparatus for tuning the resonant frequency of the resonator structure.

23. A device as claimed in claim 22 , wherein said apparatus for tuning the resonant frequency is selected from a group comprising: an adjustable wall; and a tuning screw.

24. A method of generating stimulated emission of microwave or radio frequency electromagnetic radiation, the method comprising:

providing a resonator structure comprising a resonant element and a gain medium;

supplying, to the resonator structure, microwave or radio frequency electromagnetic radiation to be amplified; and

pumping the resonator structure with an input of energy and thereby causing amplification of the electromagnetic radiation;

wherein the resonant element comprises an electrically inductive metallic loop structure having one or more half-turns, and an electrically capacitive structure;

or alternatively wherein the method comprises:

providing a resonator structure comprising a gain medium disposed within a resonant element;

supplying, to the resonator structure, microwave or radio frequency electromagnetic radiation to be amplified; and

pumping the gain medium with an input of energy and thereby causing amplification of the electromagnetic radiation;

wherein the resonant element comprises a material having a relative permittivity greater than 13.