Processing

Please wait...

Settings

Settings

Goto Application

1. WO2011001253 - CONTROLLING ABSORPTION OF LIGHT IN A CAVITY

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]

CLAIMS:

1. A method of controlling the absorption of light, the method

comprising the steps of:

providing a cavity comprising a medium having a complex index of refraction nm, the cavity adapted to confine light within the medium; irradiating the cavity in a first direction with a first beam of light having a wavelength λ; and

irradiating the cavity in a second direction with a second beam of light having a same wavelength λ;

characterised by;

configuring the first beam of light and the second beam of light such that a pattern of irradiation in the cavity created by interference between at least the first and second beams of light corresponds to the inverse of the emission pattern of a laser of wavelength λ having a complex index of refraction nm* that is the complex conjugate of the index of refraction of the medium nm; and

controlling one or more parameters of the cavity or one or both of the first and second light sources so as to control the amount of absorption of light by the medium within the cavity.

2. A method as described in claim 1 , wherein the step of controlling one or more parameters of one or both of the first and second light sources comprises controlling the relative phase between the first light source and second light source.

3. A method as described in claim 1 or claim 2, wherein the step of controlling one or more parameters of one or both of the first and second light sources comprises controlling the frequency of one or both of the first light source and second light source.

4. A method as described in any one of the preceding claims, wherein the step of controlling one or more parameters of the cavity comprises controlling the refractive index of the medium.

5. A method as described in claim 4, further comprising tuning the

refractive index of the medium onto and away from values of the index of refraction that result in coherent perfect absorption.

6. Preferably, the refractive index of the medium is controlled by

electrically or optically pumping the medium.

7. A method as described in any one of the preceding claims, wherein the cavity is defined by interfaces between the medium and another medium of differing refractive index.

8. A method as described in any one of claims 1 to 6, wherein the cavity comprises one or more reflectors which define said cavity.

9. A method as described in any one of the preceding claims, wherein the step of irradiating the cavity in a second direction with a second beam of light comprises reflecting the first beam of light to provide said second beam of light, the second direction being parallel and opposite to the first direction.

10. A method as described in any one of the preceding claims, wherein the method comprises irradiating the medium with one or more additional beams of light, each of said additional beams of light configured to interfere with the first, second and any other additional beams of light to create the pattern of irradiation.

11. A method as described in any one of the preceding claims, further comprising the step of extracting energy corresponding to the absorbed light from the medium.

12. A method as described in claim 11 , wherein the phase of the second beam of light is modulated so as to modulate the energy extracted from the medium.

13. A method as described in claim 11 , wherein the method comprises the step of monitoring the energy extracted from the medium so as to determine the relative phase between the first and second beams of light.

14. A method as described in any one of the preceding claims, wherein the step of controlling the first and second beams of light includes controllably switching on or off the second beam of light such that the medium selectively absorbs or transmits the first beam of light.

15. An absorber system for controlled absorption of light, the system comprising:

a cavity comprising a medium having an index of refraction nm; and a first light source and a second light source, the first and second light sources irradiating the cavity in different directions;

wherein the first and second light sources are configured such that a pattern of irradiation in the cavity created by interference between light from at least the first and second light sources corresponds to the inverse of the emission pattern of a laser medium having a complex index of refraction nm* that is the complex conjugate of the index of refraction of the medium nm; and

whereby varying one or more parameters of the cavity or one or both of the first and second light sources correspondingly varies the amount of absorption of light by the medium within the cavity.

16. A system as described in claim 15, wherein varying the relative phase between the first light source and second light source correspondingly varies the amount of absorption of light by the medium within the cavity.

17. A system as described in claim 15 or claim 16, wherein varying the frequency of one or both of the first light source and second light source correspondingly varies the amount of absorption of light by the medium within the cavity.

18. A system as described in any one of claims 15 to 17, wherein the cavity is defined by interfaces between the medium and another medium of differing refractive index.

19. A system as described in any one of claims 15 to 17, wherein the cavity comprises one or more reflectors which define said cavity.

20. A system as described in any one of claims 15 to 19, wherein the absorber system comprises one or more additional light sources, the or each additional light source configured such that light therefrom interferes with light from the first, second and any other additional light source to create the pattern of irradiation.

21. A system as described in any one of claims 15 to 20, wherein the medium has a complex index of refraction that varies smoothly with frequency, so that the condition for coherent perfect absorption is satisfied within a tunable frequency range of the first and second light sources.

22. A system as described in any one of claims 15 to 21 , wherein the medium comprises a semiconductor material having a bandgap close to the tunable frequency range of light from the first and second light sources, so that the index of refraction varies smoothly within said frequency range.

23. A system as described in any one of claims 15 to 22, wherein the index of refraction of the semiconductor material is controlled extrinsically.

24. A system as described in claim 23, wherein the index of refraction of the semiconductor material is controlled by doping, carrier injection or optical pumping.

25. A system as described in any one of claims 15 to 20, wherein the medium comprises a material having a complex index of refraction that may be controlled externally.

26. A system as described in claim 25, wherein the complex index of refraction is controlled by applying an electrical current or by applying light of a different frequency from that of the first and second light sources.

27. A system as described in any one of claims 25 to 26, wherein the absorber system further comprises doped regions of semiconductor material adjacent to the cavity to extract energy from the medium in the form of electrical current.

28. A system as described in any one of claims 15 to 27, wherein the second light source comprises a reflector configured so as to reflect light from the first light source and thereby provide said second light source.

29. A system as described in claim 28, wherein the reflector comprises a distributed Bragg reflector.

30. A system as described in any one of claims 15 to 29, further

comprising one or more waveguides adapted to transmit light from one or both of the first and second light sources to the cavity.

31. A system as described in claim 30, wherein the absorber system comprises a waveguide, the waveguide comprising the cavity and integrally formed with the one or more waveguides to transmit light to the cavity.

32. A system as described in any one of claims 15 to 17, wherein the absorber system comprises an optical fibre having a segment comprising the cavity.

33. An interferometer comprising;

a cavity comprising a medium having an index of refraction nm; a first arm to couple a first portion of incident light to one end of the cavity; and

a second arm to couple a second portion of incident light to another end of the cavity;

wherein the interference between light from at least the first and second light sources creates a pattern of irradiation in the medium corresponding to the inverse of the emission pattern of a laser

medium having a complex index of refraction nm* that is the complex conjugate of the index of refraction of the medium nm; and wherein variation in the optical lengths of one or both of the first and second arms results in modulation of the amount of absorption of light within the cavity.

34. An interferometer as described in claim 33, wherein the first and second arms comprise waveguides adapted to transmit light from one or more light sources to the cavity.

35. An interferometer as described in claim 33 or claim 34, wherein the cavity and the first and second arms are integrally formed on a semiconductor substrate, the cavity and/or one or both of the first and second arms comprising a ridge waveguide.

36. An interferometer as described in any one of claims 33 to 35,

wherein the cavity comprises one or more distributed Bragg reflectors which define the cavity.

37. An interferometer as described in any one of claims 33 to 35,

wherein the cavity is defined by interfaces between the medium and the first and second arms.

38. An interferometer as described in any one of claims 33 to 37,

wherein the interferometer further comprises doped regions adjacent to the cavity to extract energy from the cavity in the form of electrical current.

39. An interferometer as described in any one of claims 33 to 37,

wherein energy is extracted from the cavity as a heat signal.