Optical devices, systems and methods
First and second coherent light beams of the same wavelength are propagated in opposite directions to interact on a sub-wavelength thickness metallic metamaterial layer which is structured with a periodicity such that there is a resonance matched to the wavelength of the coherent beams. The first beam is then able to modulate the intensity of the second beam by modulating the phase and/or intensity of the first beam. The interference of the counter- propagating beams can eliminate or substantially reduce Joule loss of light energy in the metamaterial layer or, on the contrary, can lead to a near total absorption of light, depending on the mutual phase and/or intensity of the interacting beams. A modulation is thus provided without using a non-linear effect.
1. A device for processing light with light, comprising:
a first input for receiving a signal beam of coherent light at a wavelength;
a second input for receiving a control beam of coherent light having the wavelength;
a metamaterial element having a thickness and lateral structure having a size scale substantially smaller than the wavelength of the beams and arranged to receive the control beam and the signal beam on opposite sides thereof;
a phase and intensity adjuster operable to set the mutual phase of the signal and control beams such that a standing wave is formed having a node or an antinode coinciding with the metamaterial element, wherein:
absorption of the signal beam by the metamaterial element changes based on interaction between the metamaterial element and the standing wave: and
the node of the standing wave coinciding with the metematerial element causes of absorption of the signal beam by the metamaterial element to be different from absorption of the signal beam by the metamaterial element when the antidote of the standing wave coincides with the metamterial element; and
an output for transmitting a component of the signal beam after transmission through the metamaterial element.
2. The device of claim 1 , further comprising a control laser source for providing the control beam to the second input.
3. The device of claim 1 , further comprising a signal laser source for providing the signal beam to the first input.
4. The device of claim 1 , further comprising a laser source for providing both the signal beam and the control beam to the first and second inputs respectively.
5. The device of claim 1 , further comprising a sensor for detecting intensity of the component of the signal beam transmitted through the output.
6. The device of claim 5 , wherein the sensor is connected to the phase and intensity adjuster to set the mutual phase responsive to detected intensity.
7. The device of claim 1 , wherein the phase and intensity adjuster includes a phase modulator operable to vary the phase of the control beam incident on the metamaterial element, so as to switch between a node and an antinode of the interference pattern coinciding with the metamaterial element to effect a modulation of the signal beam's transmission through the metamaterial element.
8. The device of claim 1 , wherein the phase and intensity adjuster includes an intensity modulator operable to vary the intensity of the control beam incident on the metamaterial element between first and second intensities to effect a modulation of the signal beam's transmission through the metamaterial element.
9. The device of claim 1 , wherein the lateral structure of the metamaterial element has a period which provides the metamaterial element with a resonance at the wavelength.
10. The device of claim 9 , wherein the resonance is a plasmon resonance.
11. The device of claim 1 , wherein the output is also arranged to transmit a component of the control beam after transmission through the metamaterial element.
12. The device of claim 1 , wherein the thickness and lateral structure of the metamaterial element are dimensioned such that the transmitted component of the signal beam in the presence of said control beam when a node of the interference pattern is coincident with the metamaterial element has an intensity greater than in the absence of said control beam.
13. The device of claim 1 , wherein the thickness and lateral structure of the metamaterial element are dimensioned such that the transmitted component of the signal beam in the presence of said control beam when a node of the interference pattern is coincident with the metamaterial element has at least 70, 80, 90, 95 or 98% of the intensity of the signal beam incident on the metamaterial element.
14. The device of claim 1 , wherein the metamaterial element is arranged embedded in, or on the end face of, a waveguide transverse to the waveguide channel.
15. The device of claim 1 , wherein the interaction between the metamaterial element and the standing wave does not change the index of refraction of the metamaterial element for the wavelength of the signal beam.
16. A method of processing light with light comprising:
providing a signal beam of coherent light at a wavelength;
providing a control beam of coherent light having the wavelength;
providing a metamaterial element having a thickness substantially smaller than the wavelength of the beams and structured laterally on a size scale substantially smaller than the wavelength of the beams;
directing the control beam and the signal beam to be incident on the metamaterial element in opposite directions; and
setting the mutual phase of the signal and control beams such that a standing wave is formed having a node or an antinode coinciding with the metamaterial element, thereby to control transmission of the signal beam through the metamaterial element, wherein:
absorption of the signal beam by the metamaterial element changes based on interaction between the metamaterial element and standing wave; and
the node of the standing wave coinciding with the metamaterial element causes absorption of the signal beam by the metamaterial element to be different from absorption of the signal beam by the metamaterial element when the antinode of the standing wave coincides with the metamaterial element.
17. The method of claim 16 , wherein the mutual phase is modulated to alternate between a node and an antinode of the interference pattern coinciding with the metamaterial element to effect a modulation of the signal beam's transmission through the metamaterial element.
18. The method of claim 16 , wherein the intensity of the control beam is modulated to effect a modulation of the signal beam's transmission through the metamaterial element.
19. The method of claim 16 , further comprising:
measuring the intensity of the signal beam after its transmission through the metamaterial element.
20. The method of claim 16 , wherein the lateral structure has a periodicity matched to the wavelength.
21. The method of claim 16 , wherein the thickness and lateral structure of the metamaterial element are dimensioned such that the transmitted component of the signal beam in the presence of said control beam when a node of the interference pattern is coincident with the metamaterial element has an intensity greater than in the absence of said control beam.
22. The method of claim 16 , wherein the thickness and lateral structure of the metamaterial element are dimensioned such that the transmitted component of the signal beam in the presence of said control beam when a node of the interference pattern is coincident with the metamaterial element has at least 70, 80, 90, 95 or 98% of the intensity of the signal beam incident on the metamaterial element.
23. The method of claim 16 , wherein the lateral structure of the metamaterial element has a period which provides the metamaterial element with a resonance at the wavelength.
24. The method of claim 23 , wherein the resonance is a plasmon resonance.
25. The method of claim 16 , wherein the interaction between the metamaterial element and the standing wave does not change the index of refraction of the metamaterial element for the wavelength of the signal beam.