Optical metapolarizer device

• US 20100232017A1
• Filed: 06/19/2009
• Published: 09/16/2010
• Est. Priority Date: 06/19/2008
• Status: Active Grant

• Current Assignee: Ravenbrick, LLC
• Original Assignee: Ravenbrick, LLC
• Inventors: Park, Wounjhang, Powers, Richard M., McCarthy, Wil
• Granted Patent: US 9,116,302 B2
• Time in Patent Office: Days
• US Class Current: 359/486
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 1/007 made of negative effective refractive index materials
• CPC Class Codes: G02B 5/3058 comprising electrically conductive elements, e.g. wire grids, conductive particles
• CPC Class Codes: H01Q 15/0086 said selective devices having materials with a synthesized negative refractive index, e.g. metamaterials or left-handed materials

Abstract

An optical metapolarizer device polarizes light while mitigating the absorptive or reflective losses associated with traditional polarizers. The metapolarizer device transmits light of one polarity and rotates the other polarity so that it is closer to the transmitted polarity. As a result, although the light exiting the metapolarizer device is highly polarized, the total transmissivity of the device can be well in excess of 50%, and can approach 100% in the theoretical limit.

Claims

1. A method for polarizing light comprising

passing light through a structure with sub-wavelength features having an apparent capacitance and an apparent inductance that are different for a first axis than for a second axis, wherein

a portion of the light with a first polarity encounters an effective permittivity and an effective permeability in the structure similar to that of free space which does not significantly affect the light with the first polarity, and

a portion of the light with a second polarity encounters a large effective permittivity and a small effective permeability in the structure,

whereby an electric field of the light of the second polarity is phase-shifted in proportion to a magnetic field of the light of the second polarity and thereby rotationally shifting the second polarity to a third polarity closer in orientation to the first polarity.

2. The method of claim 1, wherein both the effective permittivity and the effective permeability encountered by the light with the second polarity are negative values.

3. The method of claim 1, wherein both the effective permittivity and the effective permeability encountered by the light with the second polarity are positive values.

4. The method of claim 1, wherein the third polarity is substantially equivalent to the first polarity.

5. The method of claim 1 further comprising passing the light through a series of structures with the sub-wavelength features to iteratively rotationally shift the second polarity to a final output polarity.

6. A method for continuously varying the amount of retardation an incident photon experiences as a function of its linear polarization such that a difference in retardation between any two photons equals or approaches a difference in a polarization azimuth between the two photons, the method comprising

passing a first photon and a second photon through a structure with sub-wavelength features having an apparent capacitance and an apparent inductance that are different for a first axis than for a second axis, wherein

the first photon with a first polarity encounters an effective permittivity and an effective permeability in the structure similar to that of free space which does not significantly affect the first photon, and

the second photon with a second polarity encounters a large effective permittivity and a small effective permeability in the structure,

whereby an electric field of the second photon is phase-shifted in proportion to a magnetic field of the second photon and thereby rotationally shifts the second polarity of the second photon to a third polarity closer in orientation to the first polarity of the first photon.

7. The method of claim 6, wherein both the effective permittivity and the effective permeability encountered by the second photon are negative values.

8. The method of claim 6, wherein both the effective permittivity and the effective permeability encountered by the second photon are positive values.

9. The method of claim 6, wherein the third polarity is substantially equivalent to the first polarity.

10. The method of claim 6 further comprising passing the light through a series of structures with the sub-wavelength features to iteratively rotationally shift the second polarity to a final output polarity.

11. A device for polarizing light comprising

a dielectric medium;

and

a structure of sub-wavelength conductive elements supported on the dielectric medium;

wherein

the conductive elements form capacitive and inductive features that exhibit an effective permittivity and an effective permissivity based on the size and orientation of the features;

the conductive elements are arranged axially within the structure such that incident light of a first polarity encounters different capacitive and inductive features along a first axis than incident light of a second polarity encounters along a second axis;

the incident light with the first polarity encounters a first effective permittivity and a first effective permeability in the structure similar to that of free space which does not significantly affect the incident light with the first polarity;

the incident light with the second polarity encounters a large second effective permittivity and a small second effective permeability in the structure; and

an electric field of the incident light of the second polarity is phase-shifted thereby rotationally shifting the second polarity to a third polarity closer in orientation to the first polarity.

12. The device of claim 11, wherein the sub-wavelength conductive elements further comprise

a grid of conductive dots arranged on the dielectric medium in a series of rows and columns, wherein

a first spacing between conductive dots in adjacent columns is substantially one-half of a wavelength of incident light to be polarized;

and

a second spacing between conductive dots in adjacent rows is substantially one-sixth of the wavelength of incident light to be polarized; and

a diameter of each of the conductive dots is substantially one-twentieth of the wavelength of incident light to be polarized.

13. The device of claim 12, wherein the conductive dots cover less than one-tenth of a total surface area of the dielectric medium.

14. The device of claim 12, further comprising a nano scale wire placed adjacent to each column of the conductive dots that inductively couples the conductive dots in the column.

15. The device of claim 14, wherein the nanoscale wire is continuous.

16. The device of claim 14, wherein the nanoscale wire is discontinuous.

17. The device of claim 14, wherein the nanoscale wire has an irregular surface.

18. The device of claim 11, wherein the sub-wavelength conductive elements further comprise an array of unit cells that are symmetric along both a horizontal axis and a vertical axis, but are asymmetric along a diagonal axis.

19. The device of claim 18, wherein the unit cells are formed of nanowires having irregular surfaces.

20. The device of claim 18, wherein the unit cells are formed of discontinuous nanowires.

21. The device of claim 18, wherein the unit cells are formed as transmission lines oriented vertically on the dielectric material.

22. The device of claim 11, wherein

the sub-wavelength conductive elements further comprise a column array of negative-index, planar antennas having horizontal capacitive gaps and vertical capacitive gaps;

and

a total length of the horizontal capacitive gaps is substantially twice as large as a total length of the vertical capacitive gaps.

23. The device of claim 22, wherein the planar antennas are formed of nanowires having irregular surfaces.

24. The device of claim 22, wherein the planar antennas are formed of discontinuous nanowires.

25. The device of claim 11, wherein the sub-wavelength conductive elements further comprise an array of parallel pairs of nanowire segments having a length of substantially one-eighth of a wavelength of incident light to be polarized and a diameter of an aspect ration of 1:

6.875 with respect to the length.

26. The device of claim 25, wherein the sub-wavelength conductive elements further comprise a plurality of nanowire shunt inductor segments respectively positioned between the nanowire segments in each of the parallel pairs of nanowire segments.

27. The device of claim 11, wherein the sub-wavelength conductive elements further comprise a plurality of strips of transparent birefringement material arranged in parallel on the dielectric medium and spaced apart a distance substantially less than a wavelength of incident light to be polarized.

28. The device of claim 27, wherein the distance is one-fourth or less of the wavelength of incident light to be polarized.

29. The device of claim 27, wherein the dielectric material has a significantly different index of refraction from the strips of transparent birefringement material whereby the strips have an effect on the incident light distinct from an effect of the dielectric medium.

30. The device of claim 27, wherein the strips of transparent birefringement material are arranged in parallel on the dielectric medium.

31. The device of claim 27, wherein the strips of transparent birefringement material are arranged as fractal, spade-filling shapes on the dielectric medium.

32. The device of claim 11, wherein the structure of sub-wavelength conductive elements creates a negative large second effective permittivity and a negative small second effective permeability.

33. The device of claim 11, wherein less than 50 percent of the incident light is reflected by the device.

34. A method for increasing the brightness of polarization-dependent video displays and optical shutter devices comprising

providing a metapolarizer to receive incident light, the metapolarizer further comprising

a dielectric medium;

a structure of sub-wavelength conductive elements supported on the dielectric medium;

wherein

the conductive elements form capacitive and inductive features that exhibit an effective permittivity and an effective permissivity based on the size and orientation of the features;

the conductive elements are arranged axially within the structure such that incident light of a first polarity encounters different capacitive and inductive features along a first axis than incident light of a second polarity encounters along a second axis;

the incident light with the first polarity encounters a first effective permittivity and a first effective permeability in the structure similar to that of free space which does not significantly affect the incident light with the first polarity;

the incident light with the second polarity encounters a large second effective permittivity and a small second effective permeability in the structure; and

an electric field of the incident light of the second polarity is phase-shifted thereby rotationally shifting the second polarity to a third polarity closer in orientation to the first polarity;

arranging a waveblock depolarizer in a position to receive an output of the incident light from the metapolarizer, wherein the waveblock depolarizer rotates the polarity of incident light when in a transmissive state and is neutral to the polarity of the incident light when in an opaque state;

arranging a standard polarizer in a position to receive an output of the incident light from the waveblock depolarizer, wherein the standard polarizer is selected to match the polarity of the output of the incident light from the waveblock depolarizer when in the transmissive state and to be of substantially opposite polarity to the first polarity and the third polarity; and

placing the waveblock depolarizer in the transmissive state.

35. The method of claim 34 further comprising alternately placing the waveblock depolarizer in the opaque state to cause the standard polarizer to reflect all of the incident light.