Linear polarization sensitive meta-material reflector and phase modification structure and method
View Patent ↗The present invention relates to electromagnetic meta-material structures to serve as linear polarization sensitive mirrors. Two distinct classes have been developed, including: 1) a phase cohering reflector which maintains the phase of both polarization states with a controlled delay between polarization states, and 2) a phase de-cohering reflector which preserves the phase of one polarization state and destroys the coherence in the other. These reflective structures enable mitigation of spurious resonances in dual-polarization optical systems and phase compensation between polarization states. These polarization control structures have applications in absorber coupled detectors and receiver systems for space-borne and sub-orbital remote sensing applications.
1. A linear polarization-sensitive mirror, the mirror comprising:
a structure formed of a sub-wavelength structured meta-material geometry;
wherein said structure includes a plurality of parallel, interleaved conductive plates having a fixed slot width between said plates;
wherein half of said parallel, interleaved conductive plates have uniform ridges defining an upper surface forming a first reference plane, and half of said parallel, interleaved conductive plates form a lower surface defining a second reference plane, to achieve a polarization sensitive reflection; and
wherein said structure is configured to provide one of a phase cohering reflector which maintains a phase of both linear horizontal and vertical polarization states with a controlled delay between said polarization states, or a phase de-cohering reflector which preserves a phase of one of said polarization states and destroys a coherence of the other of said polarization states.
2. The mirror of claim 1 , wherein a geometry of said second reference plane is used to coherently or incoherently reflect input light.
3. The mirror of claim 2 , wherein said subwavelength structured meta-material geometry is one of a sub-wavelength-patterned metal or a metallized substrate material.
4. The mirror of claim 3 , wherein said plates forming said lower surface include a sloped surface which is cut at a 10-degree angle to reflect undesired polarization out of an optical path.
5. The mirror of claim 4 , wherein on condition that an input beam of incident light interacts with said lower surface, a horizontal polarization signal is suppressed.
6. The mirror of claim 3 , wherein said plates forming said lower surface are of varying depth.
7. The mirror of claim 6 , wherein said plates forming lower, interleaved surfaces have a random structure at a length scale of a predetermined wavelength of light.
8. The mirror of claim 7 , wherein an input beam of incident light passes said upper surface of said plates and scatters off said random structure to diffusely diffract or scatter said horizontal polarization state of said polarization states, suppressing a horizontally polarized electric field signal or an E(H-polarization) signal.
9. The mirror of claim 8 , wherein a number of said plates having said random structure is set by a coherently illuminated area for said H-polarization.
10. The mirror of claim 3 , wherein said lower surface of said plates is a stepped surface.
11. The mirror of claim 10 , wherein a V/H-polarization sensitive phase delay compensation between said two polarization states under plane wave illumination is provided by said stepped surface.
12. The mirror of claim 11 , wherein a surface of said mirror is shaped.
13. The mirror of claim 1 , wherein the mirror is used in optical applications for polarization discrimination, including absorber coupled detectors and receiver systems for space-borne and sub-orbital remote sensing applications.
14. A method of providing polarization discrimination, the method comprising:
providing a structure of a plurality of parallel, interleaved conductive plates having a fixed slot width between said plates, the structure being formed of a sub-wavelength structured meta-material geometry;
defining an upper surface of half of said parallel, interleaved conductive plates having uniform ridges, to form a first reference plane,
defining a lower surface of the other half of said parallel, interleaved conductive plates, to form a second reference plane;
wherein defining said first reference plane and said second reference plane achieves a polarization sensitive reflection; and
providing one of a phase cohering reflector which maintains a phase of both linear, horizontal and vertical polarization states with a controlled delay between said polarization states, or a phase de-cohering reflector which preserves a phase of one of said polarization states and destroys a coherence of the other of said polarization states.
15. The method of claim 14 , wherein a geometry of said second reference plane is used to coherently or incoherently reflect input light.
16. The method of claim 15 , wherein said subwavelength structured meta-material geometry is one of a sub-wavelength-patterned metal or a metallized substrate material.
17. The method of claim 16 , wherein said plates forming said lower surface include a sloped surface which is cut at a 10-degree angle to reflect undesired polarization out of an optical path.
18. The method of claim 17 , wherein when an input beam of incident light interacts with said lower surface, a horizontal polarization signal is suppressed.
19. The method of claim 18 , wherein said plates forming said lower surface are of varying depth.
20. The method of claim 16 , wherein said plates forming lower, interleaved surfaces have a random structure at a length scale of a predetermined wavelength of light.
21. The method of claim 20 , the method further comprising:
suppressing a horizontally polarized electric field signal or an E(H-polarization) signal, by an input beam of incident light passing on said upper surface of said plates and scattering off said random structure to diffusely diffract or scatter said horizontal polarization state of said polarization states.
22. The method of claim 21 , wherein a number of said plates having said random structure is set by a coherently illuminated area for said H-polarization.
23. The method of claim 16 , wherein said lower surface of said plates is a stepped surface.
24. The method of claim 23 , wherein a V/H-polarization sensitive phase delay compensation between said two polarization states under plane wave illumination is provided by said stepped surface.
25. The method of claim 24 , wherein a surface of said mirror is shaped.
26. The method of claim 16 , wherein the mirror is used in optical applications for polarization discrimination, including absorber coupled detectors and receiver systems for space-borne and sub-orbital remote sensing applications.