Sub-wavelength efficient polarization filter (SWEP filter)

A method for forming a polarization filter, comprising the steps of:

• providing a first waveguide having a first refractive index;
• forming a first SWS in said first waveguide, said first SWS formed by disposing a first plurality of sub-wavelength features in said first waveguide with a substantially equal spacing, said first plurality of features formed from material having a refractive index greater than said first refractive index;
• providing a second waveguide having a second refractive index, and
• forming a second SWS in said second waveguide, said second SWS formed by disposing a plurality of sub-wavelength features in said second waveguide with a substantially equal spacing, said second plurality of features formed from material having a refractive index greater than said second refractive index,
• said first and second SWS optically coupled through a dielectric waveguide coupling section, said coupling section exclusive of any reflective structures therein, wherein said filter provides a polarization sensitive resonance, said polarization sensitive resonance substantially reflecting a first polarization component of incident light while substantially transmitting a second polarization component of said incident light, said polarization components being orthogonal to one another.

A method for separating orthogonal polarizations of light, comprising the steps of:

• providing a filter comprising:
• a first sub-wavelength resonant grating structure (SWS) for receiving incident light, said incident light having orthogonal polarization components, and a second SWS, said first and second SWS optically coupled through a dielectric waveguide coupling section, said coupling section exclusive of any reflective structures therein, wherein said filter substantially reflects one of said orthogonal polarization components and substantially transmits the other of said orthogonal polarization components;
• shining said incident light on said first SWS, and
• substantially reflecting one of said orthogonal polarization components and substantially transmitting the other of said orthogonal polarization components.

A method for high Q narrowband filtering, comprising the steps of:

• providing a filter comprising:
• a first sub-wavelength resonant grating structure (SWS) for receiving incident light, said incident light having orthogonal polarization components, and a second SWS, said first and second SWS optically coupled through a dielectric waveguide coupling section, said coupling section exclusive of any reflective structures therein;
• substantially reflecting a first polarization component of said incident light over a broad band of wavelengths except at least one narrow band within said broad band, said narrow band substantially transmitting said first polarization component when a spacing distance of said first and second SWS substantially equals an integer number of half optical wavelengths of said incident light, and
• substantially transmitting a second polarization component of said incident light over an entire width of said broad band.