Quadratic phase weighed solar receiver
A leaky travelling wave array of optical elements provide a solar wavelength rectenna.
1. A solar energy apparatus comprising:
a waveguide having a top surface, a bottom surface, a detection end and an collection end;
a continuous wedge lens disposed adjacent the top surface of the waveguide and coextensive with the waveguide to extend along a major axis thereof, for providing solar wavelength light to the waveguide;
a coupling structure comprising a plurality of scattering features disposed on or within the waveguide, the the coupling structure extending from the collection end to the detection end; and
a quadratic phase weight layer disposed between the waveguide and the continuous wedge lens, and coextensive with both the waveguide and the continuous wedge lens, and providing a quadratic phase weight to solar wavelength light along a primary axis of the waveguide.
2. The apparatus of claim 1 wherein the quadratic phase weight layer is imposed by the quadratic phase weight layer having a thickness tapering with distance from the detection end to the collection end.
3. The apparatus of claim 2 wherein the quadratic phase weight layer introduces linear delay to incident solar energy received by the apparatus.
4. The apparatus of claim 3 wherein the quadratic phase weight layer imparts a beam direction to the apparatus that is independent of receive solar energy wavelength.
5. The apparatus of claim 2 wherein the quadratic phase weight layer imparts an equivalent length of the waveguide along the primary axis of at least 100 λ for solar wavelengths.
6. The apparatus of claim 2 wherein the taper of the thickness of the quadratic phase weighting layer is defined by
φ( x )= e iαx 2
where x is the distance along the waveguide and α is a weighting constant.
7. The apparatus of claim 1 wherein the quadratic phase weight comprises sub-surface elements within the waveguide.
8. The apparatus of claim 7 wherein the sub surface elements are varied in length, spacing, and/or depth within the waveguide.
9. The apparatus of claim 7 wherein the sub surface elements are located deep enough within the waveguide so as to not radiate outside the waveguide.
10. The apparatus of claim 1 wherein a set of one-dimensional waveguide elements, each having a top surface, bottom surface, a detection end, and a collection end, -are positioned end to end such that their major axes are parallel and the wedge lens further comprises a single wedge lens extending along the top surfaces of the set of one dimensional waveguide elements.
11. The apparatus of claim 10 wherein the single wedge lens is a molded plastic element.
12. The apparatus of claim 11 wherein the gap is disposed between the single wedge lens and the top surfaces of the sets of waveguide elements.
13. The apparatus of claim 12 wherein an angle of the gap is configurable.