High brightness directional direct emitter with photonic filter of angular momentum
A nano-structure layer is disclosed. The nano-structure layer includes a plurality of nano-photonic structures that are configured in a first configuration such that light incident upon the nanostructured layer below a cut-off angle passes through the nanostructured layer and light incident upon the nanostructured layer above the cut-off angle is reflected back in direction of the incidence.
1. A light emitting device comprising:
a semiconductor diode structure;
a substrate transparent to light emitted by the semiconductor diode structure and comprising a top surface, an oppositely positioned bottom surface, and side surfaces connecting the top and bottom surfaces, the bottom surface disposed on or adjacent the semiconductor diode structure; and
an angular filter comprising photonic crystals, disposed on or adjacent the top surface of the substrate, and arranged to transmit light emitted by the semiconductor diode structure into the substrate and incident on the angular filter at an angle of incidence less than a cut-off angle and reflect back into the transparent substrate light emitted by the semiconductor diode structure and incident on the angular filter at an angle of incidence greater than or equal to the cut-off angle, such that transmission through the angular filter of light at angle of incidence 35 degrees and higher is 0%,
a reflective nanostructured layer disposed on or adjacent to a side surface of the substrate and configured to reflect toward the angular filter, at an angle of incidence less than the cutoff angle, light emitted by the semiconductor diode structure into the substrate that is incident on the reflective nanostructured layer at perpendicular or near perpendicular incidence, the reflective nanostructured layer comprising a specular reflector, a dielectric layer disposed between the specular reflector and the substrate, and a periodic arrangement of nano-antennas disposed between the specular reflector and the substrate and spaced apart from the specular reflector by the dielectric layer.
2. The light emitting device of claim 1 , wherein the cut-off angle is less than or equal to 10 degrees.
3. The light emitting device of claim 1 , wherein the cut-off angle is less than or equal to 20 degrees.
4. The light emitting device of claim 1 , wherein light emitted by the semiconductor diode structure into the transparent substrate and incident on the angular filter at an angle of incidence less than the cut-off angle is transmitted through the angular filter within a cone angle of +/−60 degrees.
5. The light emitting device of claim 4 , wherein light emitted by the semiconductor diode structure into the transparent substrate and incident on the angular filter at an angle of incidence less than the cut-off angle is transmitted through the angular filter within a cone angle of +/−45 degrees.
6. The light emitting device of claim 5 , wherein light emitted by the semiconductor diode structure into the transparent substrate and incident on the angular filter at an angle of incidence less than the cut-off angle is transmitted through the angular filter within a cone angle of +/−5 degrees.
7. The light emitting device of claim 1 , wherein transmission through the angular filter of light at angle of incidence 20 degrees or higher is less than 10%.
8. The light emitting device of claim 1 , wherein transmission through the angular filter of light at angle of incidence 10 degrees or higher is greater than 50%.
9. The light emitting device of claim 1 , wherein the photonic crystal is a one-dimensional photonic crystal.
10. The light emitting device of claim 1 , wherein the photonic crystal is a two-dimensional or three-dimensional photonic crystal.
11. The light emitting device of claim 1 , wherein the reflective nanostructured layer has a spatial gradient of phase.
12. The light emitting device of claim 1 , wherein the nano-antennas comprises at least one of nano-cylinders and nano-cones.
13. The light emitting device of claim 1 , wherein the nano-antennas are arranged in a hexagonal or rectangular lattice.
14. The light emitting device of claim 1 , wherein the angular filter comprises one or more nanoantennas.
15. A light emitting device comprising:
a semiconductor diode structure;
a substrate transparent to light emitted by the semiconductor diode structure and comprising a top surface, an oppositely positioned bottom surface, and side surfaces connecting the top and bottom surfaces, the bottom surface disposed on or adjacent the semiconductor diode structure;
an angular filter comprising photonic crystals, disposed on or adjacent the top surface of the substrate, and arranged to transmit light emitted by the semiconductor diode structure into the substrate and incident on the angular filter at an angle of incidence less than a cut-off angle and reflect back into the transparent substrate light emitted by the semiconductor diode structure and incident on the angular filter at an angle of incidence greater than or equal to the cut-off angle, such that transmission through the angular filter of light at angle of incidence 35 degrees and higher is 0%; and
comprising a reflective nanostructured layer disposed on or adjacent a bottom surface of the semiconductor diode structure, opposite from the transparent substrate, the reflective nanostructured layer configured to reflect toward the angular filter, at an angle of incidence less than the cutoff angle, light emitted by the semiconductor diode structure and incident on the reflective nanostructured layer at an oblique angle, the reflective nanostructured layer comprising a specular reflector, a dielectric layer disposed between the specular reflector and the substrate, and a periodic arrangement of nano-antennas disposed between the specular reflector and the substrate and spaced apart from the specular reflector by the dielectric layer.