Nanostructured meta-materials and meta-surfaces to collimate light emissions from LEDs
A system, method and device for collimating the output of a light emitting diode (LED) are disclosed. The system, method and device include an LED substrate including a top surface from which the light is emitted, and an array of subwavelength scattering antennas positioned within the emitted light path, the array of subwavelength scattering antennas configured to select directions of scatter of the LED emitted light to provide collimated light output from the device. The array may be aligned perpendicular to the plane of propagation of the light emitted from the LED and may be positioned adjacent to the top surface. The array may be at least partially, or completely, positioned within the LED substrate. The array may be spaced a distance from the top surface and the spacing may be achieved using a dielectric spacer adjacent to the top surface. The array may be positioned within the dielectric spacer.
1. A light emitting device comprising:
a light emitting diode having a light emitting surface through which light is emitted during operation of the light emitting device;
at least a first array of light scattering antennas arranged in a plane parallel to the light emitting surface, each light scattering antenna having dimensions in the plane of the first array less than or equal to a free space wavelength of light emitted by the light emitting diode, the light scattering antennas having structural, optical, or structural and optical properties that are arranged so as to affect, collectively, phase and amplitude of light emitted through the light emitting surface in a spatially varying manner that collimates or partially collimates the light emitted through the light emitting surface; and
a dielectric spacer, at least a portion of the dielectric spacer being positioned between the light emitting surface and the first array.
2. The light emitting device of claim 1 , the dielectric spacer including a solid, substantially transparent dielectric substrate having opposed first and second surfaces with the first surface of the substrate facing the light emitting surface.
3. The light emitting device of claim 2 , the light emitting diode being positioned with the light emitting surface against the first surface of the substrate, the first array being positioned within the substrate or at the second surface of the substrate.
4. The light emitting device of claim 2 , the first array being positioned within the substrate or at the first or second surface of the substrate.
5. The light emitting device of claim 1 , the light emitting device including a phosphor layer between the first array and the light emitting diode.
6. The light emitting device of claim 1 , the light scattering antennas having structural, optical, or structural and optical properties that vary with the spatial location of the light scattering antennas in the plane of the first array to affect, collectively, phase and amplitude of light emitted through the light emitting surface in a spatially varying manner that collimates or partially collimates the light emitted through the light emitting surface.
7. The light emitting device of claim 6 , spacing between the light scattering antennas varying with spatial location of the light scattering antennas in the plane of the first array.
8. The light emitting device of claim 6 , shapes or sizes, or both, of the light scattering antennas varying with spatial location of the light scattering antennas in the plane of the first array.
9. The light emitting device of claim 6 , refractive indices of the light scattering antennas varying with spatial location of the light scattering antennas in the plane of the first array.
10. The light emitting device of claim 6 , the light scattering antennas having structural, optical, or structural and optical properties that vary with distance from a center of the first array of light scattering antennas.
11. The light emitting device of claim 1 , the light scattering antennas having dimensions perpendicular to the plane of the first array less than or equal to the free space wavelength of light emitted by the light emitting diode.
12. The light emitting device of claim 1 , further comprising a second array of light scattering antennas arranged parallel to and spaced apart from the first array of light scattering antennas and between the first array and at least a portion of the light emitting diode, each light scattering antenna in the second array having dimensions in the plane of the second array less than or equal to the free space wavelength of light emitted by the light emitting diode, the light scattering antennas in the second array having structural, optical, or structural and optical properties that are arranged so as to affect, collectively, phase and amplitude of light emitted through the light emitting surface in a spatially varying manner that in combination with the first array of light scattering antennas collimates or partially collimates the light emitted through the light emitting surface.
13. The light emitting device of claim 12 , the light scattering antennas of the second array being positioned at the light emitting surface and located external to the light emitting diode or within the light emitting diode.
14. The light emitting device of claim 12 , the light scattering antennas of the second array being positioned within the dielectric spacer spaced apart from the light emitting surface.
15. The light emitting device of claim 12 , the light scattering antennas of the second array having structural, optical, or structural and optical properties that vary with the spatial location of the light scattering antennas in the plane of the second array to affect, collectively, phase and amplitude of light emitted through the light emitting surface in a spatially varying manner that in combination with the first array of light scattering antennas collimates or partially collimates the light emitted through the light emitting surface.
16. The light emitting device of claim 15 , spacing between the light scattering antennas of the second array varying with spatial location of the light scattering antennas in the plane of the second array.
17. The light emitting device of claim 15 , shapes or sizes, or both, of the light scattering antennas of the second array varying with spatial location of the light scattering antennas in the plane of the second array.
18. The light emitting device of claim 15 , refractive indices of the light scattering antennas of the second array varying with spatial location of the light scattering antennas in the plane of the second array.
19. The light emitting device of claim 15 , the light scattering antennas of the second array having structural, optical, or structural and optical properties that vary with distance from a center of the second array of light scattering antennas.
20. The light emitting device of claim 12 , the light scattering antennas of the second array having dimensions perpendicular to the plane of the second array less than or equal to the free space wavelength of light emitted by the light emitting diode.