Illumination apparatus confining light by total internal reflection and methods of forming the same
In various embodiments, an illumination apparatus includes an air gap between a sub-assembly and a waveguide attached thereto at a plurality of discrete attachment points, as well as a bare-die light-emitting diode encapsulated by the waveguide.
1. An illumination device comprising:
a waveguide;
a light-emitting diode (LED), light emitted by the LED being in-coupled into the waveguide; and
a sub-assembly providing mechanical support to the LED and disposed proximate a first surface of the waveguide,
wherein, notwithstanding the presence of the sub-assembly, light from the LED is (i) confined by the first surface of the waveguide via total internal reflection and (ii) not absorbed by the sub-assembly.
2. The illumination device of claim 1 , wherein an air gap is disposed between at least a portion of the sub-assembly and at least a portion of the first surface of the waveguide.
3. The illumination device of claim 1 , wherein the sub-assembly is attached to the first surface of the waveguide only at a plurality of discrete attachment points.
4. The illumination device of claim 3 , wherein at least one of the discrete attachment points comprises a substantially rigid joining element for facilitating alignment of the waveguide with the sub-assembly.
5. The illumination device of claim 1 , further comprising a reflector disposed over at least a portion of a second surface of the waveguide to confine light within the waveguide.
6. The illumination device of claim 5 , wherein the second surface is opposite the first surface.
7. The illumination device of claim 1 , wherein the LED is disposed at least partially within the waveguide.
8. The illumination device of claim 1 , further comprising an index-matching material disposed on at least a portion of the LED.
9. The illumination device of claim 8 , wherein at least a portion of the index-matching material is disposed between the LED and the waveguide.
10. The illumination device of claim 1 , wherein the LED comprises a bare-die LED.
11. The illumination device of claim 1 , wherein the LED consists essentially of a bare-die LED.
12. The illumination device of claim 1 , further comprising a phosphor for converting a light emitted by the LED to light having a different wavelength.
13. The illumination device of claim 1 , wherein the waveguide defines a recess in the first surface, and the LED is at least partially disposed within the recess.
14. The illumination device of claim 13 , further comprising at least one index-matching material filling at least a portion of the recess.
15. The illumination device of claim 1 , wherein the waveguide comprises an emission surface, different from the first surface, for emitting light in-coupled into the waveguide.
16. The illumination device of claim 15 , wherein the first surface and the emission surface are substantially planar.
17. The illumination device of claim 15 , wherein the waveguide comprises (i) an in-coupling region in which light emitted by the LED is in-coupled into the waveguide, and (ii) an out-coupling region, discrete from the in-coupling region, from which light is out-coupled through the emission surface.
18. The illumination device of claim 17 , wherein the out-coupling region is laterally spaced away from the LED.
19. The illumination device of claim 15 , wherein the first surface is substantially parallel to the emission surface.
20. The illumination device of claim 15 , wherein the first surface is substantially perpendicular to the emission surface.