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 having a recess defined in a first surface of the waveguide;
a light-emitting diode (LED), light emitted by the LED being in-coupled into the waveguide at the recess; and
a sub-assembly providing mechanical support to the LED and disposed proximate the first surface of the waveguide,
wherein light from the LED is (i) confined via total internal reflection over at least a portion of the first surface of the waveguide and (ii) emitted from at least a portion of an emission surface of the waveguide different from the first surface.
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 recess.
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 consists essentially of a bare-die LED.
11. The illumination device of claim 1 , further comprising a phosphor for converting a light emitted by the LED to light having a different wavelength.
12. The illumination device of claim 1 , further comprising at least one index-matching material filling at least a portion of the recess.
13. The illumination device of claim 1 , wherein the first surface and the emission surface are substantially planar.
14. The illumination device of claim 1 , 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.
15. The illumination device of claim 14 , wherein the out-coupling region is laterally spaced away from the LED.
16. The illumination device of claim 14 , wherein an emission face of the LED faces the out-coupling region, the emission face of the LED being longer than an adjoining face of the LED.
17. The illumination device of claim 1 , wherein the first surface is substantially parallel to the emission surface.
18. The illumination device of claim 1 , wherein the first surface is substantially perpendicular to the emission surface.
19. The illumination device of claim 1 , wherein the sub-assembly has at least one relief trench extending therethrough to define a relief, the relief being elastically deformable at least in a first direction.
20. The illumination device of claim 19 , wherein the waveguide is attached to the sub-assembly at least at a first attachment point disposed on the relief.