Broadband mirror
The invention describes a broadband mirror comprising an outer surface layer; and a dielectric layer stack arranged underneath the outer surface layer; characterized in that the dielectric layer stack comprises at least one patterned surface at an interface between adjacent dielectric layers of the dielectric layer stack. The invention further describes a light-emitting diode. The invention also describes a method of manufacturing a broadband mirror, which method comprises the steps of providing an outer surface layer and applying a plurality of dielectric layers to build a dielectric layer stack underneath the outer surface layer, characterized by the step of patterning the surface of at least one dielectric layer before applying a subsequent dielectric layer to the patterned surface.
1. A broadband mirror comprising
a single outer surface layer;
a dielectric layer stack arranged adjacent to the single outer surface layer and comprising an alternating arrangement of low-index layers and high-index layers,
the dielectric layer stack comprising:
at least one patterned surface formed on one side of a high-index layer at an interface between the high-index layer and a first adjacent low-index layer; and
at least one non-patterned surface formed on the other side of the high-index layer at the interface between the high-index layer and a second adjacent low-index layer, the other side of the high-index layer configured closer to the single outer surface layer than the one side of the high-index layer; and
a reflective backing layer formed adjacent to the dielectric stack distal to the single outer surface layer.
2. The broadband mirror according to claim 1 , wherein the dielectric layer stack is terminated by the reflective backing.
3. The broadband mirror according to claim 1 , wherein the high-index layer is arranged between the first adjacent low-index layer and the second adjacent low-index layer.
4. The broadband mirror according to claim 1 , wherein the patterned surface comprises a pattern with a feature size in the range of 100 nm to 2.0 μm.
5. The broadband mirror according to claim 1 , wherein the alternating arrangement of low-index layers and high-index layers includes the low-index layers and the high-index layers each having a thickness in the range of 500 nm to 2.0 μm.
6. The broadband mirror according to claim 1 , wherein the alternating arrangement of low-index layers and high-index layers comprises at most 15 layers.
7. The broadband mirror according to claim 1 , wherein the dielectric layer stack comprises at least two patterned surfaces.
8. The broadband mirror according to claim 1 , wherein the single outer surface layer comprises a high-index layer.
9. A light-emitting diode comprising a broadband mirror according to claim 1 .
10. The broadband mirror according to claim 1 , wherein the alternating arrangement of low-index layers and high-index layers comprises at most 9 layers.
11. The broadband mirror according to claim 1 , wherein the alternating arrangement of low-index layers and high-index layers comprises at most 3 layers.
12. The broadband mirror according to claim 1 , wherein the reflective backing layer directs any incident photons back toward the single outer surface layer.
13. A method of manufacturing a broadband mirror, the method comprising:
providing a single outer surface layer;
applying an alternating arrangement of low-index layers and high index layers to build a dielectric layer stack adjacent to the single outer surface layer;
forming at least one patterned surface on one side of a high-index layer at an interface between the high-index layer and a first adjacent low-index layer;
forming at least one non-patterned surface on the other side of the high-index layer at the interface between the high-index layer and a second adjacent low-index layer; and
forming a reflective backing layer adjacent to the dielectric layer stack distal to the single outer surface layer.
14. The method according to claim 13 , wherein the step of patterning a layer surface comprises any of a photo-electrochemical (PEC) etching step, a micromachining step, a photolithography step, a nanoimprint lithography step.
15. The method according to claim 13 , wherein the patterning step comprises forming a regular surface structure to achieve total internal reflection at a boundary between the patterned layer and the subsequent layer.
16. The method according to claim 13 , wherein the dielectric layer stack is built by alternatively applying silicon dioxide layers and silicon nitride layers.