Sensor device including one or more metal-dielectric optical filters
A sensor device including one or more sensor elements and one or more optical filters is provided. The one or more optical filters each include a plurality of dielectric layers and a plurality of metal layers stacked in alternation. The metal layers are intrinsically protected by the dielectric layers. In particular, the metal layers have tapered edges that are protectively covered by one or more of the dielectric layers.
1. A sensor device comprising:
one or more sensor elements; and
one or more optical filters disposed over the one or more sensor elements, wherein each of the one or more optical filters includes:
a plurality of dielectric layers; and
a plurality of metal layers stacked in alternation with the plurality of dielectric layers, wherein
each of the plurality of metal layers has a tapered edge, at a periphery of the optical filter, that is encapsulated by one or more of the plurality of the dielectric layers, and
each of the plurality of metal layers is separated from a substrate of an optical filter, of the one or more optical filters, using at least one of the plurality of dielectric layers.
2. The sensor device of claim 1 , wherein the one or more optical filters are disposed on the one or more sensor elements.
3. The sensor device of claim 2 , wherein the one or more optical filters were formed on the one or more sensor elements by a lift-off process.
4. The sensor device of claim 1 , wherein the one or more optical filters have substantially flat tops and sloped sides.
5. The sensor device of claim 1 , wherein each of the plurality of metal layers is substantially encapsulated by two nearest of the plurality of dielectric layers.
6. The sensor device of claim 1 , wherein each of the plurality of metal layers is composed of silver.
7. The sensor device of claim 1 , wherein each of the plurality of dielectric layers is composed of a high-index dielectric material having a refractive index greater than about 2.0 at 550 nm.
8. The sensor device of claim 7 , wherein the high-index dielectric material is ultraviolet-absorbing, and wherein the one or more optical filters each have an average out-of-band transmittance of less than about 2% between about 300 nm and about 400 nm.
9. The sensor device of claim 1 , wherein each of the plurality of dielectric layers is composed of titanium dioxide, zirconium dioxide, niobium pentoxide, tantalum pentoxide, or a mixture thereof.
10. The sensor device of claim 1 , wherein each of the one or more optical filters further includes a plurality of corrosion-suppressing layers disposed between the plurality of dielectric layers and the plurality of metal layers.
11. The sensor device of claim 10 , wherein the plurality of dielectric layers (D), the plurality of corrosion-suppressing layers (C), and the plurality of metal layers (M) are stacked in a sequence of D(C/M/C/D)n, and wherein n^2.
12. The sensor device of claim 10 , wherein each of the plurality of corrosion-suppressing layers is composed of ZnO.
13. The sensor device of claim 1 , further comprising a dielectric coating protectively covering the one or more optical filters.
14. The sensor device of claim 1 , wherein the one or more optical filters are one or more color filters, photopic filters, infrared-blocking filters, or a combination thereof.
15. The sensor device of claim 1 , wherein the one or more sensor elements consist of a plurality of sensor elements, and wherein the one or more optical filters consist of a plurality of optical filters.
16. The sensor device of claim 15 , wherein the plurality of sensor elements are disposed in a two-dimensional array, and wherein the plurality of optical filters are disposed in a corresponding two-dimensional array.
17. The sensor device of claim 15 , wherein the plurality of optical filters are substantially separate from one another.
18. The sensor device of claim 15 , wherein the plurality of optical filters includes different types of optical filters having different passbands from one another.
19. The sensor device of claim 18 , wherein at least two of the different types of optical filters include different numbers of metal layers from one another.
20. The sensor device of claim 18 , wherein at least two of the different types of optical filters have different metal-layer thicknesses from one another.