Sensor including dielectric metamaterial microarray
The present disclosure is directed to electromagnetic radiation sensors including micro-lenses and to methods of constructing and utilizing such electromagnetic radiation sensors. In one embodiment there is provided an electromagnetic radiation sensor comprising a dielectric substrate including a front surface and a rear surface, an electromagnetic radiation detector element disposed on the rear surface of the substrate, and a lens comprising a three dimensional polaritonic metamaterial structure including a pattern of features formed in the front surface of the substrate, the lens configured to focus electromagnetic radiation incident on the front surface of the substrate onto the electromagnetic radiation detector element.
1. An electromagnetic radiation sensor comprising:
a dielectric substrate including a front surface and a rear surface; and
a plurality of pixels, each pixel including:
an electromagnetic radiation detector element disposed on the rear surface of the substrate; and
a lens comprising a three dimensional polaritonic metamaterial structure including a pattern of features formed in the front surface of the substrate, the lens being configured to focus electromagnetic radiation incident on the front surface of the substrate onto the electromagnetic radiation detector element, wherein the pattern of features forms a layer that is antireflective to at last one frequency of the electromagnetic radiation, and wherein a spacing between adjacent features is less than a wavelength of the electromagnetic radiation.
2. The electromagnetic radiation sensor of claim 1 , wherein the pattern of features includes a plurality of one of pillars and holes.
3. The electromagnetic radiation sensor of claim 2 , wherein each of the features has a substantially constant diameter.
4. The electromagnetic radiation sensor of claim 3 , wherein the spacing between adjacent features varies across the lens.
5. The electromagnetic radiation sensor of claim 4 , wherein the pattern of features includes one of a barrel distortion and a pin-cushion distortion.
6. The electromagnetic radiation sensor of claim 2 , wherein the spacing between adjacent features is substantially constant across the lens.
7. The electromagnetic radiation sensor of claim 6 , wherein a diameter of adjacent features varies across the lens.
8. The electromagnetic radiation sensor of claim 1 , wherein the pattern of features includes a plurality of pillars and a height of the varies across the lens.
9. The electromagnetic radiation sensor of claim 1 , wherein the electromagnetic radiation detector element comprises one of a photodiode and a microbolometer.
10. The electromagnetic radiation sensor of claim 1 , wherein the pattern of features includes a plurality of holes and a depth of the holes varies across the lens.
11. The electromagnetic radiation sensor of claim 1 , wherein the dielectric substrate is one of silicon, silicon carbide, and germanium.
12. The electromagnetic radiation sensor of claim 1 , wherein, for each pixel, the electromagnetic radiation detector element is smaller than the corresponding pixel.
13. A method of fabricating a pixelated electromagnetic radiation sensor, the method comprising:
selecting a substrate having a front surface and an opposing rear surface; and
fabricating a plurality of pixel elements on the substrate, wherein fabricating each pixel element includes:
disposing an electromagnetic radiation detector element on the rear surface of the substrate; and
forming a lens configured to focus electromagnetic radiation incident on the front surface of the substrate onto the electromagnetic radiation detector element, including:
forming a plurality of one of pillars and holes in the front surface of the substrate to produce a pattern of features with substantially constant diameters in the front surface of the substrate, a spacing between adjacent features of the pattern of features being less than a wavelength of the electromagnetic radiation and varying across the lens.
14. The method of claim 13 , where selecting the substrate comprises selecting a substrate substantially transparent to a wavelength of electromagnetic radiation to which the electromagnetic radiation detector element is sensitive.
15. The method of claim 13 , wherein the pattern of features is formed by etching the front surface of the substrate.
16. The method of claim 13 , wherein forming the lens includes forming the plurality of pillars with a height that varies across the lens.
17. The method of claim 13 , wherein forming the lens includes forming the plurality of holes with a depth that varies across the lens.
18. A method of fabricating a pixelated electromagnetic radiation sensor, the method comprising:
selecting a substrate having a front surface and an opposing rear surface; and
fabricating a plurality of pixel elements of the substrate, wherein fabricating each pixel element includes:
disposing an electromagnetic radiation detector element on the rear surface of the substrate; and
forming a lens configured to focus electromagnetic radiation incident on the front surface of the substrate onto the electromagnetic radiation detector element, wherein forming the lens includes:
forming a plurality of one of pillars and holes in the front surface of the substrate to produce a pattern of features in the front surface of the substrate, a spacing between adjacent features of the pattern of features being less than a wavelength of the electromagnetic radiation and being substantially constant across the lens, and wherein a diameter of the adjacent features varies across the lens.
19. The method of claim 18 , wherein forming the lens includes forming the plurality of pillars with a height that varies across the lens.
20. The method of claim 18 , wherein forming the lens includes forming the plurality of holes with a depth that varies across the lens.
21. The method of claim 18 , where selecting the substrate comprises selecting a substrate substantially transparent to the wavelength of electromagnetic radiation.