MULTI-SPECTRAL FILTERS, MIRRORS AND ANTI-REFLECTIVE COATINGS WITH SUBWAVELENGTH PERIODIC FEATURES FOR OPTICAL DEVICES

• US 20110085232A1
• Filed: 10/08/2010
• Published: 04/14/2011
• Est. Priority Date: 10/08/2009
• Status: Abandoned Application

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation), Penn State Research Foundation
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation), Penn State Research Foundation
• Inventors: Werner, Douglas H., Mayer, Theresa S., Baleine, Clara R.
• Application Number:
  US12/900,967
• Publication Number:
  US 20110085232A1
• Time in Patent Office: Days
• US Class Current: 359/350
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 2207/101 Nanooptics
• CPC Class Codes: G02B 5/1809 with pitch less than or comparable to the wavelength

Abstract

Example apparatus have a radiation-receiving surface configured to receive electromagnetic radiation, including a sub-wavelength grating supported by a substrate. The sub-wavelength grating has a side-wall profile that may be configured and optimized to obtain desired spectral properties.

Claims

1. An apparatus, the apparatus being an optical element having an operational electromagnetic wavelength range, the apparatus comprising:

a substrate;

an array of protrusions extending from the substrate along an extension direction, the protrusions having a side-wall profile,

the side-wall profile undulating relative to the extension direction,

the protrusions having a spacing less than radiation wavelengths within the electromagnetic wavelength range.

2. The apparatus of claim 1, the optical element being a window, mirror, filter, lens, or prism.

3. The apparatus of claim 1, the apparatus being an IR optical element, the protrusions having a spacing of less than 1 micron.

4. The apparatus of claim 3, the apparatus having at least two high reflectivity peaks within the operational electromagnetic wavelength range, each high reflectivity peak having a reflectivity of at least 95%.

5. The apparatus of claim 3, the side-wall profile including an oscillatory component having an amplitude of at least 50 nm.

6. The apparatus of claim 1, the protrusions including ridges supported by the substrate,

the ridges defining grooves therebetween,

the grooves having a groove width that varies along the extension direction, the grooves having at least one narrowed region between first and second wider regions.

7. The apparatus of claim 6, the ridges having a first side-wall, a second side-wall, and a top surface,

the first and second side-walls having side wall profiles that are mirror-images of each other.

8. The apparatus of claim 1, the protrusions being pillars,

the pillars having at least one pair of side-walls, each having a side-wall profile that undulates relative to the extension direction.

9. The apparatus of claim 1, the substrate being silicon carbide.

10. An apparatus, the apparatus being an optical element having a radiation-receiving surface configured to receive electromagnetic radiation, the apparatus comprising:

a substrate; and

a sub-wavelength grating supported by the substrate, the sub-wavelength grating defining grooves along the radiation-receiving surface, the grooves having a groove base proximate the substrate, and a groove opening,

the sub-wavelength grating having a side-wall profile such that each groove has at least one narrowed portion located between the groove base and the groove opening.

11. The apparatus of claim 10, the subwavelength grating being formed by an array of protrusions extending from the substrate,

the protrusions having a protrusion spacing less than radiation wavelengths within an operational wavelength range of the apparatus.

12. The apparatus of claim 10, the optical element being a window, mirror, filter, lens, or prism.

13. The apparatus of claim 10, the apparatus being an IR optical element, the protrusions having a spacing of less than 1 micron.

14. The apparatus of claim 10, the substrate being silicon carbide, the sub-wavelength grating being formed in a dielectric coating layer supported by the substrate.

15. An optical element, comprising:

a silicon carbide substrate;

a regular array of nanoscale structures formed in a dielectric layer supported by the silicon carbide substrate,

the nanoscale structures having at least one dimensional parameter less than 1 micron,

the dimensional parameter being selected from a group consisting of structure spacing, structure thickness, and structure height.

16. The apparatus of claim 15, the dielectric layer being amorphous silicon.

17. The apparatus of claim 15, the nanoscale structures being protrusions having a sidewall profile, the side-wall profile being appreciably non-planar,

the apparatus having spectral properties correlated with the sidewall profile.

18. The apparatus of claim 15, the silicon carbide substrate supporting a first dielectric layer, a metal layer, and a second dielectric layer as a three-layer stack,

the nanoscale structures being supported by the second dielectric layer.