OPTICAL DEVICES BASED ON DIFFRACTION GRATINGS

• US 20120194911A1
• Filed: 09/23/2009
• Published: 08/02/2012
• Est. Priority Date: 09/23/2009
• Status: Active Grant

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Inventors: Li, Jingjing, Fattal, David A., Beausoleil, Raymond G., Fiorentino, Marco
• Granted Patent: US 9,354,362 B2
• Time in Patent Office: Days
• US Class Current: 359/566
• CPC Class Codes: G02B 5/1809 with pitch less than or comparable to the wavelength

Abstract

Embodiments of the present invention relate to planar optical devices composed of one or more sub-wavelength diffraction grating layers. In one embodiment, an optical device includes a first substantially planar reflective structure (104,1904), a second substantially planar reflective structure (106,1906), and a substantially planar sub-wavelength grating layer (102,1902) disposed between the first reflective structure and the second reflective structure. The grating layer is configured with lines (208-211, 214-217) having line widths, line thicknesses, and line period spacing selected to control phase changes in different portions of a beam of light transmitted through the optical device.

Claims

1. An optical device (100,1900) comprising:

a first substantially planar reflective structure (104,1904);

a second substantially planar reflective structure (106,1906); and

a substantially planar sub-wavelength grating layer (102,1902) disposed between the first reflective structure and the second reflective structure, wherein the grating layer is configured with lines (208-211,214-217) having line widths, line thicknesses, and line period spacing selected to control phase changes in different portions of a beam of light transmitted through the optical device.

2. The optical device of claim 1, wherein the first reflective structure and the second reflective structure are reflective plates (104,106).

3. The optical device of claim 1, wherein at least one of the first reflective structure and the second reflective structure are configured as sub-wavelength grating layers (1904,1906).

4. The optical device of claim 1, further comprises:

a first resonant cavity (108,1908) formed by a space separating the first reflective structure from the grating layer; and

a second resonant cavity (110,1910) formed by a space separating the second reflective structure from the grating layer.

5. The optical device of claim 4, wherein

the first resonant cavity and the second resonant cavity are air filled;

or

the first resonant cavity and the second resonant cavity are filled with a material having lower refractive index than the refractive indices associated with the first reflective structure, the second reflective structure and the grating layer.

6. The optical device of claim 1, wherein the grating layer further comprising a substrate (212), with a grating pattern disposed on a surface of the substrate and the grating pattern is formed in a material having a higher refractive index than the substrate.

7. The optical device of claim 1, wherein the grating layer further comprises a membrane.

8. The optical device of claim 1, wherein the grating pattern further comprises a one-dimensional pattern of lines.

9. The optical device of claim 3, wherein the one-dimensional pattern of lines further comprises one or more sub-regions of lines (201-203), the lines within each sub-region having a selected period and line width.

10. The optical device of claim 1, wherein the lines width, line thickness, and line period spacing are selected to form a convex lens (1000,1300).

11. The optical device of claim 1, wherein the lines widths, line thickness, and line period spacing are selected to form a concave lens (1800).

12. The optical device of claim 1, wherein the line width, line thickness, and line period spacing are selected to form a prism (1700).

13. A method for fabricating a sub-wavelength grating layer of an optical device using a computing device, the method comprising:

calculating a desired target phase change across the optical device using the computing device (1204,1404,1504), the target phase change corresponding to a desired wavefront shape in a beam of light transmitted through the optical device;

generating line widths, hue period spacing, and line thickness corresponding to the target phase change across the grating layer (1206,1406,1506) using the computing device; and

generating a set of coordinates (1207-1213,1407-1417, 1508-1515) using the computing device, each coordinate identifying the location of a line with a line width, line period spacing, and line thickness.

14. The method of claim 13 further comprising:

depositing a first layer of material corresponding to a planar first reflective structure;

depositing a first polymer material layer over the first layer;

depositing a second layer of material over the first polymer layer;

defining a grating pattern of hues in the second layer corresponding to a sub-wavelength gating pattern based on the set of coordinates;

depositing a second polymer material layer over the second layer and

depositing a third layer of material corresponding to a planar second reflective structure.

15. The method of claim 14 further comprising defining a grating pattern of lines the first layer corresponding to the first reflective structure and/or the second layer corresponding to the second reflective structure.