GRADIENT INDEX LENS USING EFFECTIVE REFRACTIVE INDEX OF MICROSTRUCTURE ARRANGED IN RADIAL PATTERN, AND METHOD FOR MANUFACTURING SAME

• US 20150002927A1
• Filed: 12/14/2012
• Published: 01/01/2015
• Est. Priority Date: 01/20/2012
• Status: Active Grant

• Current Assignee: Korea Advanced Institute of Science and Technology
• Original Assignee: Korea Advanced Institute of Science and Technology
• Inventors: Jeong, Ki-hun, Park, Sang-gil
• Granted Patent: US 9,772,476 B2
• Time in Patent Office: Days
• US Class Current: 359/356
• CPC Class Codes: B29C 45/372 provided with means for marking or patterning, e.g. numbering articles
• CPC Class Codes: B29D 11/00028 Bifocal lenses; Multifocal lenses
• CPC Class Codes: B29L 2011/0016 Lenses
• CPC Class Codes: G02B 13/14 for use with infrared or ultraviolet radiation G02B13/008, G02B13/16 take precedence
• CPC Class Codes: G02B 2207/107 Porous materials, e.g. for reducing the refractive index
• CPC Class Codes: G02B 3/0087 with index gradient

Abstract

Provided are a gradient index lens using the effective refractive index of a microstructure operating in the terahertz frequency regions and mid-infrared regions at wavelengths of 0.8 m to 3 mm and a method for manufacturing the same. Based on the effective medium theorem, the effective refractive index is controlled by using a structure smaller than the mid-infrared and terahertz wavelength, and a gradient can be provided for the refractive index in a radial direction and in an axial direction. Thus, beams in the mid-infrared and terahertz frequency region can be converged.

Claims

1. A gradient index lens using an effective refractive index of a microstructure converging a wave of mid-infrared and terahertz frequency regions, comprising:

a substrate; and

microstructures formed on the substrate to control the effective refractive index of the substrate,

wherein the microstructure has a diameter smaller than a wavelength of a wave which is incident on the substrate and has a diameter or an interval gradually increased or reduced radially or axially from a center of the substrate.

2. The gradient index lens of claim 1, wherein the substrate is a single dielectric substrate.

3. The gradient index lens of claim 1, wherein the microstructure is formed by arraying pillars or holes having the diameter smaller than the wavelength of the mid-infrared and terahertz wave on the substrate.

4. The gradient index lens of claim 1, wherein the diameter smaller than the wavelength of the mid-infrared and terahertz wave is 3 mm to 0.8 μ

m.

5. The gradient index lens of claim 3, wherein the microstructure is formed by arraying holes having a circular shape, a polygonal shape, or a composite shape on the substrate.

6. The gradient index lens of claim 3, wherein the microstructure is formed by arraying a pillar-shaped structure having a circular shape, a polygonal shape, or a composite shape and having a vertical section thereof formed in one of triangular, quadrangular, semi-circular, and semi-oval shapes on the substrate.

7. The gradient index lens of claim 6, wherein the microstructure is a structure that is formed by dry etch or wet etch.

8. The gradient index lens of claim 2, wherein the substrate is a Si, GaAs, or glass substrate.

9. The gradient index lens of claim 1, wherein the microstructure is arrayed so that a distribution of refractive index of the substrate has one of parabolic equation, multi-order equation, square root of a multi-order equation, sphere distributions in a surface direction and a depth direction.

10. A method for manufacturing a gradient index lens using an effective refractive index of a microstructure converging mid-infrared and terahertz wave, the method comprising:

providing a master substrate;

forming a mask layer on the master substrate;

forming an etch pattern for forming the microstructure having a diameter smaller than a wavelength of the mid-infrared and terahertz wave on the mask layer;

etching the substrate using the patterned mask layer as an etch mask;

removing the remaining mask layer;

injecting a polymer into the substrate;

hardening the injected polymer; and

separating the hardened polymer from the substrate to form a polymer lens in which the microstructure is formed.

11. The method of claim 10, wherein in the forming of the pattern of the microstructure, the pattern is formed so that holes having a circular shape, a polygonal shape, or a composite shape are arrayed on the substrate.

12. The method of claim 10, wherein in the forming of the pattern of the microstructure, the pattern is formed so that a pillar-shaped structure having a circular shape, a polygonal shape, or a composite shape and having a vertical section thereof formed in one of triangular, quadrangular, semi-circular, and semi-oval shapes is arrayed on the substrate.

13. The method of claim 10, wherein the diameter smaller than the wavelength of the mid-infrared and terahertz wave is 3 mm to 0.8 μ

m.

14. The method of claim 10, wherein in the etching of the substrate, the substrate is etched by dry etch or wet etch.

15. The method of claim 14, wherein the dry etch uses at least one of reactive ion etch, deep reactive ion etch, and plasma etch.

16. The method of claim 14, wherein the wet etch uses isotropic wet etch or anisotropic wet etch.

17. The method of claim 10, wherein the substrate is a Si, GaAs, or glass substrate.

18. The method of claim 10, wherein the microstructure is arrayed so that a distribution of refractive index of the substrate has one of parabolic equation, multi-order equation, square root of a multi-order equation, sphere distributions in a surface direction and a depth direction.