Gradient index lens using effective refractive index of microstructure arranged in radial pattern, and method for manufacturing same

Patent metadata

Field	Value
Publication number	US-9772476-B2
Application number	US-201214372047-A
Country	US
Kind code	B2
Filing date	Dec 14, 2012
Priority date	Jan 20, 2012
Publication date	Sep 26, 2017
Grant date	Sep 26, 2017

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.

First claim

The invention claimed is:

1. A gradient index lens using an effective refractive index of a microstructure converging an electromagnetic wave from mid-infrared to terahertz wave, comprising:
a flat plate type substrate consisting of Si or GaAs and having a predetermined thickness; and
microstructures formed in the substrate to control an effective refractive index of the flat plate type substrate,
wherein the microstructures include through-holes arranged in the substrate, the through-holes having a circular shape, a polygonal shape, or a composite shape, the through-holes having a diameter smaller than a wavelength of the electromagnetic wave,
wherein each of the through-holes does not enclose one another, and
wherein the diameter of the through-holes or an interval therebetween is gradually increased or reduced radially from a center of the substrate such that the refractive index of the microstructure gradually changes radially from the 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 a structure that is formed by dry etch or wet etch.

4. 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, and sphere distributions, in a surface direction and a depth direction.

5. A method for manufacturing a gradient index lens using an effective refractive index of a microstructure converging an electromagnetic wave from mid-infrared to terahertz wave, the method comprising:
providing a flat plate type master substrate consisting of Si or GaAs;
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 electromagnetic 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 etched substrate;
hardening the injected polymer; and
separating the hardened polymer from the etched substrate to form a polymer lens in which the microstructure is formed,
wherein in the forming of the etch pattern of the microstructure, the etch pattern is formed so that through-holes having a circular shape, a polygonal shape, or a composite shape are arranged in the substrate, the through-holes having a diameter being smaller than the wavelength of the electromagnetic wave,
wherein each of the through-holes does not enclose one another, and
wherein the diameter of the through-holes or an interval therebetween is gradually increased or reduced radially from a center of the substrate such that the refractive index of the microstructure gradually changes radially from the center of the substrate.

6. The method of claim 5 , wherein in the etching of the substrate, the substrate is etched by dry etch or wet etch.

7. The method of claim 6 , wherein the dry etch uses at least one of reactive ion etch, deep reactive ion etch, and plasma etch.

8. The method of claim 6 , wherein the wet etch uses isotropic wet etch or anisotropic wet etch.

9. The method of claim 5 , 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, and sphere distributions, in a surface direction and a depth direction.

10. The gradient index lens of claim 1 , wherein the electromagnetic wave travels parallel to the direction to which the through-holes are extended such that the electromagnetic wave is converged.

11. The method of claim 5 , wherein the electromagnetic wave travels parallel to the direction to which the through-holes are extended such that the electromagnetic wave is converged.

Assignees

• Korea Advanced Inst Sci & Tech

Inventors

• Jeong Ki-Hun
• Park Sang-Gil
• Lee Youngseop

Classifications

• G02B3/0087

  with index gradient · CPC title

• B29C45/372

  provided with means for marking or patterning, e.g. numbering articles · CPC title

• B29D11/00028

  Bifocal lenses; Multifocal lenses · CPC title

• G02B13/14 Primary

  for use with infrared or ultraviolet radiation ({G02B13/008, } G02B13/16 take precedence) · CPC title

• B29L2011/0016

  Lenses · CPC title