Holey Optical Device for Polarization-Independent Light Focusing
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Solution Overview
Problem
Current nanoslit lenses are polarization-dependent and fail to achieve high-intensity light confinement into a wavelength-size circular spot, limiting their application in compact optical systems.
Innovation Solution
A polarization-independent optical device featuring a thin film with subwavelength holes arranged in a concentric ring pattern, where the size of each hole varies to control phase changes and focus light, and can be filled with a nonlinear medium for adjustable properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If nanoslit lenses are used to achieve planar and thin optical structure, then the device thickness is reduced to subwavelength scale, but the lens becomes polarization-dependent and cannot focus light into a circular spot
Solution Approach 1:
The lens is segmented into multiple concentric rings with varying hole sizes. Each ring contributes to the overall phase modulation, and the combination of all rings enables polarization-independent focusing while maintaining the planar thin structure. The segmentation allows independent control of phase for different polarizations.
Solution Approach 2:
Different regions of the lens (different rings) have different local properties - specifically, different hole sizes that create different phase delays. This local variation in structure enables the lens to compensate for polarization effects and achieve uniform focusing for all polarizations while keeping the overall device thin.
2Ease of manufacture
If nanoslit lenses are used to achieve planar and thin optical structure, then fabrication is simplified, but high-intensity light confinement into wavelength-size circular spot is not achieved
Solution Approach 1:
The hole sizes in each concentric ring are carefully optimized to achieve the desired phase profile. By adjusting the hole diameter parameter across different rings, the lens achieves both the required phase modulation for focusing and the intensity concentration needed for wavelength-size spot formation, while maintaining ease of fabrication through standard nanofabrication techniques.
3Ease of operation
If conventional dielectric-based refraction microlenses are used, then focusing capability is achieved, but the device thickness increases to tens of micrometers
Solution Approach 1:
The patent replaces the conventional refraction-based focusing mechanism (which requires thick dielectric lenses) with a diffraction-based mechanism using subwavelength holes in a metallic film. This substitution allows achieving the same focusing capability with a thickness reduced to the subwavelength scale, enabling ultra-thin optical components.
4Shape
If gradient-index lenses are used to achieve planar structure, then the lens becomes planar, but the thickness increases to about an order of magnitude larger than the wavelength of incident light
Solution Approach 1:
Instead of achieving planar structure by varying the refractive index through the thickness dimension (gradient-index approach requiring thick lenses), the patent uses subwavelength hole patterns in the lateral plane to achieve phase modulation. This lateral dimension approach enables planar structure with subwavelength thickness, resolving the contradiction between planarity and thinness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device achieves polarization-independent focusing of light into a circular spot, with adjustable focal length via wavelength control, enabling efficient light confinement and adaptive optics applications.
Implementation Method 1
The holes create a specific pattern; for example, concentric rings with increasing diameter, where the holes of each ring are the same size, but the holes of each successive ring moving outward decrease in size. The change in hole size throughout the pattern creates various phase changes, or bending angles, of the light as it enters, proceeds through the hole, and exits on the opposite side of the film, thus focusing or diffracting the light at a desired distance.
Data Source
AI summary
A method of making an optical device including forming a plurality of holes with varying radii milled vertically into a film, wherein said holes form a pattern. The radius of each hole determines an effective refractive index for said hole. The effective refractive index modifies a phase and an intensity of an incoming electromagnetic radiation as the radiation propagates through said hole. The device is configured to be operating equally for each linearly polarized radiation simultaneously, wherein the each linearly polarized radiation is normally incident on the device.