Diffractive Optical Element Nanoantenna Array Bending Angle
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Solution Overview
Problem
Conventional diffractive optical elements, such as flat optical lenses, are limited by their maximum bending angle and numerical aperture, which restricts their resolving capability and efficiency in manipulating electromagnetic waves.
Innovation Solution
A diffractive optical element comprising an array of optical nanoantennas arranged periodically on a substrate, where each nanoantenna is configured to control the distribution of electromagnetic energy among diffraction orders, promoting scattering in desired directions and suppressing it in others, thereby achieving a highly directional scattering pattern and increased maximum bending angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional phase accumulation approaches are used to achieve bending of electromagnetic waves, then the desired bending angle can be obtained, but the maximum bending angle is limited to about 72 degrees (NA ≈ 0.95) due to the requirement of at least two inclusions in the region
Solution Approach 1:
The patent divides the optical element into multiple zones, each zone containing an array of optical nanoantennas with specific geometries and orientations. Each zone is designed to manipulate light in a specific angular range, collectively achieving a full 180-degree bending capability. This segmentation allows the system to overcome the limitation of conventional single-region approaches.
Solution Approach 2:
Different zones of the optical element are assigned different local properties, specifically different nanoantenna geometries, orientations, and spacing configurations. Each zone is optimized for its specific function in the light manipulation process, with the local nanoantenna characteristics determining the bending angle contribution of that particular zone.
2Speed
If the physical size of the region occupied by inclusions is reduced to achieve larger bending angles, then the maximum bending angle increases, but the resolution capability deteriorates due to the diffraction limit
Solution Approach 1:
The patent transitions from conventional two-dimensional inclusion arrangements to three-dimensional optical nanoantenna structures with controlled orientations. The optical element utilizes vertical orientation control of nanoantennas in addition to lateral positioning, creating a three-dimensional degree of freedom for light manipulation. This dimensional expansion allows simultaneous achievement of large bending angles and high resolution by controlling both the position and orientation of scattering centers.
3Measurement precision
If traditional lenses are used to achieve high numerical aperture, then the resolving capability is improved, but the device becomes bulky and heavy
Solution Approach 1:
The patent replaces the conventional mechanical lens structure (curved surfaces, thick glass elements) with a planar array of optical nanoantennas that manipulate light through controlled scattering and interference. This substitution of the optical mechanism from refraction-based lens to scattering-based nanoantenna array achieves high numerical aperture in a thin, flat configuration, dramatically reducing device volume and weight while maintaining or improving resolving capability.
4Speed
If more inclusions are added to the optical element to improve light manipulation capability, then the bending angle control is enhanced, but the device complexity increases
Solution Approach 1:
The patent designs optical nanoantennas with multiple functional capabilities: they serve as scattering centers, phase control elements, and polarization manipulators simultaneously. Each nanoantenna geometry (rod, disk, ring, etc.) and orientation configuration provides multi-functionality, allowing a single element to perform multiple optical manipulation tasks, thereby reducing the total number of inclusions needed compared to single-function designs.
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 solution enables the realization of optical devices with significantly improved numerical aperture and resolving capability, such as ultra-flat lenses with near-unity numerical aperture, by enhancing the scattering efficiency in desired directions and minimizing it in undesired ones.
Implementation Method 1
an array of optical nanoantennas arranged on the substrate, the array of optical nanoantennas being spaced apart periodically in a lateral direction for supporting a plurality of diffraction orders
Implementation Method 2
each optical nanoantenna in the array of optical nanoantennas is configured to control distribution of electromagnetic energy from an incident light having the predetermined wavelength amongst the plurality of diffraction orders so as to promote scattering of the electromagnetic energy in at least a first direction and suppress scattering of the electromagnetic energy in at least a second direction
Data Source
AI summary
There is provided a diffractive optical element including a substrate, and an array of optical nanoantennas arranged on the substrate, the array of optical nanoantennas being spaced apart periodically in a lateral direction for supporting a plurality of diffraction orders at a predetermined wavelength. In particular, each optical nanoantenna in the array of optical nanoantennas is configured to control distribution of electromagnetic energy from an incident light having the predetermined wavelength amongst the plurality of diffraction orders so as to promote scattering of the electromagnetic energy in at least a first direction and suppress scattering of the electromagnetic energy in at least a second direction, the first direction and the second direction corresponding to a first diffraction order and a second diffraction order of the plurality of diffraction orders, respectively. There also provided a corresponding method of forming the diffractive optical element and a flat optical element, such as a flat lens.