Metasurface Optical Device for Angular-Selective Wavefront Control
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Solution Overview
Problem
Conventional optical components in AR/VR glasses are bulky and fail to provide optimal image quality and angular performance, limiting their use in immersive user experiences due to their poor angular performance and inability to tune optical responses for different incident angles.
Innovation Solution
A compound metasurface device with at least two sets of subwavelength optical elements, each set producing a distinct optical response, utilizing a light-guiding element like a nanojet microlens to selectively excite elements for different angles of incidence, allowing for multiple optical functions across varying illumination conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional volumetric optical components are used, then optical functions can be provided, but the device size and weight increase significantly
Solution Approach 1:
The patent replaces conventional volumetric optical components with ultra-thin metasurface films that are only a fraction of the wavelength thick. These flexible thin films maintain optical functionality while dramatically reducing the volume and weight of the optical system, directly resolving the contradiction between compact size and performance.
Solution Approach 2:
The patent employs metasurfaces with tunable parameters including subwavelength element geometry, spacing, and material composition. By adjusting these parameters, the optical response can be optimized for different angular ranges, maintaining angular performance while achieving ultra-compact form factor.
2Reliability
If conventional optical components are used, then optical functions are provided, but the angular performance is poor
Solution Approach 1:
The metasurface optical components are implemented as ultra-thin films that weigh significantly less than conventional volumetric optics. These thin films achieve superior angular performance through subwavelength resonant elements that maintain consistent optical response across a wide range of incident angles.
Solution Approach 2:
The patent uses composite metasurface structures combining different materials with complementary optical properties. This composite approach enables tailored angular performance by selecting materials with specific refractive indices, absorption characteristics, and resonant frequencies optimized for wide-angle operation.
3Adaptability or versatility
If conventional optical components are used, then basic optical functions are provided, but the ability to tune optical responses for different incident angles is limited
Solution Approach 1:
The patent implements dynamic tunability in metasurface optical components by making the optical response adjustable through changes in incident angle, polarization state, or material properties. This dynamic adaptability allows a single compact component to perform multiple optical functions that would traditionally require multiple fixed components.
Solution Approach 2:
The metasurface design achieves multi-functionality by engineering subwavelength elements that can simultaneously perform focusing, beam steering, and polarization control. This universal approach replaces multiple specialized optical components with a single ultra-thin multifunctional metasurface layer.
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 improved angular-selective optical responses, enabling enhanced image quality and immersion by reshaping the wavefront of incoming electromagnetic waves, allowing for multiple optical functions based on angle of incidence, thus addressing the limitations of conventional optical components.
Implementation Method 1
Metasurfaces can be either structured or not structured with subwavelength-scaled patterns in the horizontal dimensions. Due to their negligible thickness compared to the wavelength of operation, metasurfaces can (near resonances of unit cell constituents) be considered as an interface of discontinuity enforcing an abrupt change in both the amplitude and phase of the impinging light.
Implementation Method 2
Metasurfaces may be defined as an optically thin (i.e. much thinner than the wavelength of an incident electromagnetic wave) array of sub-wavelength size, subwavelength spaced optical elements, formed of individual microparticles usually made of metal (e.g. gold) or high-index dielectric material (e.g. silicon), which may act as resonators, optical antennas
Implementation Method 3
A compound metasurface device with at least two sets of subwavelength optical elements, each set producing a distinct optical response, utilizing a light-guiding element like a nanojet microlens to selectively excite elements for different angles of incidence
Implementation Method 4
Metasurfaces may also be defined as a periodic array of scattering elements whose dimensions and periods are small compared with the operating wavelength
Implementation Method 5
A few examples of metasurface devices can be found in ' Recent advances in planar optics: from plasmonic to dielectric metasurfaces', by P. Genevet, F. Capasso et al. , Optica 4(1), 139-152, 2017, and are disclosed in figure 1. Devices having subsets of sub-wavelength optical elements which are selectively excited can be found e.g. in documents WO2016/168173, WO2016/140720, and DE102009037629
Data Source
Figure 1~2A
Figure 2B~2C
Figure 3~4C
AI summary
An optical device forming an outgoing electromagnetic wave from an incident electromagnetic wave comprises at least one unit cell (UC), comprising: at least two subwavelength optical elements (1, 2), each of them belonging to a different set (MSI, MS2) of subwavelength optical elements, a set of subwavelength optical elements being characterized by a type of optical response to an incident electromagnetic wave; means (21) enabling selective excitation of all subwavelength optical elements belonging to a given set, in response to an electromagnetic wave (20) incident on said unit cell.