Solutions | Photonics
A metalens controls light with millions to billions of nanostructures, which means solving two problems of very different scale at once: rigorous analysis of the unit structure, and the design and layout of the whole lens. This page sets out the route from unit structure analysis to manufacturing data handover as one continuous sequence.
Design challenges
The response of the unit structure (the meta-atom) needs rigorous electromagnetic analysis at wavelength scale, while the whole lens has to be judged on its performance as an optical system. Managing the design data that moves between the two is where the practical bottleneck lies.
The multiscale structure
From the electromagnetic response at nano scale, through performance as an optical system, to the fabrication conditions, each scale hands its result on to the next.
Meta-atoms
The shape of the subwavelength structures (meta-atoms) that make up a metalens depends on the optical requirements, such as the phase and polarization response, on the material system, and on the dimensions that can be fabricated. Pillars, holes and rings serve polarization-independent phase control; anisotropic geometries such as fins, ellipses and crosses serve designs that use a polarization-dependent response. Each is analyzed as a unit structure by RCWA / FDTD and handled as a phase and transmittance library.
Included: pillars / rings / holes / fins / ellipses / crosses (3D renderings; select an image to enlarge). These are examples of geometry families; the library actually used is prepared for each material, wavelength and fabrication condition.
Engineering requirements
Whichever stage you start from, unless these five are in place at the end, the design does not hold up as an optical system.
Design and simulation workflow
Working from the target wavelength, settle the material, geometry, pitch and height. The range and step of the parameters to sweep are also defined at this stage.
Output / design conditions and sweep parameters
With the Ansys Lumerical solvers, obtain the complex transmission coefficient for each set of dimensions under periodic boundaries. RCWA suits sweeps of periodic structures; FDTD suits non-periodic structures and verification of proximity effects.
Output / complex transmission coefficient per set of dimensions
Collect the sweep results into a table mapping dimensions to phase and transmittance: the meta-atom response library. This is where you establish the phase coverage, the regions where transmittance falls away, and the height slice that fits the fabrication conditions.
Output / phase and transmittance library
Define the target phase profile and, through the library, assign structural dimensions at each position. Dimensions outside the fabrication constraints are removed from the candidates at this stage.
Output / a map of structural dimensions by position
Generate the structure placement across the whole lens and check achieved phase, transmission, phase error and library usage in the placement report. Because the element count reaches millions to billions, generation and verification are built as an automated stage.
Output / layout data (GDS)
Connect the metalens design data to optical-system validation in Ansys Zemax OpticStudio and evaluate imaging performance and aberrations with the lens built into the system. If it falls outside specification, return to the definition of the target phase.
Output / optical system model and imaging performance
Pass the whole-aperture layout, the geometry assignments, the fabrication-related parameters and the GDS / manufacturing layout data to the manufacturing stage. Which constraints apply depends on the fabrication method, so the conditions are confirmed case by case.
Output / GDS, manufacturing layout and dimensional conditions
The stages differ by project. If you already have a phase design or a library, you can start partway through.
Related analysis technologies
The principles and scope of each method are explained on the Analysis Technologies pages.
Related products
The capabilities and coverage of each product are described on its own product page.
Handles electromagnetic analysis of the unit structure. With RCWA and FDTD solvers, it computes the complex transmission coefficients over the dimensional sweep.
Stage / 02
Handles the design workflow from the meta-atom response library to the layout. It builds the response library from Ansys Lumerical RCWA / FDTD results, then covers target phase definition, phase-to-geometry mapping, meta-atom placement, large-scale layout generation, built-in placement verification, and GDS / manufacturing-data output.
Stage / 03-05, 07 (+ built-in evaluation)
Handles evaluation and optimization as an optical system. It receives the metalens design data, and imaging performance and aberrations are evaluated and optimized with the lens built into a real optical system.
Stage / 06
Foundry and manufacturing
The output of the design stage is the layout data for the whole lens aperture and the dimensional conditions that make it work. Moving to manufacturing means confirming that both match the constraints of the fabrication method. Which of linewidth, aspect ratio, sidewall angle and in-plane uniformity dominates depends on the target wavelength, the material, and the fabrication method chosen.
Fabrication constraints are considered from the beginning. Minimum feature dimensions, geometry limits (height, aspect ratio, sidewall angle), pitch and spacing, material and process compatibility, the manufacturable structure families, and consistency with the foundry process rules all take effect at the stage where the meta-atom library is selected and phase is mapped to geometry.
The handover to manufacturing can include the whole-aperture layout, the geometry assignment at each position, the fabrication-related parameters, and the GDS / manufacturing layout data. Final manufacturability depends on the material, the geometry, the wavelength and the foundry process.
Which fabrication method applies, and whether it can be carried out, is judged case by case from the target wavelength, material and structural dimensions. There is no standardized process here, so please start by talking to us about the conditions for handing over the design data.
Related technical information
Tell us where the design stands, whether a phase design exists, your target specification, and any manufacturing planned, and we will propose a way forward.
