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round pillars

            round pillars
    polarization insenstive


rectangular pillars

      rectangular pillars
  for circular polarization


cross-type pillar

          cross-type pillar
x-arm length TM polarization
y-arm length TE polarization


transmission vs pillar height at 650 nm

    heat map plot showing
    transmission vs pillar height
    calculated using RCWA
    Pillar height selected for
    good transmission across
    pillar radii


phase vs radius at 650 nm

    phase vs pillar radius
    calculated using RCWA
    Pillars from 0-to-2pi phase
    are selected and saved in
    a meta-atom library
    to use as building blocks
    for metasurface layout


GDS mask enlarged

  englarged GDS mask showing
  meta-atoms placed at positions
  in the metasurface to minimize
  target wavefront error


metasurface layout

    rectangular and cross-shape
    meta-atoms placed at each
    position on the surface
    according to the phase with
    the lowest target wavefront
    error


metasurface layout

GDS mask showing metasurface
layout with weighted optimization
to split TE and TM polarization
Metalens and Grating Simulation and Design

Features of PlanOpSim MetaCell
    Gratings: 1D, 2D, blazed, slanted, subwavelength, high NA,
        volume holographic
    Metasurface pillars
    Full wave Maxwell solver
    Rigorous Coupled Wave Analysis (RCWA)

Features of PlanOpSim MetaCell + MetaComponent
    Metalenses: polarization sensitive and insensitive
    Flat diffractive lenses
    Beam shapers, beam splitters, diffusers, CGHs
    Metagratings
    Forward design - three ways:
        Input phase as an analytical expression, such as a lens formula
        Input Zemax wavefront surface response (binary2 surface)
        Use Python to create customized wavefront
    Inverse design: Input target pattern
    Interative Fourier Transform Algorithm (IFTA) used for inverse design
        to create alternative metalens
    Parameter sweep to evaluate IFTA designs against merit functions
        and minimize target pattern error
    Export GDSII fabrication files

Types of User Licenses
PlanOpSim software is available for online operation or with a dongle for
    local operation.
User licenses can either be permanent or annually renewable
    subscriptions.
Subscription user licenses can reduce initial cost, offer more thorough
    software evaluations or provide practical solutions for short-term
    projects.
Subscription user licenses can be converted to permanent licenses

Zemax interface
Importing Zemax files into PlanOpSim for metalens and grating
    applications extends Zemax ray tracing to fully vectorial
    physical optics modeling and physical structure designs.
    A full wave Maxwell solver and RCWA analysis are used to create
    individual metacells and to build libraries of meta-atoms for
    metasurface design.
Exporting metalens and grating designs to Zemax makes it easy to include
    PlanOpSim's physical optics results in familiar optical system layouts in
    Zemax.

Forward design - three ways
An analytical expression, such as a lens formula, can be used to input the
    ideal design.
Zemax can be imported as a wavefront surface response (binary2 surface).
A customized input wavefront can be described in a Python script

Inverse design - and IFTA
For inverse design a target pattern is imported, such as a JSON
    image file.
Iterative Fourier Transform Algorithm (IFTA) is used to create a
    metasurface phase design. IFTA starts by creating a random
    phase distribution in the near field, based on an input
    far field amplitude.
    The projected pattern is evaluated against the target, and each
    iteration improves the phase design until a desired pattern
    is developed.
    It takes PlanOpSim just seconds to develop, evaluate and improve
    mutiple metasurface phase designs.
Then, optimization by a parameter sweep shows the best choice based on
    design criteria.

Parameter sweep
The Parameter Sweep in PlanOpSim is used to optimize designs for
    best performance and fabrication
    Minimum and maximum ranges for each parameter can be specified,
    as well as the number of steps to vary in each range.
    Parameters can be varied linearly or randomly.
The Parameter Sweep also makes it easy to see how performance
    changes when varying such parameters as wavelength
    and angle of incidence.
Results, including spot size, spot location and wavefront can be shown
    quickly, and they can be changed using a separate slider bar
    for each variable.

PlanOpSim MetaCell - RCWA
The MetaCell program is for defining layers of structures for metasurface
pillars, as well as for gratings and coatings.
    For gratings and coatings these structures can be individual layers
    each having its own material and thickness.
    For metasurfaces these structures can be individual pillars.
    Pillar designs include selection of materials, dimensions and shapes.
    PlanOpSim includes round, rectangular and cross-shaped pillars.
The MetaCell program includes a full wave Maxwell solver and
    Rigorous Coupled Wave Analysis (RCWA) for simulating the phase
    and transmission of gratings, coatings and pillars.
    Pillar height is easy to choose from the RCWA heat map plot
    (shown on the left).
    The heat map shows transmission vs height and pillar radius.
    A pillar height with high transmission across the range of pillar sizes,
    and also having a practical fabrication size, can be determined from
    the heat map.
    The RCWA plot of pillar phase vs pillar radius is then used to select
    pillars within 0-to-2pi phase to include in pillar groups called meta-atoms.
    These pillar groups are sometimes called nanoscale building blocks.
    Each meta-atom (pillar group) can be stored in a library, along with other
    meta-atoms.
    A meta-atom includes pillars of the same height, but they can be
    different shapes.
    Meta-atoms in the library are used by the PlanOpSim Meta Component
    program to construct metasurface layouts, as described in the next
    section.

PlanOpSim MetaComponent
The MetaComponent program is for creating and optimizing metasurface
    structures and exporting GDSII fabrication files.
The MetaComponent program uses meta-atoms from the MetaCell library
    to design a metasurface. The metasurface is constructed of spatially
    varying meta-atoms. PlanOpSim places a meta-atom at each location
    on the surface determined by a weighted least square error optimization
    compared to the phase and amplitude given by the target.
The finished metasurface design is used to export a GDSII fabrication file.
    On the left is one example of a GDSII metasurface consisting of
    round pillars and another with a combination of rectangular and
    cross-shape pillars.
    Click on each image to enlarge it.

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