rcwa API¶
The main user-facing classes: Solver, Layer, LayerStack, Source, Material, Crystal, and Plotter. The Layer class is used to set up the individual simulation layers and define their properties, including thickness, material properties, and crystal structures (if applicable). The Material class can be passed into the Layer class to define a layer whose material properties are dependent on refractive index. The Crystal class is used to define layers which are periodic in x and y, and is also passed into the Layer class. Once all individual layers are constructed, they are used to create a LayerStack, which contains information about which region is considered the “incident” region and which is the “transmission” region (both are semi-infinite).
The Source class is used to define the excitation source - the wavelength, polarization, and incident angle.
Once the user has created a Source and LayerStack class, these are passed into the Solver class, which then runs the simulation, and makes the results available as a dictionary Solver.results.
- class rcwa.Solver(layer_stack, source, n_harmonics=1)¶
Main class that invokes all methods necessary to solve an RCWA/TMM simulation
- Parameters
layer_stack – layerStack: Stack of layers to simulate
source – Source object which includes wavelength and direction information
n_harmonics – The number of harmonics in x, y to simulate (number of Fourier components). For planar films this should be 1. For 1D diffraction gratings this should be a single integer. For 2D periodic films this should be a 2-tuple. Must be an odd number.
- class rcwa.Layer(er: complex = 1.0, ur: complex = 1.0, thickness: complex = 0.0, n: Optional[complex] = None, material: Union[None, rcwa.material.Material] = None, crystal: Union[None, rcwa.crystal.Crystal] = None)¶
Class for defining a single layer of a layer stack used in a simulation
- Parameters
er – Permittivity of the layer. Overridden by crystal permittivity if specified.
ur – Permeability of the layer. Overridden by crystal permeability if specified.
thickness – Thickness of the layer
n – Refractive index of the layer. Overridden by cristal er/ur if specified.
material – Material object containing the material’s permittivity and permeability as a function of wavelength/angle.
crystal – Crystal object if the layer is periodic in x and/or y. Overrides er, ur, n, and material
- class rcwa.LayerStack(*internal_layers: rcwa.layer.Layer, incident_layer: rcwa.layer.Layer = <rcwa.layer.Layer object>, transmission_layer: rcwa.layer.Layer = <rcwa.layer.Layer object>)¶
Class that defines overall geometry in terms of a stack of layers
- Parameters
internal_layers – Layer objects, starting with the top-most layer (reflection region) and ending with the top-most region (substrate)
incident_layer – Semi-infinite layer of incident region. Defaults to free space
transmission_layer – Semi-infinite layer of transmission region. Defaults to free space
- class rcwa.Source(wavelength=6.283185307179586, theta=0, phi=0, pTEM=[1, 1], layer=<rcwa.layer.Layer object>)¶
Class for defining monochromatic excitation source
- Parameters
wavelength – The wavelength (in microns, or your preferred length unit due to the scale-invariance of Maxwell’s equations.
theta – Angle with respect to the vector normal to the layer stack, in radians
phi – Rotation angle amount the vector normal to the layer stack
pTEM – Polarization vector for TE/TM polarization fraction (can be complex)
layer – Layer source is located in
- class rcwa.Crystal(*lattice_vectors, er: Union[numpy.typing._array_like._SupportsArray[numpy.dtype], numpy.typing._nested_sequence._NestedSequence[numpy.typing._array_like._SupportsArray[numpy.dtype]], bool, int, float, complex, str, bytes, numpy.typing._nested_sequence._NestedSequence[Union[bool, int, float, complex, str, bytes]]] = 1, ur: Union[numpy.typing._array_like._SupportsArray[numpy.dtype], numpy.typing._nested_sequence._NestedSequence[numpy.typing._array_like._SupportsArray[numpy.dtype]], bool, int, float, complex, str, bytes, numpy.typing._nested_sequence._NestedSequence[Union[bool, int, float, complex, str, bytes]]] = 1)¶
Class used for defining periodic structures in x and y
- Parameters
er – 2D numpy array of permittivity values
ur – 2D numpy array of permeability values
lattice_vectors – Real-space lattice vectors
- class rcwa.Material(name=None, er=1, ur=1, n=None, database_path=None, filename=None, source=None)¶
Material class for defining materials permittivity / permeability / refractive index as a function of wavelength / angle.
- Parameters
name – Material name to be looked up in database (i.e. Si)
er – Complex-valued numerical permittivity value or function of wavelength
ur – Complex-valued numerical permeability value or function of wavelength
n – Complex-valued refractive index of material. Overrides er / ur
source – Excitation source to link to material (mandatory for dispersive materials)
filename – File containing n/k data for the material in question
database_path – Raw file path within database