pytheas.Periodic2D

class pytheas.Periodic2D(analysis='direct', pola='TE', A=1, lambda0=1, lambda_mesh=1, theta_deg=0, d=0.8, h_sup=1, h_sub=1, h_layer1=0.1, h_layer2=0.1, h_des=1.0, h_pmltop=1.0, h_pmlbot=1.0, a_pml=1, b_pml=1, eps_sup=(1+0j), eps_sub=(1+0j), eps_layer1=(1+0j), eps_layer2=(1+0j), eps_des=(1+0j), eps_incl=(1+0j), mu_incl=(1+0j), mu_des=(1+0j))[source]

A class for a finite element model of a 2D mono-periodic medium.

The model consist of a single unit cell with quasi-periodic boundary conditions in the \(x\) direction enclosed with perfectly matched layers (PMLs) in the \(y\) direction to truncate the semi infinite media. From top to bottom:

  • PML top

  • superstrate (incident medium)

  • layer 2

  • design layer: this is the layer containing the periodic pattern, can be continuous or discrete

  • layer 1

  • substrate

  • PML bottom

Parameters

  • analysis (str, default "direct") – Analysis type: either “direct” (plane wave) or “modal” (spectral problem)

  • pola (str, default "TE") – Polarization case: either “TE” (E along z) or “TM” (H along z)

  • A (float, default 1) – Incident plane wave amplitude

  • lambda0 (float, default 1) – Incident plane wave wavelength in free space

  • lambda_mesh (float, default 1) – Wavelength to use for meshing

  • theta_deg (float, default 0) – Incident plane wave angle (in degrees). Light comes from the top (travels along -y if normal incidence, theta_deg=0 is set)

  • d (float, default 0.8) – Periodicity

  • h_sup (float, default 1) – Thickness superstrate

  • h_sub (float, default 1) – Thickness substrate

  • h_layer1 (float, default 0.1) – Thickness layer 1

  • h_layer2 (float, default 0.1) – Thickness layer 2

  • h_des (float, default 1) – Thickness layer design

  • h_pmltop (float, default 1) – Thickness pml top

  • h_pmlbot (float, default 1) – Thickness pml bot

  • a_pml (float, default 1) – PMLs complex y-stretching parameter, real part

  • b_pml (float, default 1) – PMLs complex y-stretching parameter, imaginary part

  • eps_sup (complex, default (1 - 0 * 1j)) – Permittivity superstrate

  • eps_sub (complex, default (1 - 0 * 1j)) – Permittivity substrate

  • eps_layer1 (complex, default (1 - 0 * 1j)) – Permittivity layer 1

  • eps_layer2 (complex, default (1 - 0 * 1j)) – Permittivity layer 2

  • eps_des (complex, default (1 - 0 * 1j)) – Permittivity layer design

  • eps_incl (complex, default (1 - 0 * 1j)) – Permittivity inclusion

cleanup()

Remove gmsh/getdp/python generated files from the temporary folder

compute_solution()[source]

Compute the solution of the FEM problem using getdp

diffraction_efficiencies(cplx_effs=False, orders=False)[source]

Postprocess diffraction efficiencies.

Parameters

  • cplx_effs (bool) – If True, return complex coefficients (amplitude reflection and transmission). If False, return real coefficients (power reflection and transmission)

  • orders (bool) – If True, computes the transmission and reflection for all the propagating diffraction orders. If False, returns the sum of all the propagating diffraction orders.

Returns

A dictionary containing the diffraction efficiencies.

Return type

dict

get_field_map(name)[source]

Retrieve a field map.

Parameters

name (str) – Choose between “u” (scattered field), “u_tot” (total field)

Returns

A 2D complex array of shape (Nix, Niy)

Return type

array

initialize()

Initialize the problem parameters.

make_inclusion(points, lcar='lc_incl', **kwargs)

Make a diffractive element geometry from points.

Parameters

  • points (array of size (Npoints, 2)) – The points defining the simply connected 2D geometry of the object.

  • lcar (str (default "lc_incl")) – Caracteristic length for the mesh.

  • **kwargs (dict) – Extra arguments.

make_mesh(other_option=None)

Mesh the geometry using gmsh.

Parameters

other_option (str) – Extra flag to pass to gmsh.

Returns

The content of the .msh file.

Return type

str

mk_tmp_dir()

Create a temporary directory

open_gmsh_gui(pos_list=None)

Open gmsh GUI to visualize geometry and postprocessing results.

Parameters

pos_list (list) – A list of .pos files giving the views to load. By default it will render all the generated views.

postpro_absorption()[source]

Compute the absorption coefficient

Returns

Q – Absorption coefficient

Return type

float

postpro_fields(filetype='txt', postop='postop_fields')

Compute the field maps and output to a file.

Parameters

  • filetype (str, default "txt") – Type of output files. Either “txt” (to be read by the method get_field_map in python) or “pos” to be read by gmsh/getdp.

  • postop (str, default "postop_fields") – Name of the postoperation

postprocess(postop)

Run getdp postoperation.

Parameters

postop (str) – Name of the postoperation to run.

rm_tmp_dir()

Remove the temporary directory

update_params()

Update the dictionary of parameters and the corresponding file

Examples using pytheas.Periodic2D