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fa34304 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 | import numpy as np
def generate_sigma_x(x, dx, wavelength, domain_size, sigma_max=0.5, pml_factor=5):
"""
Generate the 1D PML damping profile sigma(x) for the x-dimension.
Parameters:
x : 1D numpy array of x coordinates.
dx : grid spacing in x.
wavelength : wavelength in microns.
domain_size : total transverse domain size (in microns).
sigma_max : maximum damping value (default 0.5).
pml_factor : number of wavelengths to use for the PML thickness.
Returns:
sigma_x : 1D numpy array of damping values.
"""
pml_thickness = int(pml_factor * wavelength / dx)
pml_width = pml_thickness * dx
x_edge = domain_size / 2 - pml_width
sigma_x = np.where(np.abs(x) > x_edge,
sigma_max * ((np.abs(x) - x_edge) / pml_width) ** 2,
0)
return sigma_x
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