def propagated_far_field(self, layer_system):
"""Evaluate the far field intensity of the reflected / transmitted initial field.
Args:
layer_system (smuthi.layers.LayerSystem): Stratified medium
Returns:
A tuple of smuthi.field_expansion.FarField objects, one for forward (i.e., into the top hemisphere) and one
for backward propagation (bottom hemisphere).
"""
i_top = layer_system.number_of_layers() - 1
top_ff = fldex.pwe_to_ff_conversion(
vacuum_wavelength=self.vacuum_wavelength,
plane_wave_expansion=self.plane_wave_expansion(
layer_system, i_top)[0])
bottom_ff = fldex.pwe_to_ff_conversion(
vacuum_wavelength=self.vacuum_wavelength,
plane_wave_expansion=self.plane_wave_expansion(layer_system, 0)[1])
return top_ff, bottom_ff
def initial_intensity(self, layer_system):
"""Evaluate the incoming intensity of the initial field.
Args:
layer_system (smuthi.layers.LayerSystem): Stratified medium
Returns:
A smuthi.field_expansion.FarField object holding the initial intensity information.
"""
if np.cos(self.polar_angle) > 0: # bottom illumination
ff = fldex.pwe_to_ff_conversion(
vacuum_wavelength=self.vacuum_wavelength,
plane_wave_expansion=self.plane_wave_expansion(
layer_system, 0)[0])
else: # top illumination
i_top = layer_system.number_of_layers() - 1
ff = fldex.pwe_to_ff_conversion(
vacuum_wavelength=self.vacuum_wavelength,
plane_wave_expansion=self.plane_wave_expansion(
layer_system, i_top)[1])
return ff
def total_far_field(initial_field,
particle_list,
layer_system,
polar_angles='default',
azimuthal_angles='default'):
"""
Evaluate the total far field, the initial far field and the scattered far field. Cannot be used if initial field
is a plane wave.
Args:
initial_field (smuthi.initial_field.InitialField): represents the initial field
particle_list (list): list of smuthi.Particle objects
layer_system (smuthi.layers.LayerSystem): represents the stratified medium
polar_angles (numpy.ndarray or str): polar angles values (radian).
if 'default', use smuthi.coordinates.default_polar_angles
azimuthal_angles (numpy.ndarray or str): azimuthal angle values (radian)
if 'default', use smuthi.coordinates.default_azimuthal_angles
Returns:
A tuple of three smuthi.field_expansion.FarField objects for total, initial and scattered far field. Mind that the scattered far field
has no physical meaning and is for illustration purposes only.
"""
if not (type(initial_field).__name__ == 'GaussianBeam'
or type(initial_field).__name__ == 'DipoleSource'
or type(initial_field).__name__ == 'DipoleCollection'):
raise ValueError('only for Gaussian beams and dipole sources')
omega = initial_field.angular_frequency()
vacuum_wavelength = initial_field.vacuum_wavelength
if type(polar_angles) == str and polar_angles == 'default':
polar_angles = coord.default_polar_angles
if type(azimuthal_angles) == str and azimuthal_angles == 'default':
azimuthal_angles = coord.default_azimuthal_angles
if any(polar_angles.imag):
raise ValueError("complex angles not allowed in far field")
i_top = layer_system.number_of_layers() - 1
top_polar_angles = polar_angles[polar_angles < (np.pi / 2)]
bottom_polar_angles = polar_angles[polar_angles > (np.pi / 2)]
neff_top = np.sort(
np.sin(top_polar_angles) * layer_system.refractive_indices[i_top])
neff_bottom = np.sort(
np.sin(bottom_polar_angles) * layer_system.refractive_indices[0])
if len(top_polar_angles
) > 1 and layer_system.refractive_indices[i_top].imag == 0:
pwe_scat_top, _ = scattered_field_pwe(
vacuum_wavelength,
particle_list,
layer_system,
i_top,
k_parallel=neff_top * omega,
azimuthal_angles=azimuthal_angles,
include_direct=True,
include_layer_response=True)
pwe_in_top, _ = initial_field.plane_wave_expansion(
layer_system,
i_top,
k_parallel_array=neff_top * omega,
azimuthal_angles_array=azimuthal_angles)
pwe_top = pwe_scat_top + pwe_in_top
top_far_field = fldex.pwe_to_ff_conversion(
vacuum_wavelength=vacuum_wavelength, plane_wave_expansion=pwe_top)
top_far_field_init = fldex.pwe_to_ff_conversion(
vacuum_wavelength=vacuum_wavelength,
plane_wave_expansion=pwe_in_top)
top_far_field_scat = fldex.pwe_to_ff_conversion(
vacuum_wavelength=vacuum_wavelength,
plane_wave_expansion=pwe_scat_top)
else:
top_far_field = None
top_far_field_init = None
top_far_field_scat = None
if len(bottom_polar_angles
) > 1 and layer_system.refractive_indices[0].imag == 0:
_, pwe_scat_bottom = scattered_field_pwe(
vacuum_wavelength,
particle_list,
layer_system,
0,
k_parallel=neff_bottom * omega,
azimuthal_angles=azimuthal_angles,
include_direct=True,
include_layer_response=True)
_, pwe_in_bottom = initial_field.plane_wave_expansion(
layer_system,
0,
k_parallel_array=neff_bottom * omega,
azimuthal_angles_array=azimuthal_angles)
pwe_bottom = pwe_scat_bottom + pwe_in_bottom
bottom_far_field = fldex.pwe_to_ff_conversion(
vacuum_wavelength=vacuum_wavelength,
plane_wave_expansion=pwe_bottom)
bottom_far_field_init = fldex.pwe_to_ff_conversion(
vacuum_wavelength=vacuum_wavelength,
plane_wave_expansion=pwe_in_bottom)
bottom_far_field_scat = fldex.pwe_to_ff_conversion(
vacuum_wavelength=vacuum_wavelength,
plane_wave_expansion=pwe_scat_bottom)
else:
bottom_far_field = None
bottom_far_field_init = None
bottom_far_field_scat = None
if top_far_field is not None:
far_field = top_far_field
far_field_init = top_far_field_init
far_field_scat = top_far_field_scat
if bottom_far_field is not None:
far_field.append(bottom_far_field)
far_field_init.append(bottom_far_field_init)
far_field_scat.append(bottom_far_field_scat)
else:
far_field = bottom_far_field
far_field_init = bottom_far_field_init
far_field_scat = bottom_far_field_scat
far_field.polar_angles = far_field.polar_angles.real
far_field_init.polar_angles = far_field_init.polar_angles.real
far_field_scat.polar_angles = far_field_scat.polar_angles.real
return far_field, far_field_init, far_field_scat
def scattered_far_field(vacuum_wavelength,
particle_list,
layer_system,
polar_angles='default',
azimuthal_angles='default'):
"""
Evaluate the scattered far field.
Args:
vacuum_wavelength (float): in length units
particle_list (list): list of smuthi.Particle objects
layer_system (smuthi.layers.LayerSystem): represents the stratified medium
polar_angles (numpy.ndarray or str): polar angles values (radian).
if 'default', use smuthi.coordinates.default_polar_angles
azimuthal_angles (numpy.ndarray or str): azimuthal angle values (radian)
if 'default', use smuthi.coordinates.default_azimuthal_angles
Returns:
A smuthi.field_expansion.FarField object of the scattered field.
"""
omega = coord.angular_frequency(vacuum_wavelength)
if type(polar_angles) == str and polar_angles == 'default':
polar_angles = coord.default_polar_angles
if type(azimuthal_angles) == str and azimuthal_angles == 'default':
azimuthal_angles = coord.default_azimuthal_angles
if any(polar_angles.imag):
raise ValueError("complex angles not allowed in far field")
i_top = layer_system.number_of_layers() - 1
top_polar_angles = polar_angles[polar_angles < (np.pi / 2)]
bottom_polar_angles = polar_angles[polar_angles > (np.pi / 2)]
neff_top = np.sort(
np.sin(top_polar_angles) * layer_system.refractive_indices[i_top])
neff_bottom = np.sort(
np.sin(bottom_polar_angles) * layer_system.refractive_indices[0])
if len(top_polar_angles
) > 1 and layer_system.refractive_indices[i_top].imag == 0:
pwe_top, _ = scattered_field_pwe(vacuum_wavelength,
particle_list,
layer_system,
i_top,
k_parallel=neff_top * omega,
azimuthal_angles=azimuthal_angles,
include_direct=True,
include_layer_response=True)
top_far_field = fldex.pwe_to_ff_conversion(
vacuum_wavelength=vacuum_wavelength, plane_wave_expansion=pwe_top)
else:
top_far_field = None
if len(bottom_polar_angles
) > 1 and layer_system.refractive_indices[0].imag == 0:
_, pwe_bottom = scattered_field_pwe(vacuum_wavelength,
particle_list,
layer_system,
0,
k_parallel=neff_bottom * omega,
azimuthal_angles=azimuthal_angles,
include_direct=True,
include_layer_response=True)
bottom_far_field = fldex.pwe_to_ff_conversion(
vacuum_wavelength=vacuum_wavelength,
plane_wave_expansion=pwe_bottom)
else:
bottom_far_field = None
if top_far_field is not None:
far_field = top_far_field
if bottom_far_field is not None:
far_field.append(bottom_far_field)
else:
far_field = bottom_far_field
far_field.polar_angles = far_field.polar_angles.real
return far_field