Allow 2D simulations with meep in X- and Y- normal planes #672
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- remove is_3d parameter in get_meep_geometry_from_component (geometry for 2D simulation just sliced out of 3D geometry) - add parameters normal_2d and point_2d to specify 2D simulation plane - adjust simulation volume, source and monitor sizes to fit 2D dimensions - check sources & monitors to be in simulation volume - in write_sparameters_meep.py do not iterate over component ports which are not in simulation domain
Contributor
Reviewer's GuideAdds support for running Meep 2D simulations on arbitrary X/Y/Z-normal planes without re-centering components, by configuring cell size and geometry slicing from full 3D geometry, enforcing that sources/monitors lie in the chosen 2D plane, and updating S-parameter calculation and plotting to use the new behavior. Sequence diagram for write_sparameters_meep and 2D-plane-aware simulation and S-parameter flowsequenceDiagram
participant UserScript
participant write_sparameters_meep
participant get_simulation
participant is_point_in_plane
participant MeepSimulation as Meep_Simulation
participant sparameter_calculation
participant parse_port_eigenmode_coeff
UserScript->>write_sparameters_meep: call(component, is_3d, normal_2d, point_2d, ...)
write_sparameters_meep->>get_simulation: get_simulation(component, is_3d, normal_2d, point_2d, ...)
get_simulation->>get_simulation: compute_normal_vec_from_normal_2d
get_simulation->>get_simulation: compute_cell_size_with_zero_dim_for_2D
get_simulation->>is_point_in_plane: check_source_center(test_point=center, plane_support=point_2d, plane_normal=normal_vec)
is_point_in_plane-->>get_simulation: bool
get_simulation->>get_simulation: raise_error_if_source_not_in_plane
loop for_each_port_for_monitor
get_simulation->>is_point_in_plane: check_monitor_center
is_point_in_plane-->>get_simulation: bool
alt in_plane
get_simulation->>MeepSimulation: sim.add_mode_monitor
else not_in_plane
get_simulation->>get_simulation: warn_monitor_ignored
end
end
get_simulation-->>write_sparameters_meep: sim_dict(sim, cell_size, monitors, freqs)
write_sparameters_meep->>sparameter_calculation: sparameter_calculation(..., sim_dict, ...)
sparameter_calculation->>MeepSimulation: run_simulation_until_energy_decayed
loop for_each_port_in_sim_dict_monitors
loop for_each_port_mode
sparameter_calculation->>parse_port_eigenmode_coeff: parse_port_eigenmode_coeff(port_name, ports, sim_dict, port_mode)
parse_port_eigenmode_coeff-->>sparameter_calculation: (entering, exiting)
sparameter_calculation->>sparameter_calculation: update_smatrix_entries
end
end
sparameter_calculation-->>write_sparameters_meep: sparameters
write_sparameters_meep-->>UserScript: sparameters_results
Class diagram for updated Meep simulation helpers with 2D plane supportclassDiagram
class get_simulation {
+dict get_simulation(component, resolution, extend_ports_length, port_margin, port_source_name, port_source_mode, layer_stack, material_name_to_meep, dispersive, zmargin_top, zmargin_bot, xmargin, ymargin, tpml, clad_material, is_3d, normal_2d, point_2d, wavelength_start, wavelength_stop, wavelength_points, dfcen, port_symmetries, port_names, port_modes, distance_source_to_monitors, port_monitor_offset, port_source_offset, port_symmetries, **settings)
}
class is_point_in_plane {
+bool is_point_in_plane(test_point, plane_support, plane_normal, tolerance)
}
class get_meep_geometry_from_component {
+list get_meep_geometry_from_component(component, layer_stack, material_name_to_meep, wavelength, dispersive, exclude_layers, **kwargs)
}
class write_sparameters_meep {
+dict write_sparameters_meep(component, layer_stack, material_name_to_meep, resolution, is_3d, normal_2d, point_2d, wavelength_start, wavelength_stop, wavelength_points, port_source_name, port_source_mode, port_symmetries, port_source_names, port_monitor_names, port_names, port_modes, xmargin, ymargin, zmargin, tpml, clad_material, extend_ports_length, distance_source_to_monitors, port_monitor_offset, port_source_offset, animate, animate_size, animate_center, decay_by, plot_args, exclude_layers, dispersive, **settings)
}
class sparameter_calculation {
+dict sparameter_calculation(port_source_names, component, port_symmetries, port_source_mode, wavelength_start, wavelength_stop, wavelength_points, normal_2d, point_2d, is_3d, animate, decay_by, **settings)
}
class parse_port_eigenmode_coeff {
+tuple parse_port_eigenmode_coeff(port_name, ports, sim_dict, port_mode)
}
class MeepSimulation {
+mp.Simulation sim
+mp.Vector3 cell_size
+dict monitors
+list freqs
}
get_simulation --> get_meep_geometry_from_component : uses
get_simulation --> is_point_in_plane : validates_sources_and_monitors
get_simulation --> MeepSimulation : builds
write_sparameters_meep --> get_simulation : obtains_initial_sim
write_sparameters_meep --> sparameter_calculation : computes_sparameters
sparameter_calculation --> parse_port_eigenmode_coeff : reads_coefficients
sparameter_calculation --> MeepSimulation : uses
parse_port_eigenmode_coeff --> MeepSimulation : accesses_monitors
File-Level Changes
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Contributor
There was a problem hiding this comment.
Hey - I've found 1 issue, and left some high level feedback:
- Now that
get_meep_geometry_from_componentalways useslevel.zminand a nonzerosidewall_angle, the geometry for Z-normal "2D" simulations is no longer flattened to z=0 – if this isn’t intentional you may want to conditionally zerozmin/sidewall_anglewhen running a Z-normal 2D setup so objects remain inside a zero-thickness z cell. - The change from a conditional
extend_ports(..., centered=True)to always callingextend_ports(component=component, length=extend_ports_length)withoutcentered=Truewill shift port extensions relative to the original behavior; if callers rely on symmetric extensions orextend_ports_lengthbeing optional/False-y, consider restoring the conditional call or explicitly handling theNone/0case and thecenteredoption.
Prompt for AI Agents
Please address the comments from this code review:
## Overall Comments
- Now that `get_meep_geometry_from_component` always uses `level.zmin` and a nonzero `sidewall_angle`, the geometry for Z-normal "2D" simulations is no longer flattened to z=0 – if this isn’t intentional you may want to conditionally zero `zmin`/`sidewall_angle` when running a Z-normal 2D setup so objects remain inside a zero-thickness z cell.
- The change from a conditional `extend_ports(..., centered=True)` to always calling `extend_ports(component=component, length=extend_ports_length)` without `centered=True` will shift port extensions relative to the original behavior; if callers rely on symmetric extensions or `extend_ports_length` being optional/False-y, consider restoring the conditional call or explicitly handling the `None/0` case and the `centered` option.
## Individual Comments
### Comment 1
<location> `gplugins/gmeep/get_simulation.py:29-38` </location>
<code_context>
settings_meep = set(sig.parameters.keys())
+def is_point_in_plane(
+ test_point: Float3,
+ plane_support: Float3,
+ plane_normal: Float3,
+ tolerance: float = 1e-6, # 1 pm for coordinates in µm
+):
+ a, b, c = plane_normal
+ xt, yt, zt = test_point
+ x0, y0, z0 = plane_support
+ distance = (a*(xt-x0) + b*(yt-y0) + c*(zt-z0)) / np.linalg.norm(plane_normal)
+ return bool(abs(distance) <= tolerance)
+
</code_context>
<issue_to_address>
**issue:** Guard against a zero-length plane_normal in is_point_in_plane.
`is_point_in_plane` will divide by `np.linalg.norm(plane_normal)` without handling the zero (or near-zero) case. Since this is a general helper, please add a guard (e.g., raise if the norm is below a small threshold) to avoid silent NaNs when called with invalid normals.
</issue_to_address>Help me be more useful! Please click 👍 or 👎 on each comment and I'll use the feedback to improve your reviews.
Comment on lines
+29
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+38
| def is_point_in_plane( | ||
| test_point: Float3, | ||
| plane_support: Float3, | ||
| plane_normal: Float3, | ||
| tolerance: float = 1e-6, # 1 pm for coordinates in µm | ||
| ): | ||
| a, b, c = plane_normal | ||
| xt, yt, zt = test_point | ||
| x0, y0, z0 = plane_support | ||
| distance = (a*(xt-x0) + b*(yt-y0) + c*(zt-z0)) / np.linalg.norm(plane_normal) |
Contributor
There was a problem hiding this comment.
issue: Guard against a zero-length plane_normal in is_point_in_plane.
is_point_in_plane will divide by np.linalg.norm(plane_normal) without handling the zero (or near-zero) case. Since this is a general helper, please add a guard (e.g., raise if the norm is below a small threshold) to avoid silent NaNs when called with invalid normals.
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PR makes the following changes:
is_3dparameter inget_meep_geometry_from_component(geometry for 2D simulation just sliced out of 3D geometry)normal_2dandpoint_2dto specify 2D simulation planewrite_sparameters_meep.pydo not iterate over component ports which are not in simulation domainUsing the example script
all simulations are working as expected (where actual S-parameters may not be meaningful/comparable as this is just an example),
Summary by Sourcery
Support 2D Meep simulations in arbitrary X-, Y-, or Z-normal planes while keeping component coordinates fixed and ensuring only in-domain ports participate in S-parameter calculations.
New Features:
Bug Fixes:
Enhancements: