grep

Author: dmarek-flex

CHANGELOG.md

@@ -88,6 +88,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Removed mode solver warnings about evaluating permittivity of a `Medium2D`.
 - Maximum number of grid points in an EME simulation is now based solely on transverse grid points. Maximum number of EME cells is unchanged.
 - Fixed handling of polygons with holes (interiors) in `subdivide()` function. The function now properly converts polygons with interiors into `PolySlab` geometries using subtraction operations with `GeometryGroup`.
+- Fixed mode solver grid extending beyond simulation domain boundaries, causing incorrect PEC boundary application. The solver now properly truncates the computational grid to simulation bounds and zero-pads fields outside the domain.
 
 ### Removed
 - Removed deprecated `use_complex_fields` parameter from `TwoPhotonAbsorption` and `KerrNonlinearity`. Parameters `beta` and `n2` are now real-valued only, as is `n0` if specified.

tidy3d/components/mode/solver.py

@@ -161,15 +161,11 @@ def compute_modes(
             cell_max = [trim_max[0] - 1, trim_max[1] - 1]
 
             # Truncate eps_cross
-            eps_cross = cls._truncate_medium_data(
-                eps_cross, cell_min, cell_max, original_Nx, original_Ny
-            )
+            eps_cross = cls._truncate_medium_data(eps_cross, cell_min, cell_max)
 
             # Truncate mu_cross if provided
             if mu_cross is not None:
-                mu_cross = cls._truncate_medium_data(
-                    mu_cross, cell_min, cell_max, original_Nx, original_Ny
-                )
+                mu_cross = cls._truncate_medium_data(mu_cross, cell_min, cell_max)
 
             # Truncate split_curl_scaling if provided
             if split_curl_scaling is not None:
@@ -1117,7 +1113,7 @@ def eigs_to_effective_index(cls, eig_list: Numpy, mode_solver_type: ModeSolverTy
         raise RuntimeError(f"Unidentified 'mode_solver_type={mode_solver_type}'.")
 
     @staticmethod
-    def _truncate_medium_data(mat_data, cell_min, cell_max, original_Nx, original_Ny):
+    def _truncate_medium_data(mat_data, cell_min, cell_max):
         """Truncate medium data (eps or mu) to the specified cell range.
 
         Parameters
@@ -1128,10 +1124,6 @@ def _truncate_medium_data(mat_data, cell_min, cell_max, original_Nx, original_Ny
             [x_min, y_min] cell indices for truncation start.
         cell_max : list[int]
             [x_max, y_max] cell indices for truncation end.
-        original_Nx : int
-            Original number of cells in x.
-        original_Ny : int
-            Original number of cells in y.
 
         Returns
         -------