revert overly strict validation of 'freqs'

Author: dmarek-flex

CHANGELOG.md

@@ -27,6 +27,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Calculation of voltage and current in the `WavePort`, when one type of path integral is supplied and the transmission line mode is lossy.
 - Polygon vertices cleanup in `ClipOperation.intersections_plane`.
 - Removed sources from `sim_inf_structure` simulation object in `postprocess_adj` to avoid source and background medium validation errors.
+- Revert overly restrictive validation of `freqs` in the `ComponentModeler` and `TerminalComponentModeler`.
 
 ## [2.9.0] - 2025-08-04
 

tests/test_plugins/smatrix/test_terminal_component_modeler.py

@@ -235,18 +235,16 @@ def test_validate_no_sources(tmp_path):
 
 
 def test_validate_freqs():
-    """Ensure the 'freqs' array is strictly increasing and length of at least 2."""
+    """Ensure the 'freqs' array does not contain negative values nor duplicate entries."""
     modeler = make_component_modeler(planar_pec=False)
-    freqs = np.array([1.0])
-    with pytest.raises(pd.ValidationError):
-        _ = modeler.updated_copy(freqs=freqs)
-    freqs = np.array([-1.0, 5])
-    with pytest.raises(pd.ValidationError):
-        _ = modeler.updated_copy(freqs=freqs)
-    freqs = np.array([1, 2, 1.9])
+    # It should be possible to provide a single frequency point
+    freqs = np.array([1.0e6])
+    modeler = modeler.updated_copy(freqs=freqs)
+    _ = modeler._source_time
+    # Negative frequencies are not allowed
+    freqs = np.array([-1.0, 5]) * 1e9
     with pytest.raises(pd.ValidationError):
         _ = modeler.updated_copy(freqs=freqs)
-
     # Test case with non-unique value
     f_min, f_max = (0.5e9, 1.5e9)
     f0 = (f_min + f_max) / 2

tidy3d/components/validators.py

@@ -465,6 +465,19 @@ def freqs_not_empty(cls, val):
     return freqs_not_empty
 
 
+def validate_freqs_unique():
+    """Validate that the array of frequencies does not have duplicate entries."""
+
+    @pydantic.validator("freqs", always=True, allow_reuse=True)
+    def freqs_unique(cls, val):
+        """Raise validation error if ``freqs`` has duplicate entries."""
+        if len(set(val)) != len(val):
+            raise ValidationError(f"'{cls.__name__}.freqs' must not contain duplicate entries.")
+        return val
+
+    return freqs_unique
+
+
 def _warn_unsupported_traced_argument(name: str):
     @pydantic.validator(name, always=True, allow_reuse=True)
     def _warn_traced_arg(cls, val, values):

tidy3d/plugins/smatrix/component_modelers/base.py

@@ -14,7 +14,12 @@
 from tidy3d.components.data.sim_data import SimulationData
 from tidy3d.components.simulation import Simulation
 from tidy3d.components.types import Complex, FreqArray
-from tidy3d.components.validators import assert_unique_names
+from tidy3d.components.validators import (
+    assert_unique_names,
+    validate_freqs_min,
+    validate_freqs_not_empty,
+    validate_freqs_unique,
+)
 from tidy3d.config import config
 from tidy3d.constants import HERTZ
 from tidy3d.exceptions import SetupError, Tidy3dKeyError
@@ -150,24 +155,9 @@ def _sim_has_no_sources(cls, val):
             raise SetupError(f"'{cls.__name__}.simulation' must not have any sources.")
         return val
 
-    @pd.validator("freqs", always=True)
-    def _validate_freqs(cls, val):
-        """The array of frequencies must be sorted, unique and non-negative."""
-        if len(val) < 2:
-            raise SetupError(f"You must supply at least 2 entries for '{cls.__name__}.freqs'.")
-        np_val = np.array(val)
-        if not np.all(np_val >= 0):
-            raise SetupError(f"'{cls.__name__}.freqs' must be an array of non-negative numbers.")
-        # Ensure freqs is sorted
-        diff = np.diff(np_val)
-        if not np.all(diff > 0):
-            violations = np.where(diff <= 0)[0] + 1
-            raise SetupError(
-                f"'{cls.__name__}.freqs' must be strictly increasing (unique values sorted "
-                "in ascending order). "
-                f"The entries at the following indices violated this requirement: {violations}."
-            )
-        return val
+    _freqs_not_empty = validate_freqs_not_empty()
+    _freqs_lower_bound = validate_freqs_min()
+    _freqs_unique = validate_freqs_unique()
 
     @pd.validator("ports", always=True)
     def _warn_rf_license(cls, val):

tidy3d/plugins/smatrix/component_modelers/terminal.py

@@ -28,7 +28,7 @@
 from tidy3d.plugins.smatrix.ports.wave import WavePort
 from tidy3d.web.api.container import BatchData
 
-from .base import AbstractComponentModeler, TerminalPortType
+from .base import FWIDTH_FRAC, AbstractComponentModeler, TerminalPortType
 
 NetworkIndex = str  # the 'i' in S_ij
 NetworkElement = tuple[NetworkIndex, NetworkIndex]  # the 'ij' in S_ij
@@ -272,6 +272,9 @@ def _add_source_to_sim(self, source_index: NetworkIndex) -> tuple[str, Simulatio
     @cached_property
     def _source_time(self):
         """Helper to create a time domain pulse for the frequency range of interest."""
+        if len(self.freqs) == 1:
+            freq0 = self.freqs[0]
+            return GaussianPulse(freq0=self.freqs[0], fwidth=freq0 * FWIDTH_FRAC)
         return GaussianPulse.from_frequency_range(
             fmin=min(self.freqs), fmax=max(self.freqs), remove_dc_component=self.remove_dc_component
         )