Delegate PEC check from MultiPhysicsMedium to its Optical Medium

tests/test_components/test_scene.py

@@ -53,6 +53,22 @@ def test_plot_eps():
     plt.close()
 
 
+def test_plot_eps_multiphysics():
+    s = td.Scene(
+        structures=[
+            td.Structure(
+                geometry=td.Box(size=(1, 1, 1), center=(-1, 0.5, 0.5)),
+                medium=td.MultiPhysicsMedium(
+                    optical=td.Medium(permittivity=3.9),
+                    charge=td.ChargeInsulatorMedium(permittivity=3.9),
+                    name="SiO2",
+                ),
+            )
+        ]
+    )
+    s.plot_eps(x=0)
+
+
 def test_plot_eps_bounds():
     _ = SCENE_FULL.plot_eps(x=0, hlim=[-0.45, 0.45])
     plt.close()

tidy3d/components/material/multi_physics.py

@@ -98,6 +98,16 @@ class MultiPhysicsMedium(Tidy3dBaseModel):
         None, title="Charge properties", description="Specifies properties for Charge simulations."
     )
 
+    def __getattr__(self, name: str):
+        """Delegates calls to missing attributes to the inner media."""
+        if self.optical is not None and hasattr(self.optical, name):
+            return getattr(self.optical, name)
+        if self.heat is not None and hasattr(self.heat, name):
+            return getattr(self.heat, name)
+        if self.charge is not None and hasattr(self.charge, name):
+            return getattr(self.charge, name)
+        return None
+
     @property
     def heat_spec(self):
         if self.heat is not None: