fix a sign

tidy3d/plugins/mode/mode_solver.py

@@ -42,6 +42,7 @@
     ArrayFloat1D,
     Ax,
     Axis,
+    Axis2D,
     Direction,
     EpsSpecType,
     FreqArray,
@@ -181,6 +182,13 @@ def normal_axis(self) -> Axis:
         """Axis normal to the mode plane."""
         return self.plane.size.index(0.0)
 
+    @cached_property
+    def normal_axis_2d(self) -> Axis2D:
+        """Axis normal to the mode plane in a 2D plane that is normal to the bend_axis_3d."""
+        _, idx_plane = self.plane.pop_axis((0, 1, 2), axis=self.bend_axis_3d)
+
+        return idx_plane.index(self.normal_axis)
+
     @cached_property
     def solver_symmetry(self) -> Tuple[Symmetry, Symmetry]:
         """Get symmetry for solver for propagation along self.normal axis."""
@@ -489,6 +497,7 @@ def _car_2_cyn(
             fields_at_point = {
                 field_name: getattr(mode_solver_data, field_name)
                 .sel(sel_coords, method="nearest")
+                .isel({cmp_1: 0, cmp_2: 0})
                 .values
                 for field_name in ("Ex", "Ey", "Ez", "Hx", "Hy", "Hz")
             }
@@ -582,11 +591,14 @@ def _mode_rotation(
                         for comp in ["r", "theta", "axial"]
                     }
 
-                    phase = (
-                        np.exp(1j * theta_rel * beta)
-                        if self.direction == "+"
-                        else np.exp(-1j * theta_rel * beta)
-                    )
+                    # Determine the phase factor based on normal_axis_2d
+                    sign = -1 if self.normal_axis_2d == 0 else 1
+                    if (self.direction == "+" and self.mode_spec.bend_radius >= 0) or (
+                        self.direction == "-" and self.mode_spec.bend_radius < 0
+                    ):
+                        phase = np.exp(sign * 1j * theta_rel * beta)
+                    else:
+                        phase = np.exp(sign * -1j * theta_rel * beta)
 
                     # Set fixed index based on normal_axis
                     idx = [slice(None)] * 3