apply sim.plot and sim.plot_eps opacity kwargs to arrows

tidy3d/components/monitor.py

@@ -185,6 +185,9 @@ def plot(
         # call the monitor.plot() function first
         ax = super().plot(x=x, y=y, z=z, ax=ax, **kwargs)
 
+        kwargs_alpha = kwargs.get("alpha")
+        arrow_alpha = ARROW_ALPHA if kwargs_alpha is None else kwargs_alpha
+
         # and then add an arrow using the direction comuputed from `_dir_arrow`.
         ax = self._plot_arrow(
             x=x,
@@ -193,7 +196,7 @@ def plot(
             ax=ax,
             direction=self._dir_arrow,
             color=ARROW_COLOR_MONITOR,
-            alpha=ARROW_ALPHA,
+            alpha=arrow_alpha,
             both_dirs=True,
         )
         return ax

tidy3d/components/source.py

@@ -290,6 +290,9 @@ def plot(
         # call the `Source.plot()` function first.
         ax = super().plot(x=x, y=y, z=z, ax=ax, **kwargs)
 
+        kwargs_alpha = kwargs.get("alpha")
+        arrow_alpha = ARROW_ALPHA if kwargs_alpha is None else kwargs_alpha
+
         # then add the arrow based on the propagation direction
         if self._dir_vector is not None:
 
@@ -300,7 +303,7 @@ def plot(
                 ax=ax,
                 direction=self._dir_vector,
                 color=ARROW_COLOR_SOURCE,
-                alpha=ARROW_ALPHA,
+                alpha=arrow_alpha,
                 both_dirs=False,
             )
 
@@ -313,7 +316,7 @@ def plot(
                 ax=ax,
                 direction=self._pol_vector,
                 color=ARROW_COLOR_POLARIZATION,
-                alpha=ARROW_ALPHA,
+                alpha=arrow_alpha,
                 both_dirs=False,
             )