adding FAQ about save and load fitted medium (#45)

Adding FAQ about save and load fitted medium

Author: FilipeFcp

_faqs/how-can-i-save-and-load-a-fitted-medium.md

@@ -0,0 +1,27 @@
+---
+title: How Can I Save and Load a Fitted Medium?
+date: 2025-09-16 12:38:02
+enabled: true
+category: "Mediums"
+---
+After fitting a medium, as described [here](https://docs.flexcompute.com/projects/tidy3d/en/stable/notebooks/Fitting.html){: .color-primary-hover}, it is possible to save the fitted medium as an hdf5 file and save time when using it in another model. To save the file, just use the `.to_file` method:
+
+<div markdown class="code-snippet">
+{% highlight python %}
+fitted_medium.to_file('medium_name.hdf5')
+{% endhighlight %}
+{% include copy-button.html %}</div>
+
+Now, the saved medium can be loaded with the [PoleResidue](https://docs.flexcompute.com/projects/tidy3d/en/latest/api/_autosummary/tidy3d.PoleResidue.html){: .color-primary-hover} `.from_file` method:
+
+<div markdown class="code-snippet">
+{% highlight python %}
+loaded_medium = td.PoleResidue.from_file('medium_name.hdf5')
+{% endhighlight %}
+{% include copy-button.html %}</div>
+
+To use this medium via the web GUI, you have two options: 
+
+(a): open the "Material Utilities", select the "Private Library", and click the "Upload Material" button; 
+
+(b): in the workbench, create a new medium and choose the "Import Material" option in the "Add Medium" panel.

docs/faq/how-can-i-save-and-load-a-fitted-medium.md

@@ -0,0 +1,32 @@
+# How Can I Save and Load a Fitted Medium?
+
+| Date       | Category    |
+|------------|-------------|
+| 2025-09-16 12:38:02 | Mediums |
+
+
+After fitting a medium, as described [here](https://docs.flexcompute.com/projects/tidy3d/en/stable/notebooks/Fitting.html), it is possible to save the fitted medium as an hdf5 file and save time when using it in another model. To save the file, just use the `.to_file` method:
+
+
+
+```python
+fitted_medium.to_file('medium_name.hdf5')
+```
+
+
+
+Now, the saved medium can be loaded with the [PoleResidue](https://docs.flexcompute.com/projects/tidy3d/en/latest/api/_autosummary/tidy3d.PoleResidue.html) `.from_file` method:
+
+
+
+```python
+loaded_medium = td.PoleResidue.from_file('medium_name.hdf5')
+```
+
+
+
+To use this medium via the web GUI, you have two options: 
+
+(a): open the "Material Utilities", select the "Private Library", and click the "Upload Material" button; 
+
+(b): in the workbench, create a new medium and choose the "Import Material" option in the "Add Medium" panel.

docs/mediums.rst

@@ -18,3 +18,4 @@ Mediums
    faq/how-can-i-define-a-2d-material.md
    faq/how-can-i-define-graphene.md
    faq/how-can-i-define-a-nonlinear-material.md
+   faq/how-can-i-save-and-load-a-fitted-medium.md

faq_categories.json

@@ -90,7 +90,8 @@
       "_faqs/how-do-i-load-a-commonly-used-dispersive-material.md",
       "_faqs/how-can-i-define-a-2d-material.md",
       "_faqs/how-can-i-define-graphene.md",
-      "_faqs/how-can-i-define-a-nonlinear-material.md"
+      "_faqs/how-can-i-define-a-nonlinear-material.md",
+      "_faqs/how-can-i-save-and-load-a-fitted-medium.md"
     ]
   },
   {