sometimes, I realize how much is taken for granted these days that when I stop to think about is one of those "whoa" (in a Neo voice) moment. being able to time something in the picosecond range just gives me a wry smile.
This is a great post about the basics of what happens in transmission lines.
If you need really fast rise times, there are cheap pulse generators that are a couple orders of magnitude faster: https://leobodnar.com/shop/index.php?main_page=product_info&... At this level everything has to be optimized including physical geometry.
Great article!
aside: I've never seen Stack Exchange used as a blogpost medium (which normally this kind of write-up would be) and I like it! It's still formatted as Q&A so people with the same question can find it, and what's more, suggest edits or write alternative solutions (as OP explicitly invites here) on equal footing themselves. A collaborative quest for the answer, but not anonymized like a wiki.
Feed any (slow) pulse generator into the diode and make it switch. Tunnel diodes can have sub-nanosecond switching times.
We also used this technique to check/measure the rise times of our oscilloscopes.
If you need really fast rise times, there are cheap pulse generators that are a couple orders of magnitude faster: https://leobodnar.com/shop/index.php?main_page=product_info&... At this level everything has to be optimized including physical geometry.