For the last ~decade, NANOG [1] has regularly had a (two hour) presentation/tutorial called "Everything You Always Wanted to Know About Optical Networking"; most recent one:

* https://www.youtube.com/watch?v=Y-MfLsnqluM

* https://www.youtube.com/results?search_query=nanog+optics

[1] https://en.wikipedia.org/wiki/North_American_Network_Operato...