Glasfaser

https://www.youtube.com/watch?v=aNuj1_8NDEc – How Optical Fiber Connected the World

http://www.fiber-optic-transceiver-module.com/what-are-the-differences-between-sfp-sfp-xfp-qsfpqsfp-cfp-and-qsfp28.html

https://www.ip-insider.de/bereit-fuer-400-gigabit-ethernet-a-818705/