Next generation access networks present many more opportunities and challenges in the optical layer than the present
generation of such networks do. I will review the optical components that can be used advantageously in this
environment, with an emphasis on optical amplifiers in PON extension and WDM-PON.
Leo H. Spiekman,
"Active devices in next-generation access networks", Proc. SPIE 8645, Broadband Access Communication Technologies VII, 864506 (4 February 2013); doi: 10.1117/12.2010485; https://doi.org/10.1117/12.2010485