OAN - Optical Access Networks
AON - Active Optical Networks. It employs active network components to interconnect network elements, such as amplifiers.
However, there are Reach Extended PON (REPON), where using an Erbium Doped Fibre Amplifier (EDFA) is permitted.
PON - Passive Optical Networks: multipoint networks that can be classified according to the functionality of components splitting optical signals. They can be splitters or Array Waveguide Gratings (AWG). In WDM, signals can be split by optical filtering by using so-called add-drop multiplexors.