WDM PON

PON is point to multipoint optical network that lets a single fiber trunk provide data to many different nodes including individual customers who areserved digitally and interim pedestal facilities that connect electrically to customers.
PONs traditionally used for local rather than long distance transmission thus reduce the amount of fiber that a network requires.
PONs are passive, because they use pricesly engineered optical components that split and route signals via refraction rather than electrical process.
PON implementation
Mid 90s-> FSAN (Full service Access network) std given by consortium of equipment providers and ITU
ATM PON (APON)
Broadband PON (BPON)
Gigabit PON (GPON)
802.3 ah Ethernet PON (EPON)
NTT deployed world's first commercial PON, an APON network in Japan in year 2000.
Currently carriers use either GPON (2.4 Gbps down, 1.2 Gbps up) or EPON (1 GBps both ways).
ITU, FSAN and IEEE are working on faster versions of these approaches.
HOW they Work?EPON and GPON --> TDM (Time division multiplexing)
WPON

WDM PONS use either AWG (Arrayed waveguide grating) or thin film filters as multiplexers to redirect and route each wavelength of light to appropriate recepient node.
WDM is of two types:-1. Coarse WDM (CWDM)2. Dense WDM (DWDM)
CWDM uses lower cost optical components, offer lower capacity and shorter transmission ranges. CWDM uses thin film filters to multiplex and de-multiplex optical signals.