WDM technology currently used widely for ultra long distances and high capacity
Capacities more than Tera bits per second can be reached
Distances more than 5000 km can be reached
WDM has 2 types: CWDM and DWDM
WDM use laser source
DWDM used for long distances and high capacity but CWDM can be used with up to 8 channels
DWDM use single mode optical fiber
ITU has Many standards for optical cables, g652 and g655 is the most common fiber cables used with DWDM
We use c band
C band is from 1525 - 1565 nm and from 191 to 196 Tera Hertz