Development of WDM Technology

1.Wideband WDM- 2 widely spaced wavelengths in the 1310nm & 1550nm regions used in the late 1980’s.

2.Narrowband WDM –2 to 8 channels were used at an interval of 400GHz in the 1550nm window in early 1990’S

3.Dense WDM –16 to 40 channels and spacing from 100 to 200 GHz in mid 1990’s emerged.

4.DWDM-64 to 160 parallel channels densely packed at 50 or even 25GHz intervals has evolved in late 1990’s.

5.