In an optical fiber communications system, several transmission bands have been defined and standardized, from the original O-band to the U/XL-band.
Optical amplifiers are also employed at various other points in a network, for example, within an optical switching node to compensate for losses in the switch fabric.
The O-Band Amplifier is Compact and has a Low Cost. They are useful in Transceiver testing & measurement and Passive component testing. The main benefit of optical amplifiers is that they can amplify multiple optical signals at the same time. More details: Notable Features Of O-band Amplifier - Inphenix - California