Hi Ranjeet
Yes u are right.The low power requirement of SOAs and low cost makes them very suitable for use as amplifiers in Optical Netwrok units.
Since a large number of ONU units need to be deployed for Next generation networks so to keep the cost of ONUs as low as possible is equally important.Infact now most of these units make use of reflective semiconductor optical amplifiers (RSOAs) which have a lower cost compared to SOAs even.
Regards