Hello Rajguru M Mohan,
I to some extent agree with what Hamza Ali Abbas Khan has mentioned. I too feel that wideband travelling wave semiconductor optical amplifier in optical communication are being used to investigate the importance of travelling-wave effects and gain/phase dynamics in predicting device behaviour. A constant effective carrier recovery lifetime approximation is found to be reasonably accurate (±10%) within a wide range of control pulse energies.I hope this will help you to some extent.
Regards