cw laser

Hello Gaurav Rajya
You have raised a good question about continuous laser power.Usually we consider 0dBm power of laser source due the fact that low power levels of input signals are less vulnerable to non linear effects in optical fiber.No doubt with the increase of input power,system performance increase to some extent but it decrease after the power cross elastic limits of toleration and kerrs efects,FWM, SPM and XPM comes into play.There is great importance of systems operates at lower power level because these systems operates for long time and less prone to heating effects introduced by laser at higher power level.Basically these are some important reasons,Rest you can see other benefits over internet regarding this concept.

Regards

Good Reply from sam sung
Because the nonlinear distortion depend on the launching power thus we required the minimum power
In some of case for cw laser we use -4dBm or more less power.

Actually, I would not say there is a particular reason…it is just a default value, and 0dBm is easy to remember, easy for gain calculations and similar to typical SFP power levels…

Hello Alessandro
Here are some links which clearly elaborate why power of systems kept low.Please take a look
http://www.sciencedirect.com/science/article/pii/S003040261301084X
http://www.scipublish.com/journals/STSP/papers/1062
https://seagrant.mit.edu/publications/MITSG_95-10J.pdf

we take 0 dbm as transmitted power to avoid non linear effects and also for simple calculations

hi Gaurav Rajarya,
you can take any value you need , this is a defult value