What is the difference between a Preamplier EDFA and a Booster EDFA

[narra]

I know from the data sheets that a Preamplier (EDFA) requires lower input optical power, but can offer high gain (eg 25dB), and a Booster (EDFA) is specified for higher input optical power, but can offer less gain (eg 10dB).

What I was interested in knowing is what is the true nature for these separate devices (eg what where they specifically designed for and how are they made to be different)?

Can anyone provide a good explanation for these two devices, or know of a good source of information?

Many thanks.

 

[jsgruszynski]

See diagram at the bottom.

http://www.mpbc.ca/_en/web/telecom/network-ready/rmh07/rxxw.html