Maximun bps rate on an ITU channel over standard single mode fiber

[jga]

I have to find the maximun bps that it can be reach using a point-to-point link of 40 km long of optic fiber. I use an ITU normalized channel (100 GHz optic BW).

So, I can choose any electric modulation and any optic modulation, too.

Anybody could help me? Any answer is welcome. Thanks.

 

[jga]

And I can use electric and optic multiplex, too.