Entropic analysis of the information rate density of broadband active fiber-optic communication links

The maximum transfer rate characteristics of broadband active fiber-optic communication links are considered within the model of filling numbers. It is established that, for active information transmission systems, in contrast to passive ones, not only the parameters of the line itself are significant but also the input signal-to-noise ratio. It is shown that the classical approach underestimates considerably the value of the maximum information rate density of erbium fiber amplifiers. In lengthy communication links with erbium amplifiers, the value of the information rate density may reach ∼12–15 (bit/s)/Hz, which is more than one order of magnitude higher than the values achieved currently.