This Webdemo shows how signal power, optical signal-to-noise ratio (OSNR) and accumulated dispersion evolve along an optical fiber communication link. The total transmission distance $\ell_\mathrm{tot}$ is divided into $N$ spans of identical length $\ell_\mathrm{span}=\ell_\mathrm{tot}/N$. Each span consists of a single-mode fiber (SMF), a dispersion compensating fiber (DCF) and an optical amplifier (AMP) as shown in the figure. The length $\ell_\mathrm{DCF}$ of the DCF is chosen automatically so that it compensates for the dispersion caused by the SMF. Similarly, the gain $G$ of the AMP makes up for the loss in optical power caused by SMF and DCF.
The dispersion coefficient $D_\mathrm{SMF}$ and the dispersion slope $S_\mathrm{SMF}$ of the SMF are fixed with $D_\mathrm{SMF}=17\,\mathrm{ps/(nm\cdot km)}$ and $S_\mathrm{SMF}=0.053\,\mathrm{ps/(nm^2\cdot km)}$. The dispersion coefficent and slope of the DCF can be chosen freely but its length is calculated automatically, with $\ell_\mathrm{DCF}=-\ell_\mathrm{SMF}D_\mathrm{SMF}/D_\mathrm{DCF}$. All dispersion coefficients and slopes are valid at a wavelength of 1550 nm. For the power plot only one wavelength is considered (single-channel). The OSNR refers to a bandwidth of 12.5 GHz.