Physical and network aspects concerning the number of wavelengths in WDM systems

Wavelength division multiplexing (WDM) is an attractive method to exploit the enormous bandwidth of optical fibers. A key issue in amplified WDM systems is the appropriate choice of the number of wavelengths. This number is upper bounded by the available optical bandwidth and the required wavelength separation due to filter crosstalk as well as nonlinear fiber effects. By means of simulations this limit is quantified for a system with a single bitrate of 10 Gbit/s using intensity modulation and direct detection (IM/DD), standard single mode fibers (SSMF) and dispersion compensating fibers (DCF). Moreover, the benefits of wavelength routing in mesh networks can be sufficiently exploited by a rather small number of wavelengths. This aspect is investigated by a representative idealization of networks using optical bypassing and distributed interfacing. Based on these results recommendations on the number of wavelengths to be used in multiwavelength high speed transmission networks are given.