Multiple Path Interference and Its Impact on System Design

Impact of DCF properties on system design

“…Leaving more complex expressions for the beat noise terms to specialized texts (e.g., [56,18,57]), we give here a useful approximation for systems with Gaussian filters and Gaussian optical pulses, under the assumption that the optical filter bandwidth of the receiver significantly exceeds both the bandwidth of the optical signal and the electrical bandwidth of the receiver 8 . In this case, the signal-ASE and signal-DRB beat noise variances read [18,57] Simplifying further, by assuming quasi-CW signaling (B s B e ), we arrive at the frequently used approximations for signal-ASE and signal-DRB beat noise variances [58,59],…”

“…1a and 1b), the fiber spans are made of passive transmission fibers, separated by discrete optical amplifiers. Depending on whether the discrete amplification scheme is based on EDFAs [1] or on discrete Raman amplifiers [18], we distinguish between 'EDFA' and 'discrete Raman' systems. Discrete amplification is also known as lumped amplification.…”

Static and tunable dispersion management with higher order mode fibers

“…This is the most extensively employed technique to measure MPI due to Rayleigh scattering in Raman amplifiers [41,42], since it is most suitable to measure noise at high modulation frequencies. Thus, fast noise due to laser phase noise is best recorded by this technique.…”

“…Since devices such as dispersioncompensators are typically installed at every amplifier-stage (spaced by 50-200 km), long haul (∼1000-3000 km) or ultra-long-haul (∼6000-20000 km) links comprise 10 to 200 devices in series. Hence, MPI requirements for individual devices range between -30 and -50 dB so that concatenation adds negligible additional systems penalty [41].…”

Capacity limits of information transmission in optically-routed fiber networks

“…The establishment of this equivalence enabled using Shannon's formulation of channel capacity for lightwave channels impaired by ASE. Note that another source of noise besides ASE in fiber is double Rayleigh backscattering (DRB) [6]. Because Rayleigh backscattering is a directional process, one can easily show that by distributing a sufficiently large number of optical isolators in a line, DRB can be reduced to arbitrarily low values.…”