Experimental Analysis of Nonlinear Impairments in Fibre Optic Transmission Systems up to 7.3 THz

Abstract

An effective way of increasing the overall optical fibre capacity is by expanding the bandwidth used to transmit signals. In this paper, the impact of expanding the transmission bandwidth on the optical communication system is experimentally studied using the achievable rates as a performance metric. The tradeoffs between the use of larger bandwidths and higher nonlinear interference (NLI) noise is experimentally and theoretically analyzed. The growth of NLI noise is investigated for spectral bandwidths from 40 GHz up to 7.3 THz using 64-QAM and Nyquist pulse-shaping. Experimental results are shown to be in line with the predictions from the Gaussian-noise model showing a logarithmic growth in NLI noise as the signal bandwidth is extended. A reduction of the information rate of only 10% was found between linear and nonlinear transmission across several transmission bandwidths, increasing up to 7.3 THz. Finally, the power transfer between channels due to stimulated Raman scattering effect is analyzed showing up to 2-dB power tilt at optimum power for the largest transmitted bandwidth of 7.3 THz. Index Terms-GN model, nonlinear effects, optical fibre, optical fibre communications. I. INTRODUCTION O PTICAL fibres are the fundamental transmission medium for modern communication systems. Among their most attractive features they present a low-loss region that spans tens of terahertz. To increase the amount of information transmitted over optical fibres, much research effort has been focused on extending the usable spectrum beyond the conventional C-band,

Observing the effect of polarization mode dispersion on nonlinear interference generation in wide-band optical links

“…Therefore, these results suggest that, in the considered scenario, the Manakov equation is valid up to optical bandwidths much larger than PMD coherence bandwidth. Moreover, these results are consistent with the experimental demonstrations presented in [19][20][21].…”

“…However, the conditions considered in that work (number of WDM channels, pulse shaping filter) are significantly different from modern ultra-wide-band scenarios, which may reduce the application of those results over such modern scenarios. On the other hand, recent experimental demonstrations of coherent transmission well beyond the PMD coherence bandwidth [19][20][21][22], have shown a substantial agreement between models and measurements. This suggests that the ME, at least for transmission of coherent signals over long dispersion-uncompensated links, can be valid also for wide optical bandwidths, and, consequently, we infer that PMD plays a negligible role in NLI generation.…”

The Gaussian Noise Model in the Presence of Inter-Channel Stimulated Raman Scattering

“…The latter is essential for optical network abstraction and virtualization leading to optimal and intelligent techniques to maximize optical network capacity [5]. Analytical models also offer a significant reduction in computational complexity with minor This work was supported by a UK EPSRC programme grant UNLOC (EP/J017582/1) and a Doctoral Training Partnership (DTP) studentship for Daniel Semrau. D. Semrau inaccuracies compared to split-step simulations and experiments [6]- [11].…”

A Closed-Form Approximation of the Gaussian Noise Model in the Presence of Inter-Channel Stimulated Raman Scattering

“…In this section the proposed closed-form approximations (10) and (11) are validated in an optical transmission system with parameters listed in Table I. The validation is performed for a point-to-point transmission in III-A and for a mesh optical network scenario in III-B.…”