Current fiber optic backhaul systems using linear transmission formats are expected to reach the capacity limit due to the fiber’s inherent Kerr nonlinearity in near future. Nonlinear transmission formats, able of integrating this effect into signal design, are a promising approach to extend the capacity imitation. The Nonlinear Fourier Transformation as an extension of eigenvalue communication using coherent transmission technology enables such a nonlinear transmission format and provides two different kinds of spectra, a continuous and a discrete one. Different theoretical assumptions as prerequisites of the integrability of the nonlinear Schrödinger equation like a lossless and noisefree transmission are violated in realistic transmission setups. Therefore, the influences of fiber attenuation and amplifier noise of different fiber and amplifier configurations are investigated in simulations and experiments. The discrete spectrum with a variable number of eigenvalues and related discrete spectral amplitudes is used for transmission applying different modulation schemes, partly using polarization multiplexing. Design parameters for the different modulation formats are chromatic dispersion, the effective nonlinearity of the fiber and limited resolution and bandwidth of the transmitter and receiver components. A setup based on a recirculating fiber loop to evaluate different transmission distances of the signal is used for experiments. The fiber section within the loop consists of the optical fiber span and different optical amplifiers for loss compensation. Discrete or lumped amplification was realized with an erbium-doped fiber amplifier (EDFA) after each fiber span while alternatively distributed Raman amplification using the first Stokes order with co- and counter-propagating pump waves was applied. The usage of counter-propagating Raman amplification significantly improved the transmission quality and extended the transmission range compared to the EDFA. A further reduction of the signal power variation along the fiber span results from bi-directional Raman amplification and is expected to result in superior performance. Transmission experiments using a commercial off-the-shelf Raman amplifier and a prototype led to a severe degradation of the transmission quality. The well-established model for relative intensity noise (RIN) transfer between pump waves and signal falls short as it does not take all nonlinear effects of the pump waves into account. Measurements of the evolution of the pump spectra can be explained by an influence of modulation instability. Real transmissions in fiber optic systems are affected by loss and noise leading to a coupling between the nonlinear modes of the discrete spectrum and additionally to the continuous spectrum. The interactions were investigated in simulations of different amplifier configurations and verified experimentally for counter-propagating Raman amplification. The usability of these interactions for integration in equalizers was investigated as well as their influence on the choice of coding schemes. In this doctoral thesis the possible benefits of the application of distributed amplification were validated. At the same fundamental challenges for the realization of the theoretically presumed ideal Raman amplification, leading to a uniform signal power distribution along the fiber span, using prevalent telecommunication equipment are identified. Therefore, a consideration of the signal power variation of these nonlinear transmission formats is required in future as well. Depending on the modulation format transmission up to 20 Gbps and range up to 5030 km were realized proving the ability of this transmission format, resting upon a balance of dispersion and nonlinear effects, to extend the capacity of existing fiber optic backhaul systems.


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    Titel :

    Experimental Investigation of Information Transmission Using the Nonlinear Fourier Transformation


    Beteiligte:
    Geisler, Alexander (Autor:in) / Helmut-Schmidt-Universität Hamburg (Gastgebende Institution)

    Erscheinungsdatum :

    2022



    Medientyp :

    Sonstige


    Format :

    Elektronische Ressource


    Sprache :

    Englisch


    Klassifikation :

    DDC:    629





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