Nonlinear Crosstalk

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L G Kazovsky - One of the best experts on this subject based on the ideXlab platform.

  • 50 db Nonlinear Crosstalk suppression in a wdm analog fiber system by complementary modulation and balanced detection
    Journal of Lightwave Technology, 2003
    Co-Authors: Kenneth K Y Wong, M E Marhic, L G Kazovsky
    Abstract:

    We investigate, theoretically and experimentally, a novel scheme to suppress the Nonlinear Crosstalk between wavelengths in wavelength-division multiplexing (WDM) analog fiber systems. It is based on an improvement to a previously introduced Crosstalk-suppression technique by complementary modulation of two closely spaced optical twin carriers (TCs). By combining the modulated TCs by a balanced detector (TCs-balanced detection [TC-BD]), the suppression can be improved further. We have obtained up to 50-dB Crosstalk reduction at low modulation frequencies, where Crosstalk is most severe, and in the most interesting region for cable television systems.

  • 50 db Nonlinear Crosstalk suppression in a wdm analog fiber system by complementary modulation and balanced detection
    Optical Fiber Communication Conference, 2003
    Co-Authors: Kenneth K Y Wong, M E Marhic, L G Kazovsky
    Abstract:

    By combining the previously-introduced modulated twin carriers technique with balanced detection, we have obtained up to 50-dB Crosstalk reduction at low modulation frequencies, where Crosstalk is the most severe, and in the most interesting region for cable television systems.

  • 35 db Nonlinear Crosstalk suppression in a wdm analog fiber system by complementary modulation of twin carriers
    IEEE Photonics Technology Letters, 2002
    Co-Authors: Kenneth K Y Wong, M E Marhic, L G Kazovsky
    Abstract:

    We investigate, theoretically and experimentally, a novel scheme to suppress the Crosstalk between wavelengths in wavelength-division-multiplexing (WDM) analog fiber systems. The idea is based on the fact that Crosstalk (due to stimulated Raman scattering and cross-phase modulation combined with group velocity dispersion), is caused by the intensity modulation of one channel affecting a second channel in a WDM system. Then, if an auxiliary carrier (twin) with complementary modulation is introduced very close to the first channel, their combined intensity will be constant and there will be no Nonlinear Crosstalk induced at the second channel. We have obtained up to 35-dB Crosstalk reduction at low modulation frequencies, where Crosstalk is most severe.

  • Nonlinear Crosstalk suppression in a wdm analog fiber system by complementary modulation of twin carriers
    Optical Fiber Communication Conference, 2001
    Co-Authors: Kky Wong, M E Marhic, L G Kazovsky
    Abstract:

    By using complementary modulation of two closely-spaced optical carriers, Nonlinear Crosstalk on other carriers in WDM analog fiber communication systems can be greatly reduced. We have obtained up to 30 dB reduction at low modulation frequencies, where Crosstalk is most severe.

  • Nonlinear Crosstalk and two countermeasures in SCM-WDM optical communication systems
    Journal of Lightwave Technology, 2000
    Co-Authors: F S Yang, M E Marhic, L G Kazovsky
    Abstract:

    We investigate, theoretically and experimentally, Crosstalk between wavelengths in subcarrier-multiplexed (SCM) wavelength-division multiplexed (WDM) optical communication systems. Crosstalk arises mainly from interactions between subcarriers on one wavelength and the optical carrier of another wavelength. In a dispersive fiber, Crosstalk can be attributed to stimulated Raman scattering (SRS) and cross-phase modulation (XPM) combined with group velocity dispersion (GVD). We investigate the phase relationship between SRS-induced and XPM-induced Crosstalks. Crosstalks induced by SRS and XPM add in the electrical domain and can interfere constructively or destructively. Experimental results show that the combined Crosstalk level can be as high as 40 dBc after 25 km of SMF with two wavelengths and 18 dBm per wavelength of transmitted power. We propose two Crosstalk countermeasures. The first countermeasure uses parallel fiber transmission. We show theoretically that both SRS-induced and XPM-induced Crosstalks can be cancelled to the first order. We present an experimental demonstration of concept which has achieved 15 dB of Crosstalk cancellation over 200 MHz. The second countermeasure uses optical carrier suppression. We show, theoretically and experimentally, that by suppressing the optical carrier, we can significantly reduce Crosstalk while maintaining the same link budget and carrier-to-noise ratio (CNR) at the receiver, 20 dB of Crosstalk reduction over 2 GHz has been demonstrated experimentally.

M E Marhic - One of the best experts on this subject based on the ideXlab platform.

Kenneth K Y Wong - One of the best experts on this subject based on the ideXlab platform.

Roberto Llorente - One of the best experts on this subject based on the ideXlab platform.

  • unified model of linear and Nonlinear Crosstalk in multi core fiber
    Journal of Lightwave Technology, 2016
    Co-Authors: Andres Macho, Maria Morant, Roberto Llorente
    Abstract:

    In this paper, the theoretical unification of linear and Nonlinear inter-core Crosstalk (IC-XT) in step-index single-mode multicore fiber (MCF) media is reported and validated experimentally. In order to estimate the IC-XT when operating in linear and Nonlinear regimes, the coupled-mode theory (CMT) and the coupled-power theory (CPT) have been unified in both power regimes. The theoretical analysis of the CMT indicates that in coupled MCFs with reduced core-to-core distance (core pitch) the Nonlinear self-coupling and cross-coupling effects should be considered when operating with high optical powers. However, considering a core pitch value higher than three times the core radius only the self-coupling effect should be taken into account for estimating the Nonlinear IC-XT. Considering these results, the CPT is also extended to Nonlinear regime including the dominant Nonlinear coupling effect. Using both CMT and CPT, the statistical model of Nonlinear IC-XT is completed with the closed-form expressions for estimating the cumulative distribution function, the probability density function and the Crosstalk mean and variance as a function of the power level launched into a single-core of the MCF. The Crosstalk model presented is additionally extended when multiple cores are simultaneously excited. Finally, the theoretical model is experimentally validated in a homogeneous four-core fiber considering different bending radius configurations.

  • experimental evaluation of Nonlinear Crosstalk in multi core fiber
    Optics Express, 2015
    Co-Authors: Andres Macho, Maria Morant, Roberto Llorente
    Abstract:

    In this paper we evaluate experimentally and model theoretically the Nonlinear Crosstalk random process in multi-core fiber. The experimental results indicate that mode coupling in multi-core fibers is reduced in presence of fiber Kerr Nonlinearities. An analytical study of the inter-core Crosstalk probability density function in Nonlinear regime is performed, where the theoretical distribution, derived from the Nonlinear coupled-mode equation, is experimentally validated in homogeneous four-core fiber. The herein presented analysis includes the evaluation of the inter-core Crosstalk probability density function, mean and variance evolution considering the optical power launched into the fiber.

  • linear and Nonlinear Crosstalk evaluation in dwdm networks using optical fourier transformers
    EURASIP Journal on Advances in Signal Processing, 2005
    Co-Authors: Roberto Llorente, R Clavero, F Ramos, J Marti
    Abstract:

    A novel DWDM channel monitoring technique based on the conversion from wavelength domain to time domain by performing a real-time optical Fourier transform over the whole DWDM system bandwidth is proposed and experimentally demonstrated. The use of chromatic dispersion-based optical Fourier transformers has been validated in the case of a spectrum comprising light from different uncorrelated sources. Linear and Nonlinear Crosstalks between the DWDM channels appear as amplitude noise at specific time positions. The correspondence of this amplitude noise with the Crosstalk spectral distribution is evaluated theoretically and experimentally.

Mohamed Helaoui - One of the best experts on this subject based on the ideXlab platform.

  • a high performance complexity reduced behavioral model and digital predistorter for mimo systems with Crosstalk
    IEEE Transactions on Communications, 2016
    Co-Authors: Abubaker Abdelhafiz, Mohamed Helaoui, Fadhel M Ghannouchi, Laleh Behjat, Oualid Hammi
    Abstract:

    In this paper, an augmented crossover memory polynomial model (A-COMPM) is proposed and developed which can be used for characterizing and linearizing multiple-input multiple-output (MIMO) transmitters in the presence of linear and Nonlinear Crosstalk. The proposed model significantly improves the performance of the crossover memory polynomial model (CO-MPM) by more accurately incorporating the effect of Crosstalk. The proposed model performs comparably to the $2\times 2$ parallel Hammerstein ( $2\times 2$ PH) model, while requiring the same number of coefficients as CO-MPM and a lower number of coefficients than the $2\times 2$ PH. The model was tested for forward modeling and digital predistortion (DPD) applications in the presence of both linear and Nonlinear Crosstalk. Experimental results show that the model outperforms the CO-MPM and $2\times 2$ PH DPDs, at a lower number of coefficients compared to both models. Furthermore, the issue of numerical stability of the DPD extraction and implementation procedures is addressed in the model.

  • behavioral modeling of mimo Nonlinear systems with multivariable polynomials
    IEEE Transactions on Microwave Theory and Techniques, 2011
    Co-Authors: D Saffar, Fadhel M Ghannouchi, Noureddine Boulejfen, Ali Gharsallah, Mohamed Helaoui
    Abstract:

    This paper proposes a novel behavioral model for multiple-input single-output (MISO) and multiple-input multiple-output (MIMO) Nonlinear transmitters based on multivariable polynomials (MVPs). The main source of Nonlinearity in these transmitters is the RF power amplifier, which is commonly modeled using polynomial models. The proposed MVP model is capable of handling the Nonlinear effects of the RF transmitters, as well as the linear and Nonlinear Crosstalk between the input signals. At the same time, the developed model was optimized for computing efficiency without compromising its accuracy. The model was tested for MISO and MIMO wireless transmitters. The simulations and measurement results revealed that the proposed model gives excellent accuracy when modeling MIMO transmitters with different branch coupling factors.

  • crossover digital predistorter for the compensation of Crosstalk and Nonlinearity in mimo transmitters
    IEEE Transactions on Microwave Theory and Techniques, 2009
    Co-Authors: Seyed Aidin Bassam, Mohamed Helaoui, Fadhel M Ghannouchi
    Abstract:

    This paper proposes a novel crossover digital predistorter (CO-DPD) model to compensate for Crosstalk and Nonlinearity in multiple-input multiple-output (MIMO) radio systems. Crosstalk can take place before or after the power amplifiers, designated herein as Nonlinear and linear Crosstalk, respectively. This paper demonstrates that, contrary to linear Crosstalk, Nonlinear Crosstalk significantly affects the performance of the digital predistortion algorithm; and, it cannot be embedded and compensated for by the conventional channel matrix inversion algorithm at the receiver side of MIMO links. Based on a parametric study of system-level simulations and measurements, it was found that for a -20-dB Nonlinear Crosstalk level, the use of a memory multibranch polynomial predistorter, along with the channel matrix inversion algorithm, bounds the adjacent channel power ratio (ACPR) for a wideband code division multiple access (WCDMA) signal to -46 dBc and the error vector magnitude (EVM) for a world interoperability for microwave access (WiMAX) signal to -43 dB in MIMO links. The proposed CO-DPD was investigated and analyzed for the MIMO transmitter with N = 2, where N is the number of RF front-ends. Its performance was evaluated through measurements, the experimental results obtained show that, in the presence of -20-dB Nonlinear Crosstalk, the proposed CO-DPD improve the ACPR of the WCDMA signal by 13 dB to -56.81 dBc from those obtained using a conventional digital predistorter. The same improvement was observed in the EVM measurement of the WiMAX signal, where the EVM decreases from -21.22 dB for the conventional DPD to -49.71 dB for the proposed CO-DPD.

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