Phase-sensitive optical parametric amplifiers (PSAs) can provide low-noise optical amplification while simultaneously mitigating nonlinear distortions caused by the Kerr effect. However, nonlinearity mitigation using PSAs is affected by link parameters, and imperfect link design results in residual nonlinear distortions. In this paper, we use first-order perturbation theory to describe these residual nonlinear distortions, and develop a way to mitigate them using a modified third-order Volterra nonlinear equalizer (VNLE) in the receiver. Using numerical simulations, we show that our proposed VNLE reduces the residual nonlinear distortions in links using in-line PSAs for several combinations of symbol rates and modulation formats, and can increase the maximum transmission distance by up to 80%. We also perform a proof-of-concept experiment and confirm that our modified VNLE can mitigate the residual nonlinear distortions on a 10-Gbaud 16QAM signal after transmission through a 10×80-km link with in-line PSAs.
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http://dx.doi.org/10.1364/OE.27.031926 | DOI Listing |
Netw Neurosci
December 2024
Department of Cognition, Development and Education Psychology, University of Barcelona, Barcelona, Spain.
Memories are thought to use coding schemes that dynamically adjust their representational structure to maximize both persistence and efficiency. However, the nature of these coding scheme adjustments and their impact on the temporal evolution of memory after initial encoding is unclear. Here, we introduce the Segregation-to-Integration Transformation (SIT) model, a network formalization that offers a unified account of how the representational structure of a memory is transformed over time.
View Article and Find Full Text PDFACS Omega
December 2024
Institut für Theoretische Physik and Center for Materials Research (LaMa), Justus-Liebig-Universität Gießen, 35392 Gießen, Germany.
The second harmonic generation (SHG) properties of adamantane-based tetraphenyl clusters are predicted from first principles and analyzed on the basis of the involved electronic transitions. In particular, the effect of a tetrel substitution in the cluster core on the nonlinear optical response is investigated. Electronic transitions spatially localized at the substituents are found to be responsible for the optical nonlinearities.
View Article and Find Full Text PDFImaging Neurosci (Camb)
March 2024
Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.
We present MMORF-FSL's MultiMOdal Registration Framework-a newly released nonlinear image registration tool designed primarily for application to magnetic resonance imaging (MRI) images of the brain. MMORF is capable of simultaneously optimising both displacement and rotational transformations within a single registration framework by leveraging rich information from multiple scalar and tensor modalities. The regularisation employed in MMORF promotes local rigidity in the deformation, and we have previously demonstrated how this effectively controls both shape and size distortion, leading to more biologically plausible warps.
View Article and Find Full Text PDFInorg Chem
December 2024
Guangxi Key Laboratory of Electrochemical Energy Materials, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, Guangxi 530004, China.
As nonlinear optical (NLO) crystals, sulfates have the superiority of transparency for ultraviolet (UV) light, but they are often troubled by small nonlinear coefficients and birefringence owing to the high symmetry of the [SO] group. By introducing two neutral diethylenetriamine (DETA) molecules to replace the six coordinated water molecules of the [Zn(HO)] complex cation in [Zn(HO)](SO)(HO), a new sulfate with an acentric structure, namely, [Zn(DETA)](SO)(HO), has been designed and synthesized. Structural investigation reveals that the coordination modification of Zn ion tremendously enhances its intraoctahedral distortion.
View Article and Find Full Text PDFSensors (Basel)
December 2024
State Key Laboratory of Integrated Chips and Systems, Fudan University, Shanghai 200433, China.
In this work, we implemented a short-reach real-time optical communication system using MLP for pre-distortion. Lookup table (LUT) algorithms are commonly employed for pre-distortion in intensity modulation and direct detection (IM/DD) systems. However, storage limitations typically restrict the LUT pattern length to 9, limiting its effectiveness in compensating for nonlinear effects.
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