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Постійне посилання на розділhttps://repository.kpi.kharkov.ua/handle/KhPI-Press/35393
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Документ Fixed-point Realisation of Fast Nonlinear Fourier Transform Algorithm for FPGA Implementation of Optical Data Processing(SPIE, 2021) Vasylchenkova, Anastasiia; Salnikov, Dmytro; Karaman, Dmytro; Vasylchenkov, Oleg; Prilepskiy, JaroslawThe nonlinear Fourier transform (NFT) based signal processing has attracted considerable attention as a promising tool for fibre nonlinearity mitigation in optical transmission. However, the mathematical complexity of NFT algorithms and the noticeable distinction of the latter from the “conventional” (Fourier-based) methods make it difficult to adapt this approach for practical applications. In our work, we demonstrate a hardware implementation of the fast direct NFT operation: it is used to map the optical signal onto its nonlinear Fourier spectrum, i.e. to demodulate the data. The main component of the algorithm is the matrix-multiplier unit, implemented on field-programmable gate arrays (FPGA) and used in our study for the estimation of required hardware resources. To design the best performing implementation in limited resources, we carry out the processing accuracy analysis to estimate the optimal bit width. The fast NFT algorithm that we analyse, is based on the FFT, which leads to the O(N log22 N) method’s complexity for the signal consisting of N samples. Our analysis revealed the significant demand in DSP blocks on the used board, which is caused by the complex-valued matrix operations and FFTs. Nevertheless, it seems to be possible to utilise further the parallelisation of our NFT-processing implementation for the more efficient NFT hardware realisation.Документ Hydroxyflavone-containing polymers: theoretical prediction of spectral and nonlinear optical properties(STC "Institute for Single Crystals", 2019) Mishurov, D. O.; Voronkin, A. A.; Roshal, O. D.In order to evaluate spectral and nonlinear optical (NLO) properties of polymers and polymer composites containing natural hydroxyflavones as chain fragments or dopants, a theoretical analysis of absorption spectra of flavones, as well as calculations of values of their first hyperpolarizabilities and bond length alternation coefficients (BLA), were carried out. It has been shown that embedding hydroxyflavone fragments into polymer chains, glycidylation flavone hydroxyl groups, as well as twisting flavone molecules, result in improvement of optical properties of the flavone-containing polymers, namely in widening their transparency range into short-wavelength spectral region. The presence of basic amino-containing hardeners in polymers and polymer composites leads to a partial ionization of the flavone hydroxyl groups and, consequently, narrowing transparency range. The analysis of theoretical values - first hyperpolarizability values and BLA coefficients showed that natural polyhydroxyflavones are perspective chromophores for development of materials having a high NLO activity.