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1

Światłowód wielordzeniowy domieszkowany jonami Nd3+ do budowy włóknowych źródeł promieniowania koherentnego

Kochanowicz M., Żmojda J., Dorosz D.

Materiały Ceramiczne

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2012

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T. 64, nr 4

584-588

PL

W artykule przedstawiono fazowanie w światłowodzie 19-rdzeniowym domieszkowanym Nd3+. Przeanalizowano wpływ parametrów materiałowych i geometrycznych aktywnego światłowodu 19-rdzeniowego oraz wpływ odchylenia od uzgodnionej fazy promieniowania na współczynnik jakości wiązki laserowej w obszarze dyfrakcyjnym dalekiego pola. Współczynnik jakości wiązki laserowej w wytworzonym światłowodzie wynosi BQF = 0,71, gdzie V = 2,4, d = 18 žm. Wykorzystując opracowany model generacji supermodu w wielordzeniowym laserze włóknowym zbadano wpływ sprzężenia między rdzeniami na różnicę fazy promieniowania w poszczególnych rdzeniach w czasie rozwoju akcji laserowej. W rezultacie przeprowadzonych analiz numerycznych zaprojektowano i wytworzono dwupłaszczowy 19-rdzeniowy światłowód domieszkowany jonami neodymu. Ponadto, zmierzono jego widmo luminescencji oraz obraz pola dalekiego.

EN

In the paper, the phase-locking of the 19-core optical fibre doped with Nd3+ is presented. The influence of material and geometrical parameters of the active 19-core optical fibre and phase deviation on the beam quality factor of the laser beam in the far-field diffraction region has been analysed. The beam quality factor of the manufactured multicore fibre equals BQF = 0.71, when V = 2.4 and d = 18 žm. Based on a developed model of supermode generation in the multicore fibre laser, the impact of the coupling value between the cores on the difference in radiation phases between particular emitters during the development of the laser action was considered. As a result of the conducted analysis, a double-clad 19-core optical fibre doped with neodymium ions has been designed and manufactured, and its luminescence spectra and far field diffraction pattern have been measured.

2

A comparison of algorithms for separation of synchronous subspaces

Almeida M., Bioucas-Dias J., Vigário R., Oja E.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2012

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Vol. 60, nr 3

455-460

EN

Independent Subspace Analysis (ISA) consists in separating sets (subspaces) of dependent sources, with different sets being independent of each other. While a few algorithms have been proposed to solve this problem, they are all completely general in the sense that they do not make any assumptions on the intra-subspace dependency. In this paper, we address the ISA problem in the specific context of Separation of Synchronous Sources (SSS), i.e., we aim to solve the ISA problem when the intra-subspace dependency is known to be perfect phase synchrony between all sources in that subspace. We compare multiple algorithmic solutions for this problem, by analyzing their performance on an MEG-like dataset.

3

Model analysis of supermode generation in active 5-core optical fibre

Dorosz D., Kochanowicz M.

Opto-Electronics Review

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2011

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Vol. 19, No. 1

40-45

EN

In the paper, the phase-locked emitters in multi-core optical fibres for high power fibre lasers are presented. The influence of the normalized frequency and diameters of the cores on the shape of the pattern in the Fraunhofer diffraction region has been analysed. The simulation of coupling coefficient between cores influences on phase-locking and in the consequence on the far-field pattern of the fibre laser, based on the analyzed multi-core optical fibre, were performed. In the analyzed fibre laser, while exchanging power of the generated radiation between two adjacent cores on the fibre length (L = 5 m) within the range of 4-10%, the radiation becomes phased. Having satisfied this condition, in the far-field low-divergence, high-power laser beam (supermode) is attained. 5-core double clad optical fibre doped with neodymium ions was fabricated. Luminescence spectra of the manufactured fibre were measured.

4

Generacja promieniowania wzajemnie koherentnego w aktywnym światłowodzie wielordzeniowym

Kochanowicz M., Dorosz D., Zając A.

Elektronika : konstrukcje, technologie, zastosowania

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2009

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Vol. 50, nr 10

151-155

PL

W artykule przedstawiono warunki generacji wzajemnie koherentnego promieniowania w wielordzeniowych światłowodach aktywnych, stosowanych do budowy laserów włóknowych dużej mocy. Przeanalizowano zależność kształtu obrazu dalekiego pola od częstotliwości znormalizowanej i średnicy rdzeni 5-rdzeniowego światłowodu aktywnego. Wykazano wpływ sprzężenia między rdzeniami na fazowanie promieniowania, a w konsekwencji możliwość uzyskania generacji supermodu.

EN

In the paper the conditions of the phase - locked generation in multicore optical fibres for high power fibre lasers are presented. The influence of normalized frequency and cores diameter in the active five core optical fibre on the Fraunhofer diffraction pattern is analyzed. The simulation results indicate that the phase-locked (supermode) generation depends on the coupling coefficient between cores.

5

Towards spike-based speech processing: a biologically plausible approach to simple acoustic classification

Uysal I., Sathyendra H., Harris J. G.

International Journal of Applied Mathematics and Computer Science

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2008

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Vol. 18, no 2

129-137

EN

Shortcomings of automatic speech recognition (ASR) applications are becoming more evident as they are more widely used in real life. The inherent non-stationarity associated with the timing of speech signals as well as the dynamical changes in the environment make the ensuing analysis and recognition extremely difficult. Researchers often turn to biology seeking clues to make better engineered systems, and ASR is no exception with the usage of feature sets such as Mel frequency cepstral coefficients, which employ filter banks similar to cochlear filter banks in frequency distribution and bandwidth. In this paper, we delve deeper into the mechanics of the human auditory system to take this biological inspiration to the next level. The main goal of this research is to investigate the computation potential of spike trains produced at the early stages of the auditory system for a simple acoustic classification task. First, various spike coding schemes from temporal to rate coding are explored, together with various spike-based encoders with various simplicity levels such as rank order coding and liquid state machine. Based on these findings, a biologically plausible system architecture is proposed for the recognition of phonetically simple acoustic signals which makes exclusive use of spikes for computation. The performance tests show superior performance on a noisy vowel data set when compared with a conventional ASR system.