Wyniki 1-4 spośród 4 dla zapytania: authorDesc:"Michał Żelechower"

Szkła fl uoroindowe jako materiały dla optoelektroniki w zakresie średniej i dalekiej podczerwieni

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Upłynęło już ponad 30 lat od czasu, gdy bracia Poulain i Lucas z Uniwersytetu Rennes (Francja) ogłosili, iż udało się im zsyntetyzować szkła fl uorkowe, gdzie głównym składnikiem był fl uorek cyrkonu ZrF4. Było to o tyle zaskakujące, że oprócz fl uorku berylu żaden inny fl uorek nie był znany w postaci szklistej. Jednak zastosowanie układów podwójnych, a nieco później potrójnych, pozwoliło n[...]

Erbium/Ytterbium co-doped oxyfluoride glass-ceramics - promising candidate for fiber lasers and optical amplifiers at 1550 nm DOI:10.15199/28.2016.6.11


  The manufacturing of the erbium/ytterbium co-doped oxyfluoride glass-ceramics optical fiber was discussed on the background of literature review and own achievements. The role of erbium ions as NIR emitters as well as ytterbium ions in the process of stimulated emission has been explained and illustrated by several figures both from the literature and the author’s results. Glass-ceramics material advantage over glassy fibers was also considered and proved by several plots and images. The relations between the g-c materials and their optical features have been illustrated by results of SEM/TEM imaging, X-ray spectra, XRD and SAED patterns, thermal analysis (DTA/DSC) and a corresponding absorption/emission NIR spectra. Key words: fiber laser, rare earth ions, glass-ceramics, edfa, nanocrystals.1. INTRODUCTION A chance to establish the long distance waveguide communications appeared in early seventies due to super pure low-loss fused silica glass optical fibers (about 90% of SiO2) fabrication. Since silica fiber attenuation is wavelength dependent (Fig. 1), the term “optical fiber communication window" has been introduced and currently the third window (1550 nm) is utilized for long distance cables with attenuation better than 0.3 dB/km. In traditional optical communication systems a signal regeneration was achieved in the form of optoelectronic repeaters located every 20÷50 km of the fiber cable (Fig. 2). They used three steps of signal regeneration: optical-to-electric conversion, amplification, and shaping and finally electric-to-optical conversion. Currently, several more sophisticated solutions (optical amplifiers without signal conversion) have been invented (EDFA - Erbium Doped Fiber Amplifier, SOA - Semiconductor Optical Amplifier, RFA - Raman Fiber Amplifier) and of them the EDFA amplifiers seem to be most common. Their heart is silica (plus GeO2) glass erbium doped optical fiber (Fig. 3). Actually, the EDFA amplif[...]

Partial crystallization of the erbium/ytterbium co-doped oxyfluoride glass DOI:10.15199/28.2018.6.2


  1. INTRODUCTION The commercially available optical fibers (single mode or multimode) consist of a fused silica core (refraction index 1.46 < n < 1.49) and a glass cladding with lower refraction index [1, 2]. REE doped, optically active glass fibers (or rather their cores) have various matrices (fused silica [3], fluoride glasses (for instance ZBLAN) [4, 5] or silica-based oxyfluoride glasses [6]). Rare earth element doped fibers become optically active media, converting for instance NIR radiation into red light (Er3+ [7, 8]), into green light (Ho3+ [9], Tm3+ [10]) or into blue light (Pr3+ [11]). They can also amplify the NIR radiation (Er3+ 1550 nm in EDFA [12]). An apparent requirement for EDFA amplifiers is a high intensity of erbium emission. It is always higher in erbium doped single crystals (homogeneous band broadening) than that in erbium doped glasses (inhomogeneous band broadening). The best example is an erbium doped laser crystal GdVO4:Er, where the emission cross-section (related to the luminescence intensity) value achieves 1.6·10-20 cm2 [16] whereas it equals only 0.8·10-20 cm2 in fused silica glass. The consequence of a single crystal predominance as a host for REE doping (and emission) is the new material substitution (glass-ceramics), which combines technological properties of glass and optical properties of single crystal [13]. Ytterbium co-doping appeared as a next invention enhancing material (silica glass) absorption at 980 nm [4]. With respect to the higher absorption of the Er/Yb system at 980 nm in comparison to materials containing only erbium and cross-energy transfer from the ytterbium ions to the erbium ions followed by higher luminescence at 1550 nm excited by 980 nm pump, the ytterbium is sometimes called a sensitizer. To fabricate such a composite material of space-homogeneously distributed, REE enriched nanocrystals embedded in a glassy host, the glass partial crystallization (controll[...]

Struktura i skład chemiczny powłok typu galfan po obróbce cieplnej

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Wytwarzanie powłok z cynku i stopów cynkowych to jedna z najważniejszych technik przetwarzania, wykorzystywana do ochrony elementów stalowych narażonych na środowisko korozyjne [1]. Szybki wzrost produkcji blach ocynkowanych ogniowo jest związany ze zwiększającym się zapotrzebowaniem na ten produkt przede wszystkim w przemyśle samochodowym oraz w budownictwie, ale także w produkcji artykułów gospodarstwa domowego [2]. Struktura warstwy wierzchniej stali ocynkowanej w sposób zanurzeniowy obejmuje nałożoną powłokę stopu oraz warstwę pośrednią pomiędzy powłoką a podłożem stalowym, zawierającą związki międzymetaliczne aluminium, żelaza i cynku. Grubość każdego z tych obszarów jest zależna od parametrów technologii (między innymi od składu chemicznego, temperatury kąpieli, czasu zan[...]

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