Current Issue : July - September Volume : 2019 Issue Number : 3 Articles : 5 Articles
Glasses with the Na2Oâ??ZnOâ??P2O5 composition and doped with single CeO2, Sm2O3, ormixed dopants were melted and studied.\nCollective optical, photoluminescence, and FT-infrared spectral studies were carried out. CeO2-doped glasses show two extra\nUV absorption bands due to Ce4+ and Ce3+ ions while Sm2O3-doped samples reveal pronounced peaks collected into two\nsegments from 367 to 472nm and from 950 to 1623nm which are characteristic of absorption from Sm3+ ions.The mixed dopants\nglasses show combined UV-visibleâ??near-IR absorption peaks due to cerium (Ce4+, Ce3+) ions and samarium (Sm3+) ions. The\nphotoluminescence spectra (PL) of the single CeO2-doped and Sm2O3-doped glasses and even the mixed dopant sample reveal\nluminescence spectra after excitation which are characteristic of the rare-earth ions. The intensities for both excited or emitted\npeaks are found to increase with the increase of the rare-earth percent. FTIR spectra of the glasses show pronounced vibrational\npeaks related to phosphate groups (Q2 and Q3 units) in accordance with the P2O5 percent (70mol %)....
Monitoring volcanic phenomena is a key question, for both volcanological research and\nfor civil protection purposes. This is particularly true in densely populated volcanic areas, like the\nCampi Flegrei caldera, which includes part of the large city of Naples (Italy). Borehole monitoring of\nvolcanoes is the most promising way to improve classical methods of surface monitoring, although\nnot commonly applied yet. Fiber optics technology is the most practical and suitable way to operate\nin such high temperature and aggressive environmental conditions. In this paper, we describe a\nfiber optics Distributed Temperature Sensing (DTS) sensor, which has been designed to continuously\nmeasure temperature all along a 500 m. deep well drilled in the west side of Naples (Bagnoli area),\nlying in the Campi Flegrei volcanic area. It has then been installed as part of the international â??Campi\nFlegrei Deep Drilling Projectâ??, and is continuously operating, giving insight on the time variation\nof temperature along the whole borehole depth. Such continuous monitoring of temperature can in\nturn indicate volcanic processes linked to magma dynamics and/or to changes in the hydrothermal\nsystem. The developed monitoring system, working at bottom temperatures higher than 100 Degree Celsius,\ndemonstrates the feasibility and effectiveness of using DTS for borehole volcanic monitoring....
The main aim of this work was the design and development simple fiber optic Fabry-Perot\ninterferometer (FPI) sensor devices for relative humidity (RH) sensing with emphasis on high\nsensitivity and good stability. The RH fiber FPI sensor is fabricated by coating the end of a cleaved\nstandard multi-mode (MM) fiber with hydrophilic Nafion® sensing film. The Nafion® thin film\nacts as an active resonance cavity of the low-coherence interferometric sensing structure. The fringe\npattern, which is caused by interfering light beam in the Nafion® thin film will shift as the RH changes\nbecause the water molecules will swell the Nafion® film and thus change optical pathlength of the\nsensing structure. The operating principle of a FPI sensor based on the adsorption and desorption\nof water vapour in the Nafion® and the limitations of this sensor type are discussed in this work.\nThe fiber optic hygrometer was tested in the visible (400-900 nm) region of spectra for measurement\nof relative humidity (RH) in the range of 5.5â??80% at room temperature (RT) in air. The fiber optic\nhumidity sensor has a very short response time (t90 = 5-80 s) and a fast regeneration time (t10 = 5-12 s)\nas good as commercial sensors....
The temporal distribution of the spectral parametric gain was experimentally investigated\nwhen a chirped pump pulse was injected into a photonic crystal fiber. A pump-probe experiment\nwas developed and the important characteristics were measured as the chirp of the pump, the signal\npulse, and the gain of the parametric amplifier. We highlight that the amplified spectrum depends\nstrongly on the instantaneous pump wavelength and that the temporal evolution of the wavelength\nat maximum gain is not monotonic. This behavior is significantly different from the case in which the\nchirped pump has a constant peak power. This measurement will be very important to efficiently\ninclude parametric amplifiers in laser systems delivering ultra-short pulses....
The paper presents experimental results of the interaction of a focused optical beam with a suspension of CdSe/ZnS quantum dots\nin toluene. Two autographs characteristic only of the behavior of a superfluid quantum liquid were experimentally observed.The\nfirst was the fountain effect from the region of local heating of the suspension with an optical beam; the second was the complete\nâ??creeping outâ? of the QDs suspension in the form of a thin film along the walls of the cuvette in which the suspension was located.\nTheresults of the work suggest that superfluid quantumliquid may arise at roomtemperature as a result of the functioning ofmanyparticle\nquantum superposition. Bose-Einstein condensation of entangled quantum states is proposed as a physicalmechanism for\nproducing a superfluid liquid, regardless of temperature....
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