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Your search keyword '"Tinko A Eftimov"' showing total 21 results
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21 results on '"Tinko A Eftimov"'

1. Channeled Polarimetry for Magnetic Field/Current Detection

Author

Georgi Dyankov, Petar Kolev, Tinko A. Eftimov, Evdokiya O. Hikova, and Hristo Kisov

Subjects
channeled polarimetry, magnetic field sensor, current sensor, spectral interrogation, Chemical technology, TP1-1185
Abstract

Magneto-optical magnetic field/current sensors are based on the Faraday effect, which involves changing the polarized state of light. Polarimetric methods are therefore used for measuring polarization characteristics. Channeled polarimetry allows polarization information to be obtained from the analysis of the spectral domain. Although this allows the characterization of Faraday materials, the method has not yet been used for detection in magneto-optical sensors. This paper reports experimental results for magnetic field/current detection using the channeled polarimetry method. It is shown that in contrast to other methods, this method allows the detection of the phase shift caused by Faraday rotation alone, making the detection independent of temperature. Although an increase in measurement accuracy is required for practical applications by refining the data processing, the experimental results obtained show that this method offers a new approach to improving the performance of magneto-optical current sensors.

Published
2025
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2. An Effect of Boric Acid on the Structure and Luminescence of Yttrium Orthoborates Doped with Europium Synthesized by Two Different Routines

Author

Irena P. Kostova, Tinko A. Eftimov, Katya Hristova, Stefka Nachkova, Slava Tsoneva, and Alexandar Peltekov

Subjects
yttrium borate, orthoborates, photoluminescence, Crystallography, QD901-999
Abstract

In this paper, we present the characteristics of photoluminescent YBO3 successfully synthesized through a solid-state reaction and a microwave-assisted method. We used yttrium oxide and boric acid in excess as the starting reagents. The synthesis conditions were reflected in the fluorescent characteristics and the structure. Excess boric acid caused structural changes, as observed by the FTIR spectroscopy analysis. Powder X-ray diffraction (XRD) analysis confirmed the crystalline phases and purity of the samples. We observed improved photoluminescence properties in the samples synthesized by the microwave-assisted method. These findings enhance the understanding of the material’s properties and indicate potential applications in illumination, displays, and narrow-band fluorescent smartphone-readable markers.

Published
2024
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3. Rare-Earth-Ion (RE3+)-Doped Aluminum and Lanthanum Borates for Mobile-Phone-Interrogated Luminescent Markers

Author

Katya Hristova, Irena P. Kostova, Tinko A. Eftimov, Daniel Brabant, and Samia Fouzar

Subjects
rare earth, aluminum borates, lanthanum borates, smartphone interrogation, excitation–emission matrices, fluorescence, Applied optics. Photonics, TA1501-1820
Abstract

In this paper, we present the synthesis and luminescent spectra of rare-earth (RE)-doped aluminum and lanthanum borates intended to serve as narrow excitation–emission band fluorescent markers. We perform a detailed 3D excitation–emission matrix (EEM) analysis of their spectra, compare the measurements from both standard and mobile phone spectrometers, and outline the basic differences and advantages of each method. While smartphones have a different and non-uniform spectral response compared to standard spectrometers, it is shown that they offer a number of advantages such as contactless interrogation, efficient suppression of the UV excitation light, and simultaneous spectral analysis of spatially arranged arrays of fluorescent markers. The basic emission peaks have been observed and their corresponding electronic transitions identified. The obtained results show that the rare-earth-doped La and Al borates feature excitation–emission bandwidths as low 15 nm/12 nm, which makes them particularly appropriate for use as luminescent markers with UV LED excitation and smartphone interrogation.

Published
2024
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18. Fiber-coupled fluorescence light source suitable for spectroscopic applications

Author

Veselin P Vladev, Tinko A Eftimov, Stefan I Bozhkov, Krastena T Nikolova, Stefka P Minkova, Denitsa E Blazheva, Galena V Angelova, and Maria S Brazkova

Subjects
Electronic, Optical and Magnetic Materials
Abstract

An experimental study of a fluorescent broadband light source fully compatible with optical fibers is presented in the article, with the aim of using it for excitation-emission matrix fluorescence spectroscopy. A fiber optic glass ferrule filled with a solution of Rhodamine 6G in glycerin was used for the basic construction of the light source. The ferrule is coupled with optical fibers to illuminate the dye medium and to receive the fluorescent signal. A tuning of the light spectrum from the source between 528 nm and 660 nm with a shift of 1 nm is achieved by means of a monochromator. Full Text: PDF ReferencesN. Hoinka and T. Fuhrmann-Lieker, "Amplified Spontaneous Emission in Paper", Sci. Rep. 9, 1 (2019), CrossRef J. Włodarski, M. Chychłowski, "Chemically tuned light source with an optical pump", Photonics Lett. Pol. 13(2), 46 (2021). CrossRef J. Żmojda, P. Miluski, M. Kochanowicz, J. Dorosz, A. Baranowska, M. Leśniak and D. Dorosz, "Luminescent properties of active optical fibers", Photonics Lett. Pol. 11(2), 50 (2019). CrossRef K. Jakubowski, W. Kerkemeyer, E. Perret, M. Heuberger, R. Hufenus, "Liquid-core polymer optical fibers for luminescent waveguide applications", Mater. Des. 196, 1 (2020). CrossRef V. Vladev, T. Eftimov, "Fiberized fluorescent dye microtubes", Proc. SPIE 8770, 87700V-1 (2013). CrossRef V. Vladev, T. Eftimov, W. Bock, "Broad-band fluorescent all-fiber source based on microstructured optical fibers", Photonics Lett. Pol., 7(2), 41 (2015). CrossRef V. Vladev, T. Eftimov, W. Bock, "Fluorescent all-fiber light source based on micro-capillaries and on microstructured optical fibers terminated with a microbulb", Opt. Comm. 356, 34 (2015). CrossRef V. Vladev, T. Eftimov, S. Nedev, "Excitation efficiency of a side-pumped fiberized fluorescent dye microcapillary", Opt. Fib. Tech. 28, 28 (2016). CrossRef V. Vladev, M. Todorova, V. Slavchev, M. Brazkova, E. Belina, S. Bozhkov, P. Radusheva, "A new basic structure suitable for a fully integrated all-fiber-optic stimulated emission dye source", J. Phys.: Conf. Ser. 1859 (012059), 1 (2021). CrossRef V. P. Vladev, M. M. Todorova, M. S. Brazkova, S. I. Bozhkov, "Diode-pumped all-fiber-optic liquid dye laser", Laser Phys. Lett. 18 (11), 115103 (2021), CrossRef G. Dyankov, T. A. Eftimov, N. Malinowski, E. Belina, H. Kisov, P. Mikulic, W. J. Bock, "A highly efficient biosensor based on MAPLE deposited hemoglobin on LPGs around phase matching turning point", Opt. Laser Technol. 123, 1 (2020). CrossRef T. Eftimov, G. Dyankov, A. Arapova, P. Kolev and V. Vladev, W4.73 , OFS-27, Optical Fiber Sensor Conference - 2022, 29 Aug- 2 Sept., The Westin Alexandria, Alexandria, Virginia, USA. CrossRef G. Rossi, J. Durek, S. Ojha, O. K. Schlüter, "Fluorescence-based characterisation of selected edible insect species: Excitation emission matrix (EEM) and parallel factor (PARAFAC) analysis", CRFS 4, 862 (2021). CrossRef L. Li, Y. Wang, W. Zhang, S. Yu, X. Wang, N. Gao, "New advances in fluorescence excitation-emission matrix spectroscopy for the characterization of dissolved organic matter in drinking water treatment: A review Author links open overlay panel", Chem. Eng. J. 381, 1 (2020). CrossRef

Published
2022
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