Dr. Daniel C. Negut Profile

Dr. Daniel C. Negut

at Institutul National pentru Fizica Laserilor, Plasmei si Radiatiei

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Publications (10)

Proceedings Article | 30 May 2023 Paper

Post-radiation effects of core pumped monolithic holmium-doped silica fibre lasers

A. Theodosiou, L. Koutsokeras, A. Ioannou, A. Stancalie, C. Negut, J. Aubrecht, P. Peterka, G. Constantinides, K. Kalli

Proceedings Volume 12573, 125730U (2023) https://doi.org/10.1117/12.2665051

KEYWORDS: Fiber lasers, Fiber Bragg gratings, Laser radiation, Silica, Raman spectroscopy, Optical fibers, Holmium, Annealing, Temperature metrology, Spectroscopy

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Proceedings Article | 23 May 2023 Paper

Response of long period gratings written in B/Ge and P-doped optical fibers to gamma radiation

Flavio Esposito, Andrei Stancalie, Anubhav Srivastava, Mateusz Smietana, Jan Mrazek, Razvan Mihalcea, Constantin Daniel Negut, Stefania Campopiano, Agostino Iadicicco

Proceedings Volume 12643, 126430A (2023) https://doi.org/10.1117/12.2678163

KEYWORDS: Optical fibers, Optical gratings, Gamma radiation, Cladding, Signal attenuation, Manufacturing, Fiber optics sensors, Sensors, Photonics

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Proceedings Article | 2 March 2023 Paper

Third harmonics emission with nanosecond and femtosecond lasers in air: gamma radiation effects on optical fibers

Mihai Stafe, Georgiana Vasile, Răzvan Mihalcea, Constantin Daniel Negut, Constantin Negutu, Niculae Puscas

Proceedings Volume 12493, 124931E (2023) https://doi.org/10.1117/12.2643227

KEYWORDS: Optical fibers, Plasma, Gamma radiation, Transmittance, Femtosecond phenomena, Radiation effects, Multimode fibers, Pulsed laser operation, Spectroscopy, Plasma diagnostics

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Harmonics generation in plasma by high-power pulsed lasers is an important task for plasma diagnosis. This is because of the strong relationship between the plasma characteristics and the properties of the harmonics radiation. Here we analyze the spatial and temporal properties of third harmonic (TH) radiation generated by focusing ns and fs laser pulses in air at intensities of the order of tens of TW/cm2. The air is considered a non-dispersive non-linear (NL) medium due to the low density ofN2 ions in the breakdown plasma produced under the laser pulses. We address the influence of the pump laser intensity on the properties of TH radiation. We find theoretically and experimentally that the intensity of TH radiation at the output of the NL medium increases linearly with third power of the pump peak intensity, both for ns and fs laser pulses. In case of fs pulses, we demonstrate that TH pulse duration decreases with pump intensity, in correlation to the air breakdown plasma properties. In case of ns laser pulses, we demonstrate that the TH beam diameter is two times smaller than the fundamental’s. The theoretical results on the dependence of the TH signal to the driving peak intensity are supported by experimental data. We further analyze the influence of the gamma radiation on the several commercially optical fibers that are usually employed in the laser-target interaction area. The radiation effects such as photo-darkening induced in optical fibers can severely decrease the performance of optical transmission. We investigated the change of optical transmission induced by gamma-ray radiation. Multimode optical fibers, with a core diameter of 200 μm (usable in UV, ultra-highvacuum and high temperatures conditions), were investigated in order to evaluate their possible use for diagnosis of plasmas produced by high power lasers. The optical properties were studied by analyzing the transmitted spectra of the fibers before and after irradiation, demonstrating a decrease of the measured spectrum of the optical fiber output when increasing gamma dose to 16 kGy. The results are important from both fundamental and practical points of view, providing an efficient tool for prediction of the non-linear optical phenomena in laser produced plasmas and for non-contact diagnosis of the harmonics-generating plasmas.

Proceedings Article | 18 April 2021 Presentation + Paper

Radiation induced effects on FBGs using different femtosecond laser inscription methods

A. Theodosiou, A. Leal-Junior, C. Marques, A. Frizera, A. J. Fernandes, A. Stancalie, A. Ioannou, D. Negut, K. Kalli

Proceedings Volume 11773, 117730P (2021) https://doi.org/10.1117/12.2592376

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Proceedings Article | 28 August 2019 Paper

Response of long period gratings to gamma and neutron-gamma radiations

Flavio Esposito, Andrei Stăncălie, Daniel Neguţ, Agostino Iadicicco, Dan Sporea, Stefania Campopiano

Proceedings Volume 11199, 111990B (2019) https://doi.org/10.1117/12.2539791

KEYWORDS: Gamma radiation, Optical fibers, Manufacturing, Single mode fibers, Radiation effects, Refractive index

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Proceedings Article | 30 May 2016 Paper

Perfluorinated polymer optical fiber for gamma radiation monitoring

P. Stajanca, L. Mihai, D. Sporea, D. Negut, K. Krebber

Proceedings Volume 9916, 99160H (2016) https://doi.org/10.1117/12.2235528

KEYWORDS: Polymer optical fibers, Gamma radiation, Fiber optics sensors, Radiation dosimetry, Signal attenuation, Visible radiation, Mechanical sensors, Environmental sensing, Sensors, Signal detection, Optical fibers, Glasses, Polymethylmethacrylate, Spectroscopy

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Proceedings Article | 30 May 2016 Paper

Gamma radiation influence on silica optical fibers measured by optical backscatter reflectometry and Brillouin sensing technique

A. Wosniok, D. Sporea, D. Neguţ, K. Krebber

Proceedings Volume 9916, 99162J (2016) https://doi.org/10.1117/12.2236678

KEYWORDS: Signal attenuation, Glasses

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Proceedings Article | 27 April 2016 Paper

Online monitoring of gamma irradiated perfluorinated polymer optical fiber

Dan Sporea, Laura Mihai, Daniel Neguţ, Pavol Stajanca, Katerina Krebber

Proceedings Volume 9886, 98861Q (2016) https://doi.org/10.1117/12.2230688

KEYWORDS: Polymer optical fibers, Gamma radiation, Absorption, Optical fibers, Spectroscopy, Ultraviolet radiation, Radiation dosimetry, Sensors, Signal detection, Signal attenuation, Temperature metrology, Radiation effects

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Proceedings Article | 27 April 2016 Paper

Long period grating response to gamma radiation

Dan Sporea, Andrei Stӑncalie, Daniel Neguţ, Sylvie Delepine-Lesoille, Laurent Lablonde

Proceedings Volume 9886, 98861P (2016) https://doi.org/10.1117/12.2230233

KEYWORDS: Sensors, Fiber Bragg gratings, Optical fibers, Gamma radiation, Radiation effects, Radiation dosimetry, Fiber characterization, Remote sensing, Signal attenuation, Physics, Single mode fibers

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Proceedings Article | 19 July 2007 Paper

Effects of gamma irradiation on the colour of pigments

D. Negut, C. Ponta, Rodica Georgescu, I. Moise, Gh. Niculescu, A. I. M. Lupu

Proceedings Volume 6618, 66180R (2007) https://doi.org/10.1117/12.725967

KEYWORDS: Tolerancing, Mars, Gamma radiation, Radiotherapy, Cultural heritage, Spectrophotometry, Visualization, Reliability, Fungi, Bone

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Showing 5 of 10 publications

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