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141 results on '"Samek O"'

2. Enhanced Transmission and Reflection of Femtosecond Pulses by a Single Slit

Author

Mechler, M., Samek, O., and Kukhlevsky, S. V.

Subjects
Physics - Optics, Physics - Classical Physics
Abstract

We show that a physical mechanism responsible for the enhanced transmission and reflection of femtosecond pulses by a single subwavelength nanoslit in a thick metallic film is the Fabry-Perot-like resonant excitation of stationary, quasistationary and nonstationary waves inside the slit, which leads to the field enhancement inside and around the slit. The mechanism is universal for any pulse-scatter system, which supports the stationary resonances. We point out that there is a pulse duration limit below which the slit does not support the intraslit resonance., Comment: 4 pages, 3 figures

Published
2006
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3. Analytical model of the enhanced light transmission through subwavelength metal slits: Green's function formalism versus Rayleigh's expansion

Author

Kukhlevsky, S. V., Mechler, M., Samek, O., and Janssens, K.

Subjects
Physics - Optics
Abstract

We present an analytical model of the resonantly enhanced transmission of light through a subwavelength nm-size slit in a thick metal film. The simple formulae for the transmitted electromagnetic fields and the transmission coefficient are derived by using the narrow-slit approximation and the Green's function formalism for the solution of Maxwell's equations. The resonance wavelengths are in agreement with the semi-analytical model [Y. Takakura, Phys. Rev. Lett. 86, 5601 (2001)], which solves the wave equations by using the Rayleigh field expansion. Our formulae, however, show great resonant enhancement of a transmitted wave, while the Rayleigh expansion model predicts attenuation. The difference is attributed to the near-field subwavelength diffraction, which is not considered by the Rayleigh-like expansion models., Comment: submitted to Appl. Phys. B, 8 December 2005; corrected typos

Published
2006
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4. Resonant backward scattering of light by a two-side-open subwavelength metallic slit

Author

Kukhlevsky, S. V., Mechler, M., Csapo, L., Janssens, K., and Samek, O.

Subjects
Physics - Optics
Abstract

The backward scattering of TM-polarized light by a two-side-open subwavelength slit in a metal film is analyzed. We show that the reflection coefficient versus wavelength possesses a Fabry-Perot-like dependence that is similar to the anomalous behavior of transmission reported in the study [Y. Takakura, Phys. Rev. Lett. \textbf{86}, 5601 (2001)]. The open slit totally reflects the light at the near-to-resonance wavelengths. In addition, we show that the interference of incident and resonantly backward-scattered light produces in the near-field diffraction zone a spatially localized wave whose intensity is 10-10$^3$ times greater than the incident wave, but one order of magnitude smaller than the intra-cavity intensity. The amplitude and phase of the resonant wave at the slit entrance and exit are different from that of a Fabry-Perot cavity., Comment: 5 figures

Published
2005
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5. Enhanced transmission versus localization of a light pulse by a subwavelength metal slit

Author

Kukhlevsky, S. V., Mechler, M., Csapo, L., Janssens, K., and Samek, O.

Subjects
Physics - Optics
Abstract

The existence of resonant enhanced transmission and collimation of light waves by subwavelength slits in metal films [for example, see T.W. Ebbesen et al., Nature (London) 391, 667 (1998) and H.J. Lezec et al., Science, 297, 820 (2002)] leads to the basic question: Can a light pulse be enhanced and simultaneously localized in space and time by a subwavelength slit? To address this question, the spatial distribution of the energy flux of an ultrashort (femtosecond) wave-packet diffracted by a subwavelength (nanometer-size) slit was analyzed by using the conventional approach based on the Neerhoff and Mur solution of Maxwell's equations. The results show that a light pulse can be enhanced by orders of magnitude and simultaneously localized in the near-field diffraction zone at the nm- and fs-scales. Possible applications in nanophotonics are discussed., Comment: 5 figures

Published
2004
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19. The potential of SERS as an AST methodology in clinical settings

Author

Samek Ota, Bernatová Silvie, and Dohnal Fadi

Subjects
biosensor, infection disease management, surface enhanced raman scattering, vibration spectroscopy, Physics, QC1-999
Abstract

The ability to identify and characterize microorganisms from tiny sample volumes in a rapid and reliable way is the first and crucial step in the diagnostics of microbial infections. Ideal analytical techniques would require minimal and low-cost sample preparation, permit automatic analysis of many serial samples, and allow rapid classification of present microorganisms against a stable database. Current practice, however, is far from this ideal; a typical analytical procedure might require a few days. Delayed laboratory results might lead, for example, to progress/spread of the infection, more serious condition of the patient, even death, prescription of inappropriate antibiotics that could be ineffective against causative agents and may as well contribute to the emerging problem of drug resistance in microorganisms. Several studies confirmed that surface enhanced Raman scattering (SERS) is capable of a rapid identification and discrimination of biological samples including medically relevant bacteria. A typical spectrum contains a wealth of information indicative of the cellular content of nucleic acids, purine bases, proteins, carbohydrates, and lipids. Such a spectrum functions as a cellular ‘fingerprint’ and serves as a sensitive indicator of the physiological state of the cell which in turn enables to differentiate cell types, actual physiological states, nutrient conditions, and phenotype changes. Consequently, the focus of this review is on the SERS spectra of bacteria which result from secreted metabolic substances – the purine bases – which are a common feature in the label-free SERS research related to clinical diagnostics of pathogens. Here is the review of the current status of SERS applications on bacteria. A special attention is given to the efforts of profiling antimicrobial susceptibility at clinically relevant species, which in turn has a great potential for use in routine point-of-care (POC) tests. Thus, early and accurate infection disease management can be provided at the bedside or at remote care centres.

Published
2021
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22. Enhanced transmission versus localization of a light pulse by a subwavelength metal slit: Can the pulse have both characteristics?

Author

Kukhlevsky, S. V., Mechler, M., Csapo, L., Janssens, K., and Samek, O.

Subjects
FOS: Physical sciences, Physics - Optics, Optics (physics.optics)
Abstract

The existence of resonant enhanced transmission and collimation of light waves by subwavelength slits in metal films [for example, see T.W. Ebbesen et al., Nature (London) 391, 667 (1998) and H.J. Lezec et al., Science, 297, 820 (2002)] leads to the basic question: Can a light be enhanced and simultaneously localized in space and time by a subwavelength slit? To address this question, the spatial distribution of the energy flux of an ultrashort (femtosecond) wave-packet diffracted by a subwavelength (nanometer-size) slit was analyzed by using the conventional approach based on the Neerhoff and Mur solution of Maxwell's equations. The results show that a light can be enhanced by orders of magnitude and simultaneously localized in the near-field diffraction zone at the nm- and fs-scales. Possible applications in nanophotonics are discussed., Comment: 5 figures

Published
2004
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24. Application of laser-induced breakdown spectroscopy to the analysis of algal biomass for industrial biotechnology

Author

Pořízka, P., primary, Prochazka, D., additional, Pilát, Z., additional, Krajcarová, L., additional, Kaiser, J., additional, Malina, R., additional, Novotný, J., additional, Zemánek, P., additional, Ježek, J., additional, Šerý, M., additional, Bernatová, S., additional, Krzyžánek, V., additional, Dobranská, K., additional, Novotný, K., additional, Trtílek, M., additional, and Samek, O., additional

Published
2012
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29. Mapping of lead, magnesium and copper accumulation in plant tissues by laser-induced breakdown spectroscopy and laser-ablation inductively coupled plasma mass spectrometry

Author

Kaiser, J., primary, Galiová, M., additional, Novotný, K., additional, Červenka, R., additional, Reale, L., additional, Novotný, J., additional, Liška, M., additional, Samek, O., additional, Kanický, V., additional, Hrdlička, A., additional, Stejskal, K., additional, Adam, V., additional, and Kizek, R., additional

Published
2009
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33. Monitoring of the heavy-metal hyperaccumulation in vegetal tissues by X-ray radiography and by femto-second laser induced breakdown spectroscopy

Author

Kaiser, J., primary, Samek, O., additional, Reale, L., additional, Lis˘ka, M., additional, Malina, R., additional, Ritucci, A., additional, Poma, A., additional, Tucci, A., additional, Flora, F., additional, Lai, A., additional, Mancini, L., additional, Tromba, G., additional, Zanini, F., additional, Faenov, A., additional, Pikuz, T., additional, and Cinque, G., additional

Published
2007
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