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Wyświetlanie 1-5 z 5
Tytuł:
Few-Cycle Laser Pulses: The Carrier-Envelope Phase, Its Role in the THz Emission from Laser-Generated Plasmas and a New Way to Measure It
Autorzy:
Kress, M.
Löffler, T.
Thomson, M.
Roskos, H.
Dörner, R.
Gimpel, H.
Zrost, K.
Ergler, T.
Moshammer, R.
Morgner, U.
Ullrich, J.
Powiązania:
https://bibliotekanauki.pl/articles/1813184.pdf
Data publikacji:
2008-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.Re
72.30.+q
78.47.-p
Opis:
Terahertz emission from laser-generated air plasmas has recently been identified as an interesting source for THz radiation. High intensities and a large bandwidth of the THz pulses can be achieved. We briefly review several mechanisms which were employed to generate the quasi-static dipole moment needed for the optical rectification process. This leads us to a discussion of a specific application of THz emission from an air plasma, namely the investigation of the carrier-envelope phase of few-cycle optical pulses. Such pulses of a duration of less than 10 fs induce a spatial charge asymmetry in the plasma directly via non-linear tunneling ionization. The asymmetry, and with it the emission of the THz radiation from the plasma, depend on the carrier-envelope phase, with the consequence that one can determine the phase by measurement of the amplitude and polarity of the THz pulse.
Źródło:
Acta Physica Polonica A; 2008, 113, 3; 769-776
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Grating Diffraction Effects in the THz Domain
Autorzy:
Coutaz, J.-K.
Garet, F.
Bonnet, E.
Tishchenko, A. V.
Parriaux, O.
Nazarov, M.
Powiązania:
https://bibliotekanauki.pl/articles/2041624.pdf
Data publikacji:
2005-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.47.+p
72.30.+q
42.65.Re
Opis:
We study the far infrared electromagnetic response of grating devices by THz time-domain spectroscopy. We first show that THz waves are efficiently injected into silicon waveguides using grating couplers. Moreover, changing the waveguide material parameters by white-light illumination allows us to strongly modify the coupling efficiency. Then we demonstrate resonant effects in segmented grating structures that act as perfect mirrors at selected wavelengths even for focused beams. About 10 periods of the grating participate in the phenomenon, nevertheless the resonance frequency width of the device remains narrow. This collection of experiments shows that millimeter-size mock-ups and THz waves can be effectively used to extrapolate the optical response of micron-size actual devices.
Źródło:
Acta Physica Polonica A; 2005, 107, 1; 26-37
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Efficient Terahertz Pulse Generation in Laser-Induced Gas Plasmas
Autorzy:
Löffler, T.
Kress, M.
Thomson, M.
Roskos, H. G.
Powiązania:
https://bibliotekanauki.pl/articles/2041638.pdf
Data publikacji:
2005-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.Re
72.30.+q
78.47.+p
Opis:
In this contribution, we review the development of sources for far-infrared (terahertz) radiation based on laser-generated gas plasmas. We describe several generation mechanisms based on ponderomotive forces, external field screening, and optical second-harmonic biasing. These methods are compared with the standard techniques with respect to the achievable terahertz pulse energy.
Źródło:
Acta Physica Polonica A; 2005, 107, 1; 99-108
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Terahertz Emission from Narrow Gap Semiconductors Photoexcited by Femtosecond Laser Pulses
Autorzy:
Adomavičius, R.
Urbanowicz, A.
Molis, G.
Krotkus, A.
Powiązania:
https://bibliotekanauki.pl/articles/2041649.pdf
Data publikacji:
2005-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.Re
07.57.Hm
78.47.+p
72.30.+q
Opis:
Large increase in the emitted terahertz power was observed for p-InAs samples with the p-doping levels of approximately 10$\text{}^{16}$-10$\text{}^{17}$ cm$\text{}^{-3}$. This increase was explained by a large surface depletion layer and an electric-field-induced optical rectification effect in the layer. Terahertz fields radiated by the samples of all three investigated Cd$\text{}_{x}$Hg$\text{}_{1-x}$Te layers was of the same order of magnitude. No azimuthal angle dependence of the radiated signal was detected, which evidences that linear current surge effect is dominating over nonlinear optical rectification. Azimuthal angle and magnetic fields emission witness that it is caused by linear photo-Dember type processes.
Źródło:
Acta Physica Polonica A; 2005, 107, 1; 132-136
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Terahertz Emission from the Surfaces of InAs and Other Narrow-Gap Semiconductors
Autorzy:
Adomavičius, R.
Krotkus, A.
Molis, G.
Urbanowicz, A.
Malevich, V.
Powiązania:
https://bibliotekanauki.pl/articles/1813200.pdf
Data publikacji:
2008-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.Re
07.57.Hm
78.47.-p
72.30.+q
Opis:
THz pulses were used to investigate carrier dynamics in narrow-gap semiconductors. The measurement of the optically induced THz pulse absorption transients provided important insights into electron energy relaxation in the conduction band. In the second set of experiments, THz generation from the surfaces of various semiconductors was studied and compared. It was found that the most efficient THz emitters are semiconductors with a narrow band gap, large intervalley separation in the conduction band, and low nonparabolicity of the main valley.
Źródło:
Acta Physica Polonica A; 2008, 113, 3; 859-862
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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