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Wyszukujesz frazę "42.70.df" wg kryterium: Temat


Tytuł:
Influence of External Electric Field on Time of Nonlinear Optical Reorientational Effect in Nematics
Autorzy:
Bajdecki, W. K.
Karpierz, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/2035684.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.-k
42.70.Df
Opis:
Nonlinear reorientation phenomena in nematic liquid crystals cause extremely large refractive index changes. However, this effect is relatively slow and the determination of the time necessary to appearing or disappearing of the nonlinear effect is an important issue. In this work we present measurements of the time of increasing the nematics reorientation induced by the light beam passing through the liquid crystalline layer. The influence of external low-frequency electric field suppressing reorientation is also reported. The obtained results describing relations between time and optical power of light as well as between time and external electric field intensity are in good agreement with theory.
Źródło:
Acta Physica Polonica A; 2003, 103, 2-3; 187-193
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Nonlinearity in Liquid Crystalline Optical Waveguides
Autorzy:
Karpierz, M. A.
Domański, A. W.
Sierakowski, M.
Świłło, M.
Woliński, T. R.
Powiązania:
https://bibliotekanauki.pl/articles/2008217.pdf
Data publikacji:
1999-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.Wi
42.70.Df
Opis:
The analysis of optical orientational nonlinearity in nematic liquid crystalline planar waveguides is presented. The analyzed nonlinearity leads to unique properties that are not observed in other types of nonlinear waveguides. Theoretical results are confirmed by experimental data obtained in liquid crystalline directional couplers and in the self-focusing effect observed in the planar liquid crystalline waveguides.
Źródło:
Acta Physica Polonica A; 1999, 95, 5; 783-792
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nonlinear Properties of Waveguides with Twisted Nematic Liquid Crystal
Autorzy:
Karpierz, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/2015119.pdf
Data publikacji:
2001-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.Wi
42.70.Df
Opis:
Optical reorientational nonlinearity in twisted nematic liquid crystalline planar waveguide is analyzed theoretically. It is shown that optical nonlinearity for guided modes in analyzed waveguides can be approximated by saturation nonlinearity. Predicted nonlinearity is large enough to observe effects like spatial solitons formation with milliwatts of light power.
Źródło:
Acta Physica Polonica A; 2001, 99, 1; 161-173
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nonlinear Inelastic Light Scattering in a Smectic Liquid Crystal
Autorzy:
Pura, B.
Jęda, W.
Zagórski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1968843.pdf
Data publikacji:
1998-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.70.df
42.65.-k
Opis:
Results of measurements of the intensity of light scattered by a smectic liquid crystal are reported for three phases of the specimen. A strong dependence of the scattered intensity on the relative directions of polarization vector and molecular orientation is observed. A mechanism of light interaction with material is proposed, it is attributed to brillouin - like scattering of light on director - system excitations.
Źródło:
Acta Physica Polonica A; 1998, 93, 3; 465-470
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hyper-Solitons in Nematic Liquid Crystals
Autorzy:
Strinic, A.
Petrović, M.
Belić, M.
Powiązania:
https://bibliotekanauki.pl/articles/1791208.pdf
Data publikacji:
2009-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.70.Df
42.65.Tg
Opis:
We study laser light propagation in a cell containing a liquid crystal in the nematic phase. We launch hyper-Gaussian beams and follow their behavior within the cell, in time and in three spatial dimensions, utilizing an appropriately developed theoretical model and a numerical procedure based on the fast Fourier transform. We demonstrate the formation of stable "hyper-soliton" breathers in a narrow region of beam intensities, for fixed other parameters. Hyper-solitons are similar in appearance and behavior to the usual solitons, formed by launching the usual Gaussian beams; however noticeable differences persist.
Źródło:
Acta Physica Polonica A; 2009, 116, 4; 510-512
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nonlinear Optical Measurements of Elastic Constants in Nematic Liquid Crystal
Autorzy:
Bajdecki, W. K.
Karpierz, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/2008272.pdf
Data publikacji:
1999-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.-k
42.70.Df
Opis:
A new method of measurements of elastic constants of nematic liquid crystals by applying the nonlinear optical effect is presented. This method bases on measurements of a value of the reorientation threshold in a liquid crystal layer while the reorientation is induced by the light beam passing through the layer. The obtained results are in a qualitative compatibility with the results obtained by classical methods.
Źródło:
Acta Physica Polonica A; 1999, 95, 5; 793-800
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reorientational Nonlinear Phenomena in Thin Nematic Liquid Crystals Layer
Autorzy:
Brzdąkiewicz, K.
Bajdecki, W. K.
Kozanecka, A.
Karpierz, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/2023855.pdf
Data publikacji:
2001-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.-k
42.70.Df
Opis:
In this paper the detailed study of the self-diffraction phenomena due to reorientational optical nonlinearity in nematic liquid crystalline cell is presented. The optical nonlinear effect is additionally modified by external low-frequency electric field. The dependence of nonlinear response on light polarization is also analyzed. The theoretical investigations are compared with experimental results and the theoretical predictions are in excellent agreement with experimental data.
Źródło:
Acta Physica Polonica A; 2001, 99, 1; 183-192
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatial Optical Solitons in Bulk Nematic Liquid Crystals
Autorzy:
Assanto, G.
Peccianti, M.
Conti, C.
Powiązania:
https://bibliotekanauki.pl/articles/2035665.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.70.Df
42.65.Tg
Opis:
We present an overview of our recent experimental results on two-dimensional optical spatial solitons in voltage biased planar cells with nematic liquid crystals. Excitation, induced waveguiding, and interactions are illustrated and interpreted in terms of the inherent re-orientational, non-resonant and nonlocal nonlinear response.
Źródło:
Acta Physica Polonica A; 2003, 103, 2-3; 161-167
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling of Spatial Solitons in Twisted Nematics Waveguides
Autorzy:
Karpierz, M. A.
Brzdąkiewicz, K. A.
Nguyen, Q. V.
Powiązania:
https://bibliotekanauki.pl/articles/2035666.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.Wi
42.70.Df
Opis:
Theoretical analysis of light beam propagation in twisted nematic liquid crystalline waveguides is presented. Due to the optical reorientation nonlinearity, the light beam changes the direction of propagation and optical spatial soliton is formed. Modeling of such behavior is presented by using (2+1)-dimensional vector beam propagation method as well as simplified (1+1)-dimensional method. Although both approaches give similar results, the differences are discussed in detail.
Źródło:
Acta Physica Polonica A; 2003, 103, 2-3; 169-175
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamical Electro-Optical Characterization of Policryps Gratings
Autorzy:
Abbate, G.
Marino, A.
Vita, F.
Powiązania:
https://bibliotekanauki.pl/articles/2035667.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.70.Df
42.79.Kr
Opis:
We have studied the dynamical response at 633 and 1550 nm of a new polymer-liquid crystal composite, realized in a form of a thick grating. This composite is known as Policryps, an acronym that stands for "Polymer Liquid Crystals Polymer Slides", because it shows a sequence of polymeric sheets alternated by layers containing only liquid crystal. Policryps gratings can be electrically switched between diffracting and non-diffracting states with a good diffraction efficiency in the visible region. After optimization of their performances, including response time, in the near infrared region, they can be conveniently proposed as a key component in photonic devices for telecom applications. Our results show very interesting response times ranging from 1 to 3 ms (switching on) and from 0.1 to 0.4 ms (switching off). Furthermore, switching ON times appear to be ruled by two different physical mechanisms with characteristic times differing by one order of magnitude. A deeper insight of these mechanisms might lead to response times, all in the submillisecond range.
Źródło:
Acta Physica Polonica A; 2003, 103, 2-3; 177-186
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Light Polarization on Reorientation Nonlinearity in Nematic Liquid Crystals
Autorzy:
Brzdąkiewicz, K. A.
Karpierz, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/2035686.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.-k
42.70.Df
Opis:
Nematic liquid crystals are characterized by a giant optical nonlinearity which has its origin in the molecular reorientational phenomenon. Uniqueness of this nonlinear mechanism causes that response of the medium is dependent on many conditions. Among various circumstances, both an initial alignment of liquid crystal cell and geometry of the system are very important, but in this paper a significant role of light polarization in nonlinear effects observed in nematics is emphasized. Additionally, it is underlined that dependence on light polarization does not have only trivial aspect of initial conditions. More complex seems to be the fact that due to the high optical anisotropy of the medium the state of light polarization is changing on the way of beam propagation. As a consequence, the modifications of molecular orientation in the liquid crystal cell are strongly dependent upon light polarization.
Źródło:
Acta Physica Polonica A; 2003, 103, 2-3; 195-205
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Refractive Indices, Order Parameter and Optical Transmittance Studies of a Nematic Liquid Crystal Mixture
Autorzy:
Singh, A. K.
Manohar, R.
Shukla, J. P.
Biradar, A. M.
Powiązania:
https://bibliotekanauki.pl/articles/2047089.pdf
Data publikacji:
2006-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.30.-v
42.70.Df
Opis:
Measurements of ordinary refractive index, birefringence, density, and order parameter were made on a technologically important nematogen and the data obtained for its nematic and isotropic phase were reported. A modified wedge method was used for the measurement of the birefringence (δ n). The nematic-isotropic phase transition temperature matches very well as is exhibited from the value of refractive indices and densities obtained using different techniques. The optical anisotropy and density data were used to determine the order parameter and principal polarizability of the nematic mixture using the Vuks approach and their temperature dependence was discussed. The macroscopic order parameter was obtained and compared with microscopic order parameter. These two values agree very well.
Źródło:
Acta Physica Polonica A; 2006, 110, 4; 485-493
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Controlling Light by Light: Optical Modulation in Chiral Nematics
Autorzy:
Sierakowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/2008249.pdf
Data publikacji:
1999-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.-k
42.81.Wg
42.70.Df
Opis:
Nonlinear optics of chiral liquid-crystalline media have been in scope of our interest for several years. Our previous observations in the subject had already been reported. This paper discusses a possibility of utilising the nonlinear optical properties of liquid crystals for practical purposes. We discuss an idea of "in line" intensity measurements of laser beam. The idea is based on two optical phenomena which are observed in liquid-crystalline media possessing a periodically stratified structure: nonlinear optical effect and selective light reflection. The effects start to appear by activating light intensities of the order of MW/m$\text{}^{2}$, so the method can be potentially applied at present to high-intensity light beams (corresponding laser power is approximately 0.1 W), although there are now also prospects to lower this value significantly.
Źródło:
Acta Physica Polonica A; 1999, 95, 5; 777-782
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Light Propagation in Liquid Crystal Fiber Structures
Autorzy:
Nasiłowski, T.
Woliński, T. R.
Powiązania:
https://bibliotekanauki.pl/articles/2023819.pdf
Data publikacji:
2001-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.79.Hp
42.70.Df
42.81.Qb
Opis:
The paper analyzes the light propagation in anisotropic liquid crystal fiber structures in order to find the possibilities to apply them to control and switch the polarization state and modulate some parameters of the transmitted light. The long term goal and motivation of the authors was the suggestion to replace the light modulating liquid crystal cell by a new generation of liquid crystal waveguides as an all-fiber light modulator, as well as sensors for different environmental parameters.
Źródło:
Acta Physica Polonica A; 2001, 99, 1; 193-200
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Polarization Properties of Liquid-Crystal Elliptical-Core Fibers
Autorzy:
Szymańska, A.
Woliński, T. R.
Powiązania:
https://bibliotekanauki.pl/articles/2023965.pdf
Data publikacji:
2001-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.70.Df
42.81.Qb
42.81.Dp
Opis:
Polarization properties of liquid-crystal core optical fibers have been investigated. The liquid-crystal fiber is characterized by elliptical anisotropic core with low birefringence liquid crystal introduced by capillary axis. The paper presents also initial experimental results of the liquid-crystal fiber in the polarimetric configuration subjected to the influence of selected perturbations.
Źródło:
Acta Physica Polonica A; 2001, 99, 1; 201-205
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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