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Wyświetlanie 1-13 z 13
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:
Electro-Optical Behavior of Dye Doped Nematic Liquid Crystal
Autorzy:
Yadav, S.
Pandey, K.
Misra, A.
Manohar, R.
Powiązania:
https://bibliotekanauki.pl/articles/1505061.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.M-
42.79.Kr
Opis:
We report electro-optical behavior of a dye doped nematic liquid crystal. The dye doped cells have shown some improvement in some parameters important for the display devices such as threshold voltage $(V_{th})$, splay elastic constant, rotational viscosity and response time. The suppression of screening effect improves the threshold voltage for the doped sample.
Źródło:
Acta Physica Polonica A; 2011, 119, 6; 824-828
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Group Birefringence Measurement in Photonic Liquid Crystal Fibers by Use of Narrowband Light Sources
Autorzy:
Budaszewski, D.
Domański, A.
Powiązania:
https://bibliotekanauki.pl/articles/1795790.pdf
Data publikacji:
2009-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.79.Kr
42.25.Bs
Opis:
In the paper we present the results of investigating the effective group birefringence of photonic crystal fiber, partially infiltrated with 6CHBT liquid crystal mixture, which is a chemical abbreviation for 4-(trans-4-n-hexylcyclohexyl)isothiocyanatobenzene. We also introduce a novel method of group birefringence measurement based on phenomenon of depolarization of partially coherent light in birefringent media. We use Mueller-Stokes matrix formalism extended by additional depolarization matrix, which gives us possibility to calculate degree of polarization fluctuations of the light propagating in the liquid-crystal infiltrated microstructured optical fibres. We conducted the research for green and red semiconductor laser diodes. The results may contribute in construction of tunable photonic liquid crystal fibers depolarizer. Additionally, we have controlled birefringence of the photonic liquid crystal fibers by external electric field. These research may lead to designing a new type of fiber optic depolarizer based on photonic liquid crystal fibers.
Źródło:
Acta Physica Polonica A; 2009, 116, 3; 285-289
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photoelectrochemical Cell with Dye Molecules Oriented in Nematic Liquid Crystal
Autorzy:
Naser, N. S.
Planner, A.
Frąckowiak, D.
Powiązania:
https://bibliotekanauki.pl/articles/1967861.pdf
Data publikacji:
1997-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.30.Gd
42.79.Kr
42.70.Dí
Opis:
A photoelectrochemical cell consisting of two semiconducting electrodes covered by orienting SiO$\text{}_{x}$ layers and filled with merocyanine solutions in nematic liquid crystal was constructed. Dye molecules were oriented as a result of the guest-host effect. Generation of photocurrent by two components of polarized light gives different values of photocurrent amplitude but anisotropy of photocurrent is lower than that of absorption in the region of a free base form of dye. It is explained by dominant participation of a protonated form of dye in the photocurrent generation. The last form exhibits a lower degree of orientation than the free base form of dye.
Źródło:
Acta Physica Polonica A; 1997, 92, 3; 535-542
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improved Nucleation and Transition by Plasma Treatments for Fast Response Optically-Compensated-Bend Displays
Autorzy:
Wu, G.
Huang, C.
Chien, H.
Powiązania:
https://bibliotekanauki.pl/articles/1400462.pdf
Data publikacji:
2013-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.77.-j
81.65.-b
42.79.Kr
64.60.Q-
Opis:
The optically-compensated-bend mode pi-cell displays exhibit fast-response time and wide-viewing angle characteristics. However, it requires a transition of the liquid crystal molecule from an initial splay state to the bend state configuration before providing the quick operation. A high voltage and a long warm-up time are needed to transform to the bend state. In this paper, the polyimide alignment films have been modified to reduce the splay-to-bend transition time by plasma beam treatments. The proposed method was demonstrated to be highly effective in improving the overall transition time. The number of splay-to-bend nucleation sites in the assembled liquid crystal cells could be increased dramatically by up to 20 times at the initial stage, and the improvement in the cell warm-up time was achieved at 45-71% reduction at 5.5 V. The plasma processing parameters were optimized at the plasma power of 700 W, the plasma distance of 25 mm, and the plasma scan speed of 600 mm/s. In addition, we maintained the excellent optical properties and response time characteristics for the optically-compensated-bend mode liquid crystal displays.
Źródło:
Acta Physica Polonica A; 2013, 123, 5; 892-895
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Propagation Effects in Photonic Liquid Crystal Fibers with a Complex Structure
Autorzy:
Tefelska, M.
Chychłowski, M.
Woliński, T.
Dąbrowski, R.
Rejmer, W.
Wójcik, J.
Powiązania:
https://bibliotekanauki.pl/articles/1506868.pdf
Data publikacji:
2010-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.81.Gs
78.20.Bh
42.79.Kr
Opis:
Chiral nematic liquid crystals are very interesting materials to infiltrate photonic crystal fibers since they are characterized by unique optical properties such as selective Bragg reflection, circular dichroism, and optical activity. In this paper the latest experimental results of the photonic crystal fibers filled with new chiral nematic liquid crystals are presented. Spectral properties of the light propagating in the photonic liquid crystal fibers have been measured and analyzed.
Źródło:
Acta Physica Polonica A; 2010, 118, 6; 1259-1261
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An optical study to estimate orientational order parameter on some benzylideneaminophenylbenzoate liquid crystals
Autorzy:
Subhan, C.
Jeevan Kumar, R.
Panduranga, P.
Jayashreeand, B.
Fakruddin, K.
Powiązania:
https://bibliotekanauki.pl/articles/1070607.pdf
Data publikacji:
2016-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.79.Kr
78.15.+e
61.30.Gd
Opis:
The birefringence technique has been used for the evaluation of order parameter in the nematic phase along with the density measurements, which are needed for the calculation of molecular polarizabilities of the compounds. Birefringence and density studies have been carried out on the three liquid crystalline compounds viz.(1) (E)-4-((4-hexyloxy)benzylidene)amino)phenyl 4-butoxybenzoate(2) (E)-4-((4-hexyloxy)benzylidene)amino)phenyl 4-(decycloxy)benzoate and(3) (E)-4-((4-hexyloxy)benzylidene)amino)phenyl 4-(tridecycloxy)benzoate.Using birefringence and density data the molecular polarizabilities are evaluated by two different internal field models due to Vuks and Neugebauer. The mean molecular polarizability of the compounds is also evaluated by employing modified Lippincott δ-function model. The results reveal that both the theoretical and experimental values obtained are very near to each other.
Źródło:
Acta Physica Polonica A; 2016, 129, 3; 284-288
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photo-Induced Orientation of Nematic Liquid Crystals in Microcapillaries
Autorzy:
Chychłowski, M.
Ertman, S.
Tefelska, M.
Woliński, T.
Nowinowski-Kruszelnicki, E.
Yaroshchuk, O.
Powiązania:
https://bibliotekanauki.pl/articles/1506727.pdf
Data publikacji:
2010-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.81.Cn
42.79.Dj
42.81.Pa
42.79.Kr
Opis:
Axial and transversal orientational configurations of a nematic liquid crystal 6CHBT are realized inside glassy cylindrical capillaries by using photoalignment technique. It is demonstrated that this principle can be effectively used to enforce liquid crystal alignment in the desirable direction. It can be applied to control liquid crystal alignment in the photonic crystal fibers showing great potential for the modern telecommunication technologies.
Źródło:
Acta Physica Polonica A; 2010, 118, 6; 1100-1103
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Simulations of Electrically Induced Birefringence in Photonic Liquid Crystal Fibers
Autorzy:
Ertman, S.
Woliński, T.
Beeckman, J.
Neyts, K.
Vanbrabant, P.
James, R.
Fernández, F.
Powiązania:
https://bibliotekanauki.pl/articles/1506745.pdf
Data publikacji:
2010-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.81.Gs
78.20.Bh
42.79.Kr
Opis:
It has been recently experimentally demonstrated that propagation and polarization properties of the photonic liquid crystal fibers can be effectively tuned with the electric field. In particular, effective electric tuning of the phase birefringence has been obtained in the photonic liquid crystal fibers based on the high index glasses. Accurate numerical simulations of the impact of electric field on the guiding properties of the photonic liquid crystal fibers require complex methods, in which all important physical properties of the liquid crystal are taken into account (optical anisotropy, molecular orientation and relatively high losses). In this paper we present two different numerical approaches based on the finite element method. First one utilizes the simplified assumption of the "collective tilt" of molecules, and gives rough estimation of the phase birefringence tuning range. The second approach is much more rigorous, since electrically induced reorientation of the liquid crystal is calculated with a Q-tensor method giving the values of the inhomogeneous permittivity tensor. The value of the electrically induced birefringence calculated with the second method is in a good agreement with the experimental results.
Źródło:
Acta Physica Polonica A; 2010, 118, 6; 1113-1117
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Novel Electrically Tunable Long-Period Fiber Grating Using a Liquid Crystal Cladding Layer
Autorzy:
Czapla, A.
Woliński, T.
Nowinowski-Kruszelnicki, E.
Bock, W.
Powiązania:
https://bibliotekanauki.pl/articles/1506728.pdf
Data publikacji:
2010-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.81.Cn
42.79.Dj
42.81.Pa
42.79.Kr
Opis:
The main aim of the presented work is the integration of a long-period fiber grating and a liquid crystal into a hybrid structure, in order to develop an innovative fiber optic device controlled by an external electric field. The studied long-period fiber grating was fabricated using UV irradiation in a boron co-doped fiber (PS1250/1500, manufactured by Fibercore). As a liquid crystal we used a typical 5CB nematic liquid crystal. The sensing mechanism of the proposed loss filter relies on long-period fiber grating attenuation bands sensitivity to optical properties of the liquid crystal layer. The results obtained show that the long-period fiber grating with a nanosized liquid crystal layer exhibits one order of magnitude higher electrical sensitivity and a lower level of the voltage control than the long-period fiber grating with a micro-sized liquid crystal layer.
Źródło:
Acta Physica Polonica A; 2010, 118, 6; 1104-1107
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characterization of the Liquid Crystal Display Modulation. Optimization for Some Applications
Autorzy:
Campos, J.
Márquez, A.
Nicolás, J.
Moreno, I.
Iemmi, C.
Davis, J. A.
Yzuel, M. J.
Powiązania:
https://bibliotekanauki.pl/articles/2030321.pdf
Data publikacji:
2002-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.79.Kr
42.79.Hp
42.25.Ja
Opis:
In this paper we revise recent results of our team in the optimization of twisted nematic liquid crystal displays to be used as spatial light modulators for image processing and diffractive optics. In general two kind of responses are desired for the mentioned applications: amplitude-only and phase-only modulations. However, it is not a trivial task to find the polarization configurations for which these responses are obtained. We show that a reverse-engineering approach is needed to optimize the liquid crystal display response. According to this reverse-engineering approach the modulation characteristics can be calibrated by evaluating the modulation response in a few polarization configurations. These results are used to fit the liquid crystal display behavior to a simplified physical model, which uses two modulation parameters. We demonstrate that the degree of accuracy of this model is very high, thus enabling the prediction of the modulation behavior of the display at other polarization configurations. Therefore, we can perform computer searches for the optimum orientation of the polarizing elements to obtain the required optical transmission. We demonstrate the need to use short wavelengths and the need to insert wave plates in front and behind the liquid crystal displays to obtain either amplitude-only or phase-only regime.
Źródło:
Acta Physica Polonica A; 2002, 101, 1; 189-200
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of Different Liquid Crystal Materials under Planar and Homeotropic Boundary Conditions in Capillaries
Autorzy:
Chychłowski, M.
Ertman, S.
Nowinowski-Kruszelnicki, E.
Dąbrowski, R.
Woliński, T.
Powiązania:
https://bibliotekanauki.pl/articles/1493035.pdf
Data publikacji:
2011-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.70.Df
61.30.Jf
77.84.Nh
42.79.Kr
Opis:
We present a thermally-induced liquid crystal orientation method by applying an extra orienting layer onto an inner capillary surface that can induce either planar or homeotropic liquid crystal boundary conditions. Experimental evidence of boundary-induced orientation in two types of liquid crystal (nematic, chiral nematic) in a capillary are shown.
Źródło:
Acta Physica Polonica A; 2011, 120, 4; 582-584
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spectral Tuning of the Long-Period Fiber Gratings by Using Low Birefringence Liquid Crystals
Autorzy:
Czapla, A.
Bock, W.
Woliński, T.
Dąbrowski, R.
Nowinowski-Kruszelnicki, E.
Powiązania:
https://bibliotekanauki.pl/articles/1493037.pdf
Data publikacji:
2011-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.81.Cn
42.79.Dj
42.81.Pa
42.79.Kr
Opis:
The work presented in this paper is focused on investigation of the spectral properties of the long-period fiber gratings combined with the liquid crystals, named liquid crystal long-period fiber gratings. The experiments carried out showed that the proposed designs of the liquid crystal long-period fiber gratings can offer very interesting spectral properties and can introduce a new level of sensitivity. In particular, a high-efficiency thermal tuning of the long-period fiber gratings coated with low-birefringence liquid crystal layers could be achieved and gave rise to a fast and wide switching ability of the attenuation bands within their transmission spectrum.
Źródło:
Acta Physica Polonica A; 2011, 120, 4; 589-592
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-13 z 13

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