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Light-stimulated electro-optics by azo-doped aerosil/7CB nanocomposites

Hadjichristov G. B., Marinov Y. G., Petrov A. G., Prasad S. K.

Opto-Electronics Review

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2018

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Vol. 26, No. 2

172--182

EN

Photoactive nanofilled nematic is proposed. Stable three-component photoresponsive nanocompositewas prepared from photo-insensitive nanofilled nematic by inclusion of 3 wt.% azobenzene-containingphotoactive mesogen 4-(4’-ethoxyphenylazo)phenyl hexanoate (EPH). The host nanofilled nematicwas produced from the room-temperature nematic liquid crystal 4-n-heptyl cyanobiphenyl (7CB) and3 wt.% filler of Aerosil 300 hydrophilic silica nanospheres of size 7 nm. Apparent effect of stimulation with a relatively weak continuous illumination by UV light (375 nm wavelength) takes placefor both the alternating-current electric field-dependent optical transmittance and the electro-opticamplitude-frequency modulation by thin films (25 μm thick) of the EPH/aerosil/7CB nanocomposite. Thelight-stimulated electro-optics of EPH-doped aerosil/7CB films and the corresponding reversible lightcontrol are achieved through trans-cis-trans photoisomerization of the photoactive agent EPH. As such,the initial electro-optical response of the studied photoactive nanocomposites is recovered with continuous blue-light illumination. The examined EPH/aerosil/7CB nanocomposites exhibit photo-controllableelectro-optical response that is of practical interest.

2

Thermal conductivity and temperature distribution in RF excited CO/sub 2/, CO, and Xe laser media.

Pliński E. F., Witkowski J. S.

Optica Applicata

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2001

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Vol. 31, nr 1

209-222

EN

Different methods of calculations of thermal conductivity of gas laser mixtures versus temperature are compared in the paper. Approximation functions describing the experimental data of thermal conductivity and viscosity of the chosen gases (CO/sub 2/, N/sub 2/, He, Xe, CO, O, Ar) are given. The formulas introduced and data obtained allow us to predict thermal conductivity and temperature distribution of a typical high power laser gas mixture. Examples of temperature distribution in RF excited CO/sub 2/, CO, and Xe laser media are shown. Knowledge of the temperature distribution in the laser cavity can be useful for predicting general optical properties of the laser.

3

Roughness of amorphous Zn-P thin films

Jarząbek B., Jurusik J., Cisowski J., Nowak M.

Optica Applicata

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2001

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Vol. 31, nr 1

93-101

EN

The effect of thickness variation and the surface roughness of amorphous Zn/sub 32/P/sub 68/ thin films has been investigated by the interference spectroscopy of the optical transmittance and reflectance, as well as by the atomic force microscopy (AFM). The analysis of the optical data allowed determination of the standard deviation of the thin film thickness by taking into account the Gaussian distribution of the change in phase of radiation traversing a thin film. It appears that the value of the standard deviation of the film thickness determined from the optical interference spectroscopy ( sigma /sub w/ approximately=26 nm) is comparable with the value of the mean surface roughness (R/sub a/ approximately=19 nm) evaluated from the AFM studies.

4

Mutual influences of sol-gel matrices and dopants on the materials optical properties

Andrzejewski D., Podbielska H.

Optica Applicata

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2001

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Vol. 31, nr 1

223-229

EN

The optical properties of doped sol-gel derived materials were studied. Two types of materials were examined; thin films doped with titanium dioxide and bulks doped with pH indicators: Bromothymol Blue and Nile Red. Different amounts of TiO/sub 2/ (in concentrations: 20, 40, 60 and 80 mol%) were entrapped into the silica sol-gel thin films. The refractive indices of the films were measured. A linear increase of refractive index with increasing addition of TiO/sub 2/ was observed. Bromothymol Blue and Nile Red pH indicators were entrapped into the sol-gel bulks. Two methods of dye immobilization were used. In the first method, indicators were mixed with liquid hydrolyzate used for bulk preparation. In the second one, the dried sol-gel bulks were impregnated with liquid dye solutions. The absorption spectra in the visible range were examined for dyes in solutions and sol-gel bulks. Changes in absorption spectra were observed depending on the way of dopant entrapment.

5

Model examination of the reflex-halation in single-layer light-sensitive system

Latacz L., Nowak P.

Optica Applicata

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2001

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Vol. 31, nr 2

499-506

EN

The results of computer simulation of the effects of light scattering in a system composed of single silver halide light-sensitive layer coated on a transparent base are presented. The scattered light penetrating the base film can suffer from internal reflection from its lower surface and thus contributes to some loss of image sharpness. This effect, called reflex-halation, is very disadvantageous. The qualitative dependence of the MTF curve of the system on its geometric and optical parameters is examined. It has been shown, among others, that the deterioration of image quality is stronger for the thinner light-sensitive layer and is more elongated for the elementary scattering indicatrix of silver halide crystals. The result is similar to that obtained in the case of crossover effect, though in the presence of the antihalation layer the observed dependences are opposite to those just mentioned.

6

Influence of the temperature of preparation process on refractive index of sol-gel matrices.

Lechna-Marczyńska M., Podbielska H.

Optica Applicata

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2001

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Vol. 31, nr 1

257-261

EN

The preparation of sol-gel materials in the form of bulks and thin films at different temperatures is described The procedure involves running the reaction at 50 degrees C and 90 degrees C in an open vessel. Such an approach enables acceleration of hydrolysis and condensation reactions. This procedure yields crack-free sol-gel glasses. The changes in refractive index of sol-gel materials were studied by using a Pulfrich refractometer. The experimental data indicates significant differences in the optical properties of sol-gel glasses, depending on the temperature during the preparation. The samples show normal dispersion, whereas a higher refractive index was stated for films prepared at a higher temperature.

7

Determination of the thickness and optical constants of polyarylates with heterocyclic side chain group

Ratusznik G.J., Najechalski P., Ciolek R., Pura B., Zadrozna I., Mrozinski H.

Optica Applicata

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2001

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Vol. 31, nr 1

103-114

EN

The investigation of the optical properties of the novel polyarylates with heterocyclic side chain groups is reported. Optical properties of the polymers obtained have been measured. Mechanical and thermal properties are also presented. The refractive index n( lambda ) and susceptibility chi /sup (1)/ have been determined for different compositions of polymers.