Valentin N. Sizov

Holographic recording in thin C70-doped polymer organic films

Abstract The dynamic and static thin holographic gratings have been recorded in C 70 -doped photosensitive polyimide 6B and 2-cyclooctylamino-5-nitropyridine. The drastic change in diffraction efficiency has been observed under the Raman–Nath diffraction condition using the second harmonic of pulse Nd laser. The threshold of the transition from phase grating to amplitude one has been determined. The results obtained have been explained by the absorption spectral peculiarities of the fullerene-doped films and by their thermal properties.

Fullerene-doped polymer-dispersed liquid crystals: holographic recording and optical limiting effect

In the fullerene-doped polymer dispersed liquid crystals the holographic recording and optical limiting effect have been established to be intermediate between those for fullerene- doped liquid crystals and for fullerene-doped polymers. It has been shown that fullerene-doped polymer-dispersed liquid crystals could be applied for optical limiting at the incident laser power of 0-3-0.4 J cm-2. They can be used as effective diffractive optical elements.

Dynamic recording of χ(2) holograms with multifrequency object and reference waves

The transformation properties of images formed by inertialess dynamic χ(2) holograms recorded by multifrequency reference and object beams are studied theoretically and experimentally. The regular features of the spatial localization and scales of holographic images obtained with different frequency combinations of the reference and object image-forming beams are ascertained. It is shown that, in the general case of an arbitrary variation in the ratio of these frequencies, the reconstructed images of an object point source are localized on a segment of a straight line, which we referred to as the locris. The slope of the locris does not depend on the frequency ratio of the reference and object beams, and its endpoints are specified by the positions of the reference and object sources. The possibility of obtaining of achromatic holographic images for noncollinear multifrequency interactions is demonstrated. The conditions for the noncollinear phase matching of interacting waves in a KTP crystal, as well as for simultaneous attainment of phase matching for selected frequency combinations, are determined. The important role of controlling the shape of wavefronts in experiments with frequency conversion of radiation in the reference beam by stimulated Raman scattering of light is ascertained.

Monochromatic and two-color recording of holographic portraits with the use of pulsed lasers

The methods are described to obtain monochromatic and color holographic portraits, being reduced in laser and white light with the use of pulsed lasers in red and green spectral regions.

Recording of dynamic holograms by nanosecond and picosecond laser pulses in solid-state fullerene-containing matrices

The results of a complex investigation of the recording of dynamic holograms by pulsed radiation with a duration of 20 ns and 300 ps in fullerene-containing media based on porous glasses and polymethyl methacrylate matrices are reported. Spectral analysis of these media in the range 300–700 nm was performed. The efficiency of hologram recording was found to relate with the occurrence of a band at 330 nm in the absorption spectrum of a medium. It is shown that dynamic holograms can be recorded in the fullerene-containing media by nanosecond and picosecond pulses. In the latter case, holograms arise mainly due to a change in the electronic polarizability of fullerene molecules, which is almost inertialess. The results obtained can be used in the development of ultrafast switching devices based on dynamic holograms.

Dynamic holograms recording in fullerene-containing solid state media by 300 ps laser pulse

In this paper, experimental results on self-diffraction in porous glasses with fullerene C/sub 60/ or samples with PMMA are presented. Using the second harmonics of Nd-YAG laser with 532 nm only the first diffraction order was observed but no high diffraction orders were registered, which was the main difference between this experiment and experiments on holograms recording by nanosecond laser pulses.

Dynamic holograms recording in fullerene-containing solid state media by 300-ps and 20-ns laser pulses

The results of experimental investigation of dynamic holograms recording by 20 ns and 300 ps laser pulses in fullerene-containing solid-state matrices are presented in this paper. The spectral analysis in range 300 - 700 nm shows correlation between efficiency of dynamic holograms recording and presence of absorption band at nearly 330 nm. We use two types of solid-state matrices: porous glass and polymethylmethacrylate hosts, which were filled with fullerene C60. From the dynamic holograms recording experiments and from the spectral analysis we obtained data on sensitivity and stability of the media, which can be used later in practical applications like all-optical switching.

Dynamic hologram recording in fullerene-containing nano-size porous glasses

We report the theoretical and experimental results of dynamic holograms recording in nano-size porous glasses containing fullerine C60 and its use for optical limiting. To record a grating with spatial frequency 20 mm-1 we used laser pulses with 18 ns duration and 532 nm wavelength. Initial transmittance of the samples varied from 30% to 70%. We found that high diffraction orders appeared out of the medium during the experiment and investigated dependence self-diffraction on initial transmittance of the samples and in case when the samples were filled by toluene. It was found that the most effective self-diffraction is in situation when we use toluene and initial transmittance of the sample is nearly 70%. For explanation of our experimental results we made a numerical model of dynamic hologram in fullerene-containing media taking into consideration amplitude and phase grating forming during the pulse length. Our model showed good agreement with experimental results.

Dynamic hologram recording for extra-efficient optical limiting in C60 solutions

The results of experimental and theoretical investigations of dynamic hologram recording and optical limiter improvement in nano-size porous glasses containing fullerene C60 and toluene solution of C60 are presented. TO record a grating with spatial frequency 20 mm-1 we used laser pulses with 18 ns duration and 532 nm wavelength. Initial transmittance of the samples varied from 32 percent to 73 percent. Experiment showed that high diffraction orders appeared during dynamic hologram recording, and if the input intensity increased the number of orders increased, too. Presence of high diffraction orders caused more effective optical limiting because of laser energy redistribution. Taking into consideration different processes including reverse saturable absorption a model of dynamic hologram recording in fullerene solution waw carried out. The result of experiments were analyzed by numerical modeling. Analysis of computations and experimental results showed adequacy of the used model and perspective of applying of dynamic hologram recording in media containing C60 toluene solution for improvement of optical limiting.

Nonlinear optical properties of π-conjugate organic materials: holographic grating recording and optical limiting effect

Nonlinear optical properties of (pi) -conjugated organic systems based on polyimide and 2-cyclooctylamino-5- nitropyridine have been studied. The nano-pulsed Nd lasers for holographic recording and optical limiting experiments has been used as irradiation sources. The drastic change of refractive index in the fullerene-doped structures in comparison with the fullerene-free systems has been observed. The nonlinear coefficients n2 and (chi) (3) for fullerene-doped compounds have been estimated. It has been shown that the fullerene-doped systems could be used as reversible real-time holographic materials and laser nonlinear absorbers with high laser strength.