N. V. Kamanina

Mechanisms of optical limiting in fullerene-doped π-conjugated organic structures demonstrated with polyimide and COANP molecules

Possible mechanisms of optical limiting of visible radiation in conjugated organic structures based on polyimides and substituted pyridines sensitized with C60 and/or C70 fullerenes are studied using the Z-scan method. It is shown that reverse saturable absorption, two-photon absorption, and complex formation between the donor fragment of a π-conjugated molecule and fullerene contribute to the processes of nonlinear absorption. The absorption cross sections for excited states of the charge transfer complexes based on polyimide 6B-C70 and 2-cyclooctylamino-5-nitropyridine-C70 systems are calculated. The data obtained are quantitatively interpreted and compared with those provided by alternative methods.

Absorption spectra and optical limiting of the fullerene–polyimide system

Abstract Absorption spectra of the fullerene–polyimide system with various concentrations of fullerene have been investigated. Reverse saturable absorption in this system at different energies of the incident laser beam has been also found.

Reverse saturable absorption in fullerene-containing polyimides. Applicability of the Förster model

Abstract Reverse saturable absorption in systems of polyimide–dye–fullerene and polyimide–fullerene is comparatively investigated. The effect is qualitatively explained on the basis of the Forster mechanism.

Polyimide-fullerene nanostructured materials for nonlinear optics and solar energy applications

Based on the model polyimide systems the principal nonlinear optical features, such as laser induced refractive indices changes, nonlinear refraction and third order susceptibility have been established during their doping with fullerenes, shungites, carbon nanotubes, carbon nanofibers, quantum dots, etc. The evidence of the correlation between laser induced refractive indices and charge carrier mobility has been obtained. The features of new nanocomposites for their possible optoelectronics, laser techniques and solar energy applications have been considered.

Polyimides: new properties of xerographic, thermoplastic, and liquid-crystal structures

Sensitization of various structured polyimides in the wavelength range 400-750 nm has been studied. Injection sensitization with thin films of nanocrystal CdSe, structural-chemical sensitization with active acceptors, as well as spectral sensitization with various dyes have been investigated. It has been concluded that the application of polyimides as a photosensitive medium allows characteristics of numerous devices to be improved.

Recording of thin phase holograms in polymer-dispersed liquid-crystal composites based on fullerene-containing π-conjugated organic systems

The recording of thin phase holograms in promising fullerene-containing, polymer-dispersed liquid-crystal composites based on 2-cyclooctylamino-5-nitropyridine and N-(4-nitrophenyl)-(L)-prolinol using picosecond laser pulses is studied for the first time. The anisotropy of the refractive index substantially increases after laser irradiation and exceeds by a factor of five this anisotropy for liquid-crystal cells containing dyes. The results of our studies suggest that the fullerene-containing, polymer-dispersed liquid-crystal systems can be used as passive media for reversible data recording.

Optical limiting of near-IR radiation in a system based on magnesium phthalocyanine

Nanocrystals of magnesium phthalocyanine in the β-and X-crystalline forms and the magnesium phthalocyanine C60 fullerene system are studied in the near-IR spectral region. The absorption spectra of new nanocomposites are measured. The possibilities of using these systems for optical limiting in the near-IR spectral region (at the wavelength λ=1047 nm) are investigated. The relation between the photoconductivity and nonlinear absorption of phthalocyanine in different crystalline forms is discussed.

Nonlinear optical properties of polymer-dispersed liquid-crystalline systems based on fullerene-doped 2-cyclooctylamino-5-nitropyridine

Holographic recording of thin diffraction gratings by nano-and picosecond laser pulses λ=532 nm) is studied in polymerdispersed liquid-crystalline structures based on photosensitive molecules of 2-cycloocty-lamino-5-nitropyridine sensitized with C70 fullerene. Using experimental data, nonlinear refraction n2 and nonlinear third-order susceptibility χ(3) are calculated for the first time. The obained values determine the potential of the studied media for the modulation and frequency generation of laser radiation in the visible spectral range.

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.

Laser-induced processes in the IR range in nanocomposites with fullerenes and carbon nanotubes

Laser-induced processes in the IR spectral range, which are related to manifestations of the optical limiting in composite systems containing fullerenes and carbon nanotubes (CNTs), have been studied. Organic materials based on polyimides (PIs), 2-cyclooctylamine-5-nitropyridine (COANP), polyanilines, and dispersed liquid crystal (LC) structures were used as nanoparticle-sensitized matrices. Manifestations of optical limiting in the IR range at 1047, 1080, 1315, and 2940 nm are demonstrated and the position of composites studied among other systems used for optical limiting in the IR range is determined. The optical limiting at 1080 nm in CNT-containing solutions and LC cells was studied and the levels of limiting in thin-film PI-based nanocomposites with CNTs are established. A microscopic examination of thin PI films with CNTs revealed the structure of quasi-photonic crystals formed in these systems.