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Registration Number

0215U003165, 0113U005548 , R & D reports

Title

The influence of boundary conditions and selective irradiation on the characteristics of generations doped cholesteric liquid crystals.

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Head

Mykytiuk Taras Volodymyrovych,

Registration Date

23-01-2015

Organization

Institute of physics NASU

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Аn object of the researches are cholesteric liquid crystals (CLC) which are activated by organic dyes. They can be induced CLC made by twisting admixture introduction into nematic, and steroid that is a mixture of cholesterol esters, a research purpose is the optimization of threshold and spectral characteristics of lasing impurity induced CLC at reversing rebuild its frequency by selective irradiation with light of a narrow spectral range; improvement of reversible photo-tuning frequency lasing method in induced CLC for minimum rebuild time production in both directions; study the differences in spectral and spatial characteristics of lasing in steroid CLC depending on the relative orientation of the directors of the liquid crystal on the substrate, methods of researches and apparatus are optical spectroscopy, including polarization, laser spectroscopy, theoretical and practical results are: Have been applied new liquid crystal materials and methods of selective excitation photo-isomer forms of cholesteric liquid crystal molecules which led to the improvement in their planar texture. By-turn this is led to a reduction of the lasing threshold. Modified method of CLC irradiation induced with reciprocating photo-tuning frequency lasing light by using a narrow spectral range for the best excitation photo-isomer forms of liquid crystal molecules. Have been set up the optimal conditions for the implementation of the minimum time frequency tuning lasing of induced CLC and its minimum threshold; The new method of effectively photo-tuning frequency lasing in doped CLC which are formed on the base of mixtures of azo- and azoxy-photosensitive components of the liquid crystal by changing the pitch of the helix upon irradiation with light of different wavelengths. It has been established that in such materials sharply falls fluorescence quantum yield for the generation of most dyes in concentrations of 0.3-0.5% by weight. It prevents from obtaining lasing in them; It is shown that in the absence of a significant transfer of excitation energy from the dye molecules to molecules of chiral impurity in CLC based on the highly photosensitive swirl azo-impurity Li -7 have been achieved fairly low lasing threshold. In the application of this impurity induced in CLC have been improved temporal characteristics photo-tuning lasing and have been received reverse rebuild of its frequency in the range of ~ 30 nm. Have been obtained the reduction of 3 orders of magnitude (up to 148 ms) time of photo-tuning lasing at 21 nm; Have been researched the characteristics of generation in CLC lasers with parallel and perpendicular orientation of the director at the orienting substrates and the possibility of improving the spectral characteristics of the laser at a mutually perpendicular orientation of the directors on the orienting substrates. Novelty - a new method of efficient frequency photo-tuning lasing in doped CLC based on the mixtures of azo- and azoxy-photosensitive components of the liquid crystal by changing the pitch of the helix upon irradiation with light of different wavelength. Effectiveness of implementation - has not been implemented yet; sphere (industry) of application - Laser and Optoelectronics.

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Микитюк Тарас Володимирович

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2020-04-02