Search academic texts

Information × Registration Number 0213U001370, 0111U007086 , R & D reports Title Reversible phototuning of lasing frequency in a dye-doped cholesteric liquid crystal. popup.stage_title Head Mykytiuk Taras Volodymyrovych, Registration Date 30-01-2013 Organization Institute of physics NASU popup.description2 The object of researches is cholesteric liquid crystals activated by organic dyes. The aim of research is the optimization of characteristics of a phototuning of frequency of generation in lasers on the dye-doped cholesteric liquid crystals (CLC) which consists in expansion of range of a phototuning of frequency, decrease of threshold power of a pumping and narrowing of a strip of laser generation. Мethods of researches and equipment are optical spectroscopy, including polarization, laser spectroscopy. Theoretical and practical results: the optimization of a phototuning of frequency of laser generation in lasers on the cholesteric liquid crystals (CLC) by use of transparent electrodes from SnO2 which caused essential fall of a threshold of laser generation is performed; possibility of use of a nematic of ZhK-654 for laser creation with the distributed feedback with possibility of a phototuning of frequency of laser generation is shown; the optimum structure of nematic ZhK-654 and a twisting additive is selected, and also optimum thickness of planar textures at which low thresholds of laser generation are observed are determined. At research of planar texture of CLC with degenerate orientation of molecules on surfaces of one of substrates reduction of time of a phototuning and an increase of range of a phototuning of pure CLC are observed. Phototuning range in such planar texture at CLC activation by dye remained almost invariable concerning the range of reorganization of standard planar texture. At the same time decaying of quality of textures leads to substantial increase of a threshold of laser generation in it. Using of a nematic of ZhK-654 allowed improving of characteristics of laser radiation considerably. Thanks to the best orientation of such nematic on substrates in comparison with ZhK-440 it was succeeded to receive decrease of a threshold of laser generation by two orders. It was succeeded to expand the range of a phototuning of frequency of generation of the CLC-laser on the basis of ZhK-440 to 43 nanometers. In the opposite direction the phototuning of laser generation doesn't reach the initial value on 10 nanometers. Almost full reversing of range of a phototuning in ZhK-654 nematic is received. The range is amount to 24 nanometers in the short-wave part, and in long-wave - to 21 nanometers. The increase in time and reduction of range of a phototuning are explained by reduction of size of a spiral twisting in comparison with similar size in nematic ZhK-440. Novelty - the practical novelty is development of the laser on the basis of the induced nematic liquid crystals activated by dyes with possibility of a phototuning of frequency of laser generation. Efficiency of application - not prove up to now. A sphere of future application finds in - laser and optronic technique. Product Description popup.authors Микитюк Тарас Володимирович popup.nrat_date 2020-04-02 Close