A dye-doped polymer-dispersed liquid crystal film was designed and fabricated,and random lasing action was studied.A mixture of laser dye,nematic liquid crystal,chiral dopant,and PVA was used to prepare the dye-doped ...A dye-doped polymer-dispersed liquid crystal film was designed and fabricated,and random lasing action was studied.A mixture of laser dye,nematic liquid crystal,chiral dopant,and PVA was used to prepare the dye-doped polymer-dispersed liquid crystal film by means of microcapsules.Scanning electron microscopy analysis showed that most liquid crystal droplets in the polymer matrix ranged from 30 μm to 40 μm,the size of the liquid crystal droplets was small.Under frequency doubled 532 nm Nd：YAG laser-pumped optical excitation,a plurality of discrete and sharp random laser radiation peaks could be measured in the range of 575–590 nm.The line-width of the lasing peak was 0.2 nm and the threshold of the random lasing was 9 m J.Under heating,the emission peaks of random lasing disappeared.By detecting the emission light spot energy distribution,the mechanism of radiation was found to be random lasing.The random lasing radiation mechanism was then analyzed and discussed.Experimental results indicated that the size of the liquid crystal droplets is the decisive factor that influences the lasing mechanism.The surface anchor role can be ignored when the size of the liquid crystal droplets in the polymer matrix is small,which is beneficial to form multiple scattering.The transmission path of photons is similar to that in a ring cavity,providing feedback to obtain random lasing output.展开更多
This paper investigates the monomer kinetics of polymer dispersed liquid crystal （PDLC） grating. Fourier transform infrared （FTIR） spectra are used in the studies of photoreaction kinetics. The results indicate th...This paper investigates the monomer kinetics of polymer dispersed liquid crystal （PDLC） grating. Fourier transform infrared （FTIR） spectra are used in the studies of photoreaction kinetics. The results indicate that there is a relative stable stage arises after a very short initial stage. Based on FTIR studies, the monomer diffusion equation is deduced and necessary numerical simulations are carried out to analyse the monomer conversion which is an important point to improve phase separation structure of PDLC grating. Some simulation results have a good agreement with experimental data. In addition, the effects induced by monomer diffusion constant D and diffusion-polymerization-ratio rate R are discussed. Results show that monomer conversion can be improved by increasing value of D. Besides, a good equilibrium state （R = 1） is more beneficial to the diffusion of monomer which is important in the process of phase separation.展开更多
In this paper, we demonstrate an alternative approach to fabricating an electrically tunable holographic polymer tem- plated blue phase liquid crystal grating. This grating is obtained by preforming a polymer template...In this paper, we demonstrate an alternative approach to fabricating an electrically tunable holographic polymer tem- plated blue phase liquid crystal grating. This grating is obtained by preforming a polymer template comprised of periodic fringes, and then refilling it with a blue phase liquid crystal. Compared with conventional holographic polymer dispersed liquid crystal gratings, our grating can remarkably reduce its switching voltage from 200 V to 43 V while maintaining a sub-millisecond response time. The holographic polymer templated blue phase liquid crystal （HPTBPLC） grating is free from electrode patterning, thus leading to a lower cost and more flexible applications.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.61378042)the Colleges and Universities in Liaoning Province Outstanding Young Scholars Growth Plans,China(Grant No.LJQ2015093)Shenyang Ligong University Laser and Optical Information of Liaoning Province Key Laboratory Open Funds,China
文摘A dye-doped polymer-dispersed liquid crystal film was designed and fabricated,and random lasing action was studied.A mixture of laser dye,nematic liquid crystal,chiral dopant,and PVA was used to prepare the dye-doped polymer-dispersed liquid crystal film by means of microcapsules.Scanning electron microscopy analysis showed that most liquid crystal droplets in the polymer matrix ranged from 30 μm to 40 μm,the size of the liquid crystal droplets was small.Under frequency doubled 532 nm Nd：YAG laser-pumped optical excitation,a plurality of discrete and sharp random laser radiation peaks could be measured in the range of 575–590 nm.The line-width of the lasing peak was 0.2 nm and the threshold of the random lasing was 9 m J.Under heating,the emission peaks of random lasing disappeared.By detecting the emission light spot energy distribution,the mechanism of radiation was found to be random lasing.The random lasing radiation mechanism was then analyzed and discussed.Experimental results indicated that the size of the liquid crystal droplets is the decisive factor that influences the lasing mechanism.The surface anchor role can be ignored when the size of the liquid crystal droplets in the polymer matrix is small,which is beneficial to form multiple scattering.The transmission path of photons is similar to that in a ring cavity,providing feedback to obtain random lasing output.
基金supported by Natural Science Foundation of China (Grants Nos 60578035 and 50473040)Science Foundation of Jilin Province,China (Grant Nos 20050520 and 20050321-2)
文摘This paper investigates the monomer kinetics of polymer dispersed liquid crystal （PDLC） grating. Fourier transform infrared （FTIR） spectra are used in the studies of photoreaction kinetics. The results indicate that there is a relative stable stage arises after a very short initial stage. Based on FTIR studies, the monomer diffusion equation is deduced and necessary numerical simulations are carried out to analyse the monomer conversion which is an important point to improve phase separation structure of PDLC grating. Some simulation results have a good agreement with experimental data. In addition, the effects induced by monomer diffusion constant D and diffusion-polymerization-ratio rate R are discussed. Results show that monomer conversion can be improved by increasing value of D. Besides, a good equilibrium state （R = 1） is more beneficial to the diffusion of monomer which is important in the process of phase separation.
基金Project supported by the National Basic Research Program of China(Grant No.2013CB328804)the National Natural Science Foundation of China(Grant No.61307028)+1 种基金the Funds from the Science and Technology Commission of Shanghai Municipality(Grant Nos.11JC1405300,13ZR1420000,and14ZR1422300)the Fundamental Research Funds for the Central Universities,China(Grant No.XDJK 2011C047)
文摘In this paper, we demonstrate an alternative approach to fabricating an electrically tunable holographic polymer tem- plated blue phase liquid crystal grating. This grating is obtained by preforming a polymer template comprised of periodic fringes, and then refilling it with a blue phase liquid crystal. Compared with conventional holographic polymer dispersed liquid crystal gratings, our grating can remarkably reduce its switching voltage from 200 V to 43 V while maintaining a sub-millisecond response time. The holographic polymer templated blue phase liquid crystal （HPTBPLC） grating is free from electrode patterning, thus leading to a lower cost and more flexible applications.
