Tunable Dye-Doped Liquid Crystal/Polymer Laser Devices In Capillaries

Recently,Organic laser based on dye-doped liquid crystal/polymer materials has attracted much attention of people due to their tunability,low cost and simple fabricating procedure,and organic laser has broad application prospects in many areas such as photonic integration,information transmission,and display lighting.The laser dye in the organic laser produces fluorescence after absorbing the energy of pump light,and the fluorescence can gain continuously feedback and amplification in the liquid crystal/polymer materials,which can finally realize the output of the laser.Because liquid crystal molecules can redirect in an external field,which can change the optical properties of them,liquid crystal/polymer laser can be tuned by external stimuli such as electric field,temperature and light irradiation.However,the experiments of optimization and tuning for liquid crystal/polymer laser are mainly carried out in traditional liquid crystal cells,which are not conducive to miniaturization and integration of devices in practical applications.Therefore,in recent years,the miniaturization and integration of liquid crystal laser have been one of the research hotspots.This requires the preparation of liquid crystal laser in different geometric structures to facilitate the integration of devices.In this paper,the preparation of liquid crystal/polymer laser in two-dimensional capillary is mainly studied,and the output characteristics of the liquid crystal laser in the cylindrical structure are analyzed in detail.Also,the principle and mechanism of the laser control process are further analyzed.Firstly,the optical tuning properties for dye-doped polymer dispersed liquid crystal(PDLC)laser has been studied in capillaries.The optical tuning is mainly realized by doping azo dyes in capillary samples.When the intensities of UV irradiation increased,the random laser intensities decayed,and the number of laser peaks also decreased.In the optical tuning process,the polarization direction of random laser is not related to the direction of polarization of UV light.Finally,the heat effect of UV light and pump laser in the optical tuning process is excluded.Then,we also investigated the thermally and optically tunable lasing properties of dye-doped holographic polymer dispersed liquid crystal(HPDLC)in capillaries.Experimental results demonstrate the tailored lasing intensities and center wavelength with various optical and thermal conditions.The lasing intensities changed with the increasing temperature,and the emission center wavelength can be tuned about 8.60nm from 23? to 50?.In the optical tuning process,when the intensity of UV irradiation reached 200 mW/cm~2,the lasing wavelength had a blueshift about 2 nm,coupled with decreasing lasing intensities.Finally,we discussed the relative mechanism of the tunable lasing wavelength and intensity from HPDLC in capillary samples.Furthermore,we studied the influence of silver and zinc oxide nanoparticles on dye-doped polymer stabilized liquid crystal(PSLC)in capillaries.Compared with the zinc oxide nanoparticles,the silver nanoparticles with proper concentration can improve the random laser characteristics significantly.The research of this paper will help to improve the performance of liquid crystal/polymer laser,which can lay the foundation for its more extensive applications.