Study On Manufacture And Properties Of Dye-doping Liquid Crystal Laser Devices

Cholesteric liquid crystal lasers are novel lasers without resonators that use dye-doped cholesteric liquid crystal as a working substance.Because the periodic spiral structure is sensitive to external conditions(temperature,electromagnetic field,etc.),thus it is easy to realize the tuning of the cholesteric liquid crystal laser.In this paper,the radiation characteristics of cholesteric liquid crystal lasers under electric field are studied from both theoretical simulation and experiment.Two theoretical models for the variation of helical structure of cholesteric liquid crystal under transverse electric field are created.The cholesteric liquid crystal lasers with comb-shaped electrodes structure and wedge-shaped electrode structure are respectively designed and manufactured,and the electric field tuning of the laser is realized.Based on the theoretical basis of predecessors and the experimental phenomena,two models are created: the model of pitch contraction when the transverse electric field strength is weak,and the pitch extension model when the transverse electric field strength are strong.Through the combination of the two models and the theory of density of optical states,the radiation characteristics of cholesteric liquid crystal laser under transverse electric field are simulated.A cholesteric liquid crystal laser with a traditional parallel box structure is manufactured and a band-edge lasing is realized.The energy distribution of the laser beam spot is measured.A comb-shaped electrode is obtained by laser etching,and a comb-shaped electrode cholesteric liquid crystal laser device is manufactured.When the voltage is increased from 0 V to 100 V,the wavelength of output laser at the electrode width of 1 mm is found to blue-shift from 633.52 nm to 621.46 nm.In order to obtain the flexible tuning of the wavelength of output laser,two cholesteric liquid crystal lasers with a wedge-shaped electrode structure are manufactured,and that are copper electrode cholesteric liquid crystal laser and wedge-shaped negativecholesteric liquid crystal laser respectively.When the voltage is increased from 0V to60 V,in the electrode width of 600,700,800,900 microns,wavelength of the output laser of the copper electrode cholesteric liquid crystal laser is found to blue-shift16.95 nm,12.64 nm,9.77 nm,6.89 nm respectively.When the voltage is increased from0 V to 60 V,in the thickness of 10 um,20um,30 um,wavelength of the output laser of the wedge-shaped negative cholesteric liquid crystal laser is found to blue-shift18.66 um,9.19 um,3.4um respectively;there was no obvious tuning output at40 um.And wavelength of the output laser moves to the shortwave direction as the wedge cell thickness decreases at the same voltage.