Study On Manufacture And Properties Of Liquid Crystal Random Laser

Liquid crystal random laser regard dye-doped liquid crystal as the scattering media,light multiple scattering provides optical feedback.As a kind of new-type micro-cavity laser,Because of its special structure and excitation mechanism,liquid crystal random laser has many advantages of simple structure,lower threshold value,widely emission wavelength.Therefore,liquid crystal random laser has a wide application prospects in the filed of micro-size light source and biological and medical,etc.In this article,we characterized properties of random laser in both theoretical analysis and experiment.The doped one dye polymer dispersed liquid crystal laser,the doped various dye polymer dispersed liquid crystal laser and the photonic optical fiber laser filled with chiral nematic liquid crystal were designed and manufactured.A plurality of stability random laser emission is realized.The emission characterized properties of device were researched.The mixture of laser dye PM597 doped chiral nematic liquid crystal,polyvinyl alcohol solution were used to prepare polymer dispersed liquid crystal(PDLC)film by the method of microcapsule.By controlling the mixing speeds,the distribution of liquid crystal droplet with small size(30-40?m)can be realized.Regard laser as the pumping source,a plurality of discrete and sharp random laser radiation peak can be measured in the range of 575-590 nm.The line-width of the multi-mode peaks is 0.2nm and the energy threshold is 9mJ.The laser radiation peaks were disappeared with the increase of temperature.That is due to the liquid crystal exhibit anisotropy at high-temperature.The tuning output of random laser emission intensity was realized,that displays temperature controlling characteristic.In order to expand the wavelength range of random laser,laser dye PM597 and DCM were selected to prepare the polymer dispersed liquid crystal film with two kind of laser dye.The fluorescence peak of laser dye PM597 and DCM in different location,therefore,the wavelength of laser output were difference.Comparison with doped one dye polymer dispersed liquid crystal films,the polymer dispersed liquid crystal film of doped different types of laser dye is possible to achieve broad band random lasing.Selecting total internal reflection photonic crystal fiber,which has the transmission characteristic of endlessly single-mode guidance and filling the air hole of photonic crystal fiber with PM597 dye-doped chiral nematic liquid crystal.Due to the helical structure of chiral nematic liquid crystal,the closed micro cavity can be formed by the process of light multiple scatting to provide resonant feedback.A plurality of random laser radiation peak can be measured in the range of 600nm-650 nm.In order to study the temperature controlling characteristic of random laser,by controlling the temperature of the device.The chiral nematic liquid crystal as a strong scattering medium exhibits different molecular orientation and refractive index distribution,it has attracted the intensity change of random laser emission peaks lead to disappearance of random laser.