Random lasers in dye-doped polymer-dispersed liquid crystals containing silver nanoparticles

We report on the observation of random lasers for the first time in dye-doped polymer-dispersed liquid crystals (PDLCs) containing nano-sized liquid crystal droplets and silver nanoparticles. The dye-doped polymer-dispersed liquid crystal containing silver nanoparticles film is exposed by a collimated 532 nm Nd: YAG (yttrium aluminum garnet) laser beam, so that it is quickly cured. Under the excitation of a frequency-doubled Nd: YAG (yttrium aluminum garnet) laser operating at a wavelength of 532 nm, random lasing from dye-doped PDLCs containing Ag nanoparticles is observed as a result of cooperative effect due to light scattering of nano-sized liquid crystal droplets and the local field enhancement capabilities around silver nanoparticles. We show that the threshold of the random lasing is about 0.95μJ/pulse which is lower than the lasing threshold of dye-doped polymer-dispersed liquid crystals containing nano-sized liquid crystal droplets. The linewidth of the lasing peaks is shown to be 0.2 nm. We also propose a possible mechanism to explain the random lasing from dye-doped polymer-dispersed liquid crystals containing silver nanoparticles.