title: Photochromic Composite for Random Lasing Based on Porous Polypropylene Infiltrated with Azobenzene-Containing Liquid Crystalline Mixture.
abstract: We report on a new low-cost and easily fabricated type of liquid crystalline polymer composites demonstrating low threshold random lasing, which can be used as a cheap and simple mirror-less laser source. The composite is based on mass-producible commercially available porous polypropylene (Celgard 2500) infiltrated with low-molar-mass liquid crystal material doped with Rhodamine 800 laser dye. Excitation with red nanosecond laser (630 nm) induces random lasing with the emission peak in NIR spectral range (804 nm) with noticeable degree of linear polarization. The possibility to control the lasing threshold and polarization of the output light with UV radiation through photoswitching of liquid crystal phase from nematic to isotropic is demonstrated. The photocontrollable phase switching is achieved by reversible E/Z isomerization of the azobenzene dopant introduced to the nematic host matrix. It is revealed that the isotropic state of liquid crystal provides more efficient random lasing with lower threshold due to significant scattering of the ordinary wave.
authors.affiliation: Technical University of Applied Sciences Wildau , Hochschulring 1, 15745 Wildau, Germany.
authors.forename: Victor
authors.initials: V
authors.lastname: Lisinetskii
authors.affiliation: Fraunhofer Institute for Applied Polymer Research , Geiselbergstr. 69, 14476 Potsdam-Golm, Germany.|Faculty of Chemistry, Moscow State University , Leninskie Gory, 119991 Moscow, Russia.
authors.forename: Alexander
authors.initials: A
authors.lastname: Ryabchun
authors.affiliation: Faculty of Chemistry, Moscow State University , Leninskie Gory, 119991 Moscow, Russia.
authors.forename: Alexey
authors.initials: A
authors.lastname: Bobrovsky
authors.affiliation: Technical University of Applied Sciences Wildau , Hochschulring 1, 15745 Wildau, Germany.
authors.forename: Sigurd
authors.initials: S
authors.lastname: Schrader
keywords: light scattering; liquid crystal; liquid crystal alignment; porous polypropylene; random lasing