Upon S 0 −S 1 excitation, the pyrazoline derivative molecule (Z)-2-(4-nitrophenyl)-3-(1-phenyl-4,5-dihydro-1H-pyrazol-3-yl)acrylonitrile, abbreviated as PY-oCNNO 2 , can be transformed from its ground state trans (E) form to bended cis (Z) form. Similar to the case of the well-known family of the photochromic azobenzenes, such a molecular property can be employed to fabrication of photochromic polymers by suitable doping of the chromophores into polymer matrix. In this work, we prepared poly(methyl methacrylate) thin films doped with PY-oCNNO 2 and measured the characteristic for optical switchers dynamic and static photoinduced birefringence (PIB) phenomenon. Possible conformational states of PY-oCNNO 2 , energy barriers, and associated dipole moments were calculated using TD-DFT quantum chemical methods. The presented experiments show that pyrazoline derivatives constitute a prospective group of materials with a great potential for photonic applications.

Discovery of E/Z or trans-cis photoisomerization in the azobenzenes and their derivatives had the tremendous impact on the whole domain of photochromic materials including photochromic polymers and liquid crystals. Here we show similar configurational photoinduced transformation in a simple derivative of pyrazoline. The X-ray crystallographic investigations of (E)-3-(4-nitrostyryl)-1-phenyl-4,5-dihydro-1H-pyrazole (abbreviated as PYpNO 2 ) in grown crystals show two different structures comprising of either cis or trans molecules. The performed quantum chemical calculations confirm the existence of both configurations of PY-pNO 2 at the room temperature. Photophysical properties of this compound derived from quantum chemical calculations predict possibility of trans to cis switching of PY-pNO 2 by light. Indeed, molecules of PY-pNO 2 embedded in PMMA polymeric matrix when illuminated with 532 nm linearly polarized laser light show the induced optical anisotropy, i.e. birefringence characteristic for photoisomerizable molecules similar like in the group of the azobenzene derivatives.

In this letter we present the results of studies carried out on poly(n-vinylcarbazole) doped with the well-known DCM laser dye. We show that the simple incorporation of highly luminescent dye into a polymeric matrix can form an efficient solid state laser material. Naturally occurring inhomogeneities of a polymeric layer prepared by a drop casting process can scatter out light emitted in the process of photoluminescence in such a way that feedback is introduced to the system and coherent and incoherent random lasing can be observed. Moreover we show that after a nano-scale rubbing process the random lasing phenomenon occurs for a lower energy density of pumping light as compared to the virgin sample, and changes the light amplification nature from incoherent to coherent.

Room-temperature nanoimprinted, DNA-based distributed feedback (DFB) laser operation at 605 nm is reported. The laser is made of a pure DNA host matrix doped with gain dyes. At high excitation densities, the emission of the untextured dye-doped DNA films is characterized by a broad emission peak with an overall line width of 12 nm and superimposed narrow peaks, characteristic of random lasing. Moreover, direct patterning of the DNA films is demonstrated with a resolution down to 100 nm, enabling the realization of both surface-emitting and edge-emitting DFB lasers with a typical line width of <0.3 nm. The resulting emission is polarized, with a ratio between the TE- and TM-polarized intensities exceeding 30. In addition, the nanopatterned devices dissolve in water within less than 2 min. These results demonstrate the possibility of realizing various physically transient nanophotonics and laser architectures, including random lasing and nanoimprinted devices, based on natural biopolymers.