In this review article, we describe the basic principles of random laser operation with particular emphasis on π‐conjugated, dye‐doped and biologically inspired polymers. Random lasers are unusual types of lasers that use disorder in the light amplifying medium to provide positive feedback for laser operation. Organic systems like polymers are affected with disorder resulting both from their molecular structure and fabrication techniques. Due to this fact polymers seem to fit to role of random lasers and now are being extensively studied in this direction. Despite multiline and multidirectional operation polymeric random lasers have potential for several interesting applications. Here we show that they can be successfully applied to sensing in biology and medicine, encoding of information, display technology and search and rescue. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 951–974

This paper presents the structural features of ionic complexes formed by morpholine and metal ions which belong to group VA, namely Sb(III) and Bi(III). A series of target inorganic–organic hybrid compounds of the general formula [NH₂(C₂H₄)₂O]₂MX₅ (where M = Sb, Bi; X = Cl, Br) has been synthesized by incorporating the organic component (morpholine) into the highly polarizable one-dimensional halogenoantimonate(III)/halogenobismuthate(III) chain network. Among the studied compounds, four were found to crystallize in the room temperature phase in the piezoelectric, orthorhombic space group P2₁2₁2₁, Z = 4, the feature being confirmed by the powder second harmonic generation of light and piezoelectric measurements. Dielectric dispersion studies between 200 Hz and 2 MHz disclosed a relaxation process below room temperature well described by the Cole–Cole equation. Based on crystal structures available in Cambridge Structural Database (version 5.32, November 2010) we attempt to show a relationship between the acentric symmetry of compounds and the type of anionic network within the R₂MX₅-subgroup (where R denotes organic cation) of halogenoantimonates(III) and halogenobismuthates(III).

It is well known that addition of a small amount of nanoparticles to liquid crystals may enhance their nonlinear optical properties. To date, in most reports, semiconductor- or metallic-core nanoparticles in LCs have been described. Here, we report on the synthesis of two types of novel nanoparticles based on a cubic siloxane cage (RSiO_3/2)₈, known as polyhedral oligosilsesquioxane (POSS) with the Si–O skeleton surrounded by covalently attached eight groups (R) of azo-benzene mesogenes differing in the length of their aliphatic chains. These dielectric-core nanoparticles substituted with mesogenic groups are well adapted to the calamitic liquid crystal matrix. Azo-benzene units add an important light-driven functionality to the system via their conformational photoisomerisation. We report on the photochromic properties of these new compounds in chloroform. By embedding the nanoparticles in a nematic liquid crystalline matrix, a functional hybrid nanocomposite material has been obtained. Our research was focused on the characterization of the third order nonlinear optical properties in this system linked to photochromism. The experimental results of all-optical switching in an optical Kerr effect configuration are discussed in the framework of light-induced modification of the aliphatic chains containing azo-benzene photoisomerizing moieties and following local director reorientation in nematic liquid crystals. The described properties are useful in the field of real-time holography.