This study of the molecular response of a variety of push-pull organic compounds offers a starting point for macroscopic-scale investigation of azobenzene-based liquid crystalline polymeric films and their blends with highly efficient NLO chromophores.

Nonlinear optical (NLO) phenomena such as frequency conversion have played a key role in the development of photonic technologies. This thesis reports a detailed study of the molecular response of a large variety of push-pull organic compounds using the Second Harmonic Generation technique, which will serve as a starting point for the investigation at the macroscopic scale of azobenzene-based liquid crystalline polymeric films and their blends with highly efficient NLO chromophores. These materials are designed with the aim of exploiting their photoadressability in order to tailor their nonlinear behaviour. The magnitude and symmetry of their NL response was successfully controlled via light irradiation and thermal treatments. Moreover, as a specific application, the recording of efficient NLO gratings was achieved.

This book explores functional polymers containing aromatic azo chromophores in side-chain, main-chain and other parts of their structures, known as azo polymers and which share common photoresponsive properties. It focuses on the molecular architecture of azo polymers, the synthetic methods and their most important functions, such as photoinduced birefringence and dichroism, surface-relief-grating (SRG) formation, and light-driven deformation of liquid crystal elastomers. It combines a general survey of the subject and in-depth discussions of each topic, including numerous illustrations, figures, and photographs. Offering a balance between an introduction to the core concepts and a snapshot of hot and emerging topics, it is of interest to graduate students and researchers working in this and related fields. Xiaogong Wang is a Professor at the Department of Chemical Engineering, Tsinghua University, China.

The photochemical and thermal cis to trans isomerization of aromatic azo groups covalently bonded within polymers and its practical consequences as well as some other recent applications are reviewed. The kinetics and mechanism of the isomerization of azo polymers are briefly presented and then several recent developments in azo polymers research are discussed. They include liquid crystallinity, nonlinear optical properties, monolayer assemblies and the light induced birefringence and dichroism. Some of the phase transitions of liquid crystalline azo polymers can be induced photochemically by the azo groups isomerization. Second order optical nonlinearity can be obtained in polymers with donor and acceptor substituted azo groups. Using the Langmuir-Blodgett technique, azo polymer monolayers can be built and used as 'command surfaces' of liquid crystal films. The light induced birefringence is a reorientation phenonmenon which is a consequence of the trans-cis-trans isomerization. Future possible applications for a variety of practical devices, such as display devices, optical modulators, optical waveguides, holography, and reversible optical storage are mentioned. Azo polymers, Review, Optoelectronic and photonic applications.

This book offers a complete overview of photonic-enhanced materials from material development to a final photonic biomedical application. It includes fundamental, applied, and industrial photonics. The authors cover synthesis, the modification and the processing of a variety of (bio)polymers including thermoplasts (e.g. polyesters) and hydrogels (e.g. proteins and polysaccharides) for a plethora of applications in the field of optics and regenerative medicine.