New polyurethane based push-pull chromophores functionalised polymers for NLO applications

A series of new polyurethane based homopolymers were synthesised and were tested for their second-order nonlinear optical properties. The polymers are well soluble in solvents such as DMF, NMP and show an ability to form good optical quality thin films by solution cast. The absorption band of these polymers is located around 450 - 500 nm. The active chromophores were oriented by static field poling. As an example, the variation of optical absorption spectrum is shown during the corona poling. The decrease of optical density of this polymer, the largest obtained after 10 min., is a finger print of the orientation of chromophores. The amount of polar order as well as the kinetics of poling and relaxation were studied by in situ second harmonic generation technique at different temperatures and the obtained results are presented and discussed. Also the linear optical properties of these films, such as refractive index determined by the m-lines techniques are presented and discussed.