Remi Meyrueix

Fabry-Pérot interferometry applied to the study of piezoelectric and electro-optical properties of a poled NLO polyurethane

Abstract An improved Fabry-Perot interferometric technique for the in situ measurement of electrooptical coefficients, piezoelectric coefficient and birefringence of nonlinear optical (NLO) polymer films has been developed. The measurements can be done conveniently on polymer films maintained under inert gas or vacuum and at temperatures up to 200°C. The technique has been applied to the characterisation and disorientation study of an inhouse synthesised azo dye-containing polyurethane exhibiting a glass transition temperature at 143°C and having an electrooptical coefficient r 33 of 18 pm/V at 830 nm after poling under 100 V/μm. The uncertainty on the electrooptical coefficients was found to be 4% on r 13 and 8% on r 33 but raises up to 25% for the piezoelectric coefficient d which is negative and about 10% of r 33 . For poling fields E p less than 50 V/μm, r 13 , r 33 and d vary linearly with E p but r 33 increases more than linearly for higher poling fields. The ratio r 33 / r 13 is greater than 3 and raises up to 5 after poling under 120 V/μm. The rate of disorientation of the chromophores in the polymer matrix at elevated temperatures follows approximately stretched exponentials and is weakly dependent on the poling field in the range 25–92 V/μm. Our experimental results are compared to values deduced from various theoretical models such as the isotropic and the Van der Vorst-Picken models. None of them are entirely satisfactory.

Nonlinear optical polyurethane and crosslinked bismaleimide network with exceptional thermal stability

After briefly introducing a modified Perot Fabry technique which enables to differentiate the true purely electronic Pockel effect from the piezoelectric induced electro-optic effect, we discuss the Electro Optical (EO) properties of a thermoplastic polymer and of a bismaleimide- based crosslinked network. Both polymers have large EO coefficients. However, the ratio R equals r33 / r13 is greater than predicted by the isotropic model. Values as high as 6.5 are observed in the crosslinked network. In the case of the thermoplastic polymer, the stability of the oriented chromophore is good up to 100

Decay of the nonlinear susceptibility components in main-chain functionalized poled polymers

DEGC and disorientation is fitted reasonably well with a stretched exponential.

Dielectric characterization of nonlinear optical polymers

The simultaneous measurement of the xxz and zzz components of the quadratic susceptibility of Non Linear Optical functionnalized polymer films is performed by Fabry Perot under Oblique Incidence technique.Precise results are obtained without any accurate knowledge of the complex dielectric constant and the thickness of each layer.The deorientation of a non linear optical unit is compared in three main chain functionnalized polyurethanes at a constant difference of temperature below the glass transition temperature. Independently of the absolute value of the Tg, the rate of deorientation is very dependant of the monomer structure.

Synthesis and Self-Assembly Properties of Peptide−Polylactide Block Copolymers

Two nonlinear optical polymers, containing the active molecules in the main-chain and in the side-chain, have been characterized by dielectric spectroscopy in the frequency range from 0.05 Hz to 10 kHz. It is shown that dielectric spectroscopy is a powerful technique to monitor the mobility (relaxation) of active molecules. From the results a estimation about the poling temperature and -time can be made. In addition, the influence of absorbed water on the relaxation is established as well as the effect of UV-light exposure on the chromophores.