Effect of Sulfonic Groups Concentration on IEC Properties in New Fluorinated Copolyamides.

Seven aromatic polyamides and copolyamides were synthesized from two different aromatic diamines: 4,4'-(Hexafluoroisopropylidene)bis(p-phenyleneoxy)dianiline (HFDA) and 2,4-Aminobenzenesulfonic acid (DABS). The synthesis was carried out by polycondensation using isophthaloyl dichloride (1SO). The effect of an increasing molar concentration of the sulfonated groups, from DABS, in the copolymer properties was evaluated.

Experimental investigation of the nonlinear optical loop mirror with twisted fiber and birefringence bias.

We examine the transmission characteristics of a NOLM device using a symmetrical coupler, highly twisted fiber, and a quarter-wave (QW) retarder plate introducing a polarization asymmetry in the loop. We demonstrate high dynamic range with controllable transmissivity, and good stability over long times. We experimentally study the transmission behavior for different input polarization states and distinguish between different polarization components of the output beam.