Polymer dispersed liquid crystal structure for variable optical attenuator application
Résumé
To improve variable optical attenuator (VOA) performance, the object of this study is to know the most appropriate structure of a polymer-dispersed liquid crystal (PDLC) composite. In fact, using its electro-optical properties, PDLC can be inserted between two optical fibers for adjusting the coupling efficiency. We utilize here the photopolymerization-induced phase separation (PIPS) method as a fabrication process. Furthermore, we present a theoretical analysis of light scattering by anisotropic spheres based on the anomalous diffraction approach (ADA) and compare this model with some experimental results. The optical attenuation (OA) range is optimized in the case where LC, the droplets nematic directors, are randomly oriented. If the nematic directors have a quasiprivileged direction, we demonstrate that PDLC transmission depends on the incident light polarization. Polarization-dependent loss (PDL) and OA behaviors are then studied at the 1.55-μm wavelength according to several parameters such as PDLC thickness, LC droplet size, and the device driving voltage.