Nano-structured liquid crystal waveguides for optofluidic applications

We present light propagation in channel waveguides whose core consists of liquid crystals (LC) infiltrated in poly(dimethylsiloxane) (PDMS) channels (LC:PDMS waveguides) for potential optofluidic reconfigurable microsystems. Modeling, fabrication process steps, and optical characterization are described. Despite the intrinsic optical anisotropy of LC molecules, which induce polarization dependent optical propagation, experimental results on LC:PDMS optical channels show polarization independent optical transmission. We show that this is due to the molecular orientation of LC molecules induced by the interface interaction of the elongated shape of rod-like LC molecules with PDMS surfaces. To get a better explication of this system we present a detailed investigation of the cell by means of the Monte Carlo simulations, which allow to reproduce not only polarized optical images but also the molecular organization and the ordering inside the LC system. LC:PDMS waveguides can be envisaged as part of flexible photonic circuits.