Liquid-crystal long-range plasmonic switcher

Plasmonic stripe waveguides have been proposed as a platform for inter-chip photonic interconnects, owing to their ease of fabrication, relatively low propagation losses, and the potential for dynamic tuning of the propagating signal [1]. Contrary to established approaches based on thermal tuning [2], we design and study optical switches based on long-range plasmonic couplers controlled via the electro-optic effect of nematic liquid crystal layers. The switching dynamics of the nematic molecules are solved taking into account the coupling between the elastic and electrostatic underlying problems [3]. Optical waveguiding properties are calculated by a fully-anisotropic finite-element-method, and light propagation is modeled via the eigenmode- expansion method. We assess the performance of both coplanar horizontal [4] and stacked vertical [5] configurations providing a comparison in terms of coupling length, switching voltage, insertion losses, and crosstalk, as shown in Figure 1. The plasmonic waveguiding stripes are used as electrodes, thus minimizing the applied control voltage. In both cases, efficient switching is demonstrated at millimeter-scale component lengths, with sub-?W switching powers. These tunable devices are envisaged as ultra-low power switches in integrated platforms for optical inter-chip interconnects.