Optical control of plasmonic heating effects using reversible photo-alignment of nematic liquid crystals

We demonstrate and characterize an optical control of theplasmonic heat delivered by a monolayer substrate of gold nanoparticles, obtained by modulating the effectiverefractive index of the neighboringdielectric medium. The effect, which exploits the dependence of thenematic liquid crystal(NLC)refractive index on the molecular director orientation, is realized by using apolarization dependent, light-induced molecular reorientation of a thin film of photo-alignment layer that theNLC is in contact with. For a suitable alignment,plasmonic pumping intensity values ranging from 0.25 W/cm2 to 6.30 W/cm2 can induce up to 17.4  °C temperature variations in time intervals of the order of seconds. The reversibility of the optically inducedNLC molecular director orientation enables an active control of theplasmonic photo-induced heat.

Source: Applied Physics Letters - November 8, 2016 Category: Physics Authors: Giovanna Palermo, Ugo Cataldi, Luciano De Sio, Thomas B ürgi, Nelson Tabiryan and Cesare Umeton Source Type: research