Comptes rendus de l’Acad´ emie bulgare des Sciences PHYSIQUE Physique des solides SELECTIVE AMPLITUDE-FREQUENCY ELECTRO-OPTICAL MODULATION BY POLYMER-DISPERSED LIQUID CRYSTAL FILMS ALIGNED BY TEFLON NANOLAYERS Yordan G. Marinov, Georgi B. Hadjichristov, Alexander G. Petrov, Salvatore Marino * , Carlo Versace ** , Nicola Scaramuzza ** (Submitted on February 1, 2013 ) Abstract We report the amplitude-frequency electro-optical (EO) modulation by a specific type of polymer-dispersed liquid crystal (PDLC) composites – planar single layers of large nematic microdroplets aligned by teflon nanolayers. Such a surface modifying PDLC system exhibits a selective modulated 2nd harmonic EO response by the dielectric oscillations of the nematic director. The band- like behavioural characteristic of the amplitude-frequency modulation of light, achieved by the single-layered PDLC films, can be tuned by AC voltage applied on the PDLC cell. This property can be applied to tunable EO modulators operating in the infrasound frequency range. Key words: polymer dispersed liquid crystal (PDLC), PDLC films, single layers, electro-optical properties, amplitude-frequency modulation Pacs number: 61.30.Pq 1. Introduction. Due to their attractive electro-optical (EO) properties, the polymer-dispersed liquid crystal (PDLC) composite films [ 1 ] are currently applied as smart EO materials in switchable glasses [ 2,3 ], for displays [ 4 ] and devices for active control of light [ 5,6 ]. Single-layered PDLC films consisting of large microdroplets of liquid crystal (LC) disposed in an optically-transparent polymer matrix have also found advanced EO applications [ 7–10 ]. This study was supported by a joint project between CNR (Italy) and BAS (Bulgaria). 819