Electric field tuning of ferroelectric liquid-crystal microlaser

Abstract

We discuss the electric field tuning of ferroelectric liquid crystal microlasers. The microlasers were made of 90:10 wt % mixture of CE3 and CE14 ferroelectric liquid crystals (FLCs), which was doped with ~0.1% Pyrromethene 580 fluorescent dye. The ferroelectric Sm C* phase was observed between 42°C and 74°C. The droplets were embedded into the CYTOP CTX-809A, a polymer with low electric conductivity and high viscosity. Within the temperature range 42-60°C the droplets obtained good homeotropic structure with the perpendicular anchoring of the molecules to the surface of the droplets. When the droplets were illuminated with a 532 nm pulsed laser light, Whispering Gallery Mode lasing was observed. The application of a low frequency electric field induced a red-shift of the WGM resonance peaks. The shift was reversible and had a quadratic dependency on the electric field. The observed tuning range was 4.5 nm for 2 V/μm applied electric field. The observed behaviour is explained by the soliton-like deformation of the helical ferroelectric Sm C* structure in an external electric field.