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.
When liquid crystals are dispersed in an immiscible fluid, microdroplets of liquid crystal are spontaneously formed in a fraction of a second. They have optically anisotropic internal structure, which is determined by the ordering of liquid crystal molecules at the interface. Spherical droplets of a nematic liquid crystal can function as whispering-gallery-mode microresonators with an unprecedented width of wavelength tunability by an electric field. WGM pulsed lasing in dyedoped nematic microdroplets is sensitive to strain, temperature and presence of molecules that change molecular orientation at the interface. Omnidirectional 3D lasing was demonstrated in droplets of chiral nematic liquid crystals that form 3D Bragg-onion resonators. We present recent progress in this field, including electric tuning of 3D lasing from chiral nematic droplets and self-assembly of ferroelectric smectic-C* microdroplets with the onion-Bragg structure. We show that anisotropic fibres could be self-assembled from smectic liquid crystals.