RESUMO
A new tuning strategy for mirror-less liquid crystals laser is presented. A three layer cell is prepared with two cholesteric layers sandwiching a layer containing an isotropic mixture of a photoluminescent dye. One of the chiral layers contains a wide band gap material while the second layer consists of a series of small band gap materials. Through the combination of these two layers, a set of mirrors that can selectively reflect different wavelengths is obtained. A different laser wavelength is emitted from different regions of the cell under the pumping beam irradiation.
RESUMO
A new electro-optic effect in an optically active nematic chiral structure beyond Mauguin's region has been studied. The effect is revealed in the absence of oscillations of the transmission-voltage curve, low requirements for orienting surfaces, and the ability to function at any direction of polarization of incident light. The limit relationships among wavelength, helical path, and optical anisotropy of the nematic matrix are determined. The dispersion properties of the effect are studied, and the possibility of its application for white-light modulation is shown as well. The control voltage is 6 V, and the time of switching is 50 µs.