Mechanically tunable microlasers based on highly viscous chiral liquid crystals

Abstract

Chiral composition is designed for highly viscous lasing microemitters. The composition forms cholesteric liquid crystal and after doping with pyrromethene 597 was used as an active lasing media in stretchable aluminized silicone cavities. Optical pumping of the system led to lasing at the wavelengths defined by a degree of cavity deformation. Lasing thresholds were lower in aluminized cavity than in transparent cavity. A simple model allowing to predict the shift of lasing wavelength as a function of deformation is developed.

High Optical Quality Films of Liquid Crystalline Cellulose Derivatives in Acrylates

“…Most of the reported optical properties of cholesteric lyotropics based on polymers are similar to those shown in this paragraph . A low reflectance intensity perpendicular to the film, reduced transmittance values outside of the bandgap and broad bandwidths of the PBG are caused by the low quality of alignment of the liquid crystals (LC).…”

“…We assume that a poor mesogen and helix alignment are the reason for these poor optical properties, in contrast to their low molar mass counterparts, where numerous methods are reported for maximum optical quality . On the other side, cholesteric films from poly­meric materials are very interesting because of the stability of their cholesteric structure, for example, as feedback materials for cholesteric lasers . This application is, however, limited so far by their poor optical quality .…”

Distant mechanical sensors based on cholesteric liquid crystals

“…Recently, a gigantic shift of the SRB was achieved in highly viscous cholesteric liquid crystals placed between two flat silicone strips and stretched. [6][7][8][9] This system was shown also to exhibit lasing. 8,9 The major difference of such a system from cholesteric elastomers is the absence of crosslinks between molecules of cholesteric liquid crystals and the commercial availability of silicone monomers.…”

“…[6][7][8][9] This system was shown also to exhibit lasing. 8,9 The major difference of such a system from cholesteric elastomers is the absence of crosslinks between molecules of cholesteric liquid crystals and the commercial availability of silicone monomers. Moreover, a high viscosity of the CLC (5 Â 10 2 -5 Â 10 3 Pas) 6 leads to a low relaxation rate of cholesteric pitch, proportional to K cP ¼ 10 À7 À 10 À6 m/s (we used K ¼ 10 À11 N and helical pitch P ¼ 600 nm).…”

“…% of a cholesteric mixture containing 50% of cholesterol oleate and 50% of cholesteryl chloride (Sigma-Aldrich Co.) (see Ref. 9 for chemical structures of liquid crystalline compounds).…”