Band-edge-enhanced tunable random laser using a polymer-stabilised cholesteric liquid crystal

Liquid crystal random lasers

“…The tunable lasing wavelength of cholesteric LC lasers is proposed by controlling the reflection band of cholesteric LCs within the excitation fluorescence spectral range. There are various ways to achieve tunable LCRL, e.g., varying temperature, 24,25 voltage, [26][27][28][29][30] composition or cell thickness, 31,32 mechanical strain in cross-linked cholesteric LC elastomers, [33][34][35] or using reversible photochemical reactions. 36,37 Hu et al 38 reported a wavelength-tuned LCRL caused by the combined effects of multiple scattering and bandgap control of LCs.…”

“…There are various ways to achieve tunable LCRL, e.g. , varying temperature, 24,25 voltage, 26–30 composition or cell thickness, 31,32 mechanical strain in cross-linked cholesteric LC elastomers, 33–35 or using reversible photochemical reactions. 36,37…”

Recent progress and prospects of random lasers using advanced materials

“…When the dyes are injected into biologically active tissues, RL is generated in the system, which can be applied to separate cancerous and normal tissues 56,48 . Hongbo Lu et al introduced a dye-doped polymer-stabilised cholesteric liquid crystal used as the RL system 57 . The output emission is obtained at the band edge of the photonic bandgap, and the wavelength of this RL can be tuned accordingly with the electric field.…”

“…48,56 Hongbo Lu et al introduced a dye-doped polymer-stabilised cholesteric liquid crystal used as the RL system. 57 The output emission is obtained at the band edge of the photonic bandgap, and the wavelength of this RL can be tuned accordingly with the electric field.…”

Electrical Modulation of Random Lasing Emission from ZnO Nanopowder and Liquid Crystal Hybrid Polymer Film

“…One of the most important optical properties of LC is birefringence, i.e., its refractive index is strongly dependent on its molecule (nematic) axis . Controlling the alignment of LC with various external perturbations such as temperature , as well as electric − and magnetic fields , modulates its light scattering properties and subsequent random lasing characteristics such as emission intensity, spatial pattern, and wavelength. Wiersma et al first demonstrated the active control of random laser emission; they showed that lasing oscillation occurs at a certain temperature (∼43 °C) in a laser dye molecule and liquid crystal mixed in porous laser glass powder with decreasing temperature from 80 to 10 °C .…”