| External field stimuli such as light field,electric field,etc.can be used to realize the control of molecular rearrangement,the construction,unwinding and recombination of assembled microstructures,obtaining reversible and dynamic modulation of optical components and systems.In the cholesteric phase,liquid crystal molecules rotate around the helical axis and the molecular long-axes are perpendicular to the helical axis.Sustaining efforts have been devoted to dynamically manipulate parameters of the structure,such as the helical pitch,helical handedness and the direction of helical axis by electric field,light and heat,exhibiting diverse optical performances and applications in advanced photonic devices.In recent years,a twist-bending nematic phase(Ntb)that can spontaneously form twist and bend deformation has been discovered in liquid crystal dimeric compounds.The modulation of broad spectral dynamic range can be achieved under the control of electric field in the heliconical cholesteric liquid crystals system containing twist-bending nematic liquid crystal,commercial nematic liquid crystal,chiral agent.The multi-field and broad spectral range modulation of the cholesteric liquid crystal helical structure is significant for expanding its application in the view of both basic science and engineering.However,achieving performances mentioned above is still challenging.In this paper,a photosensitive heliconical cholesteric liquid crystal that can be modulated by electric field and optical field is developed.The experimental results show that continuous dynamic modulation of the reflection band from near ultraviolet to near infrared at the electric field and optical field can be realized by this material system.More specifically,both ultraviolet light and visible light radiation are valid in reversible modulation of the reflection band.The light-driven characteristic mainly depends on the thermal effect of light field and photoisomerization effect of azobenzene.Finally,a prototype of artificial neural network sensing application based on this multi-field responsive material is further developed,in which light energy given different weights is used as an input layer and acts on neurons composed of the heliconical cholesteric liquid crystal,and the output of neurons-color coordinates are calculated by function.This work has broadened methods of modulating the helical structure by light field and has great potential in the field of advanced optics. |
