Handedness inversion of the Bragg reflection light of cholesteric liquid crystal polymer network films using a half-wave plate

Abstract

Colourful cholesteric liquid crystal polymer network (CLCN) films can selectively reflect circularly polarized light whose handedness is consistent with that of the CLCN films. The CLCN patterns have been applied for decoration and anti-counterfeiting. Herein, colourful patterns are prepared using a CLCN pattern and a nematic liquid crystal polymer network (NLCN) film. The structural colours are controlled by the helical pitches of the CLCN pattern. The NLCN film acts as the half-wave plate to invert the handedness of the circularly polarized lights reflected by the CLCN pattern. The sandwiched R-CLCN (right-handed CLCN)/NLCN/R-CLCN film can reflect both a left- and a right-handed circularly polarized light. The reflectance of this sandwiched film can be tuned by changing the NLCN and R-CLCN film thicknesses. Moreover, a colour pattern is also prepared based on this sandwiched structure, which is potentially applied for decoration and anti-counterfeiting.