Selective Color Appearance of Liquid‐Crystal‐Aided Laser‐Induced Periodic Surface Structures

Abstract Laser‐Induced Periodic Surface Structure (LIPSS) combined with a layer of liquid crystal (LC) shows electronically selective color in this research. LC spontaneously aligns in parallel to the LIPSS nano grooves. An in‐plane switching (IPS) LC cell with LIPSS‐processed indium tin oxide (ITO) electrodes is fabricated, and compared to a traditional IPS LC cell with rubbed aligning polymer. At the fist place, an LC cell providing tunable gray scale is expected. Surprisingly, the LC cell shows brilliant glowing colors, which changes dramatically from golden yellow to midnight blue when the voltage is applied. The polarized optical microscope pictures show that light is diffracted and propagating in the cell. With the transmission spectra, diffraction, multiple reflection, and grating‐assisted total internal reflection (TIR) are identified. The LC switches the polarization of light, turning the diffraction and TIR on‐and‐off. LIPSS provides not only alignment but also structural color, modulated by the LC. The grating‐assisted TIR opens up new possibility for waveguides and transparent displays. Fabrication of LIPSS LC cell is fast and clean. Only laser and cleaning is required, omitting large amount of toxic materials and hazardous waste. Efforts are made to offer an environmental friendly method to produce nano optoelectronics.