Surface Acoustic Wave Driven Light Shutters Using Polymer‐Dispersed Liquid Crystals

displays, [ 3 ] microlenses, [ 4 , 5 ] lasers, [ 6 , 7 ] and data storage, [ 8 ] due to their excellent electro-optical properties. PDLC fi lms can be prepared between two conductive, transparent substrates using methods such as encapsulation, thermally induced phase separation, solvent-induced phase separation, and polymerizationinduced phase separation. [ 9 ] Within a PDLC fi lm, liquid crystals (LCs) are generally trapped in a transparent polymer medium, thus forming micrometer-scale LC droplets. The random dispersion of LC droplets in the polymer matrix causes a strong scattering of light due to the signifi cant refractive index mismatch between the two materials; therefore, a PDLC fi lm is naturally opaque. Based on laser interference holography, various periodic structures such as gratings [ 10–12 ] and photonic crystals, [ 13 , 14 ] can be also introduced inside the fi lm, coined as holographic PDLCs (HPDLCs). [ 15 ] The application of an electric fi eld can re-orientate the LC molecules inside a droplet, thus modulating the refractive index difference between the polymer matrix and the LC. A complete refractive index match between the two materials can be achieved by tuning the LCs to a specifi c orientation. In such a way, the PDLC fi lm can be switched from opaque to transparent. The switching properties of PDLCs are infl uenced by many variables including the size and shape of the LC droplets, [ 16 , 17 ] and molecular interactions between the LCs and polymer matrix. [ 18 , 19 ]