Voltage-programmable liquid optical interface

There has been intense recent interest in photonic devices based on microfluidics that include displays and refractive tunable microlenses and optical beamsteerers that work using the principle of electrowetting. Here we report a novel approach to optical devices in which static wrinkles are produced at the surface of a thin film of oil as a result of dielectrophoretic forces. We have demonstrated this voltage programmable surface wrinkling effect with periodic devices with pitch lengths of between 20 μm and 240 μm and with response times of less than 40 μs. By careful choice of oils, it is possible to optimise either for high amplitude sinusoidal wrinkles at micrometer-scale pitches or for more complex non-sinusoidal profiles with higher Fourier components at the longer pitches. This provides the possibility for rapidly responsive voltage programmable polarisation insensitive transmission and reflection diffraction devices and for arbitrary surface profile optical devices