Optical switch based on variable aperture

We report on a pixel whose aperture can be varied electrically. The pixel is confined by a hole-patterned polymer wall and a dielectric liquid forms a ring shape around the wall surface. Without an electric field, the pixel has the largest aperture. The applied fringing field stretches the liquid surface, leading to a decrease in the aperture size. The switchable aperture ratio of the pixel is over 80% and the response time is ∼10  ms. Such a device is useful for an optical attenuator, a light shutter, an adaptive iris, and an information display.