An adaptive liquid iris for an optical switch based on electrowetting is demonstrated. The device consists of a clear conductive liquid and an opaque insulate oil. In the voltage-off state, the dome of the clear liquid touches the top substrate, and an iris-like opening is formed in its central area, and the aperture of the opening is at its largest. When a voltage is applied to the device, the shape of the conductive liquid is deformed due to the electrowetting effect. As a result, the diameter of the opening is reduced. Our results show that the aperture of the device can be tuned from similar to 6.4 mm to 0 as the applied voltage is changed from 0 to similar to 60 V. The device can obtain a high optical attenuation (similar to 872:1). The response time was measured to be similar to 117 ms (shrinking time is similar to 25 ms, and relaxing time is similar to 92 ms) with turnaround speed of 55 mm/s. Our device has potential applications in light shutters, variable optical attenuators, adaptive irises, and displays. (C) 2014 Society of Photo-Optical Instrumentation Engineers (SPIE)
