Optical switch based on hydraulic actuation

In this paper we demonstrate an optical switch based on hydraulic actuation. Two chambers are filled with dyed oil and water, respectively. The oil-water interface changes as the external pressure is applied to the chamber. A transparent pillar shaped platform with a round dome is fixed on the top substrate and submerged in the oil. When pressure is increased, the shape of the oil-water interface can be changed from concave to convex and the oil is pushed aside. As a result, the water touches the transparent pillar thus forming a light channel which allows the incident light to pass through. Our experiments show that the device can obtain a wide optical attenuation from ∼1 dB to ∼29 dB. The diameter of the aperture can be tuned between 0∼5.1 mm by changing the external pressure. The switchable aperture ratio of the device is ∼39%. By using two immiscible liquids with matched densities, the gravity effect can be overcome. The proposed optical switch has potential applications in variable optical attenuators and adaptive irises.