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.