An Optofluidic Reflective Phase Modulator Based on Electrowetting

This work presents an electrowetting-based optofluidic reflective phase modulator. The modulator mainly consists of two functional cavities and one storage cavity filled with two immiscible liquids. Two transparent sheets are fixed between the liquid-liquid interfaces in the functional cavities to get planar interfaces. The flat interfaces in the two working chambers move up and down when different voltages are applied, changing the optical path length. With the aid of two vertical top reflectors, the incident beam passes through one working chamber and then enters the other chamber in the opposite direction, leading to enlarging the variation range of optical path length. To verify the feasibility and correctness of this design, a prototype of the phase modulator is fabricated and detected in an experiment. Our reflective modulator realizes continuous adjustment in optical phase up to $11.732\pi $ when the voltage is increased to 95 V.