Switchable retroreflector devices that are modulated via electrowetting. The devices include an electrically-conductive polar fluid and a non-polar fluid that is immiscible with the polar fluid. The polar and the non-polar fluids differ in at least one optical property. The fluids are contained in a fluid vessel, or an array of fluid vessels. The fluids are at least partially viewable. A voltage source is configured to selectively apply an electromechanical force to the polar fluid causing repositioning and/or geometrical change of the fluids such that retroreflection in created, or suppressed, by optical refraction or by optical attenuation.