A variable optical attenuator has a first and second waveguides that are optically coupled together. At least one of the waveguides has a movable cantilever portion that is movable relative to the other to control attenuation of an optical signal traveling between the two. Preferably, electrically driven actuators deflect the movable waveguides to a relative position at which a desired optical attenuation value is achieved. The electrically driven actuator receives a drive signal that controls the amount of deflection. The drive signal may be set to achieve a desired value for an electrical parameter that varies with the position of the movable waveguide and may be sensed by the electrically driven actuator. In some examples, the drive signal is set to achieve a desired capacitance or voltage difference between the movable waveguide and an electrode.