MEMS optical switch with stop control

An optical switch includes a bus waveguide supported by a substrate, an actuation electrode supported by the substrate, the actuation electrode having fins that protrude in a direction perpendicular to the substrate and to the bus waveguide, and a reaction electrode having interdigitated fins configured to form a comb drive with the actuation electrode. When a voltage difference between the reaction electrode and the actuation electrode is less than a lower threshold, the reaction electrode is positioned a first distance from the bus waveguide, when the voltage difference between the reaction electrode and the actuation electrode is greater than an upper threshold, the reaction electrode is positioned a second distance from the bus waveguide, and the second distance is less than the first distance.