Abstract: The present invention is an optical switch that includes a first optic fiber waveguide, a second optic fiber waveguide, and a third optical waveguide. The three waveguides are in the same plane. The third optical waveguide may be an optic fiber or a slab waveguide. The first and second optic fiber waveguides are close enough to exhibit evanescent wave coupling under non-interference conditions. The second optic fiber waveguide is between the other two waveguides and closer to the third optical waveguide. The first and second optic fiber waveguides have identical propagation constants. An information-bearing optical signal is applied to the first optic fiber waveguide. An optical control signal applied to the third optical waveguide controls its propagation constant and, therefore, controls whether or not switching occurs between the first and second fiber optic waveguides. The optical switch may be made to be normally on or normally off.