A directional optical coupler is shown and described, which includes an optical cell that is made of a first transparent conductor, a second transparent conductor and an electro-optical member interposed between the two transparent conductors, the electro-optical member having an index of refraction which can be varied only along one crystal axis by application of an electric field. The locking levers are affixed to the hook member at the mounting portion and latch onto the hook member at the catching portion. The cutting edge has a pointed, generally triangularly shaped tip and outer ends. A coil is disposed in the air gap.