A microelectromechanical structure capable of switching optical signals from an input fiber to one of two or more output fibers. In one embodiment, the MEMS optical cross-connect switch comprises a first microelectronic substrate having a pop-up mirror disposed on the surface of the substrate and a rotational magnetic field source, such as a variably controlled magnetic field source. The rotational magnetic field source allows for reliable actuation of the pop-up mirror from a non-reflective state to a reflective state. Additionally the invention is embodied in a MEMS optical cross-connect switch having a first microelectronic substrate having a pop-up mirror disposed on the surface of the substrate and a positioning structure disposed in a fixed positional relationship relative to the first substrate. The positioning structure may comprise a positioning structure extending from a second microelectronic substrate that is in a fixed positional relationship relative to the first microelectronic substrate. The positioning structure serves to restrict further movement of the pop-up mirror when the pop-up mirror has been actuated into a reflective state.