A waveguide/MEMS switch adapted to redirect optical signals between output ports based on a phase shift change generated by motion of one or more movable MEMS mirrors incorporated therein. Advantageously, such a switch has a relatively high switching speed and low power consumption. A switch according to one embodiment of the invention includes a planar waveguide device and a planar MEMS device. The MEMS device implements in-plane (i.e., parallel to the plane of that device) translation of the mirrors. As a result, in certain embodiments of the switch, the waveguide and MEMS devices are connected into a compact planar assembly.