The authors report on experimental demonstration at 12.5 Gbaud of a bandwidth-efficient technique for optical control of a photonic switching element using optical time-division multiplexing. Routing decisions are made on a bit-by-bit basis. Since the destination address is encoded in the position of the information bit within a time frame, the bandwidth is used more efficiently than in the previous case of spread-spectrum self-routing. The structure and operation of the switch are described. Although an electrooptic gate was used as a switching element, the procedure is readily extended to an N × N photonic switch. The results are also expected to apply to packet and circuit switching.