Electrical annealing for Ge ion-implanted directional couplers

Electrical annealing of erasable directional couplers (DCs) was realized. Titanium nitride (TiN) micro-heaters were used to electrically heat up and anneal the Ge-ion implanted regions in silicon, which are used as the coupling waveguides in the erasable DCs. The refractive index of implanted silicon was reduced rapidly by electrical annealing, so that the DCs were effectively erased. The whole annealing process can be accomplished in about 2 seconds. Based on the simulation results, the implanted region can be heated up to about 700 degrees C.