All-optical switching using color centers in an irradiated phosphorus-doped fiber

We report on all-optical switching of a 900-nm signal in a two-mode silica fiber based upon a resonant nonlinearity introduced by phosphorus color centers in a 22-cm irradiated P₂O₅-SiO₂ fiber. Full switching was observed with only 1 μJ of absorbed 532-nm pump energy, with a projected response time under 10 ns. This switch required a peak power two orders of magnitude lower than for a fiber Kerr effect device operated under identical conditions.