A model of nonlinear all-optical switching in doped fibers

A theoretical model of switches utilizing the resonantly enhanced nonlinearity present in doped fibers is presented. It establishes the dependence of the switching pump power, fiber length, residual resonant signal loss, and response time of the switch on the dopant spectroscopic parameters. Simple factors of merits are derived for the power and the length requirements and are evaluated for selected rare-earth transitions. The most promising candidates require only a fraction of a mW and a few cm of fiber for full switching. Similar power characteristics, but with considerably shorter response times (ns) and lengths (sub-mm), are predicted for dopants with a high oscillator strength transition, or a power-length product ten orders of magnitude smaller than for switches based on the Kerr effect in undoped silica fibers