Low-power all-optical switching using a fiber Sagnac interferometer with a pumped nonlinear coupler

We propose a novel Sagnac interferometer (SI) optical switch consisting of a pumped erbium-doped fiber 3dB coupler for a signal at 1.55 mu m and a short fiber loop. The switching between the reflected and transmitted output powers can be accomplished by two approaches: using 980nm-pump power in the cross-pumping mode or using an additional signal power in the self-pumping mode. In the two modes, the switching powers are 40mW and 20mW, and the switching times are sub-nanoseconds and milliseconds, respectively. In the both cases, the switching powers are independent of the fiber-loop length, so that the power-length products for proposed SI switch can be smaller than that of other kind of nonlinear SI switches.