All-optical modulation using two-photon absorption in silicon core optical fibers.

All-optical modulation based on degenerate and non-degenerate two-photon absorption (TPA) is demonstrated within a hydrogenated amorphous silicon core optical fiber. The nonlinear absorption strength is determined by comparing the results of pump-probe experiments with numerical simulations of the coupled propagation equations. Subpicosecond modulation is achieved with an extinction ratio of more than 4 dB at telecommunications wavelengths, indicating the potential for these fibers to find use in high speed signal processing applications.