Fiber Optics in the Multiphoton Ionization Regime

We investigate an extreme regime of nonlinear propagation in standard multimode optical fibers, where intense laser pulses trigger multiphoton ionization effects. These influence the dynamics of spatiotemporal solitons which are formed from the fission of input laser pulses. In particular, we observed a nonmonotonic Raman wavelength shift over a time scale of several hours. Moreover, the material ionization generates irreversible damages, which are visualized by means of optical microscopy and X-ray computed microtomography.