Multiphoton ionization of standard optical fibers

Atoms ionization by the simultaneous absorption of multiple photons has foundapplications in fiber optics, where it leads to unique nonlinear phenomena. Todate, studies of the ionization regime have been limited to gas-filledhollow-core fibers. Here, we investigate multiphoton ionization of standardoptical fibers, where intense laser pulses ionize the atoms constituting thefiber structure itself, instead of that of the filling gas. We characterizematerial modifications produced by optical breakdown. Their formation affectslaser beam dynamics over hours long temporal scales. The damage features arestudied by means of optical microscopy and X-ray microtomography. In theframework of glass photonics, our results pave the way for a novel glasswaveguide micromachining technique.