Abstract
Isolated waveguide modes of intense light fields are unique physical objects, which can never be observed in standard optical fibers, hollow waveguides, plasma filaments, or in the bulk of a transparent dielectric or gas. Hollow photonic-crystal fibers can for the first time produce robust isolated truly guided spatial modes of subgigawatt ultrashort light pulses, perform efficient nonlinear-optical transformations of laser fields in such states, and implement new waveguide regimes of coherent excitation and probing of molecular Raman-active modes in the gas phase.