title: Observation of self-focusing in optical fibers with picosecond pulses.
abstract: Self-focusing was observed at Raman frequencies, using picosecond pulses propagating in a large-core optical fiber of 100-microm diameter. For intense input pulses, a continuum of Stokes frequencies was generated in a small ring-waveguide structure. The ring diameter of 11 microm was about 10 times smaller than the beam diameter at low intensities. The ring structure was attributed to an induced-gradient-index profile arising from the nonlinear index of refraction.
authors.affiliation: Institute for Ultrafast Spectroscopy and Lasers, Photonics Application Laboratory, The City College of The City University of New York, New York, New York 10031, USA.
authors.forename: P L
authors.initials: PL
authors.lastname: Baldeck
authors.forename: F
authors.initials: F
authors.lastname: Raccah
authors.forename: R R
authors.initials: RR
authors.lastname: Alfano