  We experimentally demonstrate optical control of filamentation that occurs
during propagation of intense, ultrashort laser pulses through crystals like
barium fluoride and sapphire. Control is exercised by rotating the plane of
polarization of the incident laser radiation and is demonstrated by directly
visualizing filamentation in the bulk via six-photon absorption-induced
fluorescence and, concomitantly, by probing the spectral and spatial properties
of white light that is generated.
