Spatial and temporal behaviors of laser beam propagating in a atomic vapor have been investigated experimentally. The pulse reshapings of frequency‐chirped laser pulses in the near‐resonant atomic vapor have been demonstrated by making use of atomic samarium vapor. Self‐induced transparency and self‐focusing have also been observed by streak camera. Theses results will be compared with numerical or analytical results in this paper. ©1996 American Institute of Physics.