title: Ultrashort relativistic electromagnetic solitons.
abstract: Ultrashort high-intensity electromagnetic solitons in both underdense and overdense plasmas are investigated. Comparison is made for solitons with smooth and sharp electron density profiles. It is found that subcycle relativistic solitons can propagate from low-density to high-density plasmas.
authors.affiliation: Shanghai Institute of Optics and Fine Mechanics, P. O. Box 800-211, Shanghai 201800, China.
authors.forename: Baifei
authors.initials: B
authors.lastname: Shen
authors.forename: M Y
authors.initials: MY
authors.lastname: Yu
authors.forename: Ruxin
authors.initials: R
authors.lastname: Li