The Amplification in Strong Electric and Magnetic Fields

We consider the amplification in strong electric (magnetic) fields that are uniform along the direction of the electron motion and are not uniform in the transverse direction. It is shown that in such a system the gain is increased compared with that of a magnetic undulator by a value of the order of gamma ( gamma is the relativistic factor). Numerical estimates are presented that determine the possibility of amplification of a test wave in the optical and near infrared bands.