Abstract

In a free-electron laser (FEL) the energy transfer from the electron-beam to the laser mode depends on the intracavity field distribution. In FELs with thin electron beams, to achieve a good overlapping between the laser mode and the e-beam it is customary to use mirrors providing a Gaussian mode with a Rayleigh length almost equal to one-half of the undulator length. Although this solution provides a maximization of the filling factor, the transverse dimension of the laser mode is still much greater than the e-beam size.

© 1987 Optical Society of America