Abstract

We show, for the first time to our knowledge, that it is possible to attain lasing without inversion in free-electron devices. To this end, we arrange the electron-laser interaction to occur in two sequential regions involving electron, momentum states $|{\overline{h}}_1〉$ and $|{\overline{h}}_2〉$ and an electromagnetic wiggler in a superposition of ${\overline{k}}_{u1}$ and ${\overline{k}}_{u2}$ modes (Fig, l).

© 1993 Optical Society of America