Vanishing Frontier Between Far Infrared and Microwave : Fir Lasers and Gyrotrons. (An Overview)

A lack of coherent and efficient sources subsisted in the submillimetric domain. Recent work has alleviated this deficiency in a two pronged attack. One action leads to study in depth the laser mechanism based on stimulated emission and optical pumping. Another relies on a relativistic bunching in a helical electron beam obtained by a very high magnetic field: the gyrotron. It is suitable for high power.