Passive mode-locking, dissipative solitons and generation of ultrashort pulses in electron oscillators with saturable absorber in the feedback loop

Abstract

A periodic train of powerful ultrashort microwave pulses can be generated in electron oscillators with a saturable absorber installed in the feedback loop. This method of pulse formation is similar to the passive mode-locking widely used in laser physics where such pulses are also treated as dissipative solitons. We consider the method of mode-locking applied to different types of microwave amplifiers including helical gyro-TWT. For nonlinear absorption, we suggest to use cyclotron resonance absorption by an initially rectilinear electron beam. Alternative method is the installation of an additional section where mismatch of electron-wave resonance condition corresponds to the absorption regime.