A device for providing electromagnetic oscillations in the sub-millimeter range comprising one or more electron beam generators for providing a first and a second electron beam and one or more magnetic field generators for focusing the first and second electron beams. The device may comprise an oscillator comprising a slow wave circuit having a structure of an electrically non-conducting material with metallized surfaces adjacent the first electron beam and an amplifier comprising a slow wave circuit having a structure of an electrically non-conducting material with metallized surfaces adjacent the second electron beam and electrically connected to said oscillator. The oscillator and amplifier may be formed on a single substrate utilizing a single deposition process. The oscillator and amplifier may be contained in a single vacuum envelope.