Device and method for generating coherent terahertz radiation

A device for producing coherent Smith-Purcell electromagnetic radiation comprising:

• an electrically conductive diffraction grating, laterally defined by two electrically conductive outer side walls;
• a source for emitting an electron beam and propagating the electron beam above the diffraction grating, the electron beam being configured to interact with the diffraction grating so as to produce coherent Smith-Purcell electromagnetic radiation directed upstream of the diffraction grating in a predetermined direction;
• and
• a mirror configured to collect most of the electromagnetic radiation and to redirect it parallel to the diffraction grating to an exit downstream of the diffraction grating, the mirror including a reflective surface, a geometric shape of which is determined on a basis of a radiation pattern of the diffraction grating defining various modes emitted by the diffraction grating.