In the method, a pre-selected working area of a graphene film with a linear dimension of 2,000 nm, which working area is divided into sections having a dimension of 50-100 nm, is subjected to the effect of a pulsed alternating magnetic field with a frequency of 3 terahertz that corresponds to the transition from the ground energy level, corresponding to the non-excited state of spin density, to a fourth working energy level of the excited state of spin density in the graphene film, thus causing spin density pumping. A spatially localized external magnetic field is generated around the edges of the working area, which resonantly reflects spinons having a working frequency of 0.5-1 terahertz that corresponds to the transition from a third working energy level to a second working energy level of the excited state of spin density, said spinons causing the induced coherent radiation of working frequency spin waves as they pass thorough the working area. Патент США, класс 324/300.