Abstract: A magnon laser comprising: a Magnon Gain Medium, wherein the Magnon Gain Medium supports generation of nonequilibrium magnons, and a means for pumping nonequilibrium electrons into the Magnon Gain Medium. Propagation of nonequilibrium electrons in Magnon Gain Medium causes generation of nonequilibrium magnons. Magnon Gain Medium comprises ferromagnetic materials at room temperatures including the half-metallic ferromagnets.

Abstract: A magnon laser comprising: a magnon gain medium (MGM) that supports generation of nonequilibrium magnons, and a means for generating nonequilibrium magnons in the MGM further comprising a means for pumping nonequilibrium electrons into the MGM. Propagation of nonequilibrium electrons in the MGM causes generation of nonequilibrium magnons. The MGM is selected from the group consisting of: {ferromagnetic semiconductor; ferromagnetic insulator; and ferromagnetic material}. The merging of nonequilibrium magnons causes generation of terahertz waves.

Abstract: A method of tunable generation of terahertz radiation comprising: (A) providing a magnon gain medium; wherein the magnon gain medium supports generation of nonequilibrium magnons; (B) generating terahertz radiation in the magnon gain medium; and (C) tuning frequency of the terahertz radiation by causing changes in an external parameter. The substantial tuning of the frequency of the generated terahertz radiation can be achieved by applying an external magnetic field, and by causing changes in a value of the external magnetic field.

Abstract: A method of THz photon generation comprising: providing a magnon gain medium; wherein the magnon gain medium supports generation of nonequilibrium magnons; and injecting nonequilibrium electrons into the magnon gain medium. Propagation of nonequilibrium electrons in the magnon gain medium causes generation of nonequilibrium magnons. Interaction between nonequilibrium magnons causes generation of THz photons.