Abstract: An apparatus comprising a ferromagnetic conductive material including a magnon gain medium (MGM) and a tunnel junction coupled to the ferromagnetic conductive material are provided. The magnon gain medium (MGM) further comprises a conduction band that is split into two sub bands separated by an exchange energy gap, a first sub band having spin up, and a second sub band having spin down. The applied bias voltage is configured to shift the Fermi level of the external metallic contact with respect to the Fermi level of the ferromagnetic conductive material so that the injected electrons are configured to tunnel into the second sub band having spin down.

Abstract: An apparatus for tunable generation of terahertz photons is provided. The apparatus comprises a three level magnon laser, an injection means, a terahertz antenna, and a tuning means. The terahertz antenna further comprises a magnon gain medium that supports generation of nonequilibrium magnons. The magnon gain medium is selected from the group consisting of: a ferromagnetic semiconductor; a dilute magnetic semiconductor (DMS); a half-metallic ferromagnet (HMF); and a ferromagnetic conductor, with a gap in the density of states of the minority electrons around the Fermi energy.

Abstract: An apparatus for generating ultra-high frequency sound waves with frequencies between (1 GHz-10 GHz) is proposed. The apparatus comprises a magnetic phonon-gain medium configured to generate high frequency non-equilibrium phonons by non-equilibrium magnons having the magnon velocity exceeding the sound velocity in the magnetic phonon-gain medium. The non-equilibrium magnons having the magnon velocity exceeding the sound velocity in the magnetic phonon-gain medium are generated by injected non-equilibrium electrons having spin opposite to the direction of magnetization of the magnetic phonon-gain medium. The apparatus further comprises a means for outputting the ultra-high frequency non-equilibrium phonons.

Abstract: An apparatus for generating ultra-high frequency sound waves with frequencies between (1 GHz-10 GHz) is proposed. The apparatus comprises a magnetic phonon-gain medium configured to generate high frequency non-equilibrium phonons by non-equilibrium magnons having the magnon velocity exceeding the sound velocity in the magnetic phonon-gain medium. The non-equilibrium magnons having the magnon velocity exceeding the sound velocity in the magnetic phonon-gain medium are generated by injected non-equilibrium electrons having spin opposite to the direction of magnetization of the magnetic phonon-gain medium. The apparatus further comprises a means for outputting the ultra-high frequency non-equilibrium phonons.

Abstract: A four level 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 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, 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: An apparatus and method for tunable generation of terahertz waves at room temperatures are provided. The apparatus for tunable terahertz generation comprises: (A) a terahertz antenna further comprising a magnon gain medium; (B) a means for generating the nonequilibrium magnons in the magnon gain medium; wherein the terahertz antenna is configured to emit generated terahertz photons; and (C) a means for tuning frequency of terahertz photons emitted by the terahertz antenna. The magnon gain medium is selected from the group consisting of: {a ferromagnetic semiconductor; a dilute magnetic semiconductor (DMS); a half-metallic ferromagnet (HMF); and a ferromagnetic conductor, with a gap in the density of states of the minority electrons around the Fermi energy}.

Abstract: An apparatus and method for generating modulated terahertz radiation are provided. The apparatus comprises: (A) a means for generating Terahertz radiation by pumping nonequilibrium electrons into Magnon Gain Medium (MGM); wherein the nonequilibrium electrons emit nonequilibrium magnons, and wherein interaction between nonequilibrium magnons in the Magnon Gain Medium (MGM) causes generation of Terahertz radiation; and (B) a means for modulating the generated Terahertz radiation. The modulating means further comprises: an AC magnetic field generator, or an AC electric field generator.

Abstract: A method of modulation terahertz radiation comprising: (A) generating Terahertz radiation by pumping nonequilibrium electrons into a Magnon Gain Medium (MGM), wherein propagation of nonequilibrium electrons in the MGM causes generation of nonequilibrium magnons, and wherein interaction between the nonequilibrium magnons causes generation of the Terahertz radiation; and (B) frequency modulating THz radiation generated in the MGM by applying longitudinal AC magnetic field, or by applying AC electrical field bias.

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: An apparatus for generation of Terahertz radiation comprising: (A) a Magnon Gain Medium (MGM), wherein the MGM supports generation of nonequilibrium magnons; and (B) at least one magnon mirror (MM). The nonequilibrium magnons are generated in the MGM. Interaction between nonequilibrium magnons leads to generation of Terahertz photons.

Abstract: A method of modulation terahertz radiation comprising: (A) generating Terahertz radiation by pumping nonequilibrium electrons into a Magnon Gain Medium (MGM), wherein propagation of nonequilibrium electrons in the MGM causes generation of nonequilibrium magnons, and wherein interaction between the nonequilibrium magnons causes generation of the Terahertz radiation; and (B) frequency modulating THz radiation generated in the MGM by applying longitudinal AC magnetic field, or by applying AC electrical field bias.

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.

Abstract: An apparatus for generation of Terahertz radiation comprising: (A) a Magnon Gain Medium (MGM), wherein the MGM supports generation of nonequilibrium magnons; and (B) at least one magnon mirror (MM). The nonequilibrium magnons are generated in the MGM. Interaction between nonequilibrium magnons leads to generation of Terahertz photons.

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 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.

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.