Abstract: A technique to generate terahertz radiation is disclosed, where a pump beam (12) is coupled into an optical element (50) made of a medium with non-linear optical properties having plane-parallel front and rear boundary surfaces (51, 52), wherein the pump beam (12) is split into a set of partial pump beams (121) by reflection and/or diffraction on a periodic relief structure (53) of said optical element (50). The partial pump beams travel along a direction at an angle ? that satisfies the velocity matching condition of vp,cs cos(?)=vTHz,f within the given medium, where vp,cs is the group velocity of the pump beam, vTHz,f is the phase velocity of the terahertz radiation and the speed a planar envelope (212) travels toward the front boundary surface (51) of the optical element (50), and angle ? is the angle formed by the pulse front envelope and the phase front of the pump beam.

Abstract: The present specification relates to accelerating electrically charged particles. Gas is introduced into a vacuum chamber through at least one nozzle which opens into said vacuum chamber. Focusing an ionizing beam into the gas generates a plasma having a spatial distribution determined by the duration and manner of focusing the ionizing beam's laser pulses. Linearly polarized electromagnetic pulses of a wavelength at least ten times the wavelength of the ionizing beam's laser pulses tear electrons off the plasma, wherein said electromagnetic pulses include at most five optical cycles. The tearing-off of electrons is performed along a straight line defined by the resulting electric field strength of the electromagnetic pulses and simultaneously with the tearing-off of electrons, the positively charged particles of the remaining plasma with a net positive total charge are accelerated through exposure to Coulomb electrostatic forces.

Abstract: A technique to generate terahertz radiation is disclosed, where a pump beam (12) is coupled into an optical element (50) made of a medium with non-linear optical properties having plane-parallel front and rear boundary surfaces (51, 52), wherein the pump beam (12) is split into a set of partial pump beams (121) by reflection and/or diffraction on a periodic relief structure (53) of said optical element (50). The partial pump beams travels along a direction at an angle ? that satisfies the velocity matching condition of vp,cs, cos(?)=vTHz,f within the given medium, where vp;cs is the group velocity of the pump beam, vTHz;f is the phase velocity of the terahertz radiation and the speed a planar envelope (212) travels toward the front boundary surface (51) of the optical element (50), and ? is the angle formed by the pulse front envelope and the phase front of the pump beam.

Abstract: A pump beam (12) is pre-tilted by subjecting the pump beam to pulse-front-tilting, the thus obtained tilted-pulse-front pump beam is then coupled into the nonlinear optical medium. THz radiation is generated in the optical medium by nonlinear optical processes, in particular by optical rectification, by the pump beam. A pulse-front-tilt of the pump beam satisfying the velocity matching condition of vp,cs cos(?)=vTHz,f is induced as a sum of a plurality of pulse-front-tilts separately induced as a partial pulse-front-tilt of the pump beam in subsequent steps. The last step of pulse-front-tilting of the pump beam is performed by coupling the pump beam into the nonlinear optical medium through a stair-step structure (40) formed in an entry surface (51) of the nonlinear optical medium which forms an angle (?) of a given non-zero size with an exit surface (52) of said nonlinear optical medium.

Abstract: A pump beam (12) is pre-tilted by subjecting the pump beam to pulse-front-tilting, the thus obtained tilted-pulse-front pump beam is then coupled into the nonlinear optical medium. THz radiation is generated in the optical medium by nonlinear optical processes, in particular by optical rectification, by the pump beam. A pulse-front-tilt of the pump beam satisfying the velocity matching condition of vp,cs cos(?)=vTHz,f is induced as a sum of a plurality of pulse-front-tilts separately induced as a partial pulse-front-tilt of the pump beam in subsequent steps. The last step of pulse-front-tilting of the pump beam is performed by coupling the pump beam into the nonlinear optical medium through a stair-step structure (40) formed in an entry surface (51) of the nonlinear optical medium which forms an angle (?) of a given non-zero size with an exit surface (52) of said nonlinear optical medium.

Abstract: A pump beam (12) is subjected to pulse front tilting, and then guided through an imaging optics (30) and then coupled into the nonlinear optical medium through an entry surface of the nonlinear optical medium. THz radiation is generated in the optical medium by nonlinear optical processes, in particular by optical rectification, via the pump beam. The pulse front tilt of the pump beam required to satisfy the velocity matching condition of vp,cs cos(?)=vTHz,f is induced as a sum of a plurality of pulse front tilts, where each pulse front tilt is induced separately as a partial pulse front tilt of the pump beam in subsequent steps. The last step of pulse front tilting of said pump beam (12) is performed by coupling the pump beam (12) into the nonlinear optical medium through a stair-step structure (40) formed in the entry surface of the nonlinear optical medium.

Abstract: The present application relates to generating terahertz radiation, wherein a pump pulse is subjected to pulse front tilting, the thus obtained pump pulse having tilted pulse front is coupled into a nonlinear optical medium and THz pulse is generated by the optical medium in nonlinear optical processes, particularly by means of optical rectification by the pump pulse. The application also relates to a terahertz radiation source (100), comprising a pump source (10) for emitting a pump pulse and a nonlinear optical medium for generating THz pulse. The pump source (10) and the nonlinear optical medium define together a light path, said light path is arranged to guide the pump pulse from the pump source (10) to the nonlinear optical medium. A first optical element (20) having angular-dispersion-inducing property and imaging optics (30) are disposed in the light path after each other in the propagation direction of the pump pulse.

Abstract: A pump beam (12) is subjected to pulse front tilting, and then guided through an imaging optics (30) and then coupled into the nonlinear optical medium through an entry surface of the nonlinear optical medium. THz radiation is generated in the optical medium by nonlinear optical processes, in particular by optical rectification, via the pump beam. The pulse front tilt of the pump beam required to satisfy the velocity matching condition of vp,cs cos(?)=vTHz,f is induced as a sum of a plurality of pulse front tilts, where each pulse front tilt is induced separately as a partial pulse front tilt of the pump beam in subsequent steps. The last step of pulse front tilting of said pump beam (12) is performed by coupling the pump beam (12) into the nonlinear optical medium through a stair-step structure (40) formed in the entry surface of the nonlinear optical medium.

Abstract: The present application relates to generating terahertz radiation, wherein a pump pulse is subjected to pulse front tilting, the thus obtained pump pulse having tilted pulse front is coupled into a nonlinear optical medium and THz pulse is generated by the optical medium in nonlinear optical processes, particularly by means of optical rectification by the pump pulse. The application also relates to a terahertz radiation source (100), comprising a pump source (10) for emitting a pump pulse and a nonlinear optical medium for generating THz pulse. The pump source (10) and the nonlinear optical medium define together a light path, said light path is arranged to guide the pump pulse from the pump source (10) to the nonlinear optical medium. A first optical element (20) having angular-dispersion-inducing property and imaging optics (30) are disposed in the light path after each other in the propagation direction of the pump pulse.

Abstract: The invention relates to a method for generating electromagnetic radiation (preferably UV, VUV, XUV, or X-rays), to an optical short-period undulator (10) and to a free-electron laser comprising the latter. To accomplish the method, a high-energy electrically charged particle beam (5) is provided, and high-intensity electromagnetic pulses (7, 7a, 7b) are generated, and by interfering said pulses with one another an electromagnetic standing wave is created, wherein said standing wave has an electric field strength of a pre-determined peak value. The particle beam is directed through the non-steady electromagnetic field of the standing wave in or in the vicinity of a plane spanned by nodes with maximal electric field strength of said electromagnetic standing wave.

Abstract: The present invention relates to a method and an arrangement to generate a coherent electromagnetic radiation containing at most a few optical cycles in the extreme ultraviolet/vacuum ultraviolet domain. The inventive method comprises the steps of providing an electron package (15) of relativistic velocity; modulating said electron package (15) with high intensity laser light (17) in an undulator (20) having an undulator period smaller than the undulator period (?u) satisfying the resonance condition, producing thereby an electron package formed of electron microbunches; and passing the electron package (15) of electron microbunches leaving said undulator (20) through a static magnetic field, and generating thereby a coherent electromagnetic radiation, wherein said static magnetic field is generated in conformity with the coherent electromagnetic radiation to be achieved.

Abstract: The invention relates to a such particle accelerator setup (1, 11) and method based on the total reflection of electromagnetic pulses with a frequency falling into the THz frequency domain that utilize the evanescent field for the acceleration of electrically charged particles. Said setup includes a radiation source (5) to emit high-energy THz-pulses, preferably comprising a few optical cycles, having a large peak electric field strength, as well as two optical elements (2, 12) in the form of a pair of bulk crystals made of a substance that exhibits large refractive index, low dispersion and high optical destruction threshold, wherein said optical elements are transparent for the THz radiation. The inventive solutions represent much simpler, more compact and more cost effective alternatives compared to the prior art particle accelerator setups.

Abstract: The present invention relates to a method and an arrangement to generate a coherent electromagnetic radiation containing at most a few optical cycles in the extreme ultraviolet/vacuum ultraviolet domain. The inventive method comprises the steps of providing an electron package (15) of relativistic velocity; modulating said electron package (15) with high intensity laser light (17) in an undulator (20) having an undulator period smaller than the undulator period (?u) satisfying the resonance condition, producing thereby an electron package formed of electron microbunches; and passing the electron package (15) of electron microbunches leaving said undulator (20) through a static magnetic field, and generating thereby a coherent electromagnetic radiation, wherein said static magnetic field is generated in conformity with the coherent electromagnetic radiation to be achieved.

Abstract: The invention is a THz waveguide source (3) having a core (9) of great nonlinear coefficient and of a great absorption. The source (3) is adapted to behave as a waveguide in pumping and also in THz range. The THz waveguide source (3) has a cladding of smaller absorption coefficient in the THz range than that of the core. The solution according to the invention diminishes the influence of absorption, while enhances efficiency of generating THz radiation. The waveguide structure and the tilted pulse front excitation together results a greater interaction length and thus a greater THz generating efficiency. According to the solution of the invention highly efficient compact THz waveguide sources can be realized.

Abstract: The invention relates to a such particle accelerator setup (1, 11) and method based on the total reflection of electromagnetic pulses with a frequency falling into the THz frequency domain that utilize the evanescent filed for the acceleration of electrically charged particles. Said setup includes a radiation source (5) to emit high-energy THz-pulses, preferably comprising a few optical cycles, having a large peak electric field strength, as well as two optical elements (2, 12) in the form of a pair of bulk crystals made of a substance that exhibits large refractive index, low dispersion and high optical destruction threshold, wherein said optical elements are transparent for the THz radiation. The inventive solutions represent much simpler, more compact and more cost effective alternatives compared to the prior art particle accelerator setups.

Abstract: The invention relates to a method for generating electromagnetic radiation (preferably UV, VUV, XUV, or X-rays), to an optical short-period undulator (10) and to a free-electron laser comprising the latter. To accomplish the method, a high-energy electrically charged particle beam (5) is provided, and high-intensity electromagnetic pulses (7, 7a, 7b) are generated, and by interfering said pulses with one another an electromagnetic standing wave is created, wherein said standing wave has an electric field strength of a pre-determined peak value. The particle beam is directed through the non-steady electromagnetic field of the standing wave in or in the vicinity of a plane spanned by nodes with maximal electric field strength of said electromagnetic standing wave.

Abstract: The invention is a THz waveguide source (3) having a core (9) of great nonlinear coefficient and of a great absorption. The source (3) is adapted to behave as a waveguide in pumping and also in THz range. The THz waveguide source (3) has a cladding of smaller absorption coefficient in the THz range than that of the core. The solution according to the invention diminishes the influence of absorption, while enhances efficiency of generating THz radiation. The waveguide structure and the tilted pulse front excitation together results a greater interaction length and thus a greater THz generating efficiency. According to the solution of the invention highly efficient compact THz waveguide sources can be realized.