Abstract: A plurality of gas jet nozzles having equal angular separation around a central axis eject gas flows towards the central axis. The gas flows collide and form a gas channel from the neutral gas, the gas channel having a gas density depression at the center of the intersecting gas flow, where the gas density depression is surrounded by a higher density gaseous wall along the central axis. Ionization of the gas in the center produces a plasma channel that can guide a laser pulse fired into the gas along the central axis. The geometric arrangement of the gas jets and/or the backing pressure of the gas flows are configured to produce a gas channel having a predetermined density profile such that the ionized gas forms a plasma channel laser guiding structure configured to guide a laser pulse having predetermined spatial parameters.

Abstract: A plurality of gas jet nozzles having equal angular separation around a central axis eject gas flows towards the central axis. The gas flows collide and form a gas channel from the neutral gas, the gas channel having a gas density depression at the center of the intersecting gas flow, where the gas density depression is surrounded by a higher density gaseous wall along the central axis. Ionization of the gas in the center produces a plasma channel that can guide a laser pulse fired into the gas along the central axis. The geometric arrangement of the gas jets and/or the backing pressure of the gas flows are configured to produce a gas channel having a predetermined density profile such that the ionized gas forms a plasma channel laser guiding structure configured to guide a laser pulse having predetermined spatial parameters.

Abstract: A method for generating coherent, polarized, and tunable X-rays using a single laser pulse is provided. An ultrashort laser pulse is fired into a plasma. As the laser beam travels through the plasma, some of its photons are backscattered, e.g., through Raman backscattering, to generate a counter-propagating photon beam that is co-linear with the original laser beam. When the backscattered photons interact with high-energy accelerated periodic electron bunches, coherent X-rays are generated through Compton backscattering of the photons off of the electrons. The energy of the backscattered X-rays can be tuned by tuning one or more characteristics of the laser pulse and/or the plasma.

Abstract: Methods for producing a laser-guided underwater electrical discharge are provided. One or more electrodes defining a desired electrical discharge path are situated in a body of water and are attached to an external electrical power supply. A high-powered, intense laser beam is fired through one or more focusing lenses into the water. The laser beam forms an optical filament in the water, which in turn forms an ionized channel having a much greater conductivity than the surrounding water. An external power supply drives an electrical discharge along the path of the ionized channel due to its greater conductivity.

Abstract: A high power ultrashort chirped pulse amplifier laser system, with a chirped pulse amplifier laser module including an optical pulse stretcher, at least one optical power amplifier, and an optical pulse compressor, and a beam interferometer module in the optical path. The beam interferometer receives splits the pulse into at least two pulses, adds a time delay to at least one of the pulses and recombines the pulses to produce a temporally modulated pulse. The resulting modulated output pulse from the CPA laser module can have enhanced laser contrast due to greatly reduced subpicosecond pedestal in the immediate region of the peak pulse, or can have other desirable characteristics.

Abstract: A method for generating coherent, polarized, and tunable X-rays using a single laser pulse is provided. An ultrashort laser pulse is fired into a plasma. As the laser beam travels through the plasma, some of its photons are backscattered, e.g., through Raman backscattering, to generate a counter-propagating photon beam that is co-linear with the original laser beam. When the backscattered photons interact with high-energy accelerated periodic electron bunches, coherent X-rays are generated through Compton backscattering of the photons off of the electrons. The energy of the backscattered X-rays can be tuned by tuning one or more characteristics of the laser pulse and/or the plasma.

Abstract: A method for generating an extended underwater plasma. A first laser pulse is fired into a body of water to form an underwater optical filament coinciding with a low-energy plasma. A second laser pulse is fired into the water, targeted at the plasma. The second pulse heats the plasma, causing the formation of an extended superheated plasma volume in the water. The two laser pulses can be simultaneous or can be sequential, with the second pulse following the first pulse by up to the filament plasma lifetime. The extended superheated plasma creates an underwater acoustic pulse, wherein the duration, waveform and directivity of the pulse can be tailored by controlling the shape of the underwater laser-generated plasma.

Abstract: A high power ultrashort chirped pulse amplifier laser system, with a chirped pulse amplifier laser module including an optical pulse stretcher, at least one optical power amplifier, and an optical pulse compressor, and a beam interferometer module in the optical path. The beam interferometer receives splits the pulse into at least two pulses, adds a time delay to at least one of the pulses and recombines the pulses to produce a temporally modulated pulse. The resulting modulated output pulse from the CPA laser module can have enhanced laser contrast due to greatly reduced subpicosecond pedestal in the immediate region of the peak pulse, or can have other desirable characteristics.

Abstract: Methods for producing a laser-guided underwater electrical discharge are provided. One or more electrodes defining a desired electrical discharge path are situated in a body of water and are attached to an external electrical power supply. A high-powered, intense laser beam is fired through one or more focusing lenses into the water. The laser beam forms an optical filament in the water, which in turn forms an ionized channel having a much greater conductivity than the surrounding water. An external power supply drives an electrical discharge along the path of the ionized channel due to its greater conductivity.

Abstract: Methods for producing a laser-guided underwater electrical discharge are provided. One or more electrodes defining a desired electrical discharge path are situated in a body of water and are attached to an external electrical power supply. A high-powered, intense laser beam is fired into the water. The laser beam forms an optical filament in the water, which in turn forms an ionized channel having a much greater conductivity than the surrounding water. An external power supply drives an electrical discharge along the path of the ionized channel due to its greater conductivity.

Abstract: A laser pulse from an ultrashort pulse laser (USPL) is fired into the atmosphere. The USPL pulse is configured to generate a plasma filament at a predefined target in the atmosphere, in which free, or “seed,” electrons are generated by multi-photon or tunneling ionization of the air molecules in the filament. A second pulse is fired into the atmosphere to form a heater beam that impinges on the plasma filament and thermalizes the seed electrons within the plasma filament, leading to the collisional excitation of the electrons in the filament. The excited electrons collisionally excite various electronic and vibrational states of the air molecules in the filament, causing population inversions and lasing, e.g., exciting the C3?u?B3?g(v=0?0) transition of the N2 in the atmosphere to cause lasing at 337 nm.

Abstract: An electron injector including an electron source and a conducting grid situated close to the electron source, one or more RF accelerating/bunching cavities operating at the same fundamental RF frequency; a DC voltage source configured to bias the cathode at a small positive voltage with respect to the grid; a first RF drive configured to apply an RF signal between the cathode and grid at the fundamental and third harmonic RF frequencies; and a second RF drive configured to apply an RF drive signal to the accelerating/bunching cavities. Electrons are emitted by the cathode and travel through the grid to the accelerating/bunching cavities for input into an RF linac.

Abstract: A method for generating an extended underwater plasma. A first laser pulse is fired into a body of water to form an underwater optical filament coinciding with a low-energy plasma. A second laser pulse is fired into the water, targeted at the plasma. The second pulse heats the plasma, causing the formation of an extended superheated plasma volume in the water. The two laser pulses can be simultaneous or can be sequential, with the second pulse following the first pulse by up to the filament plasma lifetime. The extended superheated plasma creates an underwater acoustic pulse, wherein the duration, waveform and directivity of the pulse can be tailored by controlling the shape of the underwater laser-generated plasma.

Abstract: A device for generating terahertz radiation using a phase matched optical rectification technique. The device converts laser radiation to terahertz radiation via a particular type of photonic downconversion. The device includes a crystalline material suitable for photonic downconversion of laser radiation, a first coupling component for coupling the laser radiation to the crystalline material and a second coupling component for coupling the generated terahertz radiation from the crystalline material to the environment. By sustaining the phase matching condition over a significant distance, the device is capable of providing terahertz radiation with high peak and average power.

Abstract: A system and methods for the quasi-remote compression and focusing of a moderate-intensity laser pulse to form a much higher intensity beam that can be directed at a target and used as a probe beam or used in a probe beam converter to generate other forms of electromagnetic radiation or energetic particles. A system for the quasi-remote propagation of high-intensity laser beams in accordance with the present invention comprises a main platform on which a first, “seed” laser pulse is generated, stretched, and amplified, and a remote platform, located at a distance from the main platform, which is configured to receive the amplified and stretched pulse and convert it into the high-intensity laser beam. The high-intensity laser beam in turn can then be converted into one or more probe beams directed at a target object.

Abstract: A system and methods for the quasi-remote compression and focusing of a moderate-intensity laser pulse to form a much higher intensity beam that can be directed at a target and used as a probe beam or used in a probe beam converter to generate other forms of electromagnetic radiation or energetic particles. A system for the quasi-remote propagation of high-intensity laser beams in accordance with the present invention comprises a main platform on which a first, “seed” laser pulse is generated, stretched, and amplified, and a remote platform, located at a distance from the main platform, which is configured to receive the amplified and stretched pulse and convert it into the high-intensity laser beam. The high-intensity laser beam in turn can then be converted into one or more probe beams directed at a target object.

Abstract: Methods for producing a laser-guided underwater electrical discharge are provided. One or more electrodes defining a desired electrical discharge path are situated in a body of water and are attached to an external electrical power supply. A high-powered, intense laser beam is fired into the water. The laser beam forms an optical filament in the water, which in turn forms an ionized channel having a much greater conductivity than the surrounding water. An external power supply drives an electrical discharge along the path of the ionized channel due to its greater conductivity.

Abstract: An electron injector including an electron source and a conducting grid situated close to the electron source, one or more RF accelerating/bunching cavities operating at the same fundamental RF frequency; a DC voltage source configured to bias the cathode at a small positive voltage with respect to the grid; a first RF drive configured to apply an RF signal between the cathode and grid at the fundamental and third harmonic RF frequencies; and a second RF drive configured to apply an RF drive signal to the accelerating/bunching cavities. Electrons are emitted by the cathode and travel through the grid to the accelerating/bunching cavities for input into an RF linac.

Abstract: A device for generating terahertz radiation using a phase matched optical rectification technique. The device converts laser radiation to terahertz radiation via a particular type of photonic downconversion. The device includes a crystalline material suitable for photonic downconversion of laser radiation, a first coupling component for coupling the laser radiation to the crystalline material and a second coupling component for coupling the generated terahertz radiation from the crystalline material to the environment. By sustaining the phase matching condition over a significant distance, the device is capable of providing terahertz radiation with high peak and average power.