Abstract: An artificial saturable absorber uses additive pulse mode-locking to enable pulse operation of an on-chip laser operation. Four different artificial saturable absorbers are disclosed. The first includes an integrated coupler, two arms each containing some implementation of the end-reflector, and a phase bias element in one arm. The second includes an integrated directional coupler, two integrated waveguide arms, and another integrated coupler as an output. The third includes an integrated birefringent element, integrated birefringent-free waveguide, and integrated polarizer. And the fourth includes a multimode waveguide that allows for different modes to propagate in such a way that the difference in the spatial distribution of intensity causes a nonlinear phase difference between the modes.

Abstract: X-ray pulse source (100) for generating X-ray pulses (1) includes electron pulse source device (10) including photo-emitter device (11) being configured for photo-induced creation of free electron pulses (2) and driver device (12) being configured for creating electromagnetic driver pulses (3) accelerating electron pulses (2) along acceleration path (7), and electromagnetic interaction device (50) comprising electromagnetic pulse source device (51) being configured for creating electromagnetic pulses (4) in interaction section (5) of electromagnetic interaction device (50), wherein electron pulse source device (10) and electromagnetic interaction device (50) are operable for generating X-ray pulses (1) by an interaction of electron pulses (2) and electromagnetic pulses (4), and driver device (12) includes THz driver pulse source (13), which is configured for creating single cycle or multi cycle THz driver pulses (3). Furthermore, a method of creating X-ray pulses (1) is described.

Abstract: A method of generating THz radiation includes the steps of generating optical input radiation with an input radiation source device (10), irradiating a first conversion crystal device (30) with the optical input radiation, wherein the first conversion crystal device (30) is arranged in a single pass configuration, and generating the THz radiation having a THz frequency in the first conversion crystal device (30) in response to the optical input radiation by an optical-to-THz-conversion process, wherein a multi-line frequency spectrum is provided by the optical input radiation in the first conversion crystal device (30), and the optical-to-THz-conversion process includes cascaded difference frequency generation using the multi-line frequency spectrum. Furthermore, a THz source apparatus being configured for generating THz radiation and applications thereof are described.

Abstract: An artificial saturable absorber uses additive pulse mode-locking to enable pulse operation of an on-chip laser operation. Four different artificial saturable absorbers are disclosed. The first includes an integrated coupler, two arms each containing some implementation of the end-reflector, and a phase bias element in one arm. The second includes an integrated directional coupler, two integrated waveguide arms, and another integrated coupler as an output. The third includes an integrated birefringent element, integrated birefringent-free waveguide, and integrated polarizer. And the fourth includes a multimode waveguide that allows for different modes to propagate in such a way that the difference in the spatial distribution of intensity causes a nonlinear phase difference between the modes.

Abstract: A method of generating THz radiation includes the steps of generating optical input radiation with an input radiation source device (10), irradiating a first conversion crystal device (30) with the optical input radiation, wherein the first conversion crystal device (30) is arranged in a single pass configuration, and generating the THz radiation having a THz frequency in the first conversion crystal device (30) in response to the optical input radiation by an optical-to-THz-conversion process, wherein a multi-line frequency spectrum is provided by the optical input radiation in the first conversion crystal device (30), and the optical-to-THz-conversion process includes cascaded difference frequency generation using the multi-line frequency spectrum. Furthermore, a THz source apparatus being configured for generating THz radiation and applications thereof are described.

Abstract: X-ray pulse source (100) for generating X-ray pulses (1) includes electron pulse source device (10) including photo-emitter device (11) being configured for photo-induced creation of free electron pulses (2) and driver device (12) being configured for creating electromagnetic driver pulses (3) accelerating electron pulses (2) along acceleration path (7), and electromagnetic interaction device (50) comprising electromagnetic pulse source device (51) being configured for creating electromagnetic pulses (4) in interaction section (5) of electromagnetic interaction device (50), wherein electron pulse source device (10) and electromagnetic interaction device (50) are operable for generating X-ray pulses (1) by an interaction of electron pulses (2) and electromagnetic pulses (4), and driver device (12) includes THz driver pulse source (13), which is configured for creating single cycle or multi cycle THz driver pulses (3). Furthermore, a method of creating X-ray pulses (1) is described.

Abstract: A pulse light source device for creating fs output pulses, includes a driver source device including a ps laser pulse source for creating a ps laser pulse output, a first beam splitting device for splitting the ps laser pulse output to first and second ps driver pulses, a first spectral broadening device for creating first fs driver pulses by spectrally broadening the first ps driver pulses, an optical parametric amplifier (OPA) device for creating CEP stabilized second fs driver pulses, and for seeding on the basis of the first fs driver pulses and pumping with the second ps driver pulses, wherein the second fs driver pulses include idler pulses of the OPA device, and a second spectral broadening device for creating the fs output pulses, and arranged to be driven on the basis of the second fs driver pulses. Furthermore, a method of creating fs output pulses is described.

Abstract: An inventive composite optical gain medium capable includes a thin-disk gain layer bonded to an index-matched cap. The gain medium's surface is shaped like a paraboloid frustum or other truncated surface of revolution. The gain medium may be cryogenically cooled and optically pumped to provide optical gain for a pulsed laser beam. Photons emitted spontaneously in the gain layer reflect off or refract through the curved surface and out of the gain medium, reducing amplified spontaneous emission (ASE). This reduces limits on stored energy and gain imposed by ASE, enabling higher average powers (e.g., 100-10,000 Watts). Operating at cryogenic temperatures reduces thermal distortion caused by thermo-mechanical surface deformations and thermo-optic index variations in the gain medium. This facilitates the use of the gain medium in an image-relayed, multi-pass architecture for smoothed extraction and further increases in peak pulse energy (e.g., to 1-100 Joules).

Abstract: Feedback loops can be used to shift and stabilize the carrier-envelope phase of a frequency comb from a mode-locked fibers laser or other optical source. Compared to other frequency shifting and stabilization techniques, feedback-based techniques provide a wideband closed-loop servo bandwidth without optical filtering, beam pointing errors, or group velocity dispersion. It also enables phase locking to a stable reference, such as a Ti:Sapphire laser, continuous-wave microwave or optical source, or self-referencing interferometer, e.g., to within 200 mrad rms from DC to 5 MHz. In addition, stabilized frequency combs can be coherently combined with other stable signals, including other stabilized frequency combs, to synthesize optical pulse trains with pulse durations of as little as a single optical cycle. Such a coherent combination can be achieved via orthogonal control, using balanced optical cross-correlation for timing stabilization and balanced homodyne detection for phase stabilization.

Abstract: A substantially dispersion-free optical filter cavity includes a first multilayer mirror and a second multilayer mirror, wherein each mirror includes layers of a less-refractive material and layers of a more-refractive material, the more-refractive material having a higher index of refraction than the less-refractive material. The mirrors are separated by a spacing, and the thickness of a plurality of the layers in the second multilayer mirror differ from corresponding layers in the first multilayer mirror to provide the cavity with complementary group-delay dispersion across the cavity with a phase difference within, e.g., ±0.015 rad across a range of wavelengths spanning at least, e.g., 50 nm.

Abstract: A balanced optical cross correlator includes an optical waveguide, a first photodiode including a first n-type semiconductor and a first p-type semiconductor positioned about the optical waveguide on a first side of the optical waveguide's point of symmetry, and a second photodiode including a second n-type semiconductor and a second p-type semiconductor positioned about the optical waveguide on a second side of the optical waveguide's point of symmetry. A balanced receiver including first and second inputs is configured to produce an output current or voltage that reflects a difference in currents or voltages, originating from the first and the second photodiodes of the balanced cross correlator and fed to the first input and to the second input of the balanced receiver.

Abstract: A laser cavity includes a gain medium for amplifying a light pulse in a light path, wherein the gain medium has a gain profile for amplifying the light pulse as a function of wavelength; at least one mirror on one side of the gain medium; and an output coupler. The output coupler has an output coupling profile for inducing loss in the light pulse as a function of wavelength that substantially matches the saturated gain profile of the gain medium across a range of lasing wavelengths. The purpose of this device is to achieve a flattened net-gain profile to substantially improve mode-locking performance with respect to self-starting, beam-quality, and broadband operation.

Abstract: Coherent electronic current, which can be used to generate coherent radiation, is generated by first generating and transmitting an array of discrete electron beamlets from a nanocathode array along a longitudinal axis. The array of electron beamlets is then focused to reduce the spacing that separates the electron beamlets. The transverse-axis spacing of the electron beamlets is then transferred to the longitudinal axis via an emittance exchange beamline, creating a periodically modulated distribution of coherent electronic current. The coherent electronic current can then be directed into a stream of photons to generate coherent radiation.

Abstract: Feedback loops can be used to shift and stabilize the carrier-envelope phase of a frequency comb from a mode-locked fibers laser or other optical source. Compared to other frequency shifting and stabilization techniques, feedback-based techniques provide a wideband closed-loop servo bandwidth without optical filtering, beam pointing errors, or group velocity dispersion. It also enables phase locking to a stable reference, such as a Ti:Sapphire laser, continuous-wave microwave or optical source, or self-referencing interferometer, e.g., to within 200 mrad rms from DC to 5 MHz. In addition, stabilized frequency combs can be coherently combined with other stable signals, including other stabilized frequency combs, to synthesize optical pulse trains with pulse durations of as little as a single optical cycle. Such a coherent combination can be achieved via orthogonal control, using balanced optical cross-correlation for timing stabilization and balanced homodyne detection for phase stabilization.

Abstract: Extreme ultraviolet radiation is generated based on high-order harmonic generation. First, a driver pulse is generated from a drive laser. Second, the infrared driver pulse is passed through a second harmonic generator with an output wavelength in the range from 400 to 700 nm. Third, the pulse is then passed through a gas medium, which can be inside a resonant cavity, to generate a high-order harmonic in the form of extreme ultraviolet radiation.

Abstract: An inventive composite optical gain medium capable includes a thin-disk gain layer bonded to an index-matched cap. The gain medium's surface is shaped like a paraboloid frustum or other truncated surface of revolution. The gain medium may be cryogenically cooled and optically pumped to provide optical gain for a pulsed laser beam. Photons emitted spontaneously in the gain layer reflect off or refract through the curved surface and out of the gain medium, reducing amplified spontaneous emission (ASE). This reduces limits on stored energy and gain imposed by ASE, enabling higher average powers (e.g., 100-10,000 Watts). Operating at cryogenic temperatures reduces thermal distortion caused by thermo-mechanical surface deformations and thermo-optic index variations in the gain medium. This facilitates the use of the gain medium in an image-relayed, multi-pass architecture for smoothed extraction and further increases in peak pulse energy (e.g., to 1-100 Joules).

Abstract: A balanced optical cross correlator includes an optical waveguide, a first photodiode including a first n-type semiconductor and a first p-type semiconductor positioned about the optical waveguide on a first side of the optical waveguide's point of symmetry, and a second photodiode including a second n-type semiconductor and a second p-type semiconductor positioned about the optical waveguide on a second side of the optical waveguide's point of symmetry. A balanced receiver including first and second inputs is configured to produce an output current or voltage that reflects a difference in currents or voltages, originating from the first and the second photodiodes of the balanced cross correlator and fed to the first input and to the second input of the balanced receiver.

Abstract: Seed light pulses and pump light pulses are generated; the seed light pulses are preferably chirped; and both are directed into an enhancement cavity at a full repetition rate. The enhancement cavity defines a closed optical path that contains a nonlinear medium that provides phase matching at a wavelength different from both the central seed wavelength and the central pump wavelength. The generation of the pump light pulses and the seed light pulses are synchronized to pass the seed light pulses through the nonlinear medium simultaneously with the pump light pulses to parametrically amplify the seed light pulses in the nonlinear medium to produce an amplified signal pulse and idler pulse. Increased conversion with low average pump power can be achieved, as well as gain bandwidth enhancement approaching octave-spanning levels.

Abstract: Coherent electronic current, which can be used to generate coherent radiation, is generated by first generating and transmitting an array of discrete electron beamlets from a nanocathode array along a longitudinal axis. The array of electron beamlets is then focused to reduce the spacing that separates the electron beamlets. The transverse-axis spacing of the electron beamlets is then transferred to the longitudinal axis via an emittance exchange beamline, creating a periodically modulated distribution of coherent electronic current. The coherent electronic current can then be directed into a stream of photons to generate coherent radiation.

Abstract: Femtosecond pulse trains in waveguide lasers with high fundamental repetition rates are achieved by exploiting the nonlinearity in the waveguide. Components of the apparatus include an optical resonator, a saturable absorber for starting and stabilizing mode-locking, and a gain element. Part of the laser cavity or the entire laser cavity is made of waveguide or fiber (collectively called “waveguide” herein). The net dispersion of the laser cavity can be anomalous. This anomalous dispersion in combination with the positive self-phase modulation nonlinearity in the waveguide creates soliton formation to shorten the pulse duration in the invented lasers. Conversely, a normal dispersive waveguide with negative self-phase modulation nonlinearity can also be used.