We demonstrate the generation of a coherent water window x ray by extending plateau region high-order harmonics under neutral-medium condition. The maximum harmonic photon energies attained are 300 and 450 eV in Ne He, respectively. Our proposed scheme, combining 1.6 microm laser driver neutral gas medium, is efficient scalable output yields ray. Thus, precept design parameter for single-shot live-cell imaging contact microscopy presented.

We demonstrate methods to increase the energy incident on hollow fibers for spectral broadening by self-phase modulation. used chirped pulses broadening, lowering optical intensity avoid ionization of gaseous medium. also helium as a nonlinear medium and demonstrated generation 5.0fs, 5.0mJ at repetition rate 1kHz using pressure gradient hollow-fiber pulse compressor.

Multiphoton ionization processes in aligned ${\mathrm{I}}_{2}$ molecules are actively controlled by the homemade pulse shaping system, with which a time-dependent polarization can be generated and controlled. We find correlation between femtosecond production efficiency of evenly or oddly charged molecular ions. achieve much better controllability than having fixed ellipticity. The results suggest existence an unknown tunnel mechanism is characteristic pulse. Our experiments point to new...

We present a dramatic enhancement [Phys. Rev. Lett. 91, 043002 (2003)] of high-order harmonic generation by simultaneous irradiation booster harmonics. A key feature our experiment is the use mixed gases (Xe and He) with different ionization energies. The harmonics from Xe atoms act as to increase yield He factor 4 x 10(3). dominance effect supported simulation time-dependent Schrödinger equation well observed spatial characteristic generated dependence on medium conditions.

We report ellipticity dependence of high-order harmonic generation (HHG) from aligned ${\mathrm{N}}_{2}$, ${\mathrm{O}}_{2}$, and ${\mathrm{CO}}_{2}$ molecules. Experimentally, we find that the is sensitive to molecular alignment shape symmetry valence orbitals. It also found destructive interference in recombination process affects dependence. Theoretically, extend original Lewenstein model a more generalized model, which can be applicable HHG molecules, by introducing an electron...

We report on the first experimental evidence of destructive and constructive interference high harmonics generated in a mixed gas He Ne, which facilitates coherent control harmonic generation. Theoretically, we develop an analytical model generation gases succeed reproducing results deriving optimization conditions for process. The observed modulation is attributed to difference between phases intrinsically chirped pulses from leads novel method broadband measurement observing underlying...

We present the extension of high-power pulse compression deeper into challenging IR spectral range around 3.2 μm wavelength, where effects material absorption, dispersion, and free electron disturbance on nonlinear propagation become increasingly limiting parameters. 5 mJ, 80 fs pulses from a KTA parametric amplifier were spectrally broadened in large-core hollow fiber with argon as medium. Subsequent through anomalous dispersion CaF2 yielded 2.5 mJ close-to-transform-limited two-cycle...

We report on the parametric generation of 100 fs sub-6-cycle 40 μJ pulses with center wavelength at 5.2 μm using a 1 ps 2.1 pump laser and dispersion management scheme based bulk material. Our optically synchronized amplifier chain consists Ho:YAG chirped-pulse white-light-seeded optical amplifiers providing simultaneous passive carrier-envelope phase locking three ultrashort longwave pump, signal, idler wavelengths corresponding, respectively, to 2.1, 3.5, μm. also demonstrate bandwidth...

We present a concept of white-light-seeded-cascaded mid-infrared (mid-IR) optical parametric amplifier (OPA) based on potassium titanyl arsenate and zinc germanium phosphate nonlinear crystals producing 100-μJ level pulses centered at 5300 nm, with the spectrum supporting four-optical-cycle pulse duration. The OPA is pumped by 2090-nm master oscillator/power Tm,Ho-fiber laser seeder Ho:YAG regenerative delivering 3.8-mJ sub-ps repetition rate 1 kHz. validate that output parameters are...

We have investigated the possibility of molecular orientation using an asymmetric potential created by superposition strong, nonresonant, two-color (ω+2ω) laser fields. The time-independent Schrödinger equations are solved numerically for FCN molecules as example in adiabatic regime where proceeds slowly compared to rotational period molecules. show intensity dependence parameter 《cos θ》 and alignment 《cos2 θ is angle between polarization axis axis, their time evolution during fields,...

Power scaling of an infrared (IR) parametric amplifier chain, pumped at 800nm by a terawatt Ti:sapphire laser system has been reported. A total output energy exceeding 10mJ with 40fs pulse duration achieved in the IR region, which is highest and peak power ever reported for ultrafast optical scheme. By applying developed pulses to high-order harmonic generation, we have observed significant cutoff extension compared case driving wavelength. This source suits as driver extending photon into...

We report on the development of an optical parametric chirpedpulse amplifier at a 1-kHz repetition rate with 5.5-fs pulse duration, 2.7-mJ energy and carrier-envelope phase-control. The is pumped by 450-nm from frequency-doubled Ti:sapphire laser.

Abstract When an electron binds to its anti-matter counterpart, the positron, it forms exotic atom positronium (Ps). Ps can further bind another form negative ion, − (e e + ). Since constituents are solely point-like particles with same mass, this system provides excellent testing ground for three-body problem in quantum mechanics. While theoretical works on energy level and dynamics have been performed extensively, experimental investigations of characteristics hampered by weak ion yield...

We demonstrate that the structure of ${\mathrm{CO}}_{2}$ molecules can be determined by measuring phases harmonics from them. This is evidenced observing a phase jump generated in mixed gas aligned and their reference Kr atoms, which serve to extract net contribution due molecules. Furthermore, strong field approximation model, we derive exact conditions quantum interference during high-order harmonic generation analytically propose method control pulse duration.

We demonstrate an optical parametric chirped-pulse amplification (OPCPA) system with the pulse energy of 1.5 mJ at a 1 kHz repetition rate. The newly developed 100 ps Ti:sapphire pump laser system, which was optically synchronized OPCPA seed pulses, delivered 10 mJ, 400 nm pulses. After three-stage amplification, recompression amplifier output from 45 to 6.4 fs performed. width is, our knowledge, shortest ever obtained by OPCPA, and average power W (1.5 kHz) is believed be highest among...

Efficient high-order harmonic generation was obtained in helium below $10\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ using a linearly polarized two-color field consisting of Ti:sapphire laser pulse $(\ensuremath{\omega})$ with 40-fs duration and its second $(2\ensuremath{\omega})$ 24-fs duration. The intensity the harmonics enhanced more than that $\ensuremath{\omega}$ or $2\ensuremath{\omega}$ alone by one order magnitude along extension cutoff efficient even-order harmonics. This observation...

The pulse shape and phase of isolated attosecond extreme ultraviolet (XUV) pulses with a duration 860 asec have been determined simultaneously by using frequency-resolved optical gating based on two-photon above-threshold ionization 28-eV photons in He. From the detailed characterization, we succeeded shaping XUV an time scale precise dispersion control Ar gas density or changing driving width. These results offer novel way to excite observe electron motion atoms molecules.

We experimentally demonstrate that by longitudinally pumping 2 mm long molybdenum preformed plasma with high-intensity 475 fs duration laser pulse, a highly directive soft-x-ray at 18.9 nm wavelength is generated. The divergence of the beam evaluated to be submilliradian order, and only requires pump energy 150 mJ.

We report the results of our studies on selection quantum path in high-harmonic generation (HHG) with a relative-phase-locked two-color laser field. It is shown that by tuning relative phase between fundamental and second-harmonic fields, The timing tunnel ionization subsequent electron trajectories sub-cycle time scale can be controlled. have clearly observed phase-dependent two-step feature harmonic spectra attributed to two major field HHG.

We probe the attosecond dynamics of nuclear wavepackets in H2 and D2 molecules by measuring relative phase high harmonics generated each molecule using a novel method with mixed gas D2. find that not only single responses but also propagation effects differ between two isotopes we conclude order to discuss responses, need be excluded from raw harmonic signals. The measured as well intensity ratio are found monotonic functions successfully reproduced applying Feynman's path integral fully...

Toward the systematic search for axion-like particles in eV mass range, we proposed concept of a stimulated resonant photon collider by focusing three short pulse lasers into vacuum. In order to realize such collider, have performed proof-of-principle experiment with set large incident angles between beams overcome expected difficulty ensure space–time overlap and also established method evaluate bias on polarization states, which is useful future variable–incident–angle collision system....

We demonstrate a carrier-envelope phase (CEP)-stable, KTA (KTiOAsO4)-based optical parametric amplifier (OPA) delivering 6-cycle (79 fs), 3.8-μm pulses at 100-kHz repetition rate with an average power of 4.5 W. The pivotal achievement is the stable generation supercontinuum (SC) seed in YAG 1.4-ps pulses, which are longest for SC on its longer wavelength side to 2.2 μm. This technology offers robust and simplified OPA architecture characteristics passively stabilized CEPs, dispersion...