We demonstrated a novel optical switch to control the high-order harmonic generation process so that single attosecond pulses can be generated with multiple-cycle pulses. The technique combines two powerful gating methods: polarization and two-color gating. An extreme ultraviolet supercontinuum supporting 130 as was neon gas using 9 fs laser discovered unique dependence of spectra on carrier-envelope phase fields, which repeats every 2 pi radians.

Isolated attosecond pulses are powerful tools for exploring electron dynamics in matter. So far, such extreme ultraviolet have only been generated using high power, few-cycle lasers, which very difficult to construct and operate. We propose demonstrate a technique called generalized double optical gating generating isolated with 20 fs lasers from hollow-core fiber 28 directly an amplifier. These pulses, argon gas, measured be 260 148 as by reconstructing the streaked photoelectron...

Two-color (800 and 400 nm) short (45 fs) linearly polarized pulses are used to ionize dissociate D2 into a neutral deuterium atom deuteron. The yields energies of the ions measured left right along polarization vector. As relative phase two colors is varied, strong yield asymmetries found in ion-energy regions traditionally identified as bond softening, above-threshold dissociation rescattering. these quite different. A model based on dynamic coupling by laser field gerade ungerade states...

Laser-dressed absorption in atomic helium is studied, both theoretically and experimentally, by transient spectroscopy using isolated 400-as pulses centered at 22 eV 12-fs near-infrared (NIR) with 780-nm central wavelength. Multiple features the singly excited bound-state spectrum are observed only when NIR attosecond overlapped time. Theoretical analysis indicates that these light-induced structures (LISs) intermediate states resonant, second-order processes transfer population to multiple...

We investigate the focusability of intense coherent soft-x-ray radiation generated by high-order harmonic conversion. The 27th-harmonic wave at 29.6 nm is focused an off-axis parabolic mirror with a SiC/Mg multilayer coating. Focal-spot images are observed from visible fluorescence induced photons on Ce:YAG scintillator. demonstrate focusing beam to 1‐µm spot size peak intensity 1×1014 W/cm2, which our knowledge highest ever reported in region.

High-order (three-photon or more) above-threshold dissociation (ATD) of ${\mathrm{H}}_{2}^{+}$ has generally not been observed using 800 nm light. We demonstrate a strong enhancement its probability intense 7 fs laser pulses interacting with beams ${\mathrm{H}}_{2}^{+}$, ${\mathrm{HD}}^{+}$, and ${\mathrm{D}}_{2}^{+}$ ions. The mechanism invokes dynamic control the pathway. These measurements are supported by theory that additionally reveals, for first time, an unexpectedly large...

Attosecond science has opened up the possibility of manipulating electrons on their fundamental timescales. Here, we use both theory and experiment to investigate ionization dynamics in helium attosecond timescale by simultaneously irradiating atom with a soft x-ray pulse train (APT) an ultrafast laser pulse. Because APT resolution energy time, observe processes that could not be observed without domains simultaneously. We show resonant absorption is important excitation small changes...

The time delay between the pump and probe pulses in attosecond time-resolved experiments, such as streaking, is commonly introduced by splitting recombining two an interferometer. This technique suffers from instability optical path lengths of arms due to mechanical vibration elements fluctuating environmental conditions. We present a with which unconventional interferometer suppressed while at same controlled within 20 RMS using feedback loop. Using this scheme, streaked spectrogram pulse...

Double optical gating of high-harmonic generation was used to obtain supercontinuous spectra in the extreme UV (XUV) region including water window. The supported a 16 as pulse duration that is below one atomic unit time (24 as). dependence gated on carrier-envelope phase laser provided evidence isolated attosecond pulses were generated. In addition, ensure temporal coherence XUV light, shape and 107 using portion spectrum characterized by streaking.

For further development of a variety applications, one the most important issues is improvement output harmonic energy and conversion efficiency. We review our work on scaling high-order generation based phase-matching using loosely focused beam. Our method can be universally applied to in neutral rare gas target. In addition, we demonstrate new concept for spatial separation between high-energy pump beam increase available soft X-ray applications. This very simple highly useful not only but...

The authors report the generation of 1.2mJ pulses with a duration 5.6fs from neon filled hollow-core fiber seeded carrier-envelope phase stabilized 2.2mJ, 25fs pulses. after was measured by second, out-loop f-to-2f interferometer. With seed pulse power locked, two-cycle is controlled to standard deviation 370mrad. peak pulses, 0.2TW, twice that previously generated. significance energy stability for stabilization few-cycle laser demonstrated.

The attosecond streaking technique is used for the characterization of isolated extreme ultraviolet (XUV) pulses. This type measurement suffers from low photoelectron counts in streaked spectrogram, and thus susceptible to shot noise. For retrieval few- or mono-cycle pulses, high-intensity laser fields are required, which cause energy spectrum above-threshold ionized (ATI) electrons overlap with that photoelectrons. It found by using principal component generalized projections algorithm XUV...

Lightwave-field-induced ultrafast electric dipole oscillation is promising for realizing petahertz (1015 Hz: PHz) signal processing in the future. In building ultrahigh-clock-rate logic operation system, one of major challenges will be electron manipulation accompanied with multiple frequencies. Here we study multi-petahertz interference electronic oscillations alumina chromium dopant (Cr:Al2O3). An intense near-infrared lightwave-field induces inter-band polarizations, which are...

For f-to-2f interferometers based on white-light generation in sapphire plates, the accuracy of carrier-envelope (CE) phase measurement and stabilization is affected by laser energy fluctuation. The coupling coefficient between CE has been determined modulating pulse an in-loop interferometer while measuring variation with out-loop interferometer. When total spectral measured was locked, a 1% change caused 160 mrad shift output pulses.

We followed fast evolution of coherent nuclear wave packets in ${\text{H}}_{2}$ and ${\text{D}}_{2}$ molecules after their interaction with 8-fs 800-nm laser pulses. The were probed by another few-cycle pulse time delayed for up to 10 ps respect the pump. For neutral we observed rotational dynamics characterized periodic revivals without noticeable decoherence within scale. heavy hydrogen four states involved each two spin isomers. In light resulting was dominated beating just states....

Recording the transmitted spectrum of a weak attosecond pulse through medium, while strong femtosecond copropagates at variable delay, probes strong-field dynamics atoms, molecules, and solids. Usually, interpretation these measurements is based on assumption thin medium. Here, propagation macroscopic medium helium atoms in region fully allowed resonances investigated both theoretically experimentally. The has dramatic effects transient even relatively low pressures (50 mbar) short lengths...

It is demonstrated that the carrier-envelope (CE) phase of pulses from a high power ultrafast laser system with grating-based stretcher and compressor can be stabilized to root mean square (rms) value 180 mrad over almost 2 hours, excluding brief re-locking period. The stabilization was accomplished via feedback control grating separation in stretcher. shows long term CE stability based chirped pulse amplification as good lasers using glass-block prism pair compressor. Moreover, by adjusting...

Previously, a second harmonic field was added to polarization gating by Mach–Zehnder interferometer gate the high generation process in argon gas. To reduce losses of interferometer, we developed collinear setup consisting only two quartz plates and barium borate crystal. The intensity at focus allowed double optical be performed on neon As result, supercontinuous spectrum produced capable supporting 130as. There is no delay jitter between associated this setup, which necessary for...

Polarization engineering and characterization of coherent high-frequency radiation are essential to investigate control the symmetry properties light–matter interaction phenomena at their most fundamental scales. This work demonstrates that polarization high-harmonic generation provides an excellent ellipsometry tool can fully retrieve both amplitude phase a strong-field-driven dipole response. The is realized by transient nonlinear grating coherently induced two noncollinear counterrotating...

A compact and robust Mach-Zehnder type interferometer coupled with the double optical gating technique provides tunable isolated attosecond pulses streak field detection fields centered at either 750 nm or 400 nm. Isolated produced 45 eV (with measured pulse duration of 114 ± 4 as) 20 395 6 are temporally characterized a wavelength field. In addition, an 118 10 as is The design used herein broad flexibility for experiments, allowing pump probe to be specified independently. This capability...

Light-induced states in He atoms were characterized using attosecond transient absorption spectroscopy. A 400 as pulse covering the 20–24 eV spectral range serves probe pulse, and effect of a few-cycle near infrared (12 fs, 780 nm) on spectrum is measured function time delay near-infrared intensities varying from (5.0 ± 2) × 1010 to (1 0.4) 1013 W/cm2. resulting coupling 1s2p 1s2s, 1s3d, 1s3s are observed. Absorption features that likely result 1s3p 1s4s, 1s4d, 1s5s, 1s5d also The...

Abstract In many atomic, molecular and solid systems, Lorentzian Fano profiles are commonly observed in a broad research fields throughout variety of spectroscopies. As the profile structure is related to phase time-dependent dipole moment, it plays an important role study quantum properties. Here we determine inner-shell transition using spectral interferometry for direct electric-field reconstruction (SPIDER) with isolated attosecond pulses (IAPs). addition, propose scheme pulse generation...

The dependence of the carrier-envelope (CE) phase pulses from a hollow-core fiber on input laser energy was studied using two f-to- 2f interferometers. CE in in-loop f-to-2f interferometer measured with octave spanning white-light spectrum fiber, whereas out-of-loop based sapphire plate. By modulating power and measuring at same time, coupling coefficient between for determined to be 128 mrad per 1% change .