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We report a strong carrier-envelope-phase dependence of high-harmonics in bulk solids subjected to strong few-cycle laser fields. We discover that harmonics are delayed with respect to each other at the sub-cycle level, yielding an atto-chirp.
We investigate the broadening and compression of high average power near-infrared pulses from a Yb:KGW laser amplifier that undergo self-phase modulation in a series of thin fused silica plates. The efficiency of the technique is investigated through spectral and temporal characterization of the broadened pulses.
We exploit nonlinear self-compression in YAG to generate sub-three-cycle, 10 μJ pulses from a 50 kHz mid-IR OPA. Efficiency and cutoff enhancement of generated high-order harmonics in ZnO relative to longer driving pulses demonstrates the potential for solid-state attosecond pulse generation through nonlinear self-compression.
Isolated attosecond pulses are powerful tools for exploring electron dynamics in matter. We proposed and demonstrated a technique called generalized double optical gating for generating isolated attosecond pulses. The double optical gating scheme, relaxing the stringent requirement on laser pulse duration from ≤ 5 fs to pulse duration close to the amplifier output, would make attophysics more accessible...
OPCPA laser systems require a high-quality, high-energy picosecond pump. The challenges of energy scaling in multi-kilohertz systems include thermal loads, depolarization and gain extraction. We address these issues for a high energy/average power MOPA System.
The analysis of the filament destruction and reformation as a single aerosol is positioned along the radial and longitudinal axes of the filament provides more understanding of the propagation of filaments in aerosol-containing media.
Quantum beats with periods of 5–10 fs are observed in various near-threshold autoionizing states of krypton atoms in an attosecond transient absorption experiment, such measurement allows reconstruction of the valence state wave packets.
Supercontinuum generation by filamentation in molecular gases is optimized by studying the ellipticity of the pulse polarization during the interaction with the species of the gas medium via strong field ionization and molecular alignment effects.
The analysis of the destruction and reformation of a single laser filament interacting with a single micro-sized water droplet allows a better understanding of filament propagation through atmospheric aerosols.
We demonstrate a dramatic enhancement of the below-threshold harmonics in the vicinity of atomic resonances. The dependence on the driving laser carrier-envelope phase suggests a nonperturbative mechanism. Phase matching promises scalability to microJoule pulse energies.
We developed a method to stabilize the carrier-envelope phase of a 20 TW Ti:Sapphire laser operating at 10 Hz. Phase-dependent features were observed in the high-order harmonic spectrum generated using Generalized Double Optical Gating.
Isolated attosecond pulses are used to probe laser-perturbed hydrogen molecules using attosecond absorption spectroscopy. We observe dynamic features in the delay-dependent absorption on both the electronic and nuclear timescales for the first time.
An XUV continuum supporting 280 as isolated attosecond pulses is generated in argon with a 200 mJ, 17 fs Ti:Sapphire laser using the GDOG technique. The energy of the XUV pulse is over 100 nJ at generation location.
Isolated attosecond pulses with continuum spectra extending below 15 eV are used to probe the sub-cycle energy shifts and splitting of helium excited states. Additionally, new absorption features appear far from the 1snp absorption lines.
Single isolated attosecond pulse is a new powerful tool for studying dynamics of correlated electron motion in pump-probe experiments [1]. Such pulses, as short as 67 attoseconds, can now be generated with the Double Optical Gating (DOG) method. The broadband XUV supercontinuum spectrum of the isolated attosecond pulse is particularly suitable for probing the time variation of the electronic states...
By probing the optical Stark shifts induced by a few-cycle laser field using isolated attosecond pulses in a transient absorption scheme, we uncover a sub-cycle-laser-induced AC Stark shift in excited states of the helium atom.
Generalized Double Optical Gating is an effective scheme for generating single isolated attosecond pulses with multi-cycle driving lasers. It is to be implemented using a >100 mJ Ti:Sapphire laser to upscale the attosecond photon flux.
The dynamics of helium 1snp excited states in an intense, few-cycle laser pulse are probed using isolated attosecond pulses in a transient absorption scheme. In addition to the dynamic Stark shift, we observe half-cycle oscillations.
Characterizing shorter attosecond pulses has been limited by an approximation in the FROG-CRAB retrieval. We demonstrate a new technique based on interference in laser-assisted photoionization which can characterize ultrabroadband attosecond pulses.
Autoionization in argon atoms was studied by transient absorption spectroscopy with isolated attosecond XUV pulses. The peak position, line shape and population of the resonant states were modified by intense near infrared laser pulses.
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