Gilad Marcus

Generation of carrier-envelope-phase-stable 2-cycle 740-μJ pulses at 2.1-μm carrier wavelength

We produce carrier-envelope-phase-stable 15.7-fs (2-cycle) 740-μJ pulses at the 2.1-μm carrier wavelength, from a three-stage optical parametric chirped-pulse amplifier system, pumped by an optically synchronized 49-ps 11-mJ Nd:YLF laser. A novel seed pulse spectral shaping method is used to ascertain the true amplified seed energy and the parametric superfluorescence levels.

Carrier-envelope-phase-stable, 1.2 mJ, 1.5 cycle laser pulses at 2.1 μm

We produce 1.5 cycle (10.5 fs), 1.2 mJ, 3 kHz carrier-envelope-phase-stable pulses at 2.1 μm carrier wavelength, from a three-stage optical parametric chirped-pulse amplifier system, pumped by an optically synchronized 1.6 ps Yb:YAG thin disk laser. A chirped periodically poled lithium niobate crystal is used to generate the ultrabroad spectrum needed for a 1.5 cycle pulse through difference frequency mixing of spectrally broadened pulse from a Ti:sapphire amplifier. It will be an ideal tool for producing isolated attosecond pulses with high photon energies.

Dispersion control with reflection grisms of an ultra-broadband spectrum approaching a full octave.

We report the design, implementation, and characterization of a grism-pair stretcher in a near-infrared noncollinear optical parametric chirped-pulse amplifier (OPCPA) that is capable of controlling a bandwidth of 440 nm. Our dynamic dispersion control scheme relies on the grism stretcher working in conjunction with an acousto-optic programmable dispersive filter (Dazzler) to jointly compensate large amount of material dispersion. A spectral interference technique is used to characterize the spectral phase of the grism stretcher. This ultra-broadband device opens up the way to generate sub-2-cycle laser pulses.

Phase-separation transition in liquid mixtures near curved charged objects.

We study the thermodynamic behavior of nonpolar liquid mixtures in the vicinity of curved charged objects, such as electrodes or charged colloids. There is a critical value of charge (or potential), above which a phase-separation transition occurs, and the interface between high- and low-dielectric constant components becomes sharp. Analytical and numerical composition profiles are given, and the equilibrium front location as a function of charge or voltage is found. We further employ a simple Cahn-Hilliard type equation to study the dynamics of phase separation in spatially nonuniform electric fields. We find an exponential temporal relaxation of the demixing front location. We give the dependence of the steady-state location and characteristic time on the charge, mixture composition and ambient temperature.

Sub-cycle electron control in the photoionization of xenon using a few-cycle laser pulse in the mid-infrared

Using few-cycle laser pulses generated by optical parametric chirped pulse amplification, sub-cycle light-wave control of electrons was achieved at a carrier wavelength of 2.1 μm. We demonstrate the sub-cycle light-wave control in the case of strong field ionization of xenon atoms. Angle-resolved spectra of electrons emitted in the photoionization process were recorded as a function of the carrier-envelope phase (CEP) using an electron imaging technique. We observed a clear CEP-dependent asymmetry in the electron momentum distribution.

Generation of a high-energy ultrawideband chirped source in periodically poled LiTaO3

A method for generation of a chirped, ultrawideband infrared source by use of optical parametric generation in periodically poled crystals and pumped by a chirped Ti:sapphire laser is described. A ∼35% bandwidth in the idler branch was demonstrated in a periodically poled LiTaO3 crystal pumped by a chirped Ti:sapphire laser with 2.1% bandwidth. Optical parametric generation and optical parametric amplification configuration allowed us to generate up to a ∼250-µJ chirped pulse from 2.1 to 3 µm.

Discriminating between the Role of Phase Matching and that of the Single-Atom Response in Resonance Plasma-Plume High-Order Harmonic Generation.

For many years, HHG were generated in a variety of gases, including atomic, molecular and ionized gases. The resulting harmonic spectrum has some universal features, common to almost all gas species in use: it has a long plateau region in which the intensities of all the harmonics are almost identical, followed by a sharp drop, called the cutoff energy. The universality of the harmonics spectrum and the lack of small details related to specific gas in use, suggests that the HHG process is a non-resonant one. Recently, it was discovered that HHG in some laser-ablated plasmas do show resonance features in the harmonic spectrum. This resonance coincides with a transition from an autoionization state, back to the ground state of a singly ionized atom.

Generation and applications of sub-5-fs multi-10-TW light pulses

We report on the development and relevant characteristics of an optical parametric synthesizer light source delivering sub-5-fs pulses with 80 mJ energy. The first applications of the system are attosecond and relativistic laser-plasma physics.

Next Generation Driver for Attosecond and Laser-plasma Physics

The observation and manipulation of electron dynamics in matter call for attosecond light pulses, routinely available from high-order harmonic generation driven by few-femtosecond lasers. However, the energy limitation of these lasers supports only weak sources and correspondingly linear attosecond studies. Here we report on an optical parametric synthesizer designed for nonlinear attosecond optics and relativistic laser-plasma physics. This synthesizer uniquely combines ultra-relativistic focused intensities of about 1020 W/cm2 with a pulse duration of sub-two carrier-wave cycles. The coherent combination of two sequentially amplified and complementary spectral ranges yields sub-5-fs pulses with multi-TW peak power. The application of this source allows the generation of a broad spectral continuum at 100-eV photon energy in gases as well as high-order harmonics in relativistic plasmas. Unprecedented spatio-temporal confinement of light now permits the investigation of electric-field-driven electron phenomena in the relativistic regime and ultimately the rise of next-generation intense isolated attosecond sources.

High pulse energy passive Q-switching of a diode-pumped Tm:YLF laser by Cr:ZnSe

A passively Q-switched diode-pumped Tm:YLF laser with polycrystalline Cr:ZnSe as the saturable absorber is demonstrated for the first time, to the best of our knowledge. By using saturable absorbers with different initial transmission, the maximum pulse energy reached 4.22 mJ with peak power of 162.3 kW for a pulse duration of 26 ns. The maximum output average power amounted to 2.2 W. These results constitute significant improvement from the highest average power, pulse energy and peak power results for the PQS Tm:YLF laser to date.