Two-Color Strong-Field Photoelectron Spectroscopy and the Phase of the Phase

Abstract

The presence of a weak second-harmonic field in an intense-laser ionization experiment affects the momentum-resolved electron yield, depending on the relative phase between the ω and the 2ω component. The proposed two-color "phase-of-the-phase spectroscopy" quantifies for each final electron momentum a relative-phase contrast (RPC) and a phase of the phase (PP) describing how much and with which phase lag, respectively, the yield changes as a function of the relative phase. Experimental results for RPC and PP spectra for rare gas atoms and CO_{2} are presented. The spectra demonstrate a rather universal structure that is analyzed with the help of a simple model based on electron trajectories, wave-packet spreading, and (multiple) rescattering. Details in the PP and RPC spectra are target sensitive and, thus, may be used to extract structural (or even dynamical) information with high accuracy.

Two-color phase-of-the-phase spectroscopy with circularly polarized laser pulses

“…We chose a hydrogen 1s state with I p = 0.5 for |Ψ 0 (t) . After the calculation of PES Y (p, ϕ) for a set of equally spaced phases ϕ ∈ [0, 2π[ (typically ten) we Fouriertransform them to extract the PP Φ 1 (p) [13,15]. The result is shown in Fig.…”

“…Hence, in first order the change of the PES as a function of ϕ is captured just in two functions: the absolute value of the change ∆Y 1 (p) (relative-phase contrast) and the eponymous phase of the phase Φ 1 (p). Prominent features appearing at certain momenta in Φ 1 (p) [13,15] are laser and target-sensitive and can provide more information than an ordinary PES for just the ω field. Since any dependence on the relative phase ϕ will be spoiled by incoherent emission processes (such as thermal emission or multiple scattering in complex many-body targets), PP spectroscopy also provides the possibility to reveal coherent features when ordinary PES are cluttered by insipidly incoherent, Maxwellian contributions.…”

Forward-backward asymmetry of photoemission inC60excited by few-cycle laser pulses

“…A more recent experimental application of ω-2ω combined laser pulses on rare gas atoms and CO 2 molecule is found in Ref. [67]. On this basis, the comparison of controlling efficiency of CEP-dependent asymmetry between one-color few-cycle fields and two-color multiple-cycle fields is an intriguing topic, yet this is beyond the scope of present study, thus we postpone it to the next exploration.…”

All-optical spatio-temporal control of electron emission from SiO2 nanospheres with femtosecond two-color laser fields

“…Intense laser pulses with tailored waveforms have proven to be a powerful tool for the control of electron dynamics in atomic, molecular, and solid targets [1][2][3][4][5][6][7][8][9][10][11][12]. The laser electric field of such pulses exerts a force that varies on the attosecond time scale for visible light and enables the steering of electron motion on sub-cycle time scales and on nanometer spatial dimensions or even below [13][14][15][16][17].…”