arXiv subjects

Gian Luca Dolso

Publications and source records attributed to Gian Luca Dolso.

4 recordsLinked to original sources

arXiv2026

All-Optical Field-Resolved Spectroscopy With Interferometric Nonlinear Cross-Correlations

Direct time-domain measurements of electric fields enable sub-cycle spectroscopy of light-matter interactions, but established techniques such as electro-optic sampling are constrained in their bandwidth by gate-pulse duration and phase-matching limitations. Alternative approaches have emerged in recent years based on asymmetric interferometric nonlinear cross-correlations with highly nonlinear media, and have demonstrated, for example, the field-resolved study of exciton ensembles. However, these nonlinear cross-correlation-based techniques have been benchmarked almost exclusively by self-referenced pulse characterization rather than by their quantitative spectroscopic performance, and all-optical approaches have received less attention than those based on direct charge emission. Here we extend all-optical asymmetric interferometric cross-correlation to higher nonlinearities in sub-wavelength films and demonstrate field-resolved spectroscopy of the free-induction decay of two ro-vibrational bands of ambient water vapor with a performance comparable to state of the art electro-optic sampling. The measurement spans 190 THz of bandwidth (80 THz to 270 THz) with sub-500 GHz spectral resolution, a spectral intensity dynamic range of six orders of magnitude, and a field-strength noise floor of 100 kV per meter. We anticipate the rapid adoption of here presented all-optical sampling to many experimental settings and a broad impact beyond the ultrafast optics research community as it is drastically simplified in comparison to ionization based techniques and allows the translation of electro-optic-sampling-level sensitivity into higher frequency ranges not previously accessible by conventional tools.

physics.optics↗

arXiv2022

Field-driven attosecond photoinjection dynamics in semiconductors

The route towards manipulation of the optoelectronic properties of matter beyond the current limits of electronics starts from a comprehensive study of the ultrafast dynamics triggered by interaction with light. Among them, a fundamental role is played by charge photoinjection, a complex process that stems from the interplay of many different physical phenomena, which cannot be easily disentangled. Single- and multi-photon absorption, diabatic tunnelling, intra-band motion, and field-driven band dressing, all concur in determining the overall excited electron population, dictating the electro-optical properties of a material. Here we investigate ultrafast photoinjection in a prototypical semiconductor (monocrystalline germanium) by using attosecond transient reflection spectroscopy. The precise pump-field characterization ensured by a simultaneous attosecond streaking experiment, in tandem with a comprehensive theoretical approach, allowed us to disentangle the different physical phenomena unfolding at different positions in the reciprocal space and at different timing within the envelope of the pump pulse. Moreover, we found that intra-band phenomena hinder charge injection, in contrast to what was previously observed for resonant, direct band-gap semiconductors. Therefore, besides other known parameters as the central wavelength and peak intensity, our results indicate that the pulse temporal envelope and the local band structure probed by intra-band effects are of key importance to achieve an optimal control over the ultrafast carrier injection process and tailor the complex optical and electronic properties of a semiconductor on the few- to sub-femtosecond time scale.

physics.optics↗

arXiv2021

Reconstruction of ultrafast exciton dynamics with a phase-retrieval algorithm

The first step to gain optical control over the ultrafast processes initiated by light in solids is a correct identification of the physical mechanisms at play. Among them, exciton formation has been identified as a crucial phenomenon which deeply affects the electro-optical properties of most semiconductors and insulators of technological interest. While recent experiments based on attosecond spectroscopy techniques have demonstrated the possibility to observe the early-stage exciton dynamics, the description of the underlying exciton properties remains non-trivial. In this work we propose a new method called extended Ptychographic Iterative engine for eXcitons (ePIX), capable of reconstructing the main physical properties which determine the evolution of the quasi-particle with no prior knowledge of the exact relaxation dynamics or the pump temporal characteristics. By demonstrating its accuracy even when the exciton dynamics is comparable to the pump pulse duration, ePIX is established as a powerful approach to widen our knowledge of solid-state physics.

physics.optics↗

arXiv2021

Time-frequency mapping of two-colour photoemission driven by harmonic radiation

The use of few-femtosecond, extreme ultraviolet (XUV) pulses, produced by high-order harmonic generation, in combination with few-femtosecond infrared (IR) pulses in pump-probe experiments has great potential to disclose ultrafast dynamics in molecules, nanostructures and solids. A crucial prerequisite is a reliable characterization of the temporal properties of the XUV and IR pulses. Several techniques have been developed. The majority of them applies phase reconstruction algorithms to a photoelectron spectrogram obtained by ionizing an atomic target in a pump-probe fashion. If the ionizing radiation is a single harmonic, all the information is encoded in a two-color two-photon signal called sideband (SB). In this work, we present a simplified model to interpret the time-frequency mapping of the SB signal and we show that the temporal dispersion of the pulses directly maps onto the shape of its spectrogram. Finally, we derive an analytical solution, which allows us to propose a novel procedure to estimate the second-order dispersion of the XUV and IR pulses in real time and with no need for iterative algorithms.

physics.optics↗