The dissociation of an H2+ molecular-ion beam by linearly polarized, carrier-envelope-phase-tagged 5 fs pulses at 4×10(14) W/cm2 with a central wavelength of 730 nm was studied using a coincidence 3D momentum imaging technique. Carrier-envelope-phase-dependent asymmetries in the emission direction of H+ fragments relative to the laser polarization were observed. These asymmetries are caused by interference of odd and even photon number pathways, where net zero-photon and one-photon interference predominantly contributes at H+ + H kinetic energy releases of 0.2-0.45 eV, and net two-photon and one-photon interference contributes at 1.65-1.9 eV. These measurements of the benchmark H2+ molecule offer the distinct advantage that they can be quantitatively compared with ab initio theory to confirm our understanding of strong-field coherent control via the carrier-envelope phase.
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http://dx.doi.org/10.1103/PhysRevLett.111.163004 | DOI Listing |
We investigate the ultrafast electron correlation effects during non-sequential double ionization (NSDI) of argon subjected to a combined femtosecond field composed of counter-rotating two-color circularly polarized (TCCP) pulse laser using a 3D classical ensemble model (CEM). Our simulation results reveal that manipulation of the carrier-envelope phase (CEP) of the external driving field modulates the dynamical behavior of the two electrons, resulting in a notable sensitivity of their momentum distribution to the relative phase of two components of the counter-rotating TCCP field. Through inversion analysis, we uncover the capability to direct electrons toward a single direction, thereby facilitating focused ion-electron collisions on the attosecond timescale.
View Article and Find Full Text PDFA dual pulse retrieval algorithm is introduced that builds upon time-domain interferometric strong-field ionization to simultaneously reconstruct both involved laser pulses in a waveform-resolved manner. The pulse characterization scheme removes many restrictions posed by former methods, leaving the avoidance of resonant ionization as a single boundary. It is widely and easily applicable at low cost and effort for common attosecond beamlines and allows for the robust and accurate in-situ retrieval of two unknown laser fields.
View Article and Find Full Text PDFWe describe improved methods for locating the fixed point of an optical frequency comb. Two continuous-wave lasers are locked to a reference frequency comb and track the optical phase of a second comb-under-test (CUT) at two points separated by approximately 1.6 THz.
View Article and Find Full Text PDFNat Commun
November 2024
Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany.
Attosecond science has demonstrated that electrons can be controlled on the sub-cycle time scale of an optical waveform, paving the way towards optical frequency electronics. However, these experiments historically relied on high-energy laser pulses and detection not suitable for microelectronic integration. For practical optical frequency electronics, a system suitable for integration and capable of generating detectable signals with low pulse energies is needed.
View Article and Find Full Text PDFThe carrier-envelope phase (CEP) of a laser pulse plays a crucial role in laser-matter interactions. The inherent shot-to-shot instability of the CEP necessitates single-shot detection, which is not only vital for stabilizing the CEP but also for observing ultrafast phenomena that conventional averaging techniques cannot resolve. In this study, we demonstrate a novel approach utilizing strong-field ionization in ambient air for single-shot CEP measurement.
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