We demonstrate that the topological structure, characterized by the intensity and polarization patterns, of vector beams is preserved during filamentation. In addition, we show that continuum radiation retains the topology of the incident radiation during filamentation and also on the commonly observed air-lasing lines of 357 nm and 428 nm.

The precise characterization of ultrashort pulses is essential for optimizing laser performance and accurately modeling experimental phenomena. Dispersion scan is a popular characterization technique that can be integrated into a setup without dedicated diagnostic paths or optics, and it is ideal for characterizing few-cycle pulses that are desirable for applications utilizing strong-field phenomena, such as high harmonic generation, and ultrafast spectroscopy. Here, we demonstrate compression of a unique mid-infrared (2.5 μm), few-cycle (17 fs), high-energy (1.5 mJ) laser with a discontinuous dispersion scan by stitching together three conventional measurements taken in the presence of different materials. The pulse reconstruction uses a custom and versatile Python package and leverages a multi-stage algorithm. We discuss the advantages of discontinuous dispersion scans and the multi-stage reconstruction.

TBC

We extend four-wave mixing to the strong-field regime, leading to Kerr instability amplification, with high gain (g > 20 mm-1) and broadband amplification (550 – 950 nm). We demonstrate that these amplified broadband pulses can be used as a source for nonlinear optics (by generating the third harmonic) and spectroscopy (such as femtosecond stimulated Raman scattering). We discuss routes for few-cycle pulse amplification for attosecond science.

We explore two-color coherent control of non-perturbative high-harmonic generation in zinc oxide and observe unconventional modulations in the harmonics with respect to the weak perturbing field. By isolating the underlying photon-mixing pathways, we connect the unconventional modulations to the lack of photon emission pathways in the perturbing field. We discuss the origin of this asymmetry and the potential for all-optical attosecond measurement in this regime.

All-optical perturbative measurement of strong-field recollision process has been demonstrated to investigate time-delayed recombination phenomena while generating extreme ultraviolet (XUV) radiations. We apply a weak field to manipulate the XUV generation process in xenon and measure the emission time of XUV pulses, presenting time delay due to the plasmonic resonance. Consequently, in situ measurement of strong-field processes can be utilized for the time-domain spectroscopy as the alternative of the conventional attosecond photoelectron streaking.

We report on experiments to detect molecular chirality using strong-field photoelectron spectroscopy. Gas-phase propylene oxide molecules were subjected to intense, femtosecond laser pulses which were arranged to synthesize a locally chiral electric field.

We implement an Er:fiber dual frequency comb (DFC) at 1.55um wavelength. Stabilized only on the repetition rate difference, such setup is robust for high-resolution spectroscopy, where residual slow drifts in the carrier-envelope and repetition frequencies are corrected in post-processing of real-time radio-frequency beats.