Measurement of delayed fluorescence in N with a streak camera.

Using a streak camera, we directly measure time- and space-resolved dynamics of emission from a self-seeded filament. Fluorescence emission does not start with ionization, but with a delay in the tenth of ps range.

High-resolution remote spectroscopy and plasma dynamics induced with UV filaments.

Spectroscopy is performed on the plume created by a high-power short-pulse laser on a solid surface. It is shown that high resolution (<10  pm) and accurate spectral analysis can be performed using a self-absorption feature appearing within the emission lines. The time-dependent self-absorption study reveals dynamics of a shock wave.

Testing the Role of Recollision in N_{2}^{+} Air Lasing.

It has been known for many years that during filamentation of femtosecond light pulses in air, gain is observed on the B to X transition in N_{2}^{+}. While the gain mechanism remains unclear, it has been proposed that recollision, a process that is fundamental to much of strong field science, is critical for establishing gain. We probe this hypothesis by directly comparing the influence of the ellipticity of the pump light on gain in air filaments.

Controlling the orbital angular momentum of high harmonic vortices.

Optical vortices, which carry orbital angular momentum (OAM), can be flexibly produced and measured with infrared and visible light. Their application is an important research topic for super-resolution imaging, optical communications and quantum optics. However, only a few methods can produce OAM beams in the extreme ultraviolet (XUV) or X-ray, and controlling the OAM on these beams remains challenging.

Perturbative High Harmonic Wave Front Control.

We pattern the wave front of a high harmonic beam by intersecting the intense driving laser pulse that generates the high harmonic with a weak control pulse. To illustrate the potential of wave-front control, we imprint a Fresnel zone plate pattern on a harmonic beam, causing the harmonics to focus and defocus. The quality of the focus that we achieve is measured using the spectral wave-front optical reconstruction by diffraction method.