Directly measuring the spatio-temporal electric field of focusing ultrashort pulses.

We present the first technique for directly measuring (without assumptions) the spatio-temporal intensity and phase of a train of ultrashort pulses at and near a focus. Our method uses an experimentally simple and high-spectral resolution variant of spectral interferometry (SEA TADPOLE). To illustrate our technique, we measured the spatio-temporal electric field in and around the foci of several different types of lenses.

Experimentally simple, extremely broadband transient-grating frequency-resolved-opticalgating arrangement.

We demonstrate a simple, essentially alignment-free Transient-Grating Frequency-Resolved-Optical-Gating arrangement using a simple input mask that separates the input beam into three beams and a Fresnel biprism that crosses and delays them. It naturally operates single shot and has no moving parts. It is also extremely broadband and hence should be ideal for measuring pulses from optical parametric amplifiers.

Describing first-order spatio-temporal distortions in ultrashort pulses using normalized parameters.

We develop a first-order description of spatio-temporal distortions in ultrashort pulses using normalized parameters that allow for a direct assessment of their severity, and we give intuitive pictures of pulses with different amounts of the various distortions. Also, we provide an experimental example of the use of these parameters in the case of spatial chirp monitored in real-time during the alignment of an amplified laser system.

Crossed-beam spectral interferometry: a simple, high-spectral-resolution method for completely characterizing complex ultrashort pulses in real time.

We present a high-spectral-resolution and experimentally simple version of spectral interferometry using optical fibers and crossed beams, which we call SEA TADPOLE. Rather than using collinear unknown and reference pulses separated in time to yield spectral fringes-and reduced spectral resolution-as in current versions, we use time-coincident pulses crossed at a small angle to generate spatial fringes. This allows the extraction of the spectral phase with the full spectrometer resolution, which allows the measurement of much longer and more complex pulses.

Single-shot measurement of the full spatio-temporal field of ultrashort pulses with multi-spectral digital holography.

We present a remarkably simple technique for measuring the full spatio-temporal electric field of a single ultrashort laser pulse. It involves capturing a large digital hologram containing multiple smaller holograms, each of which characterizes the spatial intensity and phase distributions of an individual frequency component of the pulse. From that single camera frame, we numerically reconstruct the complete electric field, E(x,y,t), using a direct algorithm.

The general theory of first-order spatio-temporal distortions of Gaussian pulses and beams.

We present a rigorous, but mathematically relatively simple and elegant, theory of first-order spatio-temporal distortions, that is, couplings between spatial (or spatial-frequency) and temporal (or frequency) coordinates, of Gaussian pulses and beams. These distortions include pulse-front tilt, spatial dispersion, angular dispersion, and a less well-known distortion that has been called "time vs. angle.

Self-referenced measurement of the complete electric field of ultrashort pulses.

A self-referenced technique based on digital holography and frequency-resolved optical gating is proposed in order to characterize the complete complex electric field E (x, y, z, t) of a train of ultrashort laser pulses. We apply this technique to pulses generated by a mode-locked Ti:Sapphire oscillator and demonstrate that our device reveals and measures common linear spatio-temporal couplings such as spatial chirp and pulse-front tilt.