Andreas Valdmann

Temporal focusing of ultrashort pulsed Bessel beams into Airy–Bessel light bullets

We present measurements of the impulse response of a circular phase diffraction grating in dependence of the field point location behind it. These measurements were carried out using a white-light spectral interferometry set-up, which employs photonic crystal fibers in both the signal and reference arms, and achieves a few micron spatial and almost one-wave-cycle temporal resolution. Our study shows that the grating as a simple and robust single-element optical device (i) suppresses the material-induced spread of ultrashort pulses, (ii) thereby generates the Airy–Bessel light bullets, and (iii) enables temporal focusing of the pulses at the prescribed propagation depth.

Realization of laterally nondispersing ultrabroadband Airy pulses

We present the measurements of the spatiotemporal impulse response of a system creating nondispersing Airy pulses, i.e., ultrabroadband Airy beams whose main lobe size remains constant over propagation. A custom refractive element with a continuous surface profile was used to impose the cubic phase on the input beam. The impulse response of the Airy pulse generator was spatiotemporally characterized by applying a white-light spatial-spectral interferometry setup based on the SEA TADPOLE technique. The results were compared with the theoretical model and previously spatiotemporally characterized Airy pulses generated by a spatial light modulator.

Ultrabroadband Airy light bullets

We present the measurements of the spatiotemporal impulse responses of two optical systems for launching ultrashort Airy pulses, including ultrabroadband nonspreading Airy beams whose main lobe size remains invariantly small over propagation. First, a spatial light modulator and, second, a custom refractive element with continuous surface profile were used to impose the required cubic phase on the input field. A white-light spectral interferometry setup based on the SEA TADPOLE technique was applied for full spatio-temporal characterization of the impulse response with ultrahigh temporal resolution approaching a single cycle of the light wave. The results were compared to the theoretical model.

Spatiotemporal characterization of ultrabroadband Airy pulses

We present experimental results of a full spatiotemporal characterization of an optical system for ultrabroadband Airy pulse generation with a liquid-crystal-on-silicon spatial light modulator. Measurements with a few micrometer spatial and almost one-wave-cycle temporal resolution were performed using a white light spatial spectral interferometry setup based on the SEA TADPOLE ultrashort pulse characterization technique. The results were compared with the theoretical model for Airy pulse propagation.

White-light hyperbolic Airy beams

Ultra-broadband hyperbolic Airy beams are experimentally realized and spatio-temporally characterized. Transmissive (refractive) and reflective cubic phase elements were used to impose a cubic phase on the input beam. Nondispersing beams are produced in reflective geometry, while the main lobe of the hyperbolic Airy beam created with a transmissive refractive phase element suffered from lateral dispersion.

Ultra-broadband dispersing and nondispersing Airy pulses

We present the measurements of the spatiotemporal response of two optical systems generating broadband Airy pulses. One uses a spatial light modulator to impose a cubic phase on the input beam and the other a custom-made refractive phase plate. The main lobe of the Airy pulse is shown to quickly spread in the first case due to strong lateral dispersion while no spreading is present in the latter case. The impulse responses were characterized by applying white-light spatial-spectral interferometry setup based on the SEA TADPOLE technique. The results were compared with simulations.