Domenico Salerno

Three dimensional imaging of short pulses

Abstract We exploit a slightly non-collinear second-harmonic cross-correlation scheme to map the 3D space–time intensity distribution of an unknown complex-shaped ultrashort optical pulse, down to a resolution of 10 μm in space and 200 fs in time. Moreover, we directly show that the spatial phase information is not lost in the process, thanks to the coherence of the non-linear interaction. This implies that the concept of second-harmonic holography can be employed down to the sub-picosecond time scale, and used to discuss the features of the technique in terms of the reconstructed fields.

Noise-seeded spatiotemporal modulation instability in normal dispersion.

In optical second-harmonic generation with normal dispersion, the virtually infinite bandwidth of the unbounded, hyperbolic, modulational instability leads to quenching of spatial multisoliton formation and to the occurrence of a catastrophic spatiotemporal breakup when an extended beam is left to interact with an extremely weak external noise with a coherence time much shorter than that of the pump.

Impact of dimensionality on noise-seeded modulational instability

In second harmonic generation, the virtually infinite bandwidth of the spatio-temporal modulational instability leads to completely different scenarios for the wave-break when the input noise is monochromatic or when it carries a broad temporal spectrum.

From spatio-temporal to temporal modulational instability

We study the impact of the beam diameter on the spectrum of the instability in second harmonic generation, and we report direct evidence of a quantum origin of the instability of a spatial soliton.

Impact of wave-envelope dynamics on beam and pulse break up in X/sup (2)/ media

The evolution of a wavepacket undergoing second-harmonic generation gives rise to a deterministic break-up and multi-soliton formation either in the spatial or in the temporal domain, depending on the relative weight of diffraction and dispersion.