Space-time coupling in the up-conversion of broadband down-converted light

TL;DR

This paper explores the space-time coupling effects in the up-conversion of broadband light from parametric down-conversion, revealing a skewed spectral geometry caused by walk-off and mismatch compensation, supported by theory and experiments.

Contribution

It provides a combined theoretical and experimental analysis of the spatio-temporal spectral properties in broadband up-conversion, highlighting the skewed geometry due to walk-off and group-velocity mismatch.

Findings

Incoherent SFG spectrum exhibits a cigar-shaped space-time geometry.

Spatial walk-off and group-velocity mismatch are compensated in the process.

Theoretical modeling aligns with experimental measurements.

Abstract

We investigate the up-conversion process of broadband light from parametric down-conversion (PDC), focusing on the spatio-temporal spectral properties of the sum-frequency generated (SFG) radiation. We demonstrate that the incoherent component of the SFG spectrum is characterized by a skewed cigar-shaped geometry in space-time due to the compensation of spatial walk-off and group-velocity mismatch between the fundamental and the generated SFG fields. The results are illustrated both by a theoretical modeling of the optical system and by experimental measurements.