Two-Photon Correlation of Spontaneously Generated Broadband Four-Waves Mixing

TL;DR

This paper investigates the time-energy correlations in broadband four-wave mixing generated in a photonic crystal fiber, revealing novel power-dependent splitting effects and complex time-frequency coupling phenomena.

Contribution

It demonstrates the generation of broadband, incoherent yet correlated FWM sidebands with unique power-dependent correlation splitting, advancing understanding of quantum and classical light interactions.

Findings

Power-dependent splitting of correlations observed

Broadband, incoherent FWM sidebands generated

Sum frequency generation used for precise correlation measurement

Abstract

We measure the time-energy correlation of broadband, spontaneously generated four wave mixing (FWM), and demonstrate novel time-frequency coupling effects; specifically, we observe a power-dependent splitting of the correlation in both energy and time. By pumping a photonic crystal fiber with narrowband picosecond pulses we generate FWM in a unique regime, where broadband (>100nm), sidebands are generated that are incoherent, yet time-energy correlated. Although the observed time-energy correlation in FWM is conceptually similar to parametric down conversion, its unique dependence on pump intensity due to self and cross phase modulation effects, yields spectral and temporal structure in the correlations. While these effects are minute compared to the time duration and bandwidth of the FWM sidebands, they are well observed using sum frequency generation as a precise, ultrafast, wide-bandwidth correlation detector.