Effect of chromatic dispersion induced chirp on the temporal coherence property of individual beam from spontaneous four wave mixing

TL;DR

This study investigates how chromatic dispersion-induced chirp affects the temporal coherence of photon pairs generated via spontaneous four wave mixing, revealing that pump chirp reduces coherence while individual beam chirp affects mode matching.

Contribution

It provides experimental insights into the distinct effects of pump and individual beam chirp on temporal coherence and mode matching in quantum photon sources.

Findings

Pump chirp decreases temporal coherence.

Individual beam chirp affects mode matching, not coherence.

Optimizing mode matching improves interference visibility.

Abstract

Temporal coherence of individual signal or idler beam, determined by the spectral correlation property of photon pairs, is important for realizing quantum interference among independent sources. To understand the effect of chirp on the temporal coherence property, two series of experiments are investigated by introducing different amount of chirp into either the pulsed pump or individual signal (idler) beam. In the first one, based on spontaneous four wave mixing in a piece of optical fiber, the intensity correlation function of the filtered individual signal beam, which characterizes the degree of temporal coherence, is measured as a function of the chirp of pump. The results demonstrate that the chirp of pump pulses decreases the degree of temporal coherence. In the second one, a Hong-Ou-Mandel type two-photon interference experiment with the signal beams generated in two different fibers is carried out. The results illustrate that the chirp of individual beam does not change the temporal coherence degree, but affect the temporal mode matching. To achieve high visibility, apart from improving the coherence degree by minimizing the chirp of pump, mode matching should be optimized by managing the chirps of individual beams.