Effect of a plasma grating on pump-probe experiments near the ionization threshold in gases

TL;DR

This paper analyzes how plasma gratings influence pump-probe experiments near the ionization threshold, suggesting that observed birefringence may be due to plasma effects rather than higher-order Kerr nonlinearities.

Contribution

It provides a theoretical calculation of phase shifts caused by plasma density modulation and reinterprets experimental results as evidence of plasma grating effects.

Findings

Plasma gratings induce significant phase shifts in pump-probe setups.

Observed birefringence may originate from plasma effects, not higher-order Kerr effects.

The analysis offers a new perspective on interpreting nonlinear optical experiments near ionization thresholds.

Abstract

Calculations are performed of the phase shift caused by the spatial modulation in the plasma density due to interference between a strong pump pulse and a weak probe pulse. It is suggested that a recent experiment [Loriot et al., Opt. Express v. 17, 13429 (2009)] observed an effective birefringence from this plasma grating rather than from the higher-order Kerr effect.