Pump-probe study of plasma dynamics in gas-filled photonic crystal fiber using counter-propagating solitons

TL;DR

This paper introduces a pump-probe method to monitor ultrafast plasma density changes in gas-filled photonic crystal fibers by tracking dispersive wave shifts, offering improved stability over previous techniques.

Contribution

A novel pump-probe technique using counter-propagating solitons for stable, real-time plasma density measurement in gas-filled fibers.

Findings

Successfully measured plasma density in argon and krypton fibers.

Demonstrated the method's immunity to air turbulence and vibrations.

Validated results with numerical simulations.

Abstract

We present a pump-probe technique for monitoring ultrafast polarizability changes. In particular, we use it to measure the plasma density created at the temporal focus of a self-compressing higher-order pump soliton in gas-filled hollow-core photonic crystal fiber. This is done by monitoring the wavelength of the dispersive wave emission from a counter-propagating probe soliton. By varying the relative delay between pump and probe, the plasma density distribution along the fiber can be mapped out. Compared to the recently introduced interferometric side-probing for monitoring the plasma density, our new technique is relatively immune to instabilities caused by air turbulence and mechanical vibration. The results of two experiments on argon- and krypton-filled fiber are presented, and compared to numerical simulations. The technique provides an important new tool for probing photoionization in many different gases and gas mixtures as well as ultrafast changes in dispersion in many other contexts.