Understanding the dynamics of photoionization-induced solitons in gas-filled hollow-core photonic crystal fibers

TL;DR

This paper models pulse propagation in gas-filled hollow-core photonic crystal fibers, revealing photoionization effects that induce blue-shifted solitons, novel solitary wave behaviors, and long-range interactions, with implications for UV resonant radiation.

Contribution

It introduces a detailed model for ionization-induced soliton dynamics, predicting inverted gravity-like solitary waves and long-range interactions in gas-filled fibers.

Findings

Photoionization causes solitons to blue-shift and accelerate.

Prediction of multi-peak inverted gravity-like solitary waves.

Identification of long-range non-local soliton interactions.

Abstract

We present in detail our developed model [Saleh et al., Phys. Rev. Lett. 107] that governs pulse propagation in hollow-core photonic crystal fibers filled by an ionizing gas. By using perturbative methods, we find that the photoionization process induces the opposite phenomenon of the well-known Raman self-frequency red-shift of solitons in solid-core glass fibers, as was recently experimentally demonstrated [Hoelzer et al., Phys. Rev. Lett. 107]. This process is only limited by ionization losses, and leads to a constant acceleration of solitons in the time domain with a continuous blue-shift in the frequency domain. By applying the Gagnon-B\'{e}langer gauge transformation, multi-peak `inverted gravity-like' solitary waves are predicted. We also demonstrate that the pulse dynamics shows the ejection of solitons during propagation in such fibers, analogous to what happens in conventional solid-core fibers. Moreover, unconventional long-range non-local interactions between temporally distant solitons, unique of gas plasma systems, are predicted and studied. Finally, the effects of higher-order dispersion coefficients and the shock operator on the pulse dynamics are investigated, showing that the resonant radiation in the UV [Joly et al., Phys. Rev. Lett. 106] can be improved via plasma formation.