Effective soliton order and universal scaling laws for pulse self-compression over large dispersion variations

Abstract

Pulse propagation through hollow-core fibers (HCFs) filled with noble gas is a stable and efficient technique for pulse self-compression. The scalability of soliton dynamics in gas-filled HCFs, varying over a large range of energies, from sub-μJ to above mJ, allows to tune the energy of the generated few-cycle pulses too a great extent. Scaling relations can be used to produce propagation dynamics and effects that are invariant and essentially identical for multiple sets of input conditions. But, for the same input soliton order, the scaling relations derived under different dispersion conditions, such as different gas pressure, result in somewhat different scaling laws. This leads to an ambiguity in the compression factor and compression length for any particular soliton order N. It is thus necessary to find an accurate soliton order which can describe the self-compression dynamics over different dispersion conditions. We numerically simulate soliton self-compression in an argon gas-filled HCF across a wide range dispersion conditions and present an accurate soliton order for better understanding of the self-compression behavior. We introduce an effective soliton order Neff, for explaining the behavior of soliton dynamics in systems with high third order dispersion (TOD). This provides us with universal scaling laws for generating high-energy few-cycle pulses, which are critical for generating single and trains of attosecond pulses, as well as electron and ion acceleration strategies in intense laser pulses.