Energy Scalability Limits of Dissipative Solitons

TL;DR

This paper investigates the energy limits of dissipative solitons using a thermodynamical approach, identifying key signatures and factors that lead to soliton breakup, with implications for high-energy pulse laser design.

Contribution

It introduces a thermodynamical framework and experimental signatures for understanding the energy scaling and breakup of dissipative solitons, advancing laser pulse optimization.

Findings

Identification of spectral signatures of DSR transition

Connection between DSR breakup and entropy increase

Experimental validation with Kerr-lens mode-locked Cr:ZnS laser

Abstract

In this study, we apply a thermodynamical approach to elucidate the primary constraints on the energy scaling of dissipative solitons (DS). We rely on the adiabatic theory of strongly chirped DS and define the DS energy scaling in terms of dissipative soliton resonance (DSR). Three main experimentally verifiable signatures identify a transition to DSR: i) growth of a Lorentzian spike at the centrum of the DS spectrum, which resembles a spectral condensation in Bose-Einstein condensate (BEC), ii) saturation of the spectrum broadening, and iii) asymptotical DS stretching. We connect the DSR breakup with three critical factors: i) decoupling of two correlation scales inherent in strongly chirped DS, ii) resulting rise of the DS entropy with energy, which provokes its disintegration, and iii) transition to a nonequilibrium phase, which is characterized by negative temperature. The breakup results in multiple stable DSs with lower energy. Theoretical results are in good qualitative agreement with the experimental data from a Kerr-lens mode-locked Cr$^{2+}$:ZnS chirped-pulse oscillator (CPO) that paves the way for optimizing high-energy femtosecond pulse generation in solid-state CPO and all-normal-dispersion fiber lasers.