Entropic thermodynamics of nonlinear photonic chain networks

TL;DR

This paper introduces an entropic thermodynamic framework for analyzing the thermalization and complex dynamics of large-scale nonlinear photonic chain networks, enabling a deeper understanding of multimode lightwave systems.

Contribution

It develops a novel optical thermodynamic approach with a Sackur-Tetrode equation for entropy, providing a self-consistent way to determine temperature and chemical potential in nonlinear photonic systems.

Findings

Derived an explicit entropy expression for multimode photonic chains.

Established equations of state linking optical temperature and chemical potential.

Discussed thermodynamic processes like expansion, cooling, and conduction in these systems.

Abstract

The complex nonlinear behaviors of heavily multimode lightwave structures have been recently the focus of considerable attention. Here we develop an optical thermodynamic approach capable of describing the thermalization dynamics in large scale nonlinear photonic chain networks - a problem that has remained unresolved so far. A Sackur-Tetrode equation is obtained that explicitly provides the entropy of these systems in terms of all the extensive variables involved. This entropic description leads to a self-consistent set of equations of state from where the optical temperature and chemical potential of the photon gas can be uniquely determined. Processes like isentropic expansion/compression, Joule expansion, as well as aspects associated with beam cleaning/cooling and thermal conduction effects in such chain networks are discussed. Our results open new vistas through which one can describe in an effortless manner the exceedingly complex dynamics of highly multimoded nonlinear bosonic systems that are nowadays of importance in areas ranging from high-power photonic settings to cold atom condensates and optomechanics.