A New Thermodynamic Approach to Multimode Fiber Self‐cleaning and Soliton Condensation

Abstract A new thermodynamic theory for optical multimode systems is proposed. Theory is based on a weighted Bose–Einstein law, and includes the state equation, the fundamental equation for the entropy and a metric to measure the accuracy of the thermodynamic approach. The theory is used to compare the experimental results of two propagation regimes in multimode fibers, specifically the self‐cleaning in the normal chromatic dispersion region and the soliton condensation in the anomalous dispersion region. Surprising similarities are found in terms of thermodynamic parameters, suggesting a common basis for the thermalization processes observed in the two propagation regimes.