**Live Poster Session: ****Zoom Link**

Thursday, July 30th 1:15-2:30pm EDT

**Abstract:** The thermalization process and the nature of the equilibrium state of an optical beam launched in a multimode nonlinear photonic network is a problem with far-reaching technological applications. Examples range from the design of high-power multimode sources, to beam self-cleaning (condensation) effects in fiber optics. The first step towards this analysis is to establish a reliable kinetic equation that will allow us to derive the thermodynamical properties of such systems. The next step is an in-depth understanding of the spectral properties of the underlying linear system (assuming weak nonlinearities).

In our work, we address both these questions, using simple one-dimensional networks with finite number of nodes and band-gap structures. Surprisingly, the finite degrees of freedom, associated with a finite number of network nodes, might give rise to negative temperatures (non-Gibbsian statistics) while under certain initial conditions, a two-phase thermalization occurs.

cheng_shi_summer20-Cheng-Shi**Live Poster Session: ****Zoom Link**

Thursday, July 30th 1:15-2:30pm EDT