Replica Symmetry Breaking in a Weakly Scattering Optofluidic Random Laser

Anirban Sarkar,B N Shivakiran Bhaktha,Jonathan Andreasen

doi:10.1038/s41598-020-59575-2

Abstract

We report the observation of replica symmetry breaking (RSB) in a weakly scattering optofluidic random laser (ORL). Coherent random lasing is indicated by the presence of narrow peaks rising out of the spectral background. This coherence helps to identify a random laser threshold, which is expected to be gradual with weak scattering. We find that lasing action initiated using optical pulsed pumping coincides with the onset of both RSB and Lévy flight statistics. However, the transition from the photonic paramagnetic to photonic glass phase is more subtle in that the Parisi overlap function broadens instead of completely changing shape. This subtlety is balanced by an accompanying result of identical experimental conditions giving rise to lasing or no lasing depending on the shot. Additional statistical calculations and investigations into the fundamental physical mechanisms present in the ORL support this conclusion. Using simple numerical models, we study the critical spectral properties required for RSB to occur, as indicated by the Parisi overlap function. The simplicity of the models helps demonstrate the sensitive nature of this tool and the necessity of additional verification of the physical mechanisms present in the experiment.

Highlights

Random lasers are a special class of active disordered materials where laser oscillations survive due to the optical feedback provided by multiple scattering[1,2]
Because the evidence of Lévy statistics in the previous section is unclear, we examine the same optofluidic random laser (ORL) emission spectra again here using the exponent α calculated from the quantile-based McCulloch method[39,40]
We have studied the spectral fluctuations and statistics of optofluidic random laser (ORL) emission

Summary

Introduction

Random lasers are a special class of active disordered materials where laser oscillations survive due to the optical feedback provided by multiple scattering[1,2]. Avoiding static realizations of random scatterers, RSB was later observed without Lévy statistics[15] It is unclear exactly how replica symmetry can be broken without persistent identical systems, any common mechanisms and the precise interdependence of these effects does remain elusive[16]. Lab-on-a chip integration, mechanical stability, straightforward manipulation of fluid, and inexpensive mass production facilities make them attractive systems for future use These ORLs avoid any issues raised by non-identical realizations of randomness, since the scatterers are fixed. Because direct measurement of random laser mode time evolution is not yet possible, the indirect usage of emission intensity spectra to demonstrate RSB is appealing in its ease of use Using this method, RSB has been observed in systems without disorder but with interacting lasing modes[21,22]. We explore numerous spectral measurements in this paper as well as a few numerical models in order to verify the operational regime of the ORL and support our conclusion that RSB occurs

Methods

Results

Conclusion