Detecting a pronounced delocalized state in third-harmonic generation phenomenon; a quantum chaos approach

Nonlinear optics (NLO) deserves special attention in new optical devices, making it possible to generate coherent light more efficiently. Among the various NLO phenomena the third-harmonic generation (THG) is at the core of the effective operating mechanism of broadband wavelength conversion, in all-optical devices. Here, we aim to understand how the third-order susceptibility and the electric field may be effectively effect on the localization properties of the light in the THG process when included in a two-mode cavity coherently perturbed by a classical field. We address a stable-unstable transition due to the combination effect of the aforementioned factors. We report a reliable evidence confirming the appearance of chaos in THG under suitable conditions. By tracing the signatures of adjacent-spectral-spacing-ratio (ASSR) distribution and participation ratio, we also find a critical point (ϵc,κc)=(3.1,0.35) for which a pronounced delocalized response is seen. This study may have profound findings for practical devices, and ushers in new opportunities for practical exploitation of the electric field and the third-order susceptibility effect in nonlinear optical devices.