Effect of higher-order nonlinearities and dispersions on modulation instability in semiconductor quantum dots

This article presents the theoretical investigation of modulation instability (MI) in a one-dimensional waveguide structure embedded in a lower-index material, featuring a high-density array of InAs cone-shaped quantum dots within bulk GaAs. The system operates under electromagnetically induced transparency (EIT) conditions, wherein a weak probe field and a strong control field interact within a three-level ladder-type semiconductor quantum dot (SQD) system. Giant Kerr, quintic, and septic nonlinearities of the order ~10−11m2/V2, ~10−22m4/V4 and ~10−32m6/V6 respectively, are identified in the SQD system that exhibit strong tunability under the effect of control field parameters. These giant nonlinearities are employed to control the MI of the probe pulse. The MI gain enhances linearly with input power, when only Kerr nonlinearity is present, while quintic and septic nonlinearities contributes to the stabilization of MI towards the higher power levels. The higher-order dispersions further contribute to the reduction in the MI spectral bandwidth, enabling enhancement of the stability of the probe field against MI. These findings highlight the potential of SQD-based optical devices for controlled nonlinear optical applications and signal modulation.