Enhanced generation of higher-order sidebands in a single-quantum-dot–cavity system coupled to a PT -symmetric double cavity

Abstract

We propose and analyze an effective scheme to enhance the optical higher-order sideband generation in a three-cavity array with local parity-time ($\mathcal{PT}$) symmetry. In this three-cavity configuration, a single cavity containing a quantum dot (QD) is coupled to an assisted $\mathcal{PT}$-symmetric combination of two cavities. Beyond the weak-excitation approximation, we derive the analytic formulas used to determine the nonlinear coefficient of the optical second-order sideband (OSS) by employing the perturbation technique. Using experimentally achievable parameters, we identify the conditions under which the assisted $\mathcal{PT}$-symmetric double-cavity system allows us to modify the transmission of the probe field and improve the efficiency of OSS generation beyond what is achievable in a loss-only QD-cavity system. We examine the influence of the $\mathcal{PT}$ phase transition from unbroken- to broken-$\mathcal{PT}$ regimes on the OSS generation. It is found that the efficiency of optical second-order sideband generation can be significantly enhanced when the assisted double-cavity system is in $\mathcal{PT}$-symmetric phase, extremely in the vicinity of the transition point. The present results illustrate the potential to utilize $\mathcal{PT}$-symmetric physical systems for enhancing optical higher-order sidebands and controlling optical frequency combs, as well as to guide the design of experimental implementation.