Excitation-pulse intensity mediated control of coherent nonlinear optical response of a V-type system

Abstract

V-type three-level systems, where two excited states share a common ground state, serve as fundamental models for exploring coherent light-matter interactions in a range of quantum systems, from atomic gases to semiconductor nanostructures. In this work, we investigate the coherent evolution of such a system under strong femtosecond-pulse excitation by numerically solving the optical Bloch equations. Our analysis shows that the coherent evolution of a three-level system critically depends on the product of the excitation-pulse duration and energy separation between the excited states. Building on this understanding, we extend our analysis to simulate two-dimensional coherent spectra in a high-intensity regime. We demonstrate a control over the coherent pathway contributions to the nonlinear optical response of a V-type system by varying the intensity of the excitation pulses. This control is manifested through the ability to selectively turn individual spectral features on or off in the 2D spectra, each corresponding to distinct quantum pathways. Furthermore, the pulse intensities are varied to precisely adjust the phase of these peaks. Our approach provides a simple and robust framework for achieving control of coherent response of multilevel systems.