Interference of stimulated electronic Raman scattering and linear absorption in coherent control

TL;DR

This paper investigates how quantum interference between stimulated electronic Raman scattering and linear absorption influences photocurrent generation in graphene, revealing polarization-dependent effects and potential for tunable optoelectronic applications.

Contribution

It introduces the analysis of interference effects involving stimulated Raman scattering and linear absorption in graphene, highlighting their impact on coherent control of photocurrents and polarization sensitivity.

Findings

Interference at $ ext{ } extless extgreater extgreater$ $ ext{ } extless extgreater extgreater$ results in anisotropic photocurrent in intrinsic graphene.

Doped graphene shows isotropic photocurrent when transitions are Pauli blocked.

The effect is tunable and relevant for other narrow-gap materials.

Abstract

We consider quantum interference effects in carrier and photocurrent excitation in graphene using coherent electromagnetic field components at frequencies $\omega$ and $2\omega$. The response of the material at the fundamental frequency $\omega$ is presented, and it is shown that one-photon absorption at $\omega$ interferes with stimulated electronic Raman scattering (combined $2\omega$ absorption and $\omega$ emission) to result in a net contribution to the current injection. This interference occurs with a net energy absorption of $\hbar\omega$ and exists in addition to the previously studied interference occurring with a net energy absorption of $2\hbar\omega$ under the same irradiation conditions. Due to the absence of a bandgap and the possibility to block photon absorption by tuning the Fermi level, graphene is the perfect material to study this contribution. We calculate the polarization dependence of this all-optical effect for intrinsic graphene and show that the combined response of the material at both $\omega$ and $2\omega$ leads to an anisotropic photocurrent injection, whereas the magnitude of the injection current in doped graphene, when transitions at $\omega$ are Pauli blocked, is isotropic. By considering the contribution to coherent current control from stimulated electronic Raman scattering, we find that graphene offers tunable, polarization sensitive applications. Coherent control due to the interference of stimulated electronic Raman scattering and linear absorption is relevant not only for graphene but also for narrow-gap semiconductors, topological insulators, and metals.