Lowest-order relativistic corrections to the fundamental limits of nonlinear-optical coefficients

TL;DR

This paper investigates how small relativistic effects influence the fundamental limits of nonlinear optical coefficients, revealing that hyperpolarizability is more sensitive to these corrections than other related properties.

Contribution

It introduces the first analysis of relativistic corrections to the fundamental limits of nonlinear optical coefficients within the three-level model.

Findings

Relativistic corrections affect the maximum hyperpolarizability more significantly.

The Kuzyk limits are modified when considering semi-relativistic energies.

Intrinsic nonlinear-optical responses are altered at semi-relativistic energies.

Abstract

The effects of small relativistic corrections to the off-resonant polarizability, hyperpolarizability, and second hyperpolarizability are investigated. Corrections to linear and nonlinear optical coefficients are demonstrated in the three-level ansatz, which includes corrections to the Kuzyk limits when scaled to semi-relativistic energies. It is also shown that the maximum value of the hyperpolarizability is more sensitive than the maximum polarizability or second hyperpolarizability to lowest-order relativistic corrections. These corrections illustrate how the intrinsic nonlinear-optical response is affected at semi-relativistic energies.