Applying universal scaling laws to identify the best molecular design paradigms for third-order nonlinear optics

TL;DR

This paper uses universal scaling laws to evaluate and identify molecular classes with the most promising third-order nonlinear optical responses, focusing on size-independent metrics and super-scaling behaviors.

Contribution

It introduces a size-independent intrinsic second hyperpolarizability metric and new figures of merit to compare molecular classes for nonlinear optics.

Findings

Super-scaling homologues exhibit the largest intrinsic nonlinear responses.

The approach identifies promising molecular paradigms with efficient size-dependent nonlinear enhancement.

Analysis of literature data reveals key parameters influencing nonlinear optical performance.

Abstract

The scaling of the fundamental limits of the second hyperpolarizability is used to define the intrinsic second hyperpolarizability, which aids in identifying material classes with ultralarge nonlinear-optical response per unit of molecular size. The intrinsic nonlinear response is a size-independent metric that we apply to comparing classes of molecular homologues, which are made by adding repeat units to extend their lengths. Several new figures of merit are proposed that quantify not only the intrinsic nonlinear response, but also how the second hyperpolarizability increases with size within a molecular class. Scaling types can be classified into sub-scaling, nominal scaling that follows the theory of limits, and super-scaling behavior. Super-scaling homologues that have large intrinsic nonlinearity are the most promising because they efficiently take advantage of increased size. We apply our approach to data in the literature to identify the best super-scaling molecular paradigms and articulate the important underlying parameters.