Optimization of eigenstates and spectra for quasi-linear nonlinear optical systems

TL;DR

This paper investigates how the geometry and topology of quasi-one-dimensional quantum structures influence their optical nonlinearities, providing design heuristics to optimize their intrinsic response near physical limits.

Contribution

It offers a comprehensive analysis of geometrical optimization for superscaling structures and introduces practical heuristics for molecular design to maximize nonlinear optical response.

Findings

Optimal placement of side groups enhances nonlinear response.

Additional side groups do not significantly improve response after initial optimization.

Structural topology determines spectral scaling behavior.

Abstract

Quasi-one-dimensional quantum structures with spectra scaling faster than the square of the eigenmode number (superscaling) can generate intrinsic, off-resonant optical nonlinearities near the fundamental physical limits, independent of the details of the potential energy along the structure. The scaling of spectra is determined by the topology of the structure, while the magnitudes of the transition moments are set by the geometry of the structure. This paper presents a comprehensive study of the geometrical optimization of superscaling quasi-one-dimensional structures and provides heuristics for designing molecules to maximize intrinsic response. A main result is that designers of conjugated structures should attach short side groups at least a third of the way along the bridge, not near its end as is conventionally done. A second result is that once a side group is properly placed, additional side groups do not further enhance the response.