Dispersion of the Third-Order Nonlinear Optical Susceptibility in C_{60} Calculated with a Tight-Binding Model

TL;DR

This paper calculates the frequency-dependent third harmonic generation in C60 using a tight-binding model, showing good agreement with experiments and predicting significant enhancements at specific energies.

Contribution

It introduces a tight-binding model approach to analyze the dispersion of third-order nonlinear optical susceptibility in C60, providing theoretical insights into experimental observations.

Findings

Calculated THG magnitudes match experimental values at low energies.

Explained the magnitude near the three-photon resonance peak.

Predicted large THG enhancement at 3 omega around 6 eV due to double resonance.

Abstract

The frequency dependence of third harmonic generation (THG) in C_{60} is calculated, making use of a tight-binding model for pi-electrons. The magnitudes of the THG, about 10^{-12} esu, near zero frequency, agree with those in experiments for the low-energy region. We can also explain the order of the magnitude, 10^{-11} esu, around the three-photon resonance peak due to the lowest allowed excitation, recently measured by Meth et al. At higher energies, we predict a large enhancement of the THG at 3 omega \sim 6eV as a result of double resonance enhancement.