Second-harmonic generation and linear electro-optical coefficients of SiC polytypes and nanotubes

TL;DR

This study calculates the nonlinear optical and electro-optical properties of various SiC nanotubes and bulk polytypes, revealing their potential for advanced optical applications due to their large susceptibility coefficients.

Contribution

First-principles calculations of second-order nonlinear optical susceptibility and electro-optical coefficients for SiC nanotubes and polytypes, highlighting their superior nonlinear optical properties.

Findings

SiC nanotubes exhibit significantly larger nonlinear coefficients than bulk SiC.

The nonlinear optical spectra correlate with linear dielectric features.

SiC nanotubes outperform BN nanotubes in nonlinear optical responses.

Abstract

The second-order nonlinear optical susceptibility ($\chi_{abc}^{(2)}$) and linear electro-optical coefficient ($r_{abc}$) of a large number of single-walled zigzag, armchair and chiral SiC nanotubes (SiC-NTs) as well as bulk SiC polytypes (2H-, 4H-, 6H- and 3C-SiC) and single graphitic SiC sheet have been calculated from first-principles. The calculations are based on density functional theory in the local density approximation and highly accurate full-potential projector augmented-wave method is used. Both the zigzag and chiral SiC-NTs are found to exhibit large second-order nonlinear optical behavior with the $\chi_{abc}^{(2)}$ and $r_{abc}$ coefficients being up to ten-times larger than that of bulk SiC polytypes, and also being up to thirteen-times larger than the counterparts of the corresponding BN-NTs, indicating that SiC-NTs are promising materials for nonlinear optical and opto-electric applications. The prominant features in the spectra of $\chi_{abc}^{(2)}(-2\omega,\omega,\omega)$ of the SiC-NTs are correlated with the features in the linear optical dielectric function $\epsilon (\omega)$ in terms of single-photon and two-photon resonances.