Ultrafast Third-Order Nonlinear Optical Response of Charge Coupled Gold Nanoparticle-Ge24Se76 Heterostructure

TL;DR

This study demonstrates ultrafast third-order nonlinear optical responses in a gold nanoparticle and amorphous Ge24Se76 heterostructure, highlighting charge transfer effects and potential for advanced nonlinear optical devices.

Contribution

It introduces a novel charge-coupled heterostructure with enhanced nonlinear optical properties due to charge transfer, verified by spectroscopy and transient absorption measurements.

Findings

Ultrafast third-order nonlinear response observed

Sign reversal of nonlinear response compared to pristine Ge24Se76

Charge transfer confirmed by Raman spectroscopy and transient absorption

Abstract

The donor-acceptor interaction of a charge-coupled heterostructure encompassing a metal and an amorphous semiconductor subjected to a laser field has many potential applications in the realm of nonlinear optics. In this work, we fabricate an electron donor gold nanoparticle (AuNP) and acceptor amorphous Ge24Se76 heterostructure on a quartz substrate using a sequential thermal evaporation technique. In this charge-coupled heterostructure, we demonstrate the ultrafast third-order nonlinear absorptive and refractive response and their sign reversal compared to pristine Ge24Se76. Enhanced optical nonlinearity in these heterostructures of varying plasmonic wavelengths is due to charge transfer, verified by the Raman spectroscopy. Further, the ultrafast transient absorption measurements support the thesis of charge transfer in the AuNP/Ge24Se76 heterostructure. These findings open up exciting opportunities for developing novel device technologies with far-reaching applications in nonlinear optics.