Enhancement of third-order optical nonlinearity of VSe2 by hybridizing with CoSe2 as flower-like nanoparticles

Abstract

Through one-pot hydrothermal synthesis, we synthesized VSe₂–CoSe₂ nanostructures with a distinctive flower-like morphology. The structural characterizations were conducted using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and Fourier transform infrared spectroscopy (FTIR). By modulating the proportion of the CoSe₂ phase, we transformed these hybrid nanostructures into nanoparticles, thereby influencing their nonlinear optical properties. The third-order nonlinear optical parameters (n₂ and β) were rigorously examined via the precise Z-scan technique under various laser power conditions. The nanostructures demonstrated a self-focusing refractive response and exhibited pronounced two-photon absorption during the nonlinear absorption process. The magnitudes of n₂ and β were determined to be in the order of 10⁻⁸ (cm² W⁻¹) and 10⁻⁴ (cm W⁻¹), respectively. The exceptional figure of merit (FOM) of these composite flower-like structures underscores their superior nonlinear optical characteristics, establishing them as promising candidates for photonic applications, particularly in optical switching devices.