Enhancement of third-order optical nonlinearity of VSe 2 by hybridizing with CoSe 2 as flower-like nanoparticles.

Through one-pot hydrothermal synthesis, we synthesized VSe 2 -CoSe 2 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 CoSe 2 phase, we transformed these hybrid nanostructures into nanoparticles, thereby influencing their nonlinear optical properties. The third-order nonlinear optical parameters ( n 2 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 n 2 and β were determined to be in the order of 10 -8 (cm 2 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.