Hydrothermally Synthesized Cobalt-Doped VS₂ Nanosheets for Optical Limiting Application

The use of high-intensity lasers and the requirement of optical limiters introduces the phenomenon of nonlinear optics. Transition metal dichalcogenides (TMDs) have emerged as the leading materials for this application. The two-dimensional (2D) layered structure, high surface-to-volume ratio, and weak van der Waals force make it suitable for different real-world applications. This research introduces hydrothermally synthesized cobalt-doped VS2 by varying the cobalt concentration for the nonlinear application. The structural characterization was investigated by Raman spectra. It confirms the presence of different vibrational V–S bonds. The field effect scanning electron microscopy (FESEM) images show the nanosheet-like structure. The Z-scan technique is used to measure the nonlinear optical (NLO) properties. A diode-pumped solid-state (DPSS) continuous laser of 532 nm is used with a variable optical power of 40, 50, 60, 60, 70, 80, and 100 mW. The nonlinear absorption coefficient(β) is measured by the open-aperture curve (OA) that shows the Reverse saturable absorption (RSA) properties due to 2 photon absorption (2PA), and the closed-aperture curve shows the self-defocusing nature of the nonlinear refractive index (n2). For the first time, the nonlinear property of cobalt-doped VS2 is investigated for NLO application. This will open the door for other 2D materials for nonlinear applications. The occurrence of RSA and the self-defocusing nature of the synthesized material opens the door toward different nonlinear optical devices like optical limiters.