Abstract
Tuning of nonlinear absorption and optical limiting action of MoS2 with different morphologies was demon-strated by open aperture Z-scan technique under Nd: YAG laser (532 nm, 7 ns, 10 Hz, 1-5 GW/cm(2)) excitation. The morphology of pristine MoS2 prepared by hydrothermal method at various reaction times gets altered from nanoclusters (24 h) to nanoplatelets (36 h) and further to nanosheets (48 and 60 h). Earlier XRD confirms the formation of honeycomb lattice of hexagonal crystal phase MoS2 (2H) and Raman ascertains the arrangement of S-Mo-S as a multilayer system. Because of alteration of band structure with morphology, hyper and hypochromic effect occurred in the absorbance of MoS2 nanoparticles. Photoluminescence spectra of MoS2 nanoparticles show two excitonic prominent peaks at 624 nm and 540 nm. All MoS(2 )nanoparticles prepared at varying reaction time exhibits reverse saturable absorption (RSA) pattern ascribed to two photon absorption process. Among the samples, variation in two photon absorption coefficients with different on-axis peak intensities shows zero slope value for MoS2 nanoclusters (24 h) and thus it exhibits genuine 2 PA. While non-zero slope value of MoS(2 )nanoplatelets (36 h) and nanosheets (48 and 60 h) display sequential 2 PA mechanism. MoS2 nanoplatelet possess high nonlinear absorption coefficient (5.9 x 10(-10) m/W) with a low onset optical limiting threshold (0.73 x 10(12) W/m(2)), which suggests its superiority for developing nonlinear absorption induced optical limiting devices.