Observation of second harmonic generation from multilayer Tin diselenide

We report spatially resolved second harmonic generation from a multilayer tin di-selenide (SnSe₂) flake using a nonlinear optical microscopy setup. The second order nonlinear signal from SnSez is - 21 times weaker than that of quartz substrate. Tin di-selenide is expected to exhibit centrosymmetric lattice arrangement with vanishing secondorder nonlinear optical effects. The observed second order nonlinear effects from multi-layer SnSez is ascribed to lattice distortions.