Observation of second harmonic generation from multilayer Tin diselenide

Abstract

We report spatially resolved second harmonic generation from a multilayer tin di-selenide $(\mathrm{S}\mathrm{n}\mathrm{S}\mathrm{e}_{2})$ flake using a nonlinear optical microscopy setup. The second order nonlinear signal from $\mathrm{S}\mathrm{n}\mathrm{S}\mathrm{e}_{2}\ \mathrm{i}\mathrm{s}\sim 21$ times weaker than that of quartz substrate. Tin di-selenide is expected to exhibit centrosymmetric lattice arrangement with vanishing second-order nonlinear optical effects. The observed second order nonlinear effects from multi-layer $\mathrm{S}\mathrm{n}\mathrm{S}\mathrm{e}_{2}$ is ascribed to lattice distortions.