Observation of intense second harmonic generation from MoS2atomic crystals

Since de discovery of graphene, the family of 2-dimensional materials has\nattracted much recent attention. In this work, the nonlinear optical properties\nof few-layer MoS2 two-dimensional crystals are studied using femtosecond laser\npulses. We observed highly efficient second harmonic generation from the\nodd-layer crystals, which shows a polarization intensity dependence that\ndirectly reveals the underlying symmetry and orientation of the crystal.\nAdditionally, the measured second-order susceptibility spectra provide\ninformation about the electronic structure of the material. Our results open up\nnew opportunities for studying the non-linear optical properties in these novel\n2D crystals.\n