Nonlinear optical properties of nanocrystalline diamond.

We report on investigation of nonlinear optical phenomena in nanocrystalline diamond prepared by microwave plasma enhanced chemical vapour deposition. We observed the upconverted photoluminescence, the second and the third harmonic generation and Z-scan signal. The value of the third order nonlinear susceptibility was estimated. Our results show that nonlinear optical properties of nanocrystalline diamond have many features of the bulk diamond affected to some extent by the presence of grain boundaries.