Optical harmonic generation in nanocrystalline diamond

We report on investigation of the second- and third-harmonic generation in nanocrystalline diamond prepared by microwave plasma enhanced chemical vapor deposition. We studied the second-harmonic generation in nanocrystalline samples with different material properties and under different ambient conditions (temperature, air pressure). We compared the properties of second harmonic generated in diamond nanocrystals with signal coming from the surface of monocrystalline diamond. We also observed the third-harmonic generation in nanocrystalline diamond and we calculated the value of the third order nonlinear susceptibility χ(3).