ABSTRACT
Second harmonic generation (SHG) has been the most investigated nonlinear optical process, since its discovery by Franken in the 1960s. A noncollinear scheme was successfully employed to observe SHG from Zinc Oxide (ZnO) films. In this experimental configuration, the fundamental beam is split into two beams of comparable power, while the temporal overlap of the incident pulses is controlled with an external delay line. The chapter addresses the influence of radio frequency (rf) power on SHG from ZnO films deposited by rf sputtering. In the study of SHG from ZnO films, the effect of grain boundaries emerged from the experimental evidence that film with lower crystallinity may show larger second-order nonlinear optical response, with respect to film with higher crystallinity. In polycrystalline films both electronic and optical properties, including SHG, can be affected by the structure of grain boundaries. The chapter investigates Grain boundaries effects on SHG, where the influence of substrate temperature on the film structural and optical properties.
