The nonlinear up-conversion optical properties of ZnO micro-belt and ZnO Fabry-Pérot（F-P） microcavity were studied by using frequency-resolved interferometric autocorrelation. ZnO micro-belt were prepared by chemical vapor deposition（CVD） method and dry-transferred between a pair of distributed Bragg reflectors（DBR） to form a two-dimensional strongly coupled F-P microcavity. A home-built micro-spectroscopy system was used for interferometric autocorrelation and angle-resolved spectral measurements. The experimental results showed that when pumping ZnO samples with near-infrared ultrafast lasers， both second harmonic generation（SHG） and multi-photon absorption（MPA） upconversion fluorescence signals coexisted. The distinction between SHG and MPA signals could be achieved through different characteristic lines on the frequency spectra. In the case of ZnO F-P microcavity， SHG and MPA signals occupied different emission angles. The competitive relationship between MPA exciton-polaritons and SHG in the strong coupled microcavity system was discussed. Our results provided a reference for the study of microcavity lasers through higher-order nonlinear upconversion methods.

zinc oxide;frequency-resolved interference;second harmonic generation;multi-photon absorption;strong coupled microcavity