Nonlinear optical response of bulk ZnO crystals with different content of intrinsic defects

The nonlinear optical (NLO) properties of native defect-rich ZnO single crystals were studied in details within the excitation of the continuous wave (CW) and pulsed laser radiation at 532 nm (2.33 eV). Analysis of the experimental data of optical elastic scattering, Fourier transform infrared (FTIR), near infrared–visible–ultraviolet (NIR–Vis–UV) spectra recorded in reflection and absorption modes, and data of photoluminescence (PL) spectroscopy confirmed the contribution of both intrinsic defects and their clusters, being determined before by neutron diffraction and XRD analysis. It was shown that the high sensitivity of the NLO diagnostics via self-action of a laser beam is due to the resonant excitation of the deep defects states at wavelength 532 nm. It was also demonstrated the correlation of the real and imaginary parts of the cubic NLO susceptibility with PL and FTIR spectroscopies data dealing with the defect bands manifestation, while the elastic optical scattering and Vis-NIR spectroscopy data – with the intrinsic defect content. High photoinduced polarizabilities of the excited states provide application of the refractive NLO response and the optical elastic scattering indicatrices analysis as an express nondestructive technique to reveal the deep defects content in the bulk ZnO.