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Simultaneous Observation of Second-Harmonic Emission and Three-Photon Excited Photoluminescence from Hybrid Vapor Phase Epitaxy-Grown GaN Film

Nonlinear optical properties of the undoped hybrid vapor phase epitaxy-grown (GaN film sample) were investigated and analyzed using a tunable femtosecond laser as an excitation source. As the laser wavelength was tuned from 762–796 nm, the sample emitted signals corresponding to the second-harmonic wavelength from 381–398 nm with a quadratic power dependence. A strong three-photon-process-related signal at 367 nm with cubic power dependence was simultaneously observed for the first time.