Stack-Induced Decrease in Three-Photon Luminescence of CdSe Nanowire

The research on the nonlinear optical (NLO) properties of CdSe nanowires (NWs) have received widespread attention of researchers. In this work, the higher NLO process of CdSe NW, including three-photon luminescence (3PL) and third harmonic generation (THG), was studied by femtosecond pulse laser excitation. Particularly, we find that different from the 3PL emission of single NW, which follows about fourth power of the excitation intensity, the 3PL of multiple NWs shows a saturation-like behavior. When the excitation power density is low, the slope of fitting curve is almost constant, but with the increase of excitation power, the slope decreases gradually. Since no energy transfer is observed between 3PL and other nonlinear responses, we think the phenomenon may owe to heat accumulation between the NWs.