Excited by 1064 nm laser the three-photon coefficient γ of GaN nanowire much higher than that of bulk GaN in the picosecond time scale reported in ref In femtosecond regime the obtained 3PA coefficie

The 1064 nm laser excited GaN nanowire exhibits a significantly higher three-photon coefficient γ compared to bulk GaN in the picosecond time scale, as reported in reference []. In the femtosecond regime, the 3PA coefficients obtained for GaN crystal excited by a 1030 nm laser are an order of magnitude higher than our results. This difference can be attributed to the shorter femtosecond time scale and the higher concentration of bulk GaN in the crystal. By numerically comparing the results and observing a large modulation depth, we can speculate that GaN nanowire demonstrates better non-linear absorption (NLA) performance than GaN crystal. Additionally, we observed saturated absorption phenomena that are not present in bulk crystals. This can be attributed to electron transitions occurring in the quantum confinement effect and defect states on the surface of the nanowires. Therefore, the nonlinear properties of GaN are enhanced due to the nanoscale nature of the nanowires.