Self-Induced Second-Harmonic and Sum-Frequency Generation from Interfacial Engineered Er3+/Fe3+ Doped LiNbO3 Single Crystal via Femtosecond Laser Ablation

Abstract

An interfacial engineered 1 mol % Er3+ and 0.07 mol % Fe3+ doped LiNbO3 single crystal was prepared by processing its surface into periodic rectangular arrays under femtosecond laser ablation. We demonstrated effective self-induced second-harmonic and sum-frequency generation emission peaks at 391, 487, 582, and 762 nm excited by a continuous wave laser at 980 nm, which were accompanied by the typical upconversion spectrum. Significant scattering and localization effects were analyzed as two main factors that contributed to the second-harmonic and sum-frequency generations. In addition to these observations, nanosecond second-harmonic laser emission peaks centered at 534.6 and 532.0 nm with a full width at half-maximum of approximately 0.77 nm were also generated under nanosecond laser illumination at 1064 nm. The obvious laser mode competition between these two emission peaks was investigated, and finally, the peak at 532.0 nm won with the increase of the pumping laser energy. These findings may play a v...