Second Harmonic Generation in Nanowires

Second harmonic generation (SHG) in optical materials serves as important techniques for laser source generations in awkward spectral ranges, physical identities of materials in crystalline symmetry and interfacial configuration. Here, we present a comprehensive review on SHGs in nanowires (NWs), which have been recognized as an important element in constructing photonic and optoelectronic devices with compact footprint and high quantum yield. Relying on NW's one-dimensional geometry, its SHG could be employed as a sophisticated spectroscopy to determine the crystal phase and orientation, as well as the internal strain. The enhancements of SHG efficiency in NWs are discussed then, which were realized by hybrid integrating them with two-dimensional materials, nanophotonic and plasmonic structures. Finally, the potential applications of NW SHGs are concluded, including the areas of optical correlators and constructions of on-chip nano-laser sources.