Broadband second harmonic generation in GaAs nanowires by femtosecond laser sources

Nonlinear optical property of semiconductor nanowires plays a key role in nanoscale optoelectronics. In this paper, we demonstrate an excellent frequency converter based on GaAs nanowires (NWs), in which second harmonic generation (SHG) is excited by femtosecond lasers from 800 nm to 1800 nm. Simultaneous SHG with a bandwidth of 300-nm is excited by a super-continuum source at 1000-1600 nm. Broadband SHG can also be acquired from an isolated single NW and the process is coherent. The experimental results suggest that GaAs NWs are potential broadband optical nonlinear converters in nanoscale optoelectronics.