Fabrication of complex nanostructures on ZnO crystals by the interference of three femtosecond laser beams

► Several kinds of 2D complex nanostructures on ZnO crystals were induced by the interference of three 800 nm femtosecond laser beams. ► The 2D hexagonal nanopatterns with period of 600 nm were much more regular and uniform compared with those with period of 3.36 μm. ► The photoluminescence of the 2D nanostructures reveal bright and pure blue-light emission excited by 800 nm femtosecond laser pulses. ► The PL intensity is very uniform, with fluctuation less than 5%. ► The 2D nanostructures had potential applications in blue light-emitting diodes, high density optical storage and other optoelectronic devices.