Direct writing of Cu-based fine micropatterns using femtosecond laser pulse-induced sintering of Cu 2 O nanospheres

Cu-based micropatterns were directly fabricated using femtosecond laser pulse-induced sintering of Cu 2 O nanospheres. Cu 2 O nanospheres synthesized by the polyol method were spin-coated on glass substrates. By evaluating the nonlinear optical absorption of the Cu 2 O nanosphere films using the Z -scan method, the two-photon absorption coefficient was estimated as ∼70 cm GW −1 , which is adequate in comparison with that of bulk Cu 2 O. Although Cu and Cu 2 O composite micropatterns were obtained at a high scan speed of 100–1000 μ m s −1 , CuO micropatterns were formed at a low scan speed of 1 μ m s −1 . Compared with the femtosecond laser sintering of CuO nanoparticles using linear optical absorption, the width of line patterns obtained using Cu 2 O nanospheres was smaller at each pulse energy. These results suggest that two-photon absorption induced a decrease of the absorbed area, providing the small line width. This direct writing technique is useful for selective fabrication of Cu-based fine micropatterns.