Ultrafast nonlinear optical response of molybdenum nano-film in wide wavelength range

摘要

Nonlinear optical responses in molybdenum (Mo) nano-film with different thicknesses (15 nm, 25 nm, 50 nm and 70 nm) are investigated by using 515 and 1030 nm fs laser pulses. The investigation shows that Mo nano-film has prominent reverse saturable absorption in both wavelengths. The nonlinear absorption capability is thickness-dependent. The effective nonlinear absorption coefficients of samples are on the order of 10(3)-10(4) cm GM(-1) in both 1030 nm and 515 nm, much larger than typical semiconductors. The origin of wide wavelength range nonlinear optical absorption can be attributed to free carries absorption.