Femtosecond cubic optical nonlinearity of thin nickel films

Transient pump-probe measurements of circular anisotropy in nickel films in duced by 38-fs optical pulses show an instantaneous response that is relate d to the optical orientation of the spins of free electrons. Measurements i n a sample of variable thickness, performed in both transmission and reflec tion, revealed that the surface significantly influences the degenerate cub ic optical nonlinearity of the nickel films to a depth of approximately 4-5 nm into the bulk. (C) 1999 Optical Society of America OCIS codes: 190.7110 , 190.4710, 190.4350, 160.3900, 320.2250, 320.7110.