Interplay of major mechanisms of the light-induced transmission in one-dimensional Cu/SiO2 photonic crystals

Femtosecond time-resolved measurements in Cu/SiO₂ layered structure reveal that the difference in the response time of major mechanisms of optical nonlinearity results in the pronounced dependence of the nonlinear transmission spectrum on the pump-probe delay. Despite the fact that noble metals possess optical nonlinearity 10 times larger than that of fused silica, they are not usually considered as materials to be employed in nonlinear optical devices because of low transmittivity. However, it has been shown that multiple Bragg reflections in a 1D metal-dielectric phonic bandgap (PBG) structure allow one to create a transmission window (passband) making such structures attractive for practical applications.. Here we report time-resolved nonlinear transmission measurement in the Cu/SiO₂ PBG structure. We demonstrate in particular that femtosecond pump can induce 20% change in the transmission within the passband and show that temporal evolution of the pump-induced transmission is different at the blue and red edges of the passband.