Transiently stimulated second-harmonic generation from silicon nanogratings

Abstract

We observe that second-harmonic (SH) light generated by a femtosecond probe pulse from Si nanograting surfaces can be enhanced by a correlating pump pulse. Time-resolved anisotropy analysis shows that the enhancement arises from transient stimulation by the pump because it polarizes the periodically distributed charge from the probe photoinjection. In addition, dipole and quadrupole SH components are stimulated differently depending on the pump polarization. This effect reveals ultrafast SH dynamics in centrosymmetric materials and provides guidance for measuring nanoscale features.