LAUSR

We present the plasmon-enhanced linear and second-order surface nonlinear optical response of silver nanoparticles (Ag NPs) fabricated by using femtosecond pulse. Theoretical analysis indicates that the Ag NPs with diameter of ~100 nm has excellent linear response within visible band, and the electric field intensity enhancement factor reaches ~105 under excitation of continuous light of 632.8 nm. Meanwhile, the simulation result of second-order surface nonlinear optical response shows that the second harmonic conversion efficiency of Ag NPs dimer is two orders of magnitude higher than that of single Ag NP, under excitation of femtosecond pulse. In experiment, the linear response of Ag NPs is examined by using surface enhanced Raman spectroscopy (SERS) with Raman enhancement factor of ~1.7×1010, revealing the excellent linear optical response of Ag NPs. Moreover, the spectrum of second harmonic can be measured clearly under condition of the average pump power of 40 μW, revealing the excellent second-order surface nonlinear optical response of Ag NPs.