Observation of nonlinear saturable and reverse-saturable absorption in silver nanowires and their silica gel glass composite

Silver nanowires (Ag NWs) and their silica gel glass composite were produced. Their nonlinear optical (NLO) properties, mainly saturable absorption (SA) and reverse-saturable absorption (RSA), were investigated at 532 and 1064 nm, using the open aperture z-scan technique and a nanosecond-pulsed laser. We found that Ag NWs demonstrate rather different NLO behaviors in liquid and solid-state matrices. The Ag NWs suspension exhibited only RSA, whereas a transformation from SA to RSA occurred in the silica gel glass composite. The underlying mechanism was proposed from the viewpoint of different environments and electronic dynamics of Ag NWs in the liquid and solid-state matrices.