Saturable and reverse saturable absorption in aqueous silver nanoparticles at off-resonant wavelength

Abstract

Silver nano-colloid was prepared by chemical reduction method and its nonlinear absorption properties were investigated by using open aperture z-scan experiment with nanosecond laser pulses operating at 532 nm. Interestingly, a switch over from saturable absorption to reverse saturable absorption was observed when the input intensity is increased from 28.1 to 175.8 MW/cm 2 . The underlying mechanism responsible for the observed switching behaviour is the interplay between ground state plasmon band bleaching and excited state absorption. Theoretical fitting was done by using a model in which nonlinear absorption coefficient as well as saturation intensity are incorporated.

Saturable absorption of silver nanoparticles in glass for femtosecond laser pulses at 400 nm

“…However, just as a rough comparison, some literature data are reviewed here. The saturation intensity for Ag NPs prepared by chemical reduction of silver nitrate in aqueous solution has been reported 2 × 10 8 W·cm − 2 using 7 ns pulses at 532 nm [7], 7 × 10 7 W·cm −2 using 5 ns pulses at 532 nm [41] and 9 × 10 13 W·cm −2 using 100 fs pulses at 800 nm [41]. The difference between our results and the reported results is due to three reasons.…”

“…This nonlinear optical (i.e. intensity dependent) behavior has been observed for different kinds of metal NPs such as Ag [2,[7][8][9][10][11][12], gold [13][14][15][16] and copper [17,18] around their SPR. The SA of gold NPs and to some extent also copper NPs has been examined extensively at 532 nm [14,18] (the second harmonic of Nd:YAG laser) since their SPR lies in this spectral region.…”

Nonlinear absorption, nonlinear scattering, and optical limiting properties of MoS2–ZnO composite-based organic glasses

“…16,39,40 The total extinction coefficient a(I) can be expressed as: 16,39,40 16,39,40 The total extinction coefficient a(I) can be expressed as: 16,39,40 …”

Interaction of Pulses of Different Duration with Chemically Prepared Silver Nanoparticles: Analysis of Optical Nonlinearities

“…In the meantime, there is a lot of studies showing that at a shorter wavelength, the incident intensity affects the nonlinear absorption coefficient (for example, [31]). The growth of incident intensity in the Ag NP solution causes transformation from SA to RSA [11,26,32]. There is an intensity threshold between SA and RSA.…”