Nonlinear Optical Investigations in Nine-Atom Silver Quantum Clusters and Graphitic Carbon Nitride Nanosheets

Abstract

Absorption saturation due to surface plasmon resonance affects the optical limiting efficiency of metal nanoparticles (NPs) by raising the limiting threshold to higher laser fluences. It has been shown that in gold, compared to the larger NPs, smaller quantum clusters (QCs) exhibit better optical limiting with lower limiting thresholds due to the absence of absorption saturation. Here we report optical limiting properties of two novel materials, namely, nine-atom silver (Ag 9 ) QCs and graphitic carbon nitride (GCN) nanosheets. The relatively large nonlinear absorption of Ag 9 QCs compared to Ag NPs is revealed from openaperture Z-scan measurements carried out using 532 nm, 5 ns laser pulses. Optical nonlinearity in the QCs arises mostly from free carrier absorption and a relatively weak saturable absorption. The superior limiting efficiency of Ag 9 QCs is complemented by excellent chemical stability, which makes silver quantum clusters ideal candidates for optical limiting applications. The two-dimensional sheet-like structure of GCN is ideal for grafting metals and semiconductors, and we show that even though the nonlinearity of pristine GCN is low it can be improved substantially by grafting lightly with Ag 9 QCs.

Graphitic carbon nitride, a saturable absorber material for the visible waveband

“…Under the same experimental conditions, the T N value of black phosphorus can only reach 115% at a much higher incident intensity of 115 GW • cm −2 . For 532 nm excitation, contrary to earlier reports on OL phenomena [21,22], all of the three g-C 3 N 4 samples exhibit the SA effect under picosecond pulses. When the input fluence at the focal point is fixed at 1.66 J • cm −2 (corresponding to an intensity of 55 GW • cm −2 ), the T N values of g-C 3 N 4 -1, g-C 3 N 4 -2, and g-C 3 N 4 -3 samples are 125%, 163%, and 192%, respectively.…”

Enhanced Ultrafast Nonlinear Optical Response in Ferrite Core/Shell Nanostructures with Excellent Optical Limiting Performance

“…Despite their importance, the capabilities of existing optical limiters are still far from ideal. Thus, diverse approaches, using different types of materials such as metallic, semiconductor or organic, are being investigated to improve their performance. However, high intensities result in photofragmentation and ligand desorption in most of these materials, resulting in irreversible material damage .…”

“…Nanostructured materials are gaining increased interest both in industry and research due to their novel and enhanced [+] Present address: Photonics Laboratory, Tampere University of Technology, P.O. Box 692, FI-33101 Tampere, Finland diverse approaches, using different types of materials such as metallic, semiconductor or organic, [1,10,11] are being investigated to improve their performance. However, high intensities result in photofragmentation and ligand desorption in most of these materials, resulting in irreversible material damage.…”

Enhanced broadband optical limiting and switching of nonlinear absorption in functionalized solar exfoliated reduced graphene oxide–Ag-Fe2O3 nanocomposites

“…This energy absorbing nonlinear process can be broadly classified as saturable absorption (SA) (increased transmittance) and reverse saturable absorption (RSA) (decreased transmittance). 9 Saturable absorption (SA) is broadly utilized in nonlinear optical modulators which are used in mode-locking and passive Q-switching techniques for the generation of ultrashort pulse lasers, and reverse saturable absorbers can be used as optical limiters toward the protection of sensitive optical components including human eyes from laser induced damages. [10][11][12] These phenomena are strongly intensity dependent (in general, SA is seen at lower laser fluence and RSA becomes predominant at higher laser fluence) and can be specifically induced in a material by a proper choice of the excitation source.…”