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Graphene oxide (GO) and silver nanoparticles (AgNPs) are recently been widely employed in various sectors including in photonics applications due to their fascinating properties. On the other hand, huge interests are shown by the researchers for development of scatterer materials for achieving random laser (RL) with improved performances. In this work, the GO/Ag nanocomposite material comprising of GO nanosheets and AgNPs have been prepared and its remarkable nonlinear optical (NLO) properties are employed for the first time to demonstrate RL in the visible region by the introduction of disorder and multiple scattering within the amplifying medium of Rhodamine-B dye. Interestingly by changing the cuvette path lengths, here we have shown that the gain volume within the amplifying media can be varied effectively, which directly influence the lasing threshold. The larger value of NLO coefficients in GO/Ag scatterer induced greater refractive index contrast (Δn) between the scatterer and surrounding medium and thus enhances the light-matter interactions in the GO/Ag nanocomposite and consequently the lasing threshold for RL generation is reduced significantly by 50 % than that of bare GO as scattering center. This report opens an exciting prospect of using NLO properties of GO/Ag nanocomposite for achieving enhanced scattering in different gain media for demonstration of low threshold RL, which may revolutionize the future development of RLs. [Display omitted] • Novel Random laser comprising of GO/Ag nanocomposite has been reported in Rhodamine-B dye. • The binary influence of random scattering from GO nanosheets and surface Plasmon resonance of Ag has been utilized. • The extent of gain medium has been modified to modify the feedback for lasing. • The 3rd order nonlinear optical properties of GO/Ag have been used to decrease the lasing threshold. [ABSTRACT FROM AUTHOR]

Synthesis of 2D materials from natural resources, and having unique functionalities have created enormous research interest among material scientists. Such 2D materials can be used as impetus for light scattering to generate continuous wave (CW) pumped random laser (RL) emission at room temperature. In this work, defects-free 2D yellow pearl (2D-YP) has been synthesized from bulk south sea pearl using liquid-phase exfoliation (LPE) technique. Thereafter, 2D-YP has been employed as a passive scatterer to achieve CW pumped RL emission from a conventional gain molecule. Compared to other semiconductor (TiO 2) and 2D (Graphene and hBN) passive scatterers, ∼25 times improvement in gain volume is observed for the disordered system consisting of 2D-YP, and is due to the formation of a large refractive index gradient via thermal nonlinear optical (NLO) interaction. Hence, incoherent RL (ic-RL) emission ∼591 nm is reported at a lowest threshold input pump power and a linewidth of 65 mW and 3 nm, respectively. Additionaly, a clear transition from ic-RL to mode tunable coherent RL (c-RL) emission is also demonstrated by altering the pump configuration. Therefore, the newly designed van der Waals heterostructure, i.e. , 2D-YP with intrinsic photon trapping capability may pave an avenue towards developing exciting optoelectronic devices. [Display omitted] • 2D yellow pearl is synthesized from its bulk form using liquid phase exfoliation. • Structural and linear optical properties of 2D-YP is explored. • The 2D-YP is employed as passive scatterer to achieve RL emission under CW pumping. • NLO effect induced boosting of gain volume over other scatterers is demonstrated. • Incoherent RL emission of linewidth of ∼3 nm, and Th P in of ∼65 mW is reported. [ABSTRACT FROM AUTHOR]

Bilayer graphene nanosheets (B-GNSs) have been synthesized from dry-cell graphite electrode by using facile laser ablation in liquid technique in ambient condition. The plasma plume generated on incidence of ns pulsed Nd: YAG laser fundamental radiation of 1064 nm has facilitated the transformation of bulk graphite (BG) into B-GNSs via liquid carbon phase within 30 min of laser irradiation, and the layer number is are found to be increased with further increase in laser ablation time. The thickness dependent coherent nonlinear optical (NLO) response of the synthesized materials in aqueous dispersion has been determined by spatial self-phase modulation technique. The oxygen-containing surface defects in multilayer GNSs (M-GNSs) have led to scarcity in amount of e-h pairs in compared to that in B-GNSs. Therefore, a better NLO polarization has been observed in B-GNSs in compared to that of M-GNSs. Moreover, the thickness dependent thermal conductivity and hydrodynamic performance of GNSs-water dispersion has led to the observation of tunable NLO response with change in temperature as well as with the intensity of pump laser. The experimental findings obtained in this work may be considered as a key step towards fabrication of graphene from graphitic waste materials for development of future nonlinear photonics devices. Unlabelled Image • Bilayer graphene nanosheets (B-GNSs) are synthesized from dry cell electrode using laser ablation in liquid technique. • The laser plasma plume has transformed the BG into B-GNSs. • Layer number in GNSs is found to be increased with laser ablation time. • Thickness dependent nonlinear optical response of GNSs is demonstrated. • Nonlinear optical response of GNSs-water dispersion is tunable with pump laser intensity and temperature. [ABSTRACT FROM AUTHOR]