Demonstration of Spatial Self Phase Modulation based photonic diode functionality in MoS2/h-BN medium

Spatial self-phase modulation (SSPM) is the optical nonlinear process and is a result of spatially varying refractive index profile along the line of propagation in a medium. SSPM is proved to be a method to demonstrate different photonic functionalities. Transition metal dichalcogenides play a key role in 2D nanophononics due to their unique and fascinating properties. MoS2 is the widely studied layered TMDs among all other 2D materials. This paper demonstrates such photonic functionality using thermally induced nonlinear optical response SSPM method, of MoS2 nano bottles. Thermally induced nonlinear optical parameters have been estimated by utilizing the saturable absorption response of h- BN, the nonreciprocal light propagation has been achieved. The diode actions have also been demonstrated in liquid-solid and solid-solid devices with the help of passive elements

Influence of localized surface plasmons on Pauli blocking and optical limiting in graphene under femtosecond pumping

The Pauli blocking limit and optical limiting threshold have been found to be modified following silver-nanoparticle decoration of functionalized hydrogen induced exfoliated graphene. Femtosecond Z-scan experiments have been used to measure the Pauli blocking range, optical limiting threshold, and the third order nonlinear susceptibility (χ(3)) values. The observed results have been explained by modified band structure of graphene in the presence of silver nanoparticles and their localized surface plasmon resonances

Introducing Optical Nonlinearity in PDMS Using Organic Solvent Swelling

The feasibility of introducing optical nonlinearity in poly-dimethyl siloxane (PDMS) using organic solvent swelling was investigated. The third-order nonlinear refraction and absorption properties of the individual materials, as well as the PDMS/solvent compounds after swelling were characterized. The well-established Z-scan technique served as characterization method for the nonlinear properties under picosecond pulsed laser excitation at a 532 nm wavelength. These experiments included investigations on the organic solvents nitrobenzene, 2,6-lutidine, and toluene, which showed inherent optical nonlinearity. We showed that nitrobenzene, one of the most well-known nonlinear optical materials, has proven suboptimal in this context due to its limited swelling effect in PDMS and comparatively high (non)linear absorption, resulting in undesirable thermal effects and potential photo-induced damage in the composite material. Toluene and 2,6-lutidine not only exhibited lower absorption compared to nitrobenzene but also show a more pronounced swelling effect in PDMS. The incorporation of toluene caused a weight change of up to 116% of PDMS, resulting in substantial nonlinear optical effects, reflected in the nonlinear refractive index of the PDMS/toluene composite n2=3.1×10−15 cm2/W

Cavity induced fluorescence enhancement of graphitic carbon nitride submicron flakes

Graphitic carbon nitride (g-C3N4), which is structurally analogous to graphene, shows excellent fluorescent yield. Sharp ripple structure is observed in the fluorescence spectra of g-C3N4 flakes grafted on the surface of single polymethyl methacrylate (PMMA) microspheres. The intensities and the number of modes of these structures nonlinearly vary with the size of micro-cavity and the coupled power. Theoretical simulations carried out with the help of Mie theory show that the ripple structure is due  to modulation of the fluorescence by the whispering gallery modes (WGMs) of the spherical microcavity.</p

Control over the charge transfer in dye-nanoparticle decorated graphene

Charge transfer interaction between silver decorated graphene and three differently charged dyes, cationic (rhodamine 6G), neutral (rhodamine B) and anionic (fluorescein 27) has been studied. The ground state association constants have been evaluated and changes in the fluorescence intensity and lifetimes have been obtained in two solvents. Strength of complex-formation has been found to be higher with the cationic molecule in water. In a higher viscosity solvent, the ground state complex formation is restricted. Local field of localized surface plasmons of nanoparticles adsorbed on the graphene sheets leads to enhanced absorption and fluorescence of fluorescein 27.</p