Propagations of Fresnel diffraction accelerating beam in Schrodinger equation with nonlocal nonlinearity

Accelerating beams have been the subject of extensive research in the last few decades because of their selfacceleration and diffraction-free propagation over several Rayleigh lengths.Here,we investigate the propagation dynamics of a Fresnel diffraction beam using the nonlocal nonlinear Schrodinger equation(NNLSE).When a nonlocal nonlinearity is introduced into the linear Schrodinger equation without invoking an external potential,the evolution behaviors of incident Fresnel diffraction beams are modulated regularly,and certain novel phenomena are observed.We show through numerical calculations,under varying degrees of nonlocality,that nonlocality significantly affects the evolution of Fresnel diffraction beams.Further,we briefly discuss the two-dimensional case as the equivalent of the product of two one-dimensional cases.At a critical point,the Airy-like intensity profile oscillates between the first and third quadrants,and the process repeats during propagation to yield an unusual oscillation.Our results are expected to contribute to the understanding of NNLSE and nonlinear optics.

Graphene-integrated waveguides:Properties,preparation,and applications

Graphene-integrated waveguides(GIWGs)have shown immense potential for applications in next-generation datacom technology due to graphene’s compactness and its functional complementarity with traditional optical waveguides.However,the fabrication techniques of GIWGs lack scalability for commercial applications.Here we discuss the recent developments of GIWGs in two-dimensional optoelectronics by focusing on their properties,wave–matter interaction mechanisms,and fabrication techniques.We highlight representative advances on the advantages and potential applications of GIWGs in telecom networks.Finally,we outline major challenges and development trends to bridge the gap between proof-of-concept demonstrations and practical applications.

The molecular orientation of PNB A on silver nanoparticles

The molecular orientations of p-nitrobenzoic acid (PNBA) on the surface of silver nanoparticles and silver mirror have been investigated by using surface enhanced Raman scattering (SERS) and UV-visible absorption spectroscopy. In the mixed system of silver colloid/PNBA/ethanol, the orientation of PNBA on silver nanoparticles remarkably different from that on silver mirror was observed, and it mainly resulted from the cooperation effect of the adsorption to surface active sites on silver under the pressure of aqueous molecules. This result is of some significance for further studying surface-interfacial structures and properties of silver nanoparticles, and the technique used in this note is feasible to get the SERS spectra of some molecules insoluble in aqueous solution.

Oxygen-containing-defect-induced synergistic nonlinear optical enhancement of graphene/CdS nanohybrids under single pulse laser irradiation

Oxygen-containing defects are very important for altering the nonlinear optical (NLO) properties of graphene. To investigate the correlation between oxygen-containing defects and the synergistic NLO response in graphenebased nanocomposites, we attached CdS nanocrystals on the surface of graphene (G) and prepared G/CdS nanohybrids (NHs) consisting of various oxygen-containing functional groups via a chemical method. The NLO absorption and refraction of G/CdS NHs under single pulse laser irradiation are enhanced by 10.8 times with the concentration decrease of surface oxygen-containing groups, which might be attributed to the local field effects and synergetic effects stemming from charge transfer between the two components. However, the optical nonlinearity is decreased with further concentration decrease, which might arise from sp^2 fragment interconnection and surface defects in the NHs. The NLO absorption transformation from two-photon absorption to saturable absorption with oxygen decrease is observed, and intensity-related NLO absorption and refraction in NHs are also discussed. Meanwhile, the G/CdS NHs exhibit superior NLO properties, implying potential applications of NH material in NLO devices.