We report the observation of second-harmonic generation by type I quasi phase matching in a GaAs-AlAs superlattice waveguide. Quasi phase matching was achieved through modulation of the nonlinear coefficient chi((2))(zxy), which we realized by periodically tuning the superlattice bandgap. Second-harmonic generation was demonstrated for fundamental wavelengths from 1480 to 1520 nm, from the thir...

We observe enhanced third-harmonic generation from silicon nanodisks exhibiting both electric and magnetic dipolar resonances. Experimental characterization of the nonlinear optical response through third-harmonic microscopy and spectroscopy reveals that the third-harmonic generation is significantly enhanced in the vicinity of the magnetic dipole resonances. The field localization at the magne...

Third harmonic generation due to linearly polarized Gaussian laser pulse propagating through quantum plasma immersed in transverse wiggler magnetic field is studied using the quantum hydrodynamic (QHD)model. The effects associated with the Fermi pressure, the Bohm potential and the electron spin have been taken into account.Wiggler magnetic field plays both a dynamic role in producing the harmo...

In the process of optical second-harmonic generation an X-wave, travelling at the group velocity of the fundamental frequency, spontaneously forms. Its parameters, as well as the angular spectrum, are directly correlated to the group velocity mismatch and to the wavevector mismatch between the two harmonics. A novel mechanism for spatio-temporal localized waves generation is thus proposed. ∗Ele...

An analysis is suggested to study the impact of Hall currents in Jeffrey fluid which is chemically reactive through a porous medium limited by a semi-infinite vertical permeable plate within the existence of heat generation. An evenly distributed magnetic field turns vertically on the porous surface which absorbs the Jeffrey fluid with a changed suction velocity with time. The analytical expres...

Inclusion of the instantaneous Kerr nonlinearity in the FDTD framework leads to implicit equations that have to be solved iteratively. In principle, explicit integration can be achieved with the use of anharmonic oscillator equations, but it tends to be unstable and inappropriate for studying strong-field phenomena like laser filamentation. In this paper, we show that nonlinear susceptibility c...

A high intensity laser obliquely incident on an underdense plasma with density ripple produces resonant second and third-harmonic radiation in the reflected component. The highest efficiency of harmonic generation occurs when the pump laser is incident at critical angle and the angle between ripple wave vector q and the surface normal has a specific value / — /m, at which phase-matching conditi...

The attosecond time-scale electron-recollision process that underlies high harmonic generation has uncovered extremely rapid electronic dynamics in atoms and diatomics. We showed that high harmonic generation can reveal coupled electronic and nuclear dynamics in polyatomic molecules. By exciting large amplitude vibrations in dinitrogen tetraoxide, we showed that tunnel ionization accesses the g...

In high-order harmonic generation, resonant harmonics (RH) are sources of intense, coherent extreme-ultraviolet radiation. However, intensity enhancement of RH only occurs for a single harmonic order, making it challenging to generate short attosecond pulses. Moreover, the mechanism involved behind such RH was circumstantial, because of the lack of direct experimental proofs. Here, we demonstra...

Third and fifth harmonic generation of an IR (1.064 μm) pulsed laser has been produced in ablation plasmas of the wide bandgap semiconductors CdS and ZnS. The study of the temporal behaviour of the harmonic emission has revealed the presence of distinct compositional populations in these complex plasmas. Species ranging from atoms to nanometre-sized particles have been identified as emitters, a...