Nonlinear wave mixing in semiconductor nanoantennas and metasurfaces

We demonstrate how ultra-small dielectric nanoantennas ordered in a metasurface can enable enhanced light matter interaction for efficient nonlinear wave-mixing and in particular, to enhance sum-frequency generation and spontaneous parametric down conversion

Self-focusing and filamentation of optical vortex beams: Spatiotemporal analysis

We report numerical simulations supported by experimental observations of self-focusing, fillamentation, and supercontinuum generation by an optical vortex beam in a Kerr nonlinear medium in the regime of dominating nonlinearity. Despite the strong self-focusing resulting in multiple filaments ordered along the vortex ring the optical vortex remains well preserved at the exit of the nonlinear medium and in the far-field. The presented quasi-(3+1)- dimensional numerical simulations under azimuthal initial vortex ring perturbations confirm qualitatively the experimentally observed survival of the optical vortex in the course of the white light generation

Experimental control of pattern formation by photonic lattices

We study the control of modulational instability and pattern formation in a nonlinear dissipative feedback system with a periodic modulation of the material refractive index. We use a one-dimensional photonic lattice in a single-mirror feedback configuration and identify three mechanisms for pattern control: bandgap suppression of instability modes, periodicity induced pattern modes, and orientational pattern control.The authors acknowledge the support of the Conseil Régional de Lorraine, the bilateral FrenchAustralian Science and Technology program, and the Australian Research Council through Discovery projects

Bidirectional waveguide coupling with plasmonic Fano nanoantennas

We introduce the concept of a bidirectional, compact single-element Fano nanoantenna that allows for directional coupling of light in opposite directions of a high-index dielectric waveguide for two different operation wavelengths. We utilize a Fano resonance to tailor the radiation phases of a gold nanodisk and a nanoslit that is inscribed into the nanodisk to realize bidirectional scattering. We show that this Fano nanoantenna operates as a bidirectional waveguide coupler at telecommunication wavelengths and, thus, is ideally suitable for integrated wavelength-selective light demultiplexing

Soliton stripes in two-dimensional nonlinear photonic lattices

We study experimentally the interaction of a soliton with a nonlinear lattice. We observe the formation of a novel type of composite soliton created by strong coupling of mutually incoherent periodic and localized beam components. By imposing an initial transverse momentum on the soliton stripe, we observe the effect of lattice compression and deformation.Comment: three pages, four figure

Shaping and control of polychromatic light in nonlinear photonic lattices

We overview our recent results on spatio-spectral control, diffraction management, broadband switching, and self-trapping of polychromatic light in periodic photonic lattices in the form of rainbow gap solitons, polychromatic surface waves, and multigap color breathers. We show that an interplay of wave scattering from a periodic structure and interaction of multiple colors in media with slow nonlinear response can be used to selectively separate or combine different spectral components. We use an array of optical waveguides fabricated in a LiNbO3 crystal to actively control the output spectrum of the supercontinuum radiation and generate polychromatic gap solitons through a sharp transition from spatial separation of spectral components to the simultaneous spatio-spectral localization of supercontinuum light. We also show that by introducing specially optimized periodic bending of waveguides in the longitudinal direction, one can manage the strength and type of diffraction in an ultra-broad spectral region and, in particular, realize the multicolor Talbot effect

High-order harmonic generation yielding tunable extreme-ultraviolet radiation of high spectral purity

Production of extreme-ultraviolet radiation by high-order harmonic generation is demonstrated to yield unprecedented spectral purity of λ/Δλ=2.5×105 at wavelengths covering the entire range 40–100 nm. Tunability and sub-cm-1 bandwidth of the harmonics are demonstrated in recordings of the He (1s4p) and Ar (3p53d′) resonance lines at 52.2 and 86.6 nm. Frequency shift of the harmonics due to chirp-induced phenomena are investigated and found to be small, resulting in a frequency accuracy of about 5×10-7 in the domain of extreme-ultraviolet radiation

Monitoring ultrashort pulses by transverse frequency doubling of counterpropagating pulses in random media

The authors study experimentally the transverse second-harmonic generation of counterpropagating pulses by a quasi-phase-matching in a medium with a random ferroelectric domain structure. The authors show that this parametric process results in a direct realization of the cross correlation of two optical signals and, therefore, it can be employed for direct characterizations of ultrashort pulses including their temporal structure and pulse front tilt.The authors acknowledge the support of the Australian Research Council

Generation of Bessel beams by parametric frequency doubling in annular nonlinear periodic structures

We analyze the second-harmonic generation in two-dimensional photonic structures with radially periodic domains created by poling of a nonlinear quadratic crystal. We demonstrate that the parametric conversion of the Gaussian fundamental beam propagating along the axis of the annular structure leads to the axial emission of the second-harmonic field in the form of the radially polarized first-order Bessel beam