High-power Soliton-induced Supercontinuum Generation and Tunable Sub-10-fs VUV Pulses from Kagome-lattice HC-PCFs

We theoretically study a novel approach for soliton-induced high-power supercontinuum generation by using kagome lattice HC-PCFs filled with a noble gas. Anomalous dispersion and broad-band low loss of these fibers enable the generation of two-octave broad spectra by fs pulses, with high coherence and high spectral peak power densities up to five orders of magnitude larger than in standard PCFs. In addition, up to 20 percents of the output radiation energy forms a narrow UV/VUV band, which can be tuned by contolling the pressure in the range from 350 nm to 120 nm. In the temporal domain this corresponds to sub-10-fs UV/VUV pulses with pulse energy of few tens of microjoule, caused by the formation of a high-order soliton emitting non-solitonic radiation.Comment: 4 pages, 4 figure

Theory of plasmon-enhanced high-harmonic generation in the vicinity of metal nanostructures in noble gases

We present a semiclassical model for plasmon-enhanced high-harmonic generation (HHG) in the vicinity of metal nanostructures. We show that both the inhomogeneity of the enhanced local fields and electron absorption by the metal surface play an important role in the HHG process and lead to the generation of even harmonics and to a significantly increased cutoff. For the examples of silver-coated nanocones and bowtie antennas we predict that the required intensity reduces by up to three orders of magnitudes and the HHG cutoff increases by more than a factor of two. The study of the enhanced high-harmonic generation is connected with a finite-element simulation of the electric field enhancement due to the excitation of the plasmonic modes.Comment: 4 figure

Two-photon laser scanning fluorescence microscopy using photonic crystal fibre

We report the application of a simple yet powerful modular pulse compression system, based on photonic crystal fibres which improves upon incumbent twophoton laser scanning fluorescence microscopy techniques. This system provided more than a 7-fold increase in fluorescence yield when compared with a commercial two-photon microscopy system. From this, we infer pulses of infrared radiaton of less than 35 fs duration reaching the sample

Ionization-induced Susceptibility by Nearly-free Electrons in Gases Influenced by the Coulomb Potential

In the present paper we study the influence of the Coulomb potential on the real and imaginary parts of the plasma-induced susceptibility in a photoionized gas. We show that the real part of the susceptibility is more than one order of magnitude larger due to the action of a Coulomb potential. Surprisingly, the long-range Coulomb potential of the atomic core leads to an additional contribution to the imaginary part of the susceptibility which has no counterpart in the case of a short-range potential. We demonstrate that the origin of this behavior are electrons in states very close to the continuum (nearly-free electrons), and analyze the dependence of the susceptibility on the intensity and wavelengths.Comment: 6 pages, 7 figure

Ultrafast Nonlinear Optical Effects of Metal Nanoparticles Composites

We present a theoretical method for the calculation of the transient nonlinearity in dielectric composites doped with metal nanoparticles and demonstrate some applications of this approach. First, we describe the theoretical basis of the linear and nonlinear properties of metal nanoparticles by using the time-domain discrete-dipole approximation. By using the two-temperature model for the description of the electron-electron and electron-lattice interaction, we derive an equation for the transient third-order nonlinear susceptibility. Based on this method and the effective medium approximation, we present numerical results for the nonlinear optical susceptibility for different nanocomposites media consisting of noble metal nanoparticles surrounded by a dielectric host. With increasing pump intensities, the plasmon resonance is shifted which leads to a saturation of the absorption. We present a theory of mode-locking of solid-state and semiconductor disk lasers using metal nanocomposites as saturable absorbers. Finally, we consider a novel slow-light device based on metal nanocomposites

Multistability at arbitrary low optical intensities in a metallo-dielectric layered structure

We show that a nonlinear metallo-dielectric layered slab of subwavelength thickness and very small average dielectric permittivity displays optical multistable behavior at arbitrary low optical intensities. This is due to the fact that, in the presence of the small linear permittivity, one of the multiple electromagnetic slab states exists no matter how small is the transmitted optical intensity. We prove that multiple states at ultra-low optical intensities can be reached only by simultaneously operating on the incident optical intensity and incidence angle. By performing full wave simulations, we prove that the predicted phenomenology is feasible and very robust.Comment: 4 pages, 4 figure

Frequency-selective self-trapping and supercontinuum generation in arrays of coupled nonlinear waveguides

We study spatiotemporal dynamics of soliton-induced twooctave- broad supercontinuum generated by fs pulses in an array of coupled nonlinear waveguides. We show that after fission of the input pulse into several fundamental solitons, red and blue-shifted nonsolitonic radiation, as well as solitons with lower intensity, spread away in transverse direction, while the most intense spikes self-trap into spatiotemporal discrete solitons