We have measured the far-field angular distributions of high harmonics (orders 11—41) generated by a 1-p,m, 1-ps laser pulse [(0.3—3)X 10 W/cm ] in low-density Ar, Kr, and Xe targets (~ 1 Torr, 1-mm thick). The far-field harmonic distributions show a narrow central structure surrounded by broad wings that contain approximately 75% of the harmonic energy. Low-density targets and f/70 focusing we...

The method of the superposition of a nonlinearity modulation is employed to design a two-dimensional (2D) nonlinear photonic lattice for efficient multiple quasi-phase-matched second harmonic generation in the process of nonlinear Raman-Nath diffraction (NRND). An analytical solution is proposed to calculate the second harmonic intensity in rectangular 2D lattices. This approach can be useful f...

Generation efficiency of the high-order harmonics of femtosecond Ti:sapphire laser pulses was improved by phasematched propagation in the guiding channel. The harmonics around the 49th harmonic (16 nm) were enhanced by two orders of magnitude compared to those in the plateau with a 7-mm-long, self-guided pulse in Ne. High-harmonic conversion efficiency of 10−6 was obtained, producing > nJ harmo...

High-order harmonic generation in the presence of a chirped THz pulse is investigated numerically with a complete 3D nonadiabatic model. The assisting THz pulse illuminates the high-order harmonic generation gas cell laterally inducing quasi-phase-matching. We demonstrate that it is possible to compensate the phase mismatch during propagation and extend the macroscopic cutoff of a propagated st...

Recent studies using artificial language learning have argued that the cross-linguistic frequency of harmonic word order patterns–in which heads are ordered consistently before or after dependents across syntactic categories–reflects a cognitive bias (Culbertson, Smolensky, & Legendre, 2012; Culbertson & Newport, 2015a). These studies suggest that English speaking adults and children favor harm...

Extreme-ultraviolet high-order-harmonic pulses with 1.6·10(7) photons/pulse at 32.5 eV have been separated from multiple harmonic orders by a time-preserving monochromator using a single grating in the off-plane mount. This grating geometry gives minimum temporal broadening and high efficiency. The pulse duration of the monochromatized harmonic pulses has been measured to be in the range 20 to ...

Most previous studies have focused on high-order harmonic generation beyond the ionization threshold; mechanisms of below-threshold harmonics are less understood. We schematically study the harmonic emission process in this region by numerically solving the time-dependent Schrödinger equation of an atom in laser fields. We show that, besides the quantum path interference mechanism recently iden...

Unregulated utilization of renewable generation including residential photovoltaic (PV) systems can have a significant impact on load characteristics in distribution networks. For improving PV generation capabilities, power quality aspects have to be coordinated with present load characteristics. This paper discusses the harmonic content of PV generation and the influence to power quality indic...

We demonstrate a significant extension of the high-order harmonic cutoff by using a fully-ionized capillary discharge plasma as the generation medium. The preionized plasma dramatically reduces ionization-induced defocusing and energy loss of the driving laser due to ionization. This allows for significantly higher photon energies, up to 150 eV, to be generated from xenon ions, compared with th...