Study of high-order harmonic generation from nanoparticles

Abstract

An experimental study on high-order harmonic generation from the interaction of 45 fs Ti:sapphire laser pulses with preformed plasma plumes of metal nanoparticles was carried out. Highly efficient harmonic generation in the range of 9th order to 19th order was observed for Ag nanoparticles. The stability of harmonic generation was enhanced by utilizing special target fabrication techniques and through optimizing the conditions of plasma plume formation. Broadband harmonic generation was observed through the optimization of femtosecond laser intensity and through the use of spectrally broadened laser pulses. The harmonic generation was compared for various target materials (nano and bulk) and for Ag nanoparticle targets prepared from different fabrication techniques. Efficient generation of even- and odd-order harmonics was observed through the use of two-colour pulses. The observations can be explained qualitatively from symmetry breaking of high-order harmonic generation through the introduction of second harmonic pulses. The spectral broadening and shift of harmonic radiation can be understood from the self-modulation of the laser and harmonic radiation in the plasma.

Application of carbon cluster-contained extended plasmas for the high-order harmonic generation of ultrashort pulses

“…This led to the deterioration of the optimal plasma formation after a few hundred shots on the same spot of clustercontained target, while in the case of bulk samples (silver, graphite) ablation; the stable harmonic generation was maintained for a considerably longer time. This effect has been observed in previous studies of powdered target ablation [24][25][26][27]37,38 and is attributed to the modification of target surface (i.e., evaporation of powder, melting of heated area, modification of surface properties, etc.). The variations of harmonic spectra from the cluster-contained targets are shown in Fig.…”

“…The enhancement of harmonics in the metal nanoparticle plasmas has been achieved in various laboratories. [24][25][26][27] In the meantime, the plasmas formed on the surfaces of non-metal bulk targets (such as graphite and carboncontained materials) have demonstrated the relatively high g for the lower-order harmonics compared with the harmonics generated in the gases. The stronger harmonics from the graphite plasma compared with the argon gas were reported in Refs.…”

Ablation of nanoparticles and efficient harmonic generation using a 1-kHz laser

“…In particular, the increase of HHG generation efficiency due to surface plasmon resonance (SPR) effects was demonstrated in fullerene media [25,26]. Recently, due to the wide availability of nanoparticles in the market, it has become possible to generate by laser ablation a plasma containing a large amount of nanoparticles, and the enhancement of HHG in nanoparticle plasmas has been confirmed in various laboratories ( [27][28][29], see also the review of those studies [30]). The reported improvement in η using various metal clusters showed the appeal of this approach.…”

Electrostatic and electromagnetic oscillations of nanoparticles in the presence of magnetic field

“…Iheludev and Emel'yanov [11] have studied phase matched second harmonic generation from nanostructure metallic surfaces. Singhal et al [12] have carried out experimental studies on high order harmonic generation from the interaction of 45fs Ti:sapphire laser pulses with preformed plasma plumes of metal nanoparticles. Kovalev et al [13] have studied Coulomb explosion of nanostructures in plane, cylindrical and spherical geometries.…”