Near-circularly polarized single attosecond pulse generation from nitrogen molecules in spatially inhomogeneous laser fields

Abstract

The generation of an attosecond pulse in nitrogen molecules using spatially inhomogeneous laser fields is investigated by numerically solving the time-dependent Schrödinger equation. It is found that an isolated attosecond pulse with elliptical polarization can be generated using linearly polarized laser fields. By changing polarization direction with respect to the molecular axis, the ellipticity of the attosecond pulse can be easily controlled. At some specific angles, the intensities of the two mutually vertical harmonic components, parallel and perpendicular to the driving laser polarization direction, are comparable. Additionally, the relative phase between the two components is about π/2. As a result, it supports the generation of the isolated near-circularly polarized attosecond pulse with a duration of 155 as.

Molecular harmonic generation in bowtie-shaped nanostructure

“…As seen, (i) when + H 2 is injected into the gap center (z 0 = 0.0), the laser enhancement presents the symmetry in the negative-z and the positive-z. As a result, the harmonic cutoff beyond the classical value of I p + 3.17U p should be obtained [15][16][17][18][19][20][21][22][23][24][25][26][27][28]. Through our calculations, the higher pulse intensity is, the larger extension of the harmonic cutoff will be.…”

“…In 2008, Kim et al [15] first reported that the HHG can be generated and extended from the plasmon-enhanced nonhomogeneous field, which can be produced when the bow-tie metallic nanostructures is illuminated by a lowintensity laser pulse. Further, the investigations of the HHG in the nonhomogeneous field receive lots of attention due to its potential to extend the harmonic cutoff [16][17][18][19][20][21][22][23][24][25][26][27][28]. In earlier stage from 2008 to 2014, the investigations of the HHG driven by the nonhomogeneous field are focus on the atomic systems [16][17][18][19][20][21][22].…”

“…Further, the investigations of the HHG in the nonhomogeneous field receive lots of attention due to its potential to extend the harmonic cutoff [16][17][18][19][20][21][22][23][24][25][26][27][28]. In earlier stage from 2008 to 2014, the investigations of the HHG driven by the nonhomogeneous field are focus on the atomic systems [16][17][18][19][20][21][22]. Since 2015, the extension of the HHG from molecules in the nonhomogeneous field has been reported [23][24][25][26][27][28].…”

Generation of high-intensity single attosecond x-ray pulses with multi-laser beam superposition

“…Thus, to overcome this weakness, many improved schemes have been proposed. For example: (i) using the two-color or the three-color combined field [8,[21][22][23][24], many improved SAPs shorter than one atomic unit can be obtained; (ii) using the polarization gating scheme [25][26][27][28][29], a number of SAPs can be obtained when the multi-cycle driven pulses are adopted; (iii) using the inhomogeneous effect of the laser field [30][31][32][33][34][35][36][37], many SAPs can be produced in the lower laser intensity region; (iv) using the frequency-chirping technique [38][39][40][41][42][43], drastic changes in the HHG can be found, including extension of the harmonic cutoff and the enhancement of the HHG yield. Thus, many attractive SAPs can be obtained when the frequency-chirping technique is adopted.…”