Circularly polarized attosecond light generation from OCS molecules irradiated by the combination of linear polarized infrared and orthogonal terahertz fields

Abstract

Researching ultrafast dynamics and creating coherent light sources will both benefit significantly from the establishment of polarization control in high-order harmonic generation (HHG). By employing the time-dependent density functional theory method, we investigate HHG of carbonyl sulfide molecules using a combination of a linear polarized infrared (IR) laser and a weaker orthogonal Terahertz (THz) field. Our findings show that by adjusting the amplitude of the THz field, the movement scale of electrons in the THz direction can be tuned, thereby one can control the harmonic intensity in the IR laser direction. This method allows for the creation of near-circularly polarized attosecond pulses. Furthermore, the ellipticity of the attosecond pulse may be changed by modifying the carrier-envelope phase of the IR laser pulse.

Modeling of High-Harmonic Generation in the C60 Fullerene Using Ab Initio, DFT-Based, and Semiempirical Methods

“…Moreover, recent advancements in representing external electromagnetic fields, such as recasting Maxwell’s equations in the Schrödinger formalism, , allow for effective and accurate description of light–matter interactions. Thanks to these advantages, grid-based RT-TDDFT finds widespread application in modeling linear and nonlinear optical responses in a broad spectrum of systems, from single atoms, ,,, through clusters ,, and molecules, ,,,− to nanostructures − and solid-state materials. ,,, However, it also has its limitations. For instance, it incorrectly describes single-electron excitations and Rabi oscillations in closed-shell systems , and suffers from the nonlinearity of the time-evolution equations. − Additionally, its significant computational complexity typically restricts the treatment of larger systems at the all-electron level, necessitating the replacement of core electrons with pseudopotentials. ,,, Even with this workaround, the computational cost of RT-TDDFT greatly exceeds that of RT-TDCIS, a drawback shared with more sophisticated multideterminant methods such as real-time time-dependent coupled cluster, ,, RT-TDCISD, ,,,, and RT-TDCIS­(D). ,, An alternative approach to RT-TDDFT, proposed by Pauletti et al and also utilized in this work, is to add the exchange–correlation potential directly to the RT-TDCIS Hamiltonian, effectively turning it into the real-time time-dependent counterpart of the Tamm–Dancoff approximation (TDA).…”

“…Moreover, recent advancements in representing external electromagnetic fields, such as recasting Maxwell’s equations in the Schrödinger formalism, 114 , 127 allow for effective and accurate description of light–matter interactions. Thanks to these advantages, grid-based RT-TDDFT finds widespread application in modeling linear and nonlinear optical responses in a broad spectrum of systems, from single atoms, 91 , 94 , 95 , 128 through clusters 124 , 129 , 130 and molecules, 50 , 94 , 96 , 131 − 133 to nanostructures 134 − 137 and solid-state materials. 115 , 127 , 138 , 139 However, it also has its limitations.…”