High-Order harmonic generation of aligned acetylene in elliptically polarized strong laser fields

Abstract

We perform an experimental study on high-order harmonic generation (HHG) of aligned acetylene molecules induced by a 35-fs 800-nm strong laser field, by using a home-built HHG spectrometer. It is observed that the molecular HHG probability declines with increasing the laser ellipticity, which is in consistence with the deduction from the well-known tunneling-plus-rescattering scenario. By introducing a weak femtosecond laser pulse to nonadiabatically align the molecules, we investigated the molecular orbital effect on the HHG in both linearly and elliptically polarized driving laser fields. The results show that the harmonic intensity is maximum for the molecular axis aligned perpendicularly to the laser electric field. It indicates that both the highest occupied molecular orbitals (HOMO) and HOMO−1 contribute to the strong-field HHG of acetylene molecules. Our study should pave the way for understanding the interaction of molecules with ultrafast strong laser fields.

Quantum interference of multi-orbital effects in high-harmonic spectra from aligned carbon dioxide and nitrous oxide*

“…The experimental setup used for generation and detection of HHG has already been described in our previous work. [32][33][34] Briefly, a Ti: sapphire laser system operating at 1 kHz repetition was used to deliver ∼ 35 fs pulses centered at 800 nm. The output pulse is divided into two parts by using a 30 : 70 beam splitter.…”

Resolving multi-orbital effects on high harmonic generation from aligned N2 molecules in linearly and elliptically polarized intense laser fields*

“…Molecular harmonics were generated and measured by a home-built XUV flat-field grating spectrometer, which has been described in detail in our previous publications. [32][33][34] Briefly, the output of a Ti: sapphire laser system (1 kHz, 35 fs, 800 nm) was divided into two laser beams by a 30 : 70 beam splitter. One beam with lower energy (the aligning laser) was used to create rotational wave packets to nonadiabatically align the molecules.…”