Spectral modulation of high-order harmonic generation from prealigned CO2 molecules

Area of Science:

• Quantum optics
• Molecular physics
• Nonlinear optics

Background:

• High-order harmonic generation (HHG) is a crucial process for producing coherent X-ray radiation.
• Molecular alignment influences the dynamics of HHG, but its precise effects on spectral properties require further elucidation.
• Understanding spectral modifications is key to controlling and optimizing HHG for various applications.

Purpose of the Study:

• To experimentally investigate the impact of prealigned molecules on the spectral characteristics of high-order harmonic generation.
• To differentiate and analyze the contributions of molecular alignment to spectral redshift and blueshift.
• To explore the underlying mechanisms, including the role of alignment gradients and plasma density variations.

Main Methods:

• Experimental setup involving the generation of high-order harmonics from prealigned molecules.
• Spectroscopic analysis to observe and quantify spectral shifts (redshift/blueshift).
• Theoretical considerations to distinguish the effects of alignment gradient and plasma density modulation.

Main Results:

• Observable spectral redshift and blueshift were experimentally demonstrated in high-order harmonic generation from prealigned molecules.
• Two distinct effects of molecular alignment on harmonic phase modulation were identified: one due to alignment gradients and another due to alignment-induced plasma density changes.
• The findings provide direct experimental evidence linking molecular alignment to spectral modifications.

Conclusions:

• Molecular alignment is a critical factor in controlling the spectral distribution of high-order harmonics.
• The study offers a novel method for fine-tuning the harmonic spectrum by manipulating molecular alignment.
• This research deepens the understanding of light-matter interactions in nonlinear processes involving aligned molecules.