High-harmonic-driven inverse Raman scattering

Area of Science:

• Quantum optics
• Molecular spectroscopy
• Nonlinear optics

Background:

• High-order harmonic generation (HHG) is a key process in strong-field physics.
• Inverse Raman scattering (IRS) is a technique used to study molecular vibrations.

Purpose of the Study:

• To investigate the spectral signatures of inverse Raman scattering in molecular nitrogen using HHG.
• To explore the potential of HHG as a novel platform for studying IRS.

Main Methods:

• Ultrashort mid-infrared pulses were used to generate high-order harmonics in molecular nitrogen.
• Spectral analysis was performed on the generated harmonics to identify IRS signatures.
• The driver pulse was tuned to resonance with specific vibrational transitions in nitrogen.

Main Results:

• Well-resolved signatures of inverse Raman scattering were observed near nitrogen's vibrational transition frequencies.
• A distinctive antisymmetric spectral profile with red-shifted bright and blue-shifted dark features indicated stimulated Raman gain and loss.
• The eleventh harmonic of a 3.9 µm driver exhibited these features when tuned to the v^'=0→v=0 pathway.

Conclusions:

• High-order harmonic generation provides a sensitive probe for inverse Raman scattering in molecular systems.
• This approach extends the application of the inverse Raman effect to strong-field light-matter interactions.
• The observed spectral features offer insights into stimulated Raman gain and loss dynamics.