Flexible and broadly tunable infrared light source based on shaped sub-10-fs pulses for a multimodal microscopy setup

Area of Science:

• Spectroscopy
• Nonlinear Optics
• Materials Science

Background:

• Mid-infrared (MIR) spectroscopy is crucial for molecular identification.
• Existing MIR techniques face limitations in spectral flexibility and resolution.
• Nonlinear multimodal microscopy requires versatile spectroscopic tools.

Purpose of the Study:

• To present a versatile approach for MIR spectroscopy.
• To enable flexible control over difference-frequency-generation (DFG) using femtosecond (fs) pulse shaping.
• To demonstrate independent selection of spectral position and resolution within the molecular fingerprint region.

Main Methods:

• Utilized a broadband sub-10-fs oscillator.
• Employed femtosecond pulse shaping and spectral focusing for DFG control.
• Configured pulse shaper for independent spectral position and resolution tuning.

Main Results:

• Achieved independent selection of spectral position and resolution (>2000 cm^-1 range).
• Demonstrated spectral resolution better than 20 cm^-1, dependent on pulse shaper.
• Validated the concept through an absorption experiment on polystyrene.

Conclusions:

• The developed method offers versatile MIR spectroscopy.
• It provides precise control over spectral characteristics.
• This technique can be integrated as an additional modality in nonlinear multimodal microscopy.