Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing

Area of Science:

• Spectroscopy
• Physical Chemistry
• Chemical Engineering

Background:

• Quantitative detection of low-concentration gas species is crucial for combustion research.
• Traditional methods often struggle with spatial resolution or are intrusive.
• Species lacking visible or near-IR transitions pose detection challenges.

Purpose of the Study:

• To present a detailed protocol for infrared degenerated four-wave mixing (IR-DFWM) gas spectroscopy.
• To enable spatially resolved, quantitative detection of trace gas species.
• To optimize the alignment of IR-DFWM optics and upconversion detection systems.

Main Methods:

• Utilized infrared degenerated four-wave mixing (IR-DFWM) for gas-phase analysis.
• Implemented upconversion detection via sum-frequency generation to shift mid-IR signals to near-IR.
• Focused on precise alignment of IR-DFWM laser optics and intracavity upconversion setup.

Main Results:

• Demonstrated a nonintrusive method for quantitative gas detection in the ppm-to-single-percent range.
• Successfully shifted IR-DFWM signals to the near-IR, leveraging superior silicon detector performance.
• Minimized interference from thermal background radiation through the upconversion process.

Conclusions:

• The presented protocol facilitates accurate, spatially resolved detection of challenging gas species.
• IR-DFWM combined with upconversion offers a robust solution for in-situ combustion diagnostics.
• Optimized optical alignment is key to achieving high sensitivity and signal quality.