Self-gated mid-infrared short pulse upconversion detection for gas sensing

Area of Science:

• Nonlinear optics
• Spectroscopy
• Infrared technology

Background:

• Mid-infrared signal detection is crucial for various applications, including gas spectroscopy.
• Existing methods may face limitations in sensitivity and background noise.
• Pulsed nonlinear-optical upconversion offers a promising approach for enhanced detection.

Purpose of the Study:

• To develop and demonstrate a pulsed nonlinear-optical upconversion system for sensitive mid-infrared signal detection.
• To utilize the system for gas spectroscopy and stand-off leak detection.
• To achieve high quantum efficiencies and effective background suppression.

Main Methods:

• A single pump laser was used for both mid-infrared generation and upconversion.
• The setup employed pulsed nonlinear-optical upconversion techniques.
• Spectral and temporal gating were utilized for background suppression.

Main Results:

• Quantum efficiencies exceeding 80% for Gaussian beam upconversion and 25% for backscattered radiation were achieved.
• Results align with theoretical predictions.
• Methane sensing in an open path geometry demonstrated a concentration resolution better than 1.5 ppm·m.

Conclusions:

• The demonstrated pulsed setup enables highly sensitive mid-infrared detection.
• The system shows significant potential for stand-off leak detection applications.
• Efficient background suppression and high quantum efficiencies are key to the system's performance.