[Intra-pulse spectroscopy based on room-temperature pulsed quantum-cascade laser for N2O detection]

Area of Science:

• Spectroscopy
• Laser Technology
• Gas Analysis

Context:

• Mid-infrared lasers are crucial for high-sensitivity trace gas detection due to their overlap with fundamental absorption lines.
• Quantum-cascade lasers (QCLs) offer high power, wide tuning, and room-temperature operation, making them ideal light sources.

Purpose:

• To introduce and experimentally demonstrate intra-pulse spectroscopy using a room-temperature distributed-feedback pulsed QCL for trace gas detection.
• To qualitatively and quantitatively detect trace gases using a simple and effective method.

Summary:

• A 500 ns excitation pulse applied to a QCL induced a thermal chirp, enabling fast wavelength scanning and a wave number tuning of approximately 1 cm⁻¹.
• This technique allowed for the recording of all absorption spectral elements during a single laser pulse.
• The nitrous oxide (N2O) absorption spectrum centered at 1273.7 cm⁻¹ was successfully obtained and precisely matched HITRAN database data.

Impact:

• This research validates intra-pulse spectroscopy as a precise and efficient method for identifying trace gas spectral fingerprints.
• The findings contribute to advancements in sensitive gas detection technologies for environmental monitoring and industrial applications.