Tunable Microcavity-Stabilized Quantum Cascade Laser for Mid-IR High-Resolution Spectroscopy and Sensing

Area of Science:

• Optics and Photonics
• Spectroscopy
• Laser Physics

Background:

• Developing compact and stable mid-infrared (mid-IR) systems is crucial for molecular sensing and metrology.
• Crystalline microresonators offer promising solutions for frequency stabilization and linewidth narrowing of quantum cascade lasers (QCLs).

Purpose of the Study:

• To report the first mid-IR high-resolution spectroscopy system utilizing a QCL locked to a CaF₂ microresonator.
• To demonstrate enhanced laser performance for molecular absorption line analysis.

Main Methods:

• Employing a quantum cascade laser (QCL) locked to a crystalline calcium fluoride (CaF₂) microresonator.
• Utilizing electronic locking techniques for laser frequency stabilization and tuning.
• Performing direct sub-Doppler recording of molecular absorption lines.

Main Results:

• Achieved a one-order-of-magnitude reduction in QCL linewidth through electronic locking.
• Demonstrated long-term frequency stability and precise tunability of the laser source.
• Successfully recorded sub-Doppler molecular absorption lines, showcasing improved spectral resolution.

Conclusions:

• The developed CaF₂ microresonator-based QCL system provides a compact and robust platform for high-resolution mid-IR spectroscopy.
• This approach significantly enhances laser stability and resolution, enabling advanced molecular sensing and metrology applications.