Multi-gas dual-comb spectroscopy with tunable gain-switched laser diodes

Area of Science:

• Spectroscopy
• Optical Physics
• Gas Analysis

Background:

• Dual-comb spectroscopy (DCS) is a powerful technique for high-resolution molecular analysis.
• Existing DCS systems often operate in the mid-infrared, limiting applications.
• Near-infrared spectroscopy offers advantages for certain gas detection scenarios.

Purpose of the Study:

• To develop and demonstrate a tunable multi-gas spectroscopic scheme in the near-infrared domain.
• To establish a stable optical frequency comb generation method for gas characterization.
• To validate the system's performance against established databases and manufacturer data.

Main Methods:

• Utilized a dual-comb architecture with two gain-switched Fabry-Perot laser diodes.
• Employed external injection from a tunable laser source to generate optical frequency combs.
• Systematically studied injection wavelength, line spacing, and optical span for stability.
• Performed proof-of-concept gas analysis on four different samples.

Main Results:

• Generated stable optical frequency combs with a 40 GHz bandwidth and over 400 lines.
• Achieved a low repetition rate of 100 MHz and covered a wavelength range exceeding 40 nm.
• Demonstrated gas analysis with results comparable to HITRAN and manufacturer data (standard deviation of residuals = 0.005).

Conclusions:

• The developed tunable near-infrared dual-comb spectroscopy system is effective for multi-gas analysis.
• The system's simplicity, tunability, and high accuracy make it highly replicable.
• This technology holds significant potential for commercial applications in gas sensing and characterization.