Detection of oxygen using short external cavity GaAs semiconductor diode lasers

Area of Science:

• Spectroscopy
• Laser Physics
• Analytical Chemistry

Background:

• Semiconductor diode lasers are crucial for spectroscopic applications.
• Achieving high sensitivity and spectral coverage in laser-based detection is challenging.

Purpose of the Study:

• To report high sensitivity detection of oxygen (O2) in the near-infrared region.
• To demonstrate the enhanced performance of AlGaAs semiconductor diode lasers using a short external cavity (SXC).

Main Methods:

• Utilizing AlGaAs semiconductor diode lasers with a short external cavity (SXC) for mode control.
• Employing second harmonic detection techniques for enhanced sensitivity.
• Individually selecting and scanning up to ten single laser modes over extended frequency intervals.

Main Results:

• Achieved high sensitivity detection of O2 at atmospheric pressure with minimum detectable absorbance of approximately 4 x 10(-6) at SNR=1.
• Demonstrated nearly complete spectral coverage of up to 40 cm(-1) using overlapping modes at constant temperature.
• Successfully monitored absorbances of 1 x 10(-2) for up to 15 hours with rms uncertainty of +/-6 x 10(-5).

Conclusions:

• SXC technology significantly enhances diode laser performance for spectroscopic applications.
• The developed system provides a stable and reproducible platform for high-sensitivity O2 detection.
• This method is suitable for continuous monitoring of absorption signals over extended periods.