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Construction and Characterization of External Cavity Diode Lasers for Atomic Physics
Published on: April 24, 2014
Multiplexed continuous-wave diode-laser cavity ringdown measurements of multiple species
G Totschnig1, D S Baer, J Wang
1High Temperature Gasdynamics Laboratory, Department of Mechanical Engineering, Stanford University, Stanford, California 94305, USA. gtotsch@mail.zserv.tuwien.ac.at
Applied Optics
|March 18, 2008
Summary
This study demonstrates rapid cavity ringdown spectroscopy for detecting broadband absorbers like methanol and isopropanol. The technique achieves high sensitivity, enabling detection of water vapor below 2 parts per billion.
Area of Science:
- Analytical Chemistry
- Spectroscopy
- Laser Physics
Background:
- Cavity Ringdown Spectroscopy (CRDS) is a sensitive technique for gas-phase measurements.
- Previous CRDS methods faced limitations in speed and multiplexing capabilities for broadband absorbers.
Purpose of the Study:
- To develop and demonstrate a rapid CRDS method for simultaneous detection of multiple broadband absorbing species.
- To achieve high sensitivity and fast acquisition rates for gas mixture analysis.
Main Methods:
- Utilized two multiplexed continuous-wave distributed-feedback diode lasers operating near 1.4 µm.
- Employed a static gas cell with high reflectivity mirrors (99.94%) for enhanced sensitivity.
- Performed rapid cavity ringdown measurements with optimized decay time constant acquisition.
Main Results:
- Achieved a measurement sensitivity of 2.4 x 10⁻⁹ cm⁻¹ with a 4.3-s averaging time.
- Demonstrated a water vapor detection limit below 2 ppb (parts in 10⁹) for strong H₂O lines.
- Recorded shot-to-shot noise of approximately 0.3-0.7% for the decay time constant.
- Attained ringdown acquisition rates as high as 900 Hz.
Conclusions:
- The developed CRDS technique enables rapid and highly sensitive detection of broadband absorbers in gas mixtures.
- This method offers a significant advancement for trace gas analysis, particularly for water vapor.
- The high acquisition rates and sensitivity make it suitable for dynamic and demanding applications.
