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Distributed-feedback-laser-based NICE-OHMS in the pressure-broadened regime.
Aleksandra Foltynowicz1, Junyang Wang, Patrick Ehlers
1Department of Physics, Umeå University, SE-901 87 Umeå, Sweden.
Optics Express
|October 14, 2010
Summary
A new compact noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) system achieves high sensitivity for detecting weak acetylene transitions. This system demonstrates linear signal response and a minimum detectable absorption of 2 × 10(-10) cm(-1).
Area of Science:
- Spectroscopy
- Laser Physics
- Molecular Physics
Background:
- Cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) offers high sensitivity for molecular detection.
- Developing compact and robust NICE-OHMS systems is crucial for practical applications.
- Previous systems often face challenges with size, complexity, or noise immunity.
Purpose of the Study:
- To develop a compact, noise-immune NICE-OHMS system.
- To demonstrate its capability in measuring weak molecular transitions.
- To characterize the system's performance, including sensitivity and linearity.
Main Methods:
- Utilized a narrow linewidth distributed-feedback laser.
- Employed fiber-coupled acousto-optic and electro-optic modulators.
- Implemented multiline fitting routines for parameter extraction on acetylene transitions at 1551 nm.
Main Results:
- Achieved a minimum detectable on-resonance absorption of 2 × 10(-10) cm(-1) with a finesse of 460.
- Demonstrated linear signal strength dependence on pressure and concentration.
- Confirmed signal independence from detection phase.
- Successfully measured absorption and dispersion signals up to 1/3 atmosphere.
Conclusions:
- The developed compact NICE-OHMS system is effective for sensitive molecular spectroscopy.
- The system exhibits robust performance, including noise immunity and linear response.
- This technology holds promise for various applications requiring precise molecular detection.
