A precise high-resolution near infrared continuous wave cavity ringdown spectrometer using a Fourier transform based...

Area of Science:

• Spectroscopy
• Laser Physics
• Metrology

Background:

• High-resolution spectroscopy demands precise wavelength calibration.
• Cavity ringdown spectroscopy (CRDS) requires stable and accurate wavelength scales.
• Ambient influences can degrade laser stability and measurement accuracy.

Purpose of the Study:

• To develop and demonstrate a reliable wavelength calibration technique for high-resolution CRDS.
• To achieve high wavelength precision and accuracy without complex laser stabilization.
• To suppress ambient influences on laser sources during spectral measurements.

Main Methods:

• Combined a Fourier transform wavelength meter with a distributed feedback laser locked to a molecular transition.
• Utilized the locked laser as a frequency marker for spectral calibration.
• Performed continuous reference measurements to mitigate ambient effects.
• Measured high-resolution CRDS spectra of N(2)O isotopomers around 1687 nm.

Main Results:

• Achieved a near-infrared wavelength precision of 6 x 10(-8).
• Demonstrated an absolute wavelength accuracy on the order of 1 x 10(-7).
• Successfully determined the line strength of several N(2)O absorption lines.
• Showcased the technique's ability to suppress ambient influences.

Conclusions:

• The described technique provides a reliable wavelength scale for high-resolution CRDS.
• It eliminates the need for probe laser stabilization and precisely known molecular transitions.
• The method is easily implementable and offers potential for further accuracy improvements with additional reference lasers.