Precise Determination of Brillouin Scattering Spectrum Using a Virtually Imaged Phase Array (VIPA) Spectrometer and...

Area of Science:

• Optical Physics
• Materials Science
• Spectroscopy

Background:

• Brillouin spectroscopy offers noninvasive assessment of viscoelastic properties.
• Atomic-molecular absorption cells enable Brillouin spectroscopy in turbid samples by filtering strong elastic scattering.
• Existing methods struggle with altered Brillouin line shapes caused by absorption cells, hindering precise shift determination.

Purpose of the Study:

• To develop a simple and accurate method for analyzing Brillouin spectra acquired using atomic-molecular absorption cells.
• To address the challenge of altered Brillouin line shapes and improve the precision of spectral shift measurements.
• To validate the proposed analysis method with experimental data.

Main Methods:

• A customized least-square fitting algorithm was developed for Brillouin spectrum analysis.
• The method explicitly incorporates the absorption spectrum induced by the atomic-molecular cell.
• Experimental spectroscopic data from pure water at various temperatures were processed.

Main Results:

• The developed method effectively analyzes Brillouin spectra, considering the absorption cell's spectral signature.
• Precise determination of Brillouin shifts was achieved, overcoming limitations of previous methods.
• Experimental validation demonstrated the capability of the method, achieving an accuracy of ±1 MHz for spectral line shift measurements.

Conclusions:

• The proposed least-square fitting method provides a simple and accurate approach for analyzing Brillouin spectra obtained with atomic-molecular absorption cells.
• This advancement enhances the noninvasive assessment of viscoelastic properties in turbid materials.
• The method's demonstrated accuracy opens avenues for more reliable material characterization using Brillouin spectroscopy.