Correction method for absorption-dependent signal enhancement by a liquid-core optical fiber

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Optical Fiber Technology

Background:

• Liquid-core optical fiber (LCOF) Raman spectroscopy enhances signal detection for dissolved chemicals.
• Chemical absorption within the LCOF disrupts the linear relationship between concentration and Raman peak intensity.
• Accurate quantification requires addressing this absorption-dependent signal enhancement.

Purpose of the Study:

• To investigate the absorption dependence of Raman scattering enhancement in LCOF systems.
• To develop and validate a method for correcting absorption-induced variations in LCOF Raman spectroscopy.
• To restore the linear correlation between chemical concentration and Raman signal intensity.

Main Methods:

• Augmenting a standard LCOF Raman spectroscopy setup with spectrophotometric capabilities.
• Performing sequential measurements of Raman and absorption spectra within the LCOF.
• Analyzing samples with consistent Raman scatterer concentrations but varying absorption coefficients.

Main Results:

• Demonstrated that Raman scattering enhancement in LCOF is significantly dependent on sample absorption.
• Implemented a correction method utilizing measured absorption values.
• Reduced measurement variations in Raman intensities from 60% to under 1%.

Conclusions:

• The developed correction method effectively mitigates absorption-related errors in LCOF Raman spectroscopy.
• This technique is crucial for analyzing complex biological samples like urine and blood serum with variable absorption.
• Enables more accurate and reliable quantitative analysis in LCOF-based chemical sensing.