Vibrational phase imaging by stimulated Raman scattering via polarization-division interferometry

Area of Science:

• Nonlinear optics
• Molecular spectroscopy
• Chemical analysis

Background:

• Stimulated Raman scattering (SRS) identifies chemicals via third-order nonlinear vibrational susceptibility (χ(3)(ω)).
• Standard SRS implementations are limited to measuring only the imaginary component of χ(3)(ω).

Purpose of the Study:

• Introduce interferometric SRS (iSRS) to measure both real and imaginary parts of nonlinear susceptibility.
• Enhance chemical identification capabilities beyond standard SRS.

Main Methods:

• Modified SRS setup by adding optical elements to the pump beam path.
• Generation of an intrinsic phase-coherent local oscillator within the iSRS setup.
• Maintained SRS acquisition speed and simplicity.

Main Results:

• iSRS successfully measures both real and imaginary parts of the nonlinear susceptibility.
• Vibrational phase information is now accessible.
• Distinguishes overlapping species in complex spectra.
• Improved robustness against noise compared to standard SRS.

Conclusions:

• iSRS significantly increases the information content of SRS measurements.
• Provides a more comprehensive understanding of chemical substances.
• Offers a powerful tool for analyzing complex mixtures and congested spectra.