All-fiber single-cavity dual-comb for coherent anti-Stokes Raman scattering spectroscopy based on spectral focusing

Area of Science:

• Optics and Photonics
• Spectroscopy
• Laser Physics

Background:

• Coherent Anti-Stokes Raman Scattering (CARS) spectroscopy offers label-free chemical analysis.
• Traditional CARS systems often require complex and bulky laser setups.
• Developing compact and robust laser sources is crucial for advancing CARS applications.

Purpose of the Study:

• To report an all-fiber, free-running, bidirectional dual-comb laser system.
• To demonstrate its application in CARS spectroscopy using spectral focusing.
• To showcase its potential for label-free imaging.

Main Methods:

• Utilized a bidirectional ring-cavity erbium fiber laser mode-locked at ~114 MHz.
• Employed supercontinuum generation to wavelength-shift one laser output for a pump source.
• Applied spectral focusing techniques for CARS measurements.

Main Results:

• Successfully recorded Raman spectra of polystyrene, olive oil, PMMA, and polyethylene.
• Demonstrated the system's capability within the C-H stretching vibrational window.
• Confirmed the dual-comb laser's suitability for CARS spectroscopy.

Conclusions:

• The all-fiber bidirectional dual-comb laser system is a viable and promising platform for CARS.
• This design simplifies CARS instrumentation, paving the way for practical applications.
• The system holds potential for label-free chemical imaging in diverse fields.