Sub millimetre flexible fibre probe for background and fluorescence free Raman spectroscopy

TL;DR

This paper introduces a portable, sub-millimetre fibre optic probe for Raman spectroscopy that minimizes background and fluorescence interference, enabling high-quality biomedical tissue analysis.

Contribution

The development of a novel flexible fibre probe with negative curvature core and shifted-excitation technique for background-free Raman spectroscopy in biomedical applications.

Findings

Probe is compatible with bronchoscopes.

Achieved fluorescence-free Raman spectra of human lung tissue.

Demonstrated effective separation of fluorescence and Raman signals.

Abstract

Using the shifted-excitation Raman difference spectroscopy technique and an optical fibre featuring a negative curvature excitation core and a coaxial ring of high numerical aperture collection cores, we have developed a portable, background and fluorescence free, endoscopic Raman probe. The probe consists of a single fibre with a diameter of less than 0.25 mm packaged in a sub-millimetre tubing, making it compatible with standard bronchoscopes. The Raman excitation light in the fibre is guided in air and therefore interacts little with silica, enabling an almost background free transmission of the excitation light. In addition, we used the shifted-excitation Raman difference spectroscopy technique and a tunable 785 nm laser to separate the fluorescence and the Raman spectrum from highly fluorescent samples, demonstrating the suitability of the probe for biomedical applications. Using this probe we also acquired fluorescence free human lung tissue data.