Background-penalty-free waveguide enhancement of CARS signal in air-filled anti-resonance hollow-core fiber

TL;DR

This paper demonstrates a 170-fold enhancement of CARS signal in air-filled anti-resonance hollow-core fiber, with near-zero background, making it highly suitable for improved coherent Raman spectroscopy.

Contribution

It introduces the use of revolver fiber for background-penalty-free enhancement of CARS signals in air, showing significant improvement over free-space measurements.

Findings

170 times signal enhancement in fiber

Near-zero non-resonant background in fiber

Revolver fiber's suitability for Raman spectroscopy

Abstract

We study coherent anti-Stokes Raman spectroscopy in air-filled anti-resonance hollow-core photonic crystal fiber, otherwise known as 'revolver' fiber. We compare the vibrational coherent anti-Stokes Raman signal of N$_2$, at 2331 cm$^{-1}$, generated in ambient air (no fiber present), with the one generated in a 2.96 cm of a revolver fiber. We show a 170 times enhancement for the signal produced in the fiber, due to an increased interaction path. Remarkably, the N$_2$ signal obtained in the revolver fiber shows near-zero non-resonant background, due to near-zero overlap between the laser field and the fiber cladding. Through our study, we find that the revolver fiber properties make it an ideal candidate for the coherent Raman spectroscopy signal enhancement.