Origin and suppression of parasitic signals in Kagom\'e lattice hollow core fibers used for SRS microscopy and endoscopy

TL;DR

This paper investigates parasitic signals in Kagomé lattice hollow core fibers used for SRS microscopy and endoscopy, revealing their origin and conditions to suppress them, thus enhancing noise-free imaging applications.

Contribution

It uncovers the origin of parasitic signals in these fibers and identifies specific experimental conditions to eliminate them, improving their suitability for SRS applications.

Findings

Parasitic signals originate from Kerr nonlinearity and fiber losses.

Certain experimental parameters can suppress parasitic signals.

Hollow core fibers can be optimized for noise-free SRS microscopy.

Abstract

Hollow core fibers are considered as promising candidates to deliver intense temporally overlapping picosecond pulses in applications such as stimulated Raman scattering (SRS) microscopy and endoscopy because of their inherent low nonlinearity compared to solid-core silica fibers. Here we demonstrate that, contrary to prior assumptions, parasitic signals are generated in Kagom\'e lattice hollow core fibers. We identify the origin of the parasitic signals as an interplay between the Kerr nonlinearity of air and frequency-dependent fiber losses. Importantly, we identify the special cases of experimental parameters that are free from parasitic signals, making hollow core fibers ideal candidates for noise-free SRS microscopy and endoscopy.