Multiphoton fluorescence excitation and detection with a single negative curvature hollow core fibre

Abstract

In this letter, we propose a single fiber-based sensor setup allowing for simultaneous excitation and detection of multiphoton fluorescence. Presented sensor’s key element is the negative curvature hollow core fiber (NCHCF) with three transmission bands in the visible spectral range (414–423 nm, 510–552 nm and 680–784 nm), allowing for nearly dispersion-free guidance of 160 fs-long laser pulses at 730 nm photon wavelength. Total temporal broadening of a laser pulse propagating in the proposed sensor setup is only (7 ± 1) fs. The NCHCF output beam was additionally focused with a microlensed, multimode fiber tip, increasing the efficiency of multiphoton absorption. The usefulness of the sensor for the multiphoton spectroscopy experiments is tested on the solutions of fluorescein and flavin adenine dinucleotide. This optical fiber sensor combines simplicity, minimal size, and good optical properties, and can be found an interesing solution for the non-linear optical methods used in chemistry, biology and medicine.