Scientific Results

A self-operating broadband spectrometer on a droplet

Year: 2020

Authors: Malara P., Giorgini A., Avino S., Di Sarno V., Aiello R., Maddaloni P., De Natale P., Gagliardi G.

Autors Affiliation: Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica (INO), via Campi Flegrei 34, 80078 Pozzuoli, Naples, Italy; Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica (INO), Largo E. Fermi 6, 50125 Firenze, Italy

Abstract: Small-scale Fourier transform spectrometers are rapidly revolutionizing infrared spectro-chemical analysis, enabling on-site and remote sensing applications that were hardly imaginable just few years ago. While most devices reported to date rely on advanced photonic integration technologies, here we demonstrate a miniaturization strategy which harnesses unforced mechanisms, such as the evaporation of a liquid droplet on a partially reflective substrate. Based on this principle, we describe a self-operating optofluidic spectrometer and the analysis method to retrieve consistent spectral information in spite of the intrinsically non-reproducible droplet formation and evaporation dynamics. We experimentally realize the device on the tip of an optical fiber and demonstrate quantitative measurements of gas absorption with a 2.6 nm resolution, in a 100 s acquisition time, over the 250 nm span allowed by our setup’s components. A direct comparison with a commercial optical analyzer clearly points out that a simple evaporating droplet can be an efficient small-scale, inexpensive spectrometer, competitive with the most advanced integrated photonic devices.

Journal/Review: NATURE COMMUNICATIONS

Volume: 11      Pages from: 2263-1  to: 2263-5

KeyWords: spectrometer, spectroscopy, FTIR, fiber optic.
DOI: https://doi.org/10.1038/s41467-020-16206-8