Time resolved Brillouin fiber-spectrometer

Abstract

This report introduces a novel time resolved Brillouin spectrometer, consisting of an opto-acoustic transducer which resides on the tip of a single-mode optical fiber of arbitrary length with 125 \&{\#}x003BC;m outer diameter and 5 \&{\#}x003BC;m sensing diameter. Demonstrated here are proof of concept spectroscopic measurements \&{\#}x02013; shifts in Brillouin frequency \&{\#}x02013; with sensitivities of 41\&{\#}x000B1;3MHz/\&{\#}x00025;wt and 2.5\&{\#}x000B1;0.6 MHz/\&{\#}x000B0;C for changes in water-salinity and water-temperature, respectively, and an interpolated frequency resolution of 9\&{\#}x000B1;2 MHz. The technique benefits from low-cost raw materials, scalable fabrication, scalable pixel density, easy alignment, and data acquisition speeds down to 0.4 s: traits which make this compatible with in vivo applications.