Liquid jet waveguide for spectroscopic sensors

A spectroscopic sensor based on a liquid jet waveguide has been successfully applied in fluorescence and Raman spectroscopy of liquid solutions. The jet waveguide is obtained by ejecting the solution under analysis through a capillary nozzle. A self-aligned configuration allows to couple the liquid waveguide with an optical fiber used to deliver the detected signals towards a spectrophotometer. The numerical aperture of a water jet exceeds the one of any other liquid waveguide, enabling high collection efficiency. This approach removes the usual background noise sources avoiding any necessity to contain the solution by means of solid walls.