An illustration of the waveguide in a flow cell together with an absorption spectrum of 4 % acetylene measured through the waveguide. Laser beam of 2566 nm wavelength is coupled with an objective lens into the waveguide enclosed in a flow cell with controlled atmosphere. The transmitted light is collected using a detector and the recorded absorption signal is fitted with a known reference spectrum to determine the air-confinement factor. A free-space beam spectrum of a beam passed through the same but empty cell is shown as reference. The graph inset highlights that a 7 % stronger absorption signal is obtained with the waveguide than with the free-space beam, signifying stronger light-analyte interaction.
by Marek Vlk, Anurup Datta, Sebastián Alberti, Henock Demessie Yallew, Vinita Mittal, Ganapathy Senthil Murugan, Jana Jágerská