Applied Physics B

, Volume 88, Issue 1, pp 131-135

Fiber-optic ring-down spectroscopy using a tunable picosecond gain-switched diode laser

  • M. AndachiAffiliated withKyoto Prefectural Technology Center for Small and Medium Enterprises, Kyoto Research Park
  • , T. NakayamaAffiliated withDepartment of Molecular Engineering, Kyoto University
  • , M. KawasakiAffiliated withDepartment of Molecular Engineering, Kyoto University Email author 
  • , S. KurokawaAffiliated withNational Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology
  • , H.-P. LoockAffiliated withDepartment of Chemistry, Queen’s University

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Visible and near-infrared laser light pulses were coupled into two different types of optical fiber cavities. One cavity consisted of a short strand of fiber waveguide that contained two identical fiber Bragg gratings. Another cavity was made using a loop of optical fiber. In either cavity ∼40 ps laser pulses, which were generated using a custom-built gain-switched diode laser, circulated for a large number of round trips. The optical loss of either cavity was determined from the ring-down times. Cavity ring-down spectroscopy was performed on 200 pL volumes of liquid samples that were injected into the cavities using a 100 μm gap in the fiber loop. A detection limit of 20 ppm of methylene blue dye in aqueous solution, corresponding to a minimum absorptivity of εC<6 cm-1, was realized.