Optimization and characterization of femtosecond laser inscribed in-fiber microchannels for liquid sensing

Graham C.B. Lee, Chengbo Mou, Kaiming Zhou, Kate Sugden

Research output: Contribution to journalArticlepeer-review


In-fiber microchannels were fabricated directly in standard single mode fiber using the femtosecond laser inscribe and etch technique. This method of creating in-fiber microchannels offers great versatility, since it allows complex three-dimensional structures to be inscribed and then preferentially etched with hydrofluoric acid. In addition, inscription does not require a photosensitive fiber; the modification is induced through nonlinear processes triggered by an ultrashort laser pulse. Four in-fiber microchannel designs were experimentally investigated using this technique - microhole, microslot channel along the core, microslot channel perpendicular to the core and helical channel around the core. Each device design was evaluated through monitoring the optical spectral change while inserting a range of index matching oils into each microchannel; an R.I. sensitivity up to 1.55 dB/RIU was achieved in these initial tests. Furthermore, an all femtosecond laser inscribed Fabry-Pérot-based refractometer with an R.I. sensitivity of 2.75 nm/RIU was also demonstrated. The Fabry-Pérot refractometer was formed by positioning a microchannel between two femtosecond laser inscribed point-by-point fiber Bragg gratings.

Original languageEnglish
Pages (from-to)2561-2565
Number of pages5
JournalJournal of Lightwave Technology
Issue number12
Early online date3 Nov 2014
Publication statusPublished - 15 Jun 2015

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  • etching
  • laser machining
  • liquids
  • optical device fabrication
  • optical fiber devices


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