Study of π-phase-shifted, fiber Bragg gratings for ultrasonic detection

Thomas Fink, Qi Zhang, Wayne Ahrens, Ming Han

Research output: Chapter in Book/Report/Conference proceedingConference contribution

6 Scopus citations


We present a high-sensitivity fiber-optic ultrasonic sensor based on a π-phase-shifted fiber Bragg grating (πFBG). A π- phase-shift at the center of a traditional fiber Bragg grating results in the formation of a narrow-bandwidth notch in the reflection spectrum, leading to much higher sensitivity than standard fiber-Bragg-grating (FBG) sensors. A method of fabrication is introduced, including a method of removing introduced polarization dependence. A tunable-cavity diode laser is used to interrogate the πFBG by locking the wavelength to the linear slope of the spectral notch. High-sensitivity detection of ultrasonic waves is demonstrated. The directivity of the grating is characterized. The effect of strain induced polarization dependence is investigated. Preliminary tests using ultrasonic pressure waves in water are performed.

Original languageEnglish (US)
Title of host publicationFiber Optic Sensors and Applications IX
StatePublished - 2012
Externally publishedYes
EventFiber Optic Sensors and Applications IX - Baltimore, MD, United States
Duration: Apr 26 2012Apr 27 2012

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


ConferenceFiber Optic Sensors and Applications IX
Country/TerritoryUnited States
CityBaltimore, MD


  • Fiber Bragg gratings
  • ultrasonic sensors
  • π-phase-shifted fiber Bragg grating

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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